• TABLE OF CONTENTS
HIDE
 Front Cover
 Abstracts of papers presented at...
 Biochemical bases of resistance...
 Biological control of bakanae disease...
 Biological control of radopholus...
 Biological control of tylenchulus...
 Effects of various cultural management...
 Optimum dose of deltamethrin for...
 Phytopathological notes: Occurence...
 Phytopathological notes: Occurence...
 Information for contributors
 Back Matter
 Back Cover














Group Title: Journal of Tropical Plant Pathology
Title: Journal of tropical plant pathology
ALL VOLUMES CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00090520/00028
 Material Information
Title: Journal of tropical plant pathology
Series Title: Journal of tropical plant pathology.
Alternate Title: Journal of Philippine phytopathology
Philippine phytopathology
Physical Description: v. : ill. (some col.) ; 26 cm.
Language: English
Creator: Philippine Phytopathological Society
Publisher: Philippine Phytopathological Society
Place of Publication: Philippines
College Laguna
Publication Date: January-June 1986
Frequency: semiannual
regular
 Subjects
Subject: Plant diseases -- Periodicals -- Philippines   ( lcsh )
Plants, Protection of -- Periodicals -- Philippines   ( lcsh )
Genre: periodical   ( marcgt )
 Notes
Dates or Sequential Designation: v. 1, no. 1 (January 1965)-
General Note: Title from cover.
General Note: "Official publication of the Tropical Plant Pathology."
 Record Information
Bibliographic ID: UF00090520
Volume ID: VID00028
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 54382605
issn - 0115-0804

Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Abstracts of papers presented at the twenty-third annual meeting of the Philipine phytopathological society, Iloilo City, May 8-10 1986
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
    Biochemical bases of resistance to java black rot caused by diplodia tubericola (Ell & Ev.) taubenh in sweet potato root (ipomoea batatas (L.) Lam.)
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
    Biological control of bakanae disease of rice with antagonistic bacteria
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
    Biological control of radopholus similis on banana with three nematophagous fungi
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
    Biological control of tylenchulus semipenetrans on citrus radopholus similis on banana with paecilomyces and penicillium anatolicum
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
    Effects of various cultural management practices and weather factors on the development of sorghum stalk rot in mindanao
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
    Optimum dose of deltamethrin for tungro prevention and vector control
        Page 58
        Page 59
        Page 60
        Page 61
        Page 62
        Page 63
        Page 64
    Phytopathological notes: Occurence of race 7 of xanthomonas campestris pv malvacearrum (Smith) dye in the Philippines
        Page 65
        Page 66
        Page 67
    Phytopathological notes: Occurence of sclerotium boll rot of cotton in the Philippines
        Page 68
        Page 69
    Information for contributors
        Page 70
    Back Matter
        Page 71
        Page 72
    Back Cover
        Page 73
        Page 74
Full Text





-aa[-w K- `


: llAJ u.Vr



'V UME 22 JANUARY






CON'

Abstracts of Papers Presented at the
Philippine Phytopathological
1986 .................

Biochemical Bases of Resistance to Ja
ricola (Ell & Ev.) Taubenh in St
Lam.) R.F. Dalisay, G.G. Div

Biological Control of Bakanae Disea
-Avelita M. Rosales, F.L. Nuqi

Biological Control of Radopholus si
phagous Fungi Lourdes C. C

Biological Control of Tylenchulus sa
similis on Banana with Paecilo
licum Irma C. Tandingan an

/Effects of Various Cultural Managen
the Development of Sorghum
Tangonan and Tricita H. Quimi

Optimum Dose of Deltamethrin for'
G. Bhaktavatsalam and A. An

Phytopathological Notes:
Occurrence of Race 7 of Xan;
(Smith) Dye in the Philippines -
Reyes.................

Occurrence of Sclerotium Bol
Teodora O. Dizon and Tiburcio


LA '%


...;llLy-ii n..- -llllu ...li1 il .j .l ....i
iciety, Iloilo City, May 8-10,
........................ 1-14

lack Rot Caused by Diplodia tube-
Potato Root (/pomoea batatas (L.)
*acia and E.M.T. Mendoza ...... 15-28

f Rice with Antagonistic Bacteria
id T.W. Mew ............ . 29-35

s on Banana with Three Nemato-
ralao and R.G. Davide ........ 36-41

'netrans on Citrus and Radopholus
es /ilacinus and Penicillium anato-
G. Davide .............. 42-48

Practices and Weather Factors on
Ik Rot in Mindanao Naomi G.
........................ 49-57

gro Prevention and Vector Control
yulu ................... 58-64


nonas campestris pv malvacearum
odora O. Dizon and T. T.
........................ 65-67

it of Cotton in the Philippines -
leyes ................... 68-68


< s










hilippine Phytopathol


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JOSE M. BANDONG
OSCAR S. OPINA
ROSALINDA P. GARC]
CASIANA M. VERA CI
OSCAR S. OPINA
TIBURCIO T. REYES
CEFERINO A. BANIQI
JOHN M. BONMAN
REBECCA C. de GUZ1V
ROMULO G. DAVIDE
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ARCADIO J. QUIMIO



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May 8-10, 1986






al Control of Bakanae Disease of Rice by furanoterpenes ipomeamarone, dehydroipc
istic Bacteria. A. M. Resales, T. W. Mew, marone, ipomeamaronol, substances B, C
L. Nuque, International Rice Research D were most toxic to D. tubericola. These
(IRRI) Los Bafios, Laguna. stances strongly inhibited spore germination
mycelial growth with the subsequent produ,
icial bacteria were tested to experimental- of abnormal spores and variants to the nc
-ol bakanae of rice caused by Fusarium hyphal morphology. Accumulation of these r
rme. Forty-seven fluorescent and nine- bolites were considered responsible for the de:
lonfluorescent bacteria collected from rice reaction of the sweet potato to D. tubericola.
elds were used. Sixty percent of the total
inhibited the mycelial growth of F. monili- Effect of Cultural Management Practices and
Bakanae incidence ranging from 0.9 to their Factors on Sorghum Stalk Rot in Minds
curred when IR 42 seeds were soaked in N. G. Tangonan and T. H. Quimio, Universil
...... .....- -.... r;... Southern Mindanao (USM-. Kabacan Cots


application 24% incidence was observed
rally-infested seedbed. Bacterization of
-infected IR 42 seeds reduced bakanae
e to 18-19%; a figure almost compa-
th benomyl treatment in a farmer's field
: IRRI farm, where bakanae has been
ally occurring since 1978.

iical Bases of Resistance to Java Black Rot
a tubericola (Ell. Ev.) Taubenh.] in Sweet
Ipomoea baatas (L.) Lam.] R. F. Dalisay,
ivinagracia and E. M. T. Mendoza, Univer-
he Philippines at Los Bafios (UPLB), Col-
;una 3720
at fractionation and thin layer chromato-
evealed 9 furanoterpenes, 3 coumarins and
ienols as stress metabolites in roots infec-
i Diplodia tubericola. These metabolites
ithesized more in infected resistant than
>le roots, qualitatively and quantitively.
, there were more furanoterpenes pro-
ian coumarins and phenols based on chro-
phic and time-course studies.
loterpenes (LD50 fi 169.92 ul of 1.37
i polyphenols (LD50 = 3.91 mg/g) caused
re inhibition after 22.30 and 55.84 hr,
ely. Coumarin synthesis were negligibly
llne.v an substantial snnre inhibition


u urrLD, coulege Laguna.

Two sorghum croppings, a main and
an crop, were used to determine the effei
ious cultural management practices and
ling weather conditions on the occurrence
velopment of sorghum stalk rot.
Except for lesion length, no other disease
ster was significantly influenced by tillage
e. Deep field plowing and weeding appar,
lited the lesion size or infection severity on
m plants regardless of NPK fertilizer I
plied, and population density. Conversely,:
um tillage without weeding resulted in I
ger lesion size. Grain yield of sorghum in
oppings was higher where maximum t
pplemented with hand weeding are empl(
NPK fertilizers applied at higher rates res
a significantly higher percentage stalk rc
:tion in both main and ratoon crops. How
significant effect on the rate of infection
ted.
Plant population density did not have
nificant effect on both percentage and ra
Alk rot infection. Lesion size, on the other 1
nificantly increased with higher population
y or closer planting.
Weather factors, such as high temperature
rih m-nfall ilrnmA A ,nmu infrftinn rt+p arh









at Potato Resistance Population Flue


lin layer chromatography (TLC) showed two indicators, bush sitao, peanut, okra, music
lct blue fluorescent spots in susceptible and pechay were susceptible to R. reniformn
ant sweet potato extracts with Rf values cor- was highly susceptible to M. incognita, as ii
finding to chlorogenic acid, scopoletin and by significant yield reductions, high root
in. More phenolics accumulated in root root necrosis ratings, and high population
cts of resistant sweet potato cultivars follow- harvest. None of the crops showed susce
ifection as indicated by the stronger intensity to the nematode genera.
lor of the fluorescent spots. Population fluctuations were influence
initial nematode density and the crops'
Screening of Systemic Fungicides for their stages. Competition for food by the ni
acy Against Vascular Streak Dieback (VSD) during the early stage of crop develop
se of Cacao. R. G. Atabug and M. O. San fluenced the change of the nematode pot
,Twin River Research Center (TRRC),Davao in the succeeding crop stages.
Phenamiphos applied at the rate of 101
groups of six Amelonade cacao seedlings repli- was effective against nematodes through
Four times were each sprayed with bitertanol entire crop growth stages. This was indic
cor 30 EC) at 2 ml/1 ;triadimeton (Bayleton 25 the relatively low nematode counts in trea
at 2 gm/1; Prochloraz 45 EC at 2 ml/1; tride- plots throughout the three cropping period
th (Calixin 75 EC) at 2 ml/1, and benomyl Multiple regression analyses indicated
ate 50 WP) at 3 gm/1 at one week interval, relationship between nematode density a
rs were applied from January, 1985 up to loss of bush sitao.


ided in each treatment served as untreat
k. All experimental plants were placed unt
canopy of five-year old cacao trees infect
Oncobasidum theobromae Talbot and Kea
our months after exposure to natural infi
,the seedlings showed typical symptoms
ilar streak dieback. The yellow leaves h
d green spots and three brown dots on I
mission layer of the petiole. The brown de
aded as brown streaks to the xylem vessels
infected branch.
differences between chemical treatments (
differ significantly but among the system
icides tested, triadimefon reduced infection
percent; tridemorph to 20.83 percent; a
imyl, 41.66 percent. The untreated cont
50.00 percent infected plants. Testing of otl
nidines. triazoles. morDholines and ben


Development of Tar Spot (Phyllachora so
Susceptible and Resistant Sorghum Line
Paderes and S. C. Dalmacio,UPLB, College,

The rate of tar spot development on on4
tible (Acc. 1127) and two resistant (Acc. 2
BTx 623) sorghum lines were compared I
percentage leaf area infected and stromati
The r-values based on percent leaf area
were 0.0877, 0.0512 and 0.0488 per day
1127, Acc. 2059 and BTx 623, respectively,
Based on stromatal count, tar spot di
at the rate of 3.08, 0.46 and 0.23 stroma
cm2 leaf area per day on Acc. 1127, A(
and BTx 623, respectively. The number ol
ta formed over the 4-week assessment per
63.8, 10.6 and 5.2 stromata per 3 cm2
in the respective sorehum lines.


olics Involvemen









mber of physiologic


rcorrhizal Fungi in a Rice-based Cropping Populations of Pyricularia oryzae from sei
L. L. Ilag, A. M. Resales, F. A. Elazegui regions of the Philippines were assayed for t
'.Mew, IRRI, Los Bafios, Laguna. virulence to commonly-grown rice cultivars in
Philippines and to newly released cultivars.
populationss of indigenous vesicular-arbus- ability of the international, Japanese, and Kol
rcorrhizal (VAM) fungi were determined differential cultivar sets to differentiate agrict
ent stages of crops in the rice-based crop- rally important isolates was tested also. Viruk
tem in Guimba, Nueva Ecija. The Most to IR' cultivars was high in isolate populat
Number Method, an indicative of the ino- from lowland areas, where IR cultivars are wii
potential, was used to assess the VAM po- cultivated. Virulence to IR cultivars among
lates from predominantly upland areas was ra
numbers of infectious endomycorrhizal observed, instead these populations had a high
ere consistently less in the low-lying quency of virulence to upland cultivars, UPLF
ingog) which has a rice-rice cropping pat- and Denorado. Generally, isolates originating f
pared to the field in the upper stratum IR cultivars were virulent to IR cultivars, and
with a rice-corn-grain legume pattern. lates obtained from nurseries and seed incr
ulum potential was generally low after the plots planted to several cultivars showed a bi
of the dry season crop. Fluctuations in spectrum of virulence. Virulence to newly relei
ber of effective VAM fungal propagules cultivars such as IR 58, IR 60, and IR 62 was
parently affected by the prevailing mois- sent in the pathogen population. IR 60 and IE
editions in the field and by the cropping exhibited a higher frequency of intermediate r
tion types compared to IR 58. Agriculturally
portant isolates that differed from one ano


ngco, R. C. Cabunagan, Z. M. Flores and
, IRRI, Los Bafios, Laguna.

tudy was conducted to monitor the dev-
of tungro infection in the field. Varieties
-rent levels of green leafhopper resistance
iosed to natural infection in the IRRI
ed weekly for the presence of tungro-
I viruses by latex agglutination.
ice tungro spherical virus (RTSV) infec-
recorded not only in leafhopper-suscep-
Sand IR 22 but also in the leafhopper-
ly resistant IR 42 in the initial weeks of
Thereafter, a gradual decline in percen-
:tion by TSV alone but with increase in
by both rice tungro bacilliform virus
md RTSV source was predominant in the
e RTBV/TRSV source plants were scarce
itial weeks. RTBV/RTSV infection dev-
uickly in susceptible TN1 but slowly
and IR 42. Leafhopper-resistant IR 54
8 had very low infection of any of the
while a relatively higher RTSV. infection
led.
with tungro symptoms increased with in-
olants infected with RTBV and RTSV


lanese, or Korean differential cultivar sets. 1
lely grown Philippine cultivars should be i
tools to describe P. oryzae populations in
lippines.

iort Life and Reproductivity Tables of Pucc
chidis Causing Rust of Peanut. E. Valencia
S. Opina, UPLB, College, Laguna.

When a cohort of uredospores (about 24 ui
cm.) was allowed to undergo infection cycle
ict leaves of three peanut varieties, survive
action units varied according to the state:
action process and variety. Low survival r
*e associated with delayed uredospore germ
i and appressorium formation which were n
aren'tt on UPL-Pn4. This resulted in about 2-
uction of infection efficiency (IE) compi
h the two susceptible varieties. Consequer
,er estimate of the relative growth rate was
led. The mean generation time (14 days)
vary among varieties.
Results indicate that the degree of resists
Iferred by UPL-Pn4 against P. arachidis cai
ributed to its ability to block germination 1


Rice ]









and control of f


wum raecuumyces macmus ana asazoios. Trichoderma aureoviride and T. glaucum
, Davide and R. A. Zorilla, NCPC, UPLB, control Agents Against Damping-off of
,e, Laguna. Plated after Rice. R. C. De la Peia, A. M.

sults of two field plot trials revealed that and T.W. Mew, IRRI, Los Bafos, Laguna.
omyces lilacinus (Thor.) Samson, applied cholera aureovde and T. glauu
as a soil drench, or inoculum in rice hulls eed agan olorne
ce bran (1:1 W/W) or in chopped water lily tested against soil-borne diseases of mu
ate incorporated into the soil, significantly cowpea soybean and corn grown after upla
Trichoderma inocula were applied as see4
>lled root-knot nematodes (Meloidogyne
taled root-knot ner plants. Three months rment or incorporated into the soil before
lita) attacking okra plants. Three months .


me fungus treatment mne nemartoe popui
a the soil was reduced by 66-77% resulting
ce to slight gall of plants in the untreate
. The nematicide Isasofos (Miral 10G at
,/ha) effected a 10% higher namatode redu
a the soil than the fungus treatment although
growth in both treatments appeared compi
ly normal.
e nematode control by P. lilacinus result
gnificant increase in okra yield. The nunbe
uit weights increased by 39-41% and 45-549
tively. Isazofos treatment increased the yiel
-tter than the fungus treatment. In terms c
weight, however, there was no significant d
a between the treatments indicating the
cinus may be comparatively effective or ec(
ally better than the nematicide.
fication and Control of Fungi on Storei
leeds Collected at NFA Warehouses of Cota
i. C. Silvestre, F. D. Amorada and Narieta R
), USM, Kabacan, Cotabato.


effectively controlled and yields increased
corporation of T. aureoviride. Soil incorps
Af T. glaucum significantly reduced damp
>f cowpea but not of mungbean and soybean
treatment with either species of Trichoderr
effective in controlling damping-off of al
)lanted. Trichoderma aureoviride popular
:reased 30 days after soil incorporation at
lually declined until harvest. Seed treatmer
)oth species and soil incorporation with 1
uum did not increase Trichoderma popular
he soil. The natural population of both spe
:reased in the rhizosphere of cowpea, mur
.oybean and corn.

influence of Fungicides in the Interactic
ween Soil-borne Pathogens. F. A. Elazeq
r. W. Mew, IRRI, Los Bafios, Laguna.

In evaluating fungicides for control of da
)ff caused by Rhizoctonia solani, Sclerotiu
ii. and Pythium debarvanum in a munabea


, development.









z damp- The incidence


onia, only Sclerotium infected the plants
in Sclerotium and Rhizoctonia-infested
icating that Sclerotium is more competitive
hizoctonia. PNCB plus thiadiazole and
a plus captain, which were effective on
onia alone became ineffective in the pre-
f both Pythium and Rhizoctonia. The com-
1 of Sclerotium and Pythium in the ortho-
atment resulted in significantly higher in-
; by both than by either pathogen alone.
ithogens had equal percentage recovery in
a plates. In the orthocide treatment, Py-
appeared to be more competitive than
tonia.

native Efficacies of Several Fungicides in
itrol of Black Pod Rot of Cacao. M. O. San
d R. G. Atabug, TRRC, Davao.

ral systemic and contact fungicides were
experimentally in the control of Phytoph-
'almivora Butl., the cause of black pod rot
o. Aliette and Ridomil MZ58 WP were the
c fungicides used while Brestan Cone.,
x Forte NC, Galben Cu, Sandofan 518F
thane M-45 were the contact fungicides.
es including the pods were sprayed at two-
iterval except Aliette which was sprayed
nonth.
ilts showed no significant differences
the fungicides and their respective dosages
11 fungicides performed well in reducing the
ce of the disease.

Blotch of Rice in the Philippines. A. K. M.
Lan and T. W. Mew, IRRI, Los Bafios,


.th blotch caused by Pyrenochaeta oryzae
on rice in the Philippines. The disease pro-
ypical oval shaped, brownish, blotchlike
ms near the middle of the outer leaf
of rice tillers. The lesion enlarges as the
latures, covering the whole sheath and kill-
leaf. Pycnidia of P. oryzae can be seen
led in the diseased tissues.
survey conducted in 1985 the disease was
prevalent in IRRI farm as in farmers' field
hem Tagalog, Bicol, Visayas and Mindanao.
... C9L' nft the field nr nint examined


fected with the disease.
The rate of sheath blotch development was
ed in the greenhouse using two isolates of P.
e and five IR-varieties. IR 58 showed the hig
.204) rate followed by IR 36, IR 26, IR 60,
, 62. No differences in virulence between
ro isolates and no interactions between the
tes and the vareities was observed.

sture and Expression of Resistance in Flue-c
)bacco Cultivars to the Root Knot Nemat
eloidogyne incognita. D. A. Luna and S
ilmacio, UPLB, College, Laguna.

Rates of larval penetration, histopathology
ochemical analysis of roots of flue-cured tob
iltivars (Balikbayan, PT-1, NCBY, Mamr
old, Coker 86, and NC 95) infected with
lot nematode, M. incognita were investigated
Second stage larvae of M. incognita re;
,netrated each of the tobacco cultivars, but f
itered the resistant cultivar, Mammoth (
ost of the larvae that penetrated Mammoth I
id and deteriorated as shown by zero nemal
cover at 32 and 39 days after inoculation.
The mechanism of resistance in resistant <
Lrs (Mammoth Gold, NC 95, and Coker 8(
uded both pre-and post-infectional resistan
dicated by reduced rate or delayed larval I
ation and non-development of second
rvae in the second generation of the nema
ter penetration in Mammoth Gold. The
vars (Balikbayan, PT-1, and NCBY) was cor
:d in 18 to 32 days after inoculation and
nued through the second generation. The i
Irs NC 95 and Coker 86 succumbed to n
ide infection due to high population den
syond the tolerance level.
Histopathology of galled roots in suscer
iltivars showed the formation of multinucle
lick-walled and granulated cytoplasm,
clear and nucleolar hypertrophy of giant
he resistant cultivars had smaller and fewer
Ills. Cell necrosis and thickening of endodi
ere observed in Mammoth Gold.
The chemicals in root extracts of both sus<
le and resistant cultivars were separated by
yer chromatography. Chromatographic plat
Isceptible and resistant flue-cured tobacco
tracts showed one blue fluorescent soot.


was as ]





Philippine Phytopathology


value of scopoletin. The intensity of the fluores-
cent spot color indicates more scopoletin in the
root extracts of resistant cultivars after infection
than in the susceptible ones. The toxicity of the
compound was confirmed by the high larval mor-
tality and zero egg hatching when exposed to the
test cultivars root extract. Concentrated root ex-
tracts from the other cultivars showed similar
effects.

Resistant Assessment of Selected Rice Varieties
to Bacterial Blight (Xanthomonas campestris pv.
oryzae, Races 1'and 2). R. C. Reyes and T. W.
Mew, IRRI, Los Baios, Laguna.

A spray method of inoculation for varietal eva-
luation to bacterial blight (BB) was used for 522
IRRI Germplasm Bank varieties. Thirty two va-
rieties were further selected for field assessment
resistance to BB. These entries were spray-inocu-
lated with races 1 and 2 before transplanting
then were socred 7 times at weekly intervals after
inoculation.
The bacterial blight incidence and intensity in
each plot was high during the first scoring com-
pared to other scoring times. The fourth scoring
gave the highest correlation between incidence and
intensity for race 1 but relatively lower correla-
tion for race. 2.
Only 4 varieties were resistant (11-20%) to
race 1 and only one variety (20-30%) to race 2.
The incidence and intensity of other varieties
ranged from 3140% to either races 1 and 2.
Varieties. showing consistent reactions (31-40%)
to races 1 and 2 were Maharaja Wee (Acc. No.
36479), Laksmijota (Ace. No. 31595), CO 21 Pop
rice (Ace. No. 3996), 0 13 (Acc. No. 4897), and
MTU 15 (Ace. No. 6365). Likewise, Kottiyaran
(Acc. No. 36300), also showed consistent reaction
of 41-50% to both races.


Reaction of Green Leafhopper-Resistant Varieties
to Rice Tungro Associated Viruses. G. B. Jonson,
Z. M. Flores, R. C. Cabunagan and H. Hibino,
IRRI, Los Baios, Laguna.

Varieties with different genes for resistance to
the green leafhopper (Nephotettix virescens) were
tested against rice tungro bacilliform virus (RTBV)
and rice tungro spherical virus (RTSV). Six-day
old individual seedlings of test varieties in test
tubes were exposed for one day to 5 green leaf-
hoppers previously fed on source plants with both
viruses. The presence of the tungro associated vi-


ruses was detected one month after inoculation by
latex agglutination test.
Varieties with the same resistant gene reacted,
differently to infections with the viruses. Both
Jingasail and Pankhari 203 have the same gene,
GLH1. Jingasail plants were infected with RTBV
and RTSV, while Pankhari 203, with RTBV alone.
Similarly, TAPL 796 and IR 36 have the same
gene GLH6. IR 36 was generally infected with
both RTBV and RTSV, while TAPL 796 with
RTBV alone. Pankhari 203, Palasithari 601 with
GLH2, and ASD with GLHs showed low levels of
infection. The results proved further that resis-
tance to tungro is not always correlated with re-
sistance to the vector.

Reaction of Selected Resistant Varieties to Tungro-
Associated Viruses. R. D. Daquioag, G. B. Johnson,
E. L. Mesina, P. Q. Cabauatan and H. Hibino,
IRRI, Los Bafios, Laguna.

In the 1964-1982 mass screening for resistance
to tungro at IRRI, 350 accessions showed consis-
tent resistance (0-30% infection) to the disease.
These accessions were retested 6 times and those
that showed an average infection of 35% or less
were selected.
Six-day-old seedlings of the selected varieties
were individually exposed for one day to five
Nephotettix virescens previously fed for 2-3 days
on TN 1 plants infected with rice tungro baccili-
form (RTBV) and rice tungro spherical (RTSV)
viruses, or with RTSV alone. One month later, leaf
samples were collected and tested for the pre-
sence of the tungro-associated viruses in ELISA.
When dually infected plants were used as virus
sources, many varieties were infected mostly with
RTBV alone. Basmati 376 showed lowest RTBV
infection, Balimau putih was mostly infected with
RTBV/RTSV but did not show typical tungro
symptoms. When RTSV-infected plants were used
as virus sources, percentage infection ranged from
0-83%. Varieties with less than 30% RTSV infec-
tion were: Adday Sci., PI 184675-2, ARC 7140,
ARC 12596, ARC 12778, Gachia, Basmati 375-A
and Basmati 376.
Evaluation of Rice Cultivars for Blast Resistance in
Indonesia and the Philippines. B. A. Estrada, Ir-
mansyah Rusi, and J. M. Bonman, IRRI, Los
Bafios, Laguna.

Several experiments (1984-1986) were conduc-
ted in Sumatra, Indonesia and the Philippines


Vol. 22





Abstracts of Papers


(IRRI) to measure the relative level of partial
(quantitative) resistance to blast in some rice culti-
vars and lines. The area under disease progress
curve for each cultivar was estimated by making
disease assessment twice a week for a period of
four weeks. A few upland varieties, such as IRAT
13, Tetep, Moroberekan, and OS 6 showed
consistent resistance in the tests. Other cultivars,
however, showed apparent partial resistance in
Indonesia, but greater susceptibility at IRRI. IR
54, IR 58, and IR 60, which were moderately sus-
ceptible at IRRI, were relatively resistant in Indo-
nesia even though compatible races were appa-
rently present. These reaction differences may in-
dicate race specificity for some types of partial
resistance. Some cultivars gave consistent rank
order of resistance in the two test sites. IR 36,
Milyang 42 and Milyang 30 showed higher resis-
tance than IR 36, Milyang 42 and Milyang 30
showed higher resistance than IR 50, Milyang 57
and Suweon 264 even at varying degrees of disease
pressures. Repeated multilocation trials and re-
cords from farmers' field are the best methods pre-
sently available for identifying blast resistance.

Screening Sweet Potato Roots for Resistance to
Java Black Rot Caused by Diplodia tubericola
(Ell. & Ev.) Taubenh. R. F. Dalisay, G. G. Divina-
gracia and E.M. T. Mendoza, IPB, UPLB, College,
Laguna.

Out of 34 sweet potato crosses screened for re-
sistance to Java black rot (Diplodia tubericola)
only G8ir-8a was resistant whereas, 3, 2 and 28
were moderately resistant, susceptible and very
susceptible, respectively. Susceptible and very
susceptible roots exhibited extensive rotting of
the infected tissues 7 days after inoculation. Mo-
derately resistant roots produced limited lesions
without distinct wound periderm typically ob-
served in resistant G8 ir-8a. In vitro assays of the
different crude extracts from infected resistant
G8ir-8a and susceptible G52-5 roots revealed
the presence of inhibitory factors not found in
newly harvested and stored roots. Moreover, ex-
tracts from infected resistant G8ir-8a roots inhi-
bited spore germination and mycelial growth of
D. tubericola.

Detection and Identification of Xanthomonas
campestris pv oryzae by Direct Immuno-fluo-
rescent Procedure. A. J. Quimio, N. Unnamalai
and T. W. Mew, IRRI, Los Bailos, Laguna.

A direct fluorescent antibody stain (DFAS) was


effective in the detection and identification of
Xanthomonas campestris pv. oryzae (Xco), the pa-
thogen of bacterial leaf blight of rice, from diffe-
rent rice growing areas of the Philippines. The anti-
serum for the DFAS was prepared from New Zea-
land White Rabbits injected with bacterial cells
(PXO-86, Phillippines Race 2) fixed in 2.5% gluta-
raldehyde. The antibody (IgG), isolated by am-
monium sulfate precipitation was labelled with
fluorescein isothiocyante (FITC). The labelled
antibody (FIT-1G) was separated from uncon-
jugated FITC by Sephadex gel filtration and puri-
fied by DEAE-cellulose column chromatography.
Slides were examined using a Zeiss standard photo-
microscope with a high pressure mercury ultra-
violet (UV) lamp (HBO 50). G. 365 exciter filter
and barrier LP 420 were used under epi-illumi-
nation (epicondenser IV FI) at a magnification of
X-400X and 1000X. All 117 Xco pure culture
isolates composed of Races 1, 2, 3, 4, 5, and 6
from 29 provinces representing 12 regions of the
Philippines reacted positively with the DFAS. Xco
from both naturally infected and artificially ino-
culated (with Races 1,2, 3, 4, 5, 6) rice leaves was
also positively detected by DFAS. Yellow colony-
forming bacteria and other bacterial contaminants
that dominated nutrient agar platings of washings
of rice seeds from various sources did not react
with DFAS. It is concluded that DFAS using anti-
serum to glutaraldehyde-fixed cells has the poten-
tial for use in the rapid detection and identifica-
tion of Xco.

Recovery of Rice Tungro Bacilliform Virus
(RTBV) from IR 52 Infected Plants. Z. M. Flores,
R. C. Cabunagan and H. Hibino, IRRI, Los Bafios,
Laguna.

IR 52 which is resistant to the tungro vector is
mostly infected with RTBV alone when exposed
to the leafhoppers previously fed on plants infec-
ted with both RTBV and rice tungro spherical
virus (RTSV). Transmission of RTBV is dependent
on RTSV. Effects of RTSV on the recovery of
RTBV from infected IR 52 plants were examined.
RTBV-infected IR 52 plants at 45 days old were
used as a source. The leafhoppers previously fed
on RTSV-infected plants for 1 day were allowed a
2-day acquisition access to the source. Then the
leafhoppers were given a 24-hour inoculation ac-
cess on 6-day old TN1 or IR 52 seedlings at one
leafhopper per seedling in test tubes. All inocula-
ted plants were tested for the presence of rice
tungro associated viruses by latex agglutination
test.


Jan. & June 1986









Which Detection of


covery was higher from susceptible TNI
m IR 52 indicating that tungro disease can
in the field with leafhopper-resistant
if RTSV is present.

fied Dot Immunobinding Assay for the
n of Rice Grassy Stunt Virus in Infected
P. Q. Cabauatan, H. Hibino and H. T. Hsu,
)s Bafios, Laguna.

: immunobinding assay (DIBA) was modi-
detect rice grassy stunt virus (RGSV) in
of infected plants. Horseradish peroxi-
') gave strong non-specific reactions (NSR)
sed for labeling RGSV antibody (IgG).
P was substituted with alkaline phospha-
the substrate was changed from 4-chloro-
al to a mixture of nitro blue tetrazolium
omo-4-chloro-3-indolyl phosphate p-tolui-
:, NSR was markedly reduced. DIBA de-
.GSV antigen in 2.5 ul sap or 1/1,000 sap
(w/v) NSR was further reduced when
lonal IgG was used instead of conventional


n of Xanthomonas campestris pv. oryzae
Seeds by Phage Method. N. Unnamalai and
Iw,IRRI, Los Bafios, Laguna.

us were isolated from seeds naturally-infec-
artificially-inoculated with X. campestris
ae (Xco). Seed suspension was centrifuged
10 rpm for 10 min. The supernatant and
ere assayed for free phage and adsorbed
,spectively. Phage plaque counts increased
upernatant and pellet after 10 hr incuba-
icating the presence of Xco in the seeds.
detected in the seeds after harvest were
nately 102 cells/ml but survival of bacteria
than a month. Free phage survived longer
Bacteria. In naturally infected seeds, free
vere detected in green immature seeds up
months while in matured seeds, only up to
after collection. Phage counts from homo-
seeds and husks were higher than those
- surface of the seeds and the grains (endo-
nd embryo). Embryo was not infected.
iges isolated from seeds were specific to
,estris pv. oryzae. These results indicate
ifnn nf hor/'on ni nk a annA amnhnlnc irhir


The effect of storage on antigenicity of tur
iociated viruses, rice tungro bacilliform (RT
d rice tungro spherical (RTSV) viruses
ited.
One hundred TNI leaves infected with I
[BV and RTSV were cut into 3-equal pi
King a total of 3 sets. Each set was dried
)red under room temperature, in refrigern
in freezer. Ten leaf samples from each set i
rologically tested to detect the viruses
'ferent intervals up to 8 months of storage. I
- latex agglutination and ELISA tests were 1
r testing.
ELISA was more efficient in detecting 1
FBV and RTSV antigen in infected dry le
>red at any condition. When leaf samples
>red under room temperature, the latex
uld detect the virus for only one week. On
nples stored in the refrigerator or freezer,
it detected the viruses even after 8 month
>rage. ELISA could detect the viruses from
-s stored for 8 months under any condil
Lese results indicate that ELISA is applic
tungro diagnosis on dried leaf samples m;
handcarried from remote areas.


bsequent Infection of Rice Tungro Bacillil
rus (RTBV)-Infected IR 54 by Rice Tu
herical Virus (RTSV) Alone. R. C. Cabuna
R. Tiongco, Z. M. Flores and H. Hibino, I]
>s Bafios, Laguna.

A study was conducted to determine whe
allenge inoculation of RTBV-infected p]
th RTBV and RTSV together or RTSV a
>uld increase the number of infected plants
th RTBV and RTSV.
Plants initially infected with RTBV sho
nificantly higher infection with both vir
ien challenge inoculated by green leaf ho
LH) which previously fed on source plants
rSV alone than by GLH which fed on so
mts containing both RTBV and RTSV. P1
thout initial RTBV infection did not show
iptoms when infected with RTSV. It indit
e potential threat of RTSV as a disease agei
a fiTrA ranlfnrmno RTRV-infp.t'P.d nlant


es from














hitter test snowea tnat tne major species <
found in blackpoint disease of wheat we
ninantly Drechslera sorikiniana, D. Sacci
I Curvularia lunata. Blackpoint had no dra
ect on germination.
dling symptom and blotter tests showed
he high percentage of shrivelled seeds w;
used by Septoria nodorum, the causal o
I of glume blotch disease. The 26 species <
isolated from shrunken seed may have a
ive effect" on the reduction of germination
ken seeds varied in length which ranged fro;
S5.9 mm; width from 2.0 to 2.7 mm an
ess from 2.7-3.5 mm.


ice of Length of Storage and Moisture Coi
n Corn Seeds Mycoflora. J. C. Silvestre, I


Pathogenicity of Phytophthora palmivora
Butler Causing Black Rot of Orchids. G. (
nagracia and L. B. Ros, UPLB, College, Lag

The pathogenicity of Phytophthora pa
(Butl.) Butler, isolated from Vanda lamelk
tested on this orchid plant. Bits of the funi
or zoospore suspension were inoculated
excised and unexcised leaves using four
tion treatments: 1) wounded/wet, 2) w<
dry, 3) unwounded/wet and 4) unwounc
Unwounded crown was also inoculated
zoospore suspension only. Excised and ur
leaves and unwounded crowns of several
genera were also inoculated with myceli
under moist or wet condition.
-^---I-J-* Tr 7- .7.-. ...:..A^ n*<


5l cu oI DmUac&


ourunien LonUl- oays alter mocul









y on mvaaea parencnymatous cells. Comparison ot ratnogenicity ana rnage sensi
bundles also appeared invaded. Fungal within Xanthomonascampestrispv. oryzae ise
iere observed as far as 30 mm away from V. Vermeulon and T. W. Mew, IRRI, Los B
--soaked areas of lesions. Laguna.


ad Internal Spread of Diplodia tubericola One hundred X. campestris pv. oryzae iso
Ev.) Taubenh. on Sweet Potato Root. belonging to six pathogenicity races, were t
rdsud and G. G. Divinagracia, UPLB, Col- against 110 phages collected from several loca
na. in the Philippines. The results obtained by the
plate method, using the multipoint inocu
showed a high correlation between phage sen
ingus was artificially inoculated success- ty and pathogenicity. It was, however, impo
weet potato roots through a hole (5 mm to find a set of differentiating phages which]
:er and 8 mm deep) made by cork borer, clearly distinguish all six pathogenicity races.
agar discs induced disease development a more diverse phage-collection from more
an spore suspension. The mycelia could rent locations in the Philippines, a better difi
rate through the well-formed periderm of tiation could probably be obtained. It is also
tato storage roots 12 days after harvest. sible that phage-typing gives more detailed i
vly harvested storage roots with loosely mation about the bacterial strains than the p
oeriderm, the mycelia invaded intercellu- genicity test. In this case, the bacterial strains
were restricted in the cork layer. A peri- an exceptional phage reaction can be consider
s formed in response to the penetration, a subgroup, which cannot be distinguished b
derm separated the healthy tissues from presently used set of differential rice vari
treated cells and some cortical cells which Further study has to be conducted to col
ahead of mycelial penetration. Penetra- these results.
i inter- and intracellularly through wound


i pycmouospores were release aier o
I resistant varieties, the infected area were
yy a wound periderm which was formed
ise to injury and infection.


:nt of Sheath Blight Resistance at Tissue
y Measuring Electrolyte Leakage. S. W.
W. Mew and B. L. Candole, IRRI, Los
aguna.


ige increases with increasing sheath blight-
areas. Leakage increase from infected leaf
generally higher than that from sheath
wide varietal variation in the degree of
was observed in both infected leaf blades
th.
g positive correlation between percentage
of electrolytic leakage and disease severity
leld was noted. The results indicated that
th tissue resistance plays a maior role in


Phage method was applied to estimate
,pulation of X. camptestris pv. oryzae (Xi
acium chloride vitamin-free liquid me
he multiplication of a bacteriophage speci
co was also studied. One-step growth
lowed that P80, a phage virulent to bac
rain PX080 had a latent period of 40 min
first size of 12. Based on this information
iage method was carried out with the additi
rrous sulfate solution in the absence of antiL
Sinactivate the unadsorbed phage in the p
icteria mixture. No plaque count was obt
:fore and after incubation in ferrous s
heated sample while plaque count in sample
it ferrous sulfate increased significantly
,cubation. These results indicate that ft
Llfate not only inactivated the unadsorbed
it also interfered with phage-bacteria
;tion. The estimated number of bacterial
ised on phage method was comparable t
;tual number of bacterial cells by plate. By
ethod, bacterial population can thus be









anutDoay on serodiag- don 101 per stick, c) 2 stick


onoclonal antibody (McAb) to rice gras
virus (RGSV) was obtained by injecting in
a hybridoma cell line from fused spleen ce
imunized BALB/C mice and myelomal cee
b was used to detect RGSV antigen in inf4
plant sap using latex agglutination test (LA'
me linked immunosorbent assay (ELISA) a
mmunobinding assay (DIBA). RGSV antig
detected in sap of infected plants dilut
) 1/1024, 1/10,000 and 1/1,000 in LA
A and DIBA, respectively. Optimum antibo
ion was 1,/1000, 1/1000 and 1/500 for LA
A and DIBA, respectively.

detached Leaf Technique for Measuring Rea
: to Leaf Scald of Rice. A. O. Mackill anc
anman, IRRI, Los Bafios, Laguna.

detached leaf technique was developed a
pared with standard intact plant method
sing leaf scald resistance. The third fully
ed leaf from 55-day-old plants was excis
then cut into 7 cm segments and placed
imidazole (80 ppm) agar in Petri dish.
elial disk, 4 mm in diameter, was taken fr<
lay-old culture of Gerlachia oryzae and ii
ed at the center of the leaf piece. Lesi
h was recorded after 72 hours incubati
approximately 25eC. Thirty rice cultiv
ng in leaf scald resistance were tested us
methods. Lesion length values obtain
Both methods were correlated (r = 0.5
ating that the detached leaf technique I
ntial as a method of assessing resistance
scald.

parative Efficacy of Dicamba and Tordon 1
egnated Bamboo Sticks in Eradicati
hy-Top Infected Cavendish Banana. R.
ug, M. O. San Juan and M. C. Obello, TRR
o.

portion of a young bamboo pole was cut in
x 110 mm sticks with one end sharpened ai
-ied for two days before they were immers
Herbicide solution for 8 hours and air dri
6 hours. The pseudostems of banana plain
ted with bunchy-top disease were insert
a) 4 sticks impregnated with 1 ml Dicam


the dosage or the mother plant.
All the pseudostems inserted with imp
sticks produced a crack at the base and
down in 4-10 days. Suckers within the mat
turned black and ultimately decayed. A
month however, production of live sucl
observed on 100%, 60% and 20% of the i
treatments b, c and d; respectively. Only
serted with 4 sticks impregnated by 1 ml I
per stick were absolutely killed as no regro
noted even after 5 months. No herbicide
symptoms were manifested by tissue-cull
pagated Dwarf Cavendish seedlings plante
treated mother plants.



Optimum Conditions for Mechnical Tran
of Cadang-cadang Disease to Coconut Seed
Bautista-Olfato and J. S. Imperial, PCA
Albay.

Factors related to the inoculum, te:
mode, and site of inoculation influenced
ciency of the transmission of the cadan
disease agent to coconut seedlings.
Inocula with the fast eletrophoretic for
coconut cadang-cadang viroid gave high:
incidence than that of inocula with the sl
trophoretic form within three years after
tion. Partially purified nucleic acids from
coconut leaflets suspended in a sodium
sodium citrate buffer gave efficient transmi
0.8 to 8.0 micrograms of viroid per plan
was no reduction in infectivity of this ir
stored at 150C as precipitates in ethanc
long as three years.
One to 7-day-old sprouts emerging from
seednuts yielded 60 to 90% transmission
years after inoculation while one to 3 mn
seedlings had 10 to 30% transmission
years after inoculation. Younger emerging
from dehusked seednuts had high mortality
The hand-primed high pressure injector \
efficient and easiest to manipulate compi
the other methods tried. Higher transmissi
obtained when injections were made at
and central portions of the sprouts than
portion or at the primary root tips. Altl


Icanon o0 mono













the strains. EPS of weakly virulent strains contained
lesser pyruvic acid than the virulent ones. No sig-
Production by Peanut Leaves Infected by nificant differences on wilting of rice seedlings
ridium personatum (Berk. and Curt.) were observed on different concentrations of
. B. R. Khadge and L.L. Ilag, UPLB, Col- EPS. The EPS of all the strains induced plugging of
ana. vascular tissues, reduced water uptake, increased
water potential, reduced transpiration rate and in-
creased diffusive resistance of rice seedlings. There
etched leaf technique of Ketr (1969) was no relationship between virulence and the
to determine the ethylene produced by ability of EPS produced by virulent and weakly
inut genotypes, CES101, UPLPn4 and PI virulent strains to cause any of these changes in
infected by three isolates of Cercospori- rce seedings.
'sonatum. Four inoculum levels: 5,000,
20,000; and 40,000 spores per ml were
rninoculated healthy leaves did not pro-
Ininoculated healthy leaves did not pro- Isolation and Biological Efficacy Evaluation of
re than ep ml ethylene/g dry wt/hr Plant Growth Promoting Rhizobacteria. A. J.
ut risthe exp7 days after inoculation (DAI) and Quimio and Aurorita G. Coroza, UPLB, College,
rise 7 days after inoculation (DAI) and Lgn
maximum at 21 DAI then declined. The Laguna.
:eptible genotypes CES 101 produced the Sixty seven rhizobacteria isolates from root
mount of ethylene when infected by iso-
mount a of ethylene when infected 3by o surfaces of corn, upland rice, tomato, cabbage,
with mean value of 7.7, 37.5 and 30.9
with me/g dry wt/hr at 14, 21 and 24 DAnd res- soybean, cotton, sweet potato, white potato,
ne/g dry wt/hr at 4,21 and 24 DAI, res- Cyperus rotundus, Imperata cylindrica, Paspalum
The highly resistant genotype P l 259-conugatum, Eleusine indica and aharum pn-
e h y r n g 2 conjugatum, Eleusmine indica and Saccharum spon-
uced the least ethylene with mean value c a m _









IrrcncC 01 lRCCe


in Korea than did the most susceptible
rance of Balimau Putih to Rice Tungro-Asso- Korea than dd e most
d Viruses. R.D. Daquioag, P. Q. Cabauatan cultivars.
H. Hibino, IRRI, Los Bafios, Laguna.

rice cultivar, Balimau Putih (IRRI Acc. No. Field Evaluation of Two Vesicular A
)4) which showed strong resistance to tungro Mycorrhizae on Rice in an Acid Upland (


to the rice tungro-associated viruses.
alimau Putih seedlings exposed to the vec
Loppers that fed on plant infected with b<
tungro bacilliform (RTBV) and spherical vi
vere tested by ELISA for the presence of 1
;es. More than 90% of the plants were infecl
either RTBV or both RTBV and RTSV. I
:ted plants did not show typical tungro syn
i. The relative amount of RTBV in Balim
1 was about one fifth of that in infected T
ts. When infected with RTBV alone and b<
V and RTSV, plant height was reduced to
40% in TNl, and 4 and 10% in Balimau Pul
actively. The results show Balimau Putih
eptible to tungro infection but limits


The effect of two endophytes, Glomus
and G. fasciulatus on rice were evaluated
acid upland condition in Cavinti, Laguna
mosseae performed better in terms of he
matter and grain yield as compared to G..
tus. When the soil was amended with ph<
however, inoculation with G. fasciculatus]
better results. Statistical analysis showe
cant differences in height and dry mat
between inoculated and uninoculated ric
The grain yield, however, did not differ sil
ly because of bird damage.
The following indigenous endophytes


D~~ao ul vtr~r~uu 1 Inup. ~u uv~urlluu uv vlluv~ vl


~') '0"--'














h blight (ShB), sheath spot (ShS) and ShB than ShS and AShS in all the 10 varieties. The
: sheath spot (AShS) caused by three reaction of the varieties to the three diseases were
mia species: R. solani, R. oryzae, and not uniform. The result indicates that R. solani is
ae-sativae, respectively, is a complex more destructive than the other two species.
occurring in the Philippines. The sym-
aduced by these three species are very
but can be distinguished if carefully Screening for Resistance to Aspergillus flavus In-
d. vasion in Peanut. A. R. Pua and E. C. Medalla,
threee diseases are prevalent in the IRRI IPB, UPLB, College. Laguna.
well as in the farmer's fields in Southern
Bohol, Visayas and Mindanao regions. Ninety-one (91) peanut accessions/lines/va-
tive incidence during the wet season of rieties were screened for resistance to A. flavus
,re as follows: 77.0, 15.5, and 34.0% of invasion using "dry seed resistance" test. Five
Is examined showed plants with disease (5) peanut genotypes were identified to be re-
is, and on the average of 8.2 0.4 and 1.2% sistant to A. flavus colonization. These were:
were found infected with ShB, ShS, and PI 234375, UPL Pn, 4, ICG No. 4786 Celebes,
respectively. Almost all the IR varieties CES 48-30 And Ace 63. Nineteen (19) lines were
these areas were found infected although moderately resistant while the rest (about 73.6%)
Varied among varieties and locations, were susceptible.





Philippine Phytopathological Society, Inc.
1986 PhiL Phytopath. 22: 15-28

Biochemical Bases of Resistance to Java Black Rot Caused by
Diplodia tubericola (Ell. & Ev.) Taubenh. in Sweet
Potato Root (Ipomoea batatas (L.) Lam.)


R. F. Dalisay, G. G. Divinagracia and E. M. T. Mendoza

Respectively, Senior Research Assistant, Institute of plant Breeding (IPB); Professor Depart-
ment of Plant Pathology and Research Biochemist, IPB and College of Agriculture, University of
the Philippines at Los Bafios, UPLB College, Laguna, Philippines, 3720.

Portion of M.S. Thesis of the senior author submitted to UPLB



ABSTRACT


Solvent fractionation and thin layer chromatogra-
phy revealed 9 furanoterpenes, 3 coumarins and 5
polyphenols as stress metabolites in roots infected
with Diplodia tubericola. These metabolites were
synthesized more in infected resistant than suscepti-
ble roots, qualitatively and quantitatively. However,
furanoterpenes were produced more than coumarins
and phenols based on chromatographic and time-
course studies.
Furanoterpenes (LD50 = 169.92 uL or 1.37A/g)
and polyphenols (LD50 = 3.91 mg/g) caused 50%
spore inhibition after 22.30 and 55.84 hr, respectively.


Coumarin synthesis was negligibly low to cause any
substantial spore inhibition.
In vitro assays showed that with the exception of
coumarin A and polyphenol A, most furanotepenes
- ipomeamarone, dehydroipomeamarone, ipomearo-
nol, substances B, C. and D to be most toxic to D.
tubericola. These substances strongly inhibit spore
germination and mycelial growth with the subsequent
production of abnormal spores and variants of the
normal hyphal morphology. Thus, accumulation of
these metabolites are responsible for the defense
reaction of the sweet potato root to D. tubericola.


INTRODUCTION


Sweet potato (Ipomoea batatas (L.) Lam.) is
grown primarily for its edible roots. Moreover,
young stems, petioles and laminae of sweet potato
are also popular as leafy vegetable in the country
(28). Livestock feed made from shoots is also de-
manding interest (4) and the roots are also known
to be processed for starch and other industrial
products (23).
Some of the peculiar post production problems,
such as storage losses due to pathological damage
have yet to be tackled. In the Philippines and
other tropical countries, one of these is the Java
black rot caused by Diplodia tubericola (El 1. &
Ev.) Taubenh. Reyes (20) found that storage losses
of edible roots due to black rot reach 50%. In
1975, Divinagracia (7) surveyed diseases of root
crops in the country and observed that D. tuberi-
cola was most prevalent among the diseased sweet
potato roots. This disease was formerly thought to
occur only in storage (8) but Daines (5) found that
it was also a serious problem in plant beds where
the macroscopic symptoms on the sprouts appeared


to be identical with the black rot disease.
Chemical control measures have not been suc-
cessful in preventing Java black rot. In 1972,
Martin (15) found that thiabendazole and 2,6-
dichloro-4-nitroaniline (DCNA) did not control
this disease. Daines (5) also reported that carba-
mate had a very little effect on it. On the other
hand, the use of resistant sweet potato varieties of-
fers better possibilities for control. Sardsud (21)
and Palomar et al. (19) have screened sweet potato
varieties for resistance to Java black rot. Both
have found that some varieties showed resistance
to the disease.
Studies on the biochemical bases of resistance
of sweet potato roots to black rot caused by Cera-
tocystis fimbriata (Ell. & Haust.) are many and
well documented (11, 12, 14, 22). However, few
have been conducted specifically on Java black rot
caused by D. tubericola. Accordingly, this paper
presents a comprehensive study of (a) com-
pound(s) accumulating in both resistant and sus-
ceptible roots which could account for resistance;









ints, their time-course Time-i


MATERIALS AND METHODS

Source of Test Materials

blemished roots of G81r-8a and G52-5 wer
sted 4 months after planting. These two cro:
:re previously rated resistant and susceptib]
va black rot, respectively (6). They wer
4d, air-dried and stored in clean net bags a
temperature prior to inoculation.

Source and Maintenance of Inoculum

Le Batanes isolate of Diplodia tubericola El:
.) Taubenh. was used as inoculum. This wa
lost virulent among twelve isolates tested o
differential varieties (6). Pure cultures mair
I in PDA slants were stored at 27-30 C und(
iuous artificial illumination.

Preparation of Tissue Extracts

K days after harvest, clean unblemished roo
ith resistant G81r-8a and susceptible G52.
surface-sterilized with 0.1% sodium hypochlh
washed and air-dried. They were cut into 2.
ices and were inoculated on one surface b
kg the sliced tissues on a 4-day old culture c
lusal fungus. The inoculated pieces were the
ated for 3 days at 27-30 C in moist chamber
were cubed, lyophilized and powdered. Tb
ant materials were extracted and fractions
nploying the procedure of Uritani (25).

isolation and Identification of Metabolites

e fractions obtained were resolved by thl
chromatography (TLC). Kielselgel G 6
i, 20 x 20 cm with or without fluorescent
itors were used.
ranoterpenes were detected by spraying tl
i with Ehrlich's reagent. The plates wei
usly developed in chromatography chan
iturated with n-hexane: ethyl acetate (8:2
umarins were determined by exposing de'
d plates (n-butanol: acetic acid: water, 4:1 :'
Slamp.
enols were detected with Hofner's reagei
developed plates saturated with n-butano


susceptible G52-5 and resistant G81r-8a rc
hr) were obtained, lyophilized and extract
TLC analyses.
Furanoterpenes were assayed chromato
cally and quantitatively by the method of
et al. (9). The total phenolic contents were
mined by the method of Zucker and Ahrer
Coumarins were assayed through spectre
metry and concentrations of both coumari
phenols were determined on standard curve
kilown amounts of their authentic sample
concentration of furanoterpenes was dete:
on standard curves from eluates of the re
G8 lr-8a 72 hr after inoculation with D. tubi

Inhibitory Dosage Levels

Furanoterpenes. Aliquots of 0, 50, 10(
300, 400, 450 and 500 IQ from isolated to
were made up to a final volume of 500 t
ethanol.
Coumarins. A 1 mg/ml stock solut
standard coumarins was prepared. In th
medium of 0.50 ml ethanol, dosages of 0.0(
0.10, 0.22, 0.29, 0.36, 0.43 and 0.50 mg/i
obtained.
Phenols. Chlorogenic acid at 0.00, 0.71
2.14, 2.59, 3.57, 4.28 and 5.00 ug/ml w
pared from 10 ml stock solution.
All the test media were seeded with 5
spore suspension (50,000 spores/ml), rep
and incubated for 24 hr in a waterbath
(100 strokes/min) at 27-30 C. Data were pre
as percent spore inhibition with about 200
counted per replicate per test medium. Thi
dosage at 50% (LD50) was recorded.

Bioassays of Partially Purified Compou

All identified metabolites extracted fr
sistant G81r-8a were isolated from their
tive TLC plates. The hyphal and mycelial
assays employed by Menancio (16) were m
in this study.
Hyphal growth assay. Fifty ul of eacl
solved eluate were pipetted into depression
After 2-hour drying, 50 -ul spore suspensi
50,000 spores/ml) of the causal fungi
added and slides were incubated in sterile
plates for 12 hr at 30 C. Data on percent


lere identity an(










-rP f.l ?f =


center of plated PDA. The hole was pre-
treated with 50 ul of each redissolved
Mycelial growth was measured in terms of
extension.


RESULTS AND DISCUSSION

art L Production of Stress Metabolites

mn and Identification of Stress Metabolites

:tionation and chemical analyses established
ots respond to infection by producing fura-
enes, coumarins and phenols. In general, a
number of metabolites of higher amounts
*oduced by resistant than by susceptible
is.
moterpenes. With authentic samples of
terpenes as marker, 10 Ehrlich's reagent-
: compounds were observed. These are ipo-
rone (Ip), dehydroipomeamarone (DIp),
muaronol (IpOH), 4-hydroxy-ipomeamarone
and unknown terpenes A, B, C, D, E and F
f values of 0.56, 0.53, 0.28, 0.44, 0.19,


nd 0.00, light brown and brown, respect:
vhich were produced in larger amounts i
infected resistant line than in other sample
infected susceptible line did not produce
phenol PoB.
The production of these metabolites in
'otato roots to D. tubericola is similar to
observed in sweet potato roots infected
imbriata (26), Fusarium oxysporum f. sp. b
3) and Itheobromae (2).


Time-course Analyses

Chromatographic evidences for furanote
synthesis showed differences in synthetic pa
or both resistant G81r-8a and susceptible (
ifected with D tubericola. Sequentially, Ip
pOH, A, B, C and F were detected earlier ('
hen followed by D (36 hr) and E (48 hr)
ifected resistant roots (Figure 4). In ini
isceptible roots, A was synthesized earlier
r), then IpOH (36 hr), B, Ip (48 hr), DI
r) and D (72 hr). Compound C was not s)
zed earlier (24 hr), then IpOH (36 hr), B, ]
-\. TNT- fC 1-, -.-A Y% \ 1171U- nl%


iols. Five Hofner's positive compounds
detected in developed plates with eluates Inhibitory Donaee Levels


_










ubericola. furanoter- antibiotic to the natl


v./ r --uv umv- vL uLs' vur l. .lal ucl
.t in infected susceptible G5.2-5 at the same
22.30 hr) was not high enough to caus
parent spore inhibition. The early synthesis
inoterpenes may prevent spores of D. tuberi
o grow further and subsequently colonize
.ssue thus accounting for the limited lesiol
pment.
imarins. After 72 hr inoculation with D
*ola, Um synthesis at 16.01 and 37.21
id, Sco synthesis at 6.47 and .13.81 ug/g ii
tible and resistant roots, respectively wern
bly low to cause 50% spore inhibition
1) Higher levels of Um (LD50 = 292
nd Sco (LD50 = 343 ug/g) were found t<
ibitory to D. tubericola. In C. fimbriata
d roots, the amounts of Um and Sc<
ses in the diseased tissues have not beei
enough to account for their role in the de
mechanism of the host (17, 25). Therefore
two coumarins could not have a poten
:hogenic function on D. tubericola in th,
d sweet potato roots.
rphenols. Synthesis of polyphenols at 3.9]
n resistant roots 58.24 hr after inoculation
9. tubericola gave 50% spore inhibition
1). However polyphenol synthesis in suscep
oots at 2.06 mg/g 72 hr after infection
ed spores only by 9.24%. Akasawa and Wad
md that chlorogenic acid synthesis at 96 h
3ots were infected with C. fimbriata was no

I. Lethal dosage (50%) and amounts of fura
different hr after inoculation with D. tubl

'ANCE LD50
24
G52 5 G81

)terpenes1 1.37 A/g 0.58 1.
liferone2 291.00 ug/g 3.82 9.!
tin3 343.00 ug/g 1.28 4.!
lenols4 3.91 mg/g 1.42 2.(
arogenic
L)

anoterpenes were expressed in absorbance/g fresh)
Sfuranoterpenes extracted from resistant G81r I
= 11.55%
= 13.21%


ormed after inoculation with D. tuberic
i possible that other polyphenols have ant
properties against D. tubericola.


n Vitro Bioassays of Partially-Purified
'ompounds

Most of the inhibitory activities from e
*f infected roots were distributed in the i
erpene fraction. With the exception of Cc
'oA, other coumarins and phenols did no
icantly inhibit spore germination and m
rowth of D. tubericola. (Table 2). Howev
11 furanoterpenes were antipathogenic. Oi
)Ip, IpOH, B, C and D were most toxic by
y inhibiting spore germination and m
growth with the subsequent production of
nal spores and variants from the .normal
norphology (Table 2, Figures 6 and 7). Sim
a their antifungal properties suggest that tl
sitory activities from infected roots cou
inly be ascribed to one but to the co-aci
hese stress metabolites. Kojima and Urita
toted that antifungal properties extract(
oots infected with C. fimbriata were due
ious furanoterpene synthesized. Ipomeal
caused several antibiotic effects against C. fir
uch as inhibition of growth, protein syi
phosphate metabolism and respiration
others (24).

rpenes, coumarins and polyphenols synthes
la.

UNTS SYNTHESIZED AT (hours)
48 72
la G52-5 G81r-8a G52-5 G81

0.65 2.97 1.20 4.
8.26 23.99 16.01 37.
4.45 7.98 6.47 13.J
1.52 3.22 2.06 4.,



;ht calculated from standard curves prepared
ts 72hr after infection.


innulatinn wuritl

















SPORE NUMBER
NDS1 GERMINATION2 ABNORMAL S
(%) (%)

penes
99.00 abc5 63.00 efl
42.00 ij 66.00 efl
32.00 j 83.00 g
55.00 hi 43.00 cd
70.00 gh 31.00 bc
56.00 hi 42.00 cd
36.00 i 85.00 g
48.00 i 79.00 g
H 34.00 ii 70.00 fg

s
92.00 bcdef 18.00 bc
90.00 cdefg 24.00 bc
A 94.00 abcde 21.00 bc
Std. 87.00 efg 49.000 d
Std. 84.00 defg 41.00 cd

ols
99.00 ab5 12.00 b
o 98.00 abcd 14.00 b
34.00 ii 74.00 g
Std. 95.00 abcde 32.00 bc
o Std. 73.00 fgh 40.00 cd

100.00 a 0.00 a

rpenes: A, B, C, D, E and F unknown furanote
leamaronol: Coumarins: Um umbelliferone: Sco
ne standard; Sco Std. scopoletin standard; Phel
rphenol; Ca Std. caffeic acid standard; Chlo Std.
of 4 replications, 200 spores per replication. Data
of 3 replications, 200 spores per replication.
of 4 replications
>f the same letter in vertical columns are not sig
'est.


HYPHAL
F GROWTH (urn) MYCELIA
RES2 Length Diameter GROWTI
(cm)


28.28 defg5 4.46 cd5 2.95 bc
19.51 efg 3.46 abcd 2.38 d
14.51 g 3.45 abc 2.50 d
15.11 g 3.48 abcd 2.67 cd
31.35 defg 3.14 a 3.06 bc
16.77 fg 3.25 ab 2.83 bc
14.41 g 3.96 abcd 1.08 e
15.07 g 3.69 abcd 1.15 e
15.54 g 3.17 a 1.45 e


111.28 b 3.54 abcd 3.47 b(
124.54 b 3.46 abcd 3.51 b
72.85 c 4.46 cd 1.26 e
36.43 de 4.41 cd 2.67 cc
34.17 de 4.43 cd 2.69 cc


115.66 bs 3.47 abcd5 3.59 b
108.29 b 3.68 bcd 3.63 b
13.59 g 4.37 cd 2.46 d
43.37 d 4.19 bcd 3.43 bi
45.89 d 4.47 d 2.91 be

160.05 a 3.15 a 4.54 a

es; Ip ipomeamarone; DIp dehydroipomeamaj
scopoletin; CoA unknown coumarin; Um Std.
a caffeic acid; Chlo chlorogenic acid; PoA u
torgenic acid standard.
: transformed to Arc. Sine Percentage prior to anal


antly different at 5% level using the Duncan's Mi


~___ _







Niippime Phytop~aoogy2


dark


Components Rf

F 0.5

Ip 0.5
Dip 0.5
E 0.5
D 0.4
Ipn 0.4



C 0.3
IpOH 0.2
B 0.2
A 0.1


I Standard
G81r-8a


Figure la. Thin layer chromatogram of root extracts from uninoculated and inoculated susceptible G52-
5 and resistant G81r-8a sweet potato crosses together with a standard furanoterpene
lb. Schematic representation of Figure la with corresponding band numbers, color intensities.
components and Rf values. Components are: A, B, C, D, E and F unknown furanoterpenes,
Ip ipomeamarone; Dip dehydroipomeamarone; Ipn hydroxymyoporone; and IpOH -
ipomeamaronol.


Band No


U
Susceptible


light




















G52-5


Legend:


moderate



















U
Resistant


Vol. 22










Legend:


moderate dark


Rf Color under UV


S R S R S R S R, Standards
I 11 III IV


Figure 2. Schematic diagram of chromatogram of Fractions I, H, HI and IV showing distribution of umbelliferone (Um), scopeletin (Sco),
esculentin (Esc), esculin (Es) and unknown coumarin (CoA) with standards as markets in both healthy and inoculated susceptible G52-5
and resistant G81r-8a roots. Diagram with corresponding Rf values and color intensities.


light


Band No.




1

2
3
4




5


violet (CoA)
fluorescent light
blue
flourescent blue
violet


0.49 light blue







































Dallu INi.
I


3 0.48 (Po/



4 : 0.14 (PoB


5 :0.00 (PoC
U I U I Chlo Ca
Susceptible G52-5 Resistant G81r-8a Standards

B


? 3a. Thin layer chromatogram of phenolic substances isolated from uninoculated and inot
roots of susceptible G52-5 and resistant G81r-8a sweet potato crosses together with st
chlorogenic and caffeicd acids
3b. Schematic representation of Figure 3a with corresponding band numbers, color intensity


"~ 'ItjU. 14
'-: *:.:.- "-.'-..:":.: .."---:;":::'.-.:-:^ I u0.74
::. ":'::::::i:1 0.71







Biochemical Bases of Resistance to Java Black Rot


dark


















S R S R
60 72


Components Rf

F 0.59

Ip 0.56
Dip 0.53
E 0.50
D 0.46
Ipn 0.44



C 0.33
IpOH 0.28
B 0.24
A 0.19


I

Figure 4a. Chromatographic examination of the formation of furanoterpenes isolated from sweet potato
roots of susceptible G52-5 and resistant G81r-8a as a function of infection period.
4b. Schematic representation of Figure 4a with corresponding band numbers, color intensities and
components. Components are: A, B, C, D, E and F unknown furanoterpenes; Ip ipomea-
marone; Dip dehydroipomeamarone; Ipn hydroxymyoporone and IpOh ipomeamaro-
nol.


Band No.


S
12


light


















S R
24


Legena:


moderate







mHm









S R S
36
(hours)


R
48


Jan. & June 1986







Phiippine Phytopathololg


6

5
-C
- 4


Ag o


-2 /2
0o /

....-*---**

0 12 24 36 48 60 72
(hours)
A


A
/ &
A&


40 .


.35
cr
30
r
025

S20
Ca.
515

10

5


a



.7


0 12


2.00

1.75

1.50
41
-C
.o 1.25
3^
l' .00

r- CN
0p.50

c 0.25


24 36 48
(hours)
B


/


60 72


0 12 24 36 48 60
(hours)


0 12 24 36 48 60 72
(hours)
C


Legend:
resistant G81r-8a
---- susceptible G52-5


0 12 24 36 48
(hours)
E


I _
Figure 5. Time course of changes in the amounts of furanoterpenes (a), umbeliferone (B), scopoletin
(C), coumarin A (D) and phenols (E) isolated from roots of susceptible G52-5 and resistant
G81r-8a sweet potato crosses inoculated with the Batanes isolate of D. tubericola.


14

12
4-,
-c
Or
S10
3
S8

6
S .


60 72


.. . I I


Vol. 22















































C


Wiplodia tubericola spores grown in distille


D


water (A, x 420) as control and in solution c























3 Fi


Figure 7. Mycelial growth assays of the B
IpOH ipomeamaronol; D/P dehydroip
Um umbelliforone; Sco scopoletin; U
rin; Phenols: Ca- caffeic acid; Chlo chlo
unknown Phenol; and, control- absolute e\


Witanes Isolate of Diplodia Tubericola in plain
omeamarone; IP ipomeamarone; unknown
rm Std umbelliferone standard; Sco Std s4
rogenic acid: Ca Std-caffeic acid standard; (
thanol.


sl r g


c











vdroi- meamarone, ip


(2) found that direct bioassay of chro- against the germinating spores and mycelia of
With C. cucumerinum spores showed tubericola may affect not only the pathogen I
rone and ipomeamaronol to be anti- also the penetrated host cells and the adjaci
a present study clearly shows that these healthy tissues. Such root cells may be injured
s are responsible for the defense reac- least cytologically to cause drastic metabc
sweet potato roots to D. tubericola. disturbances leading to the accumulation of th
)n these findings, it can be concluded stress metabolites and subsequently, cell necro
nce of sweet potato roots to D. tuberi- These events, then are probably the initial 1
verned by the rapid accumulation of ponse of the sweet potato root to infection w
s such as ipomeamarone, dehydroipo- D. tubericola.


LITERATURE CITED


WA, T. and K. WADA. 1961. Analytical study 11.KATO, Y. and I. URITANI. 1976. Changes in ca
omeamarone and chlorogenic acid alterations hydrate content of sweet potato in response
weet potato roots infected by Ceratocystis cutting and infection by black rot fungus. A
iata. Plant Physiol. 36:139-144. Phytopathol. Soc. Japan 42:181-186.
;. A. E. and I. M. SMITH. 1979. Production of 12.KIM, W1K. and I. URITANI, 1974. Fungal extr
;alacturonase complex by Botryodiplodia theo- that induce phytoalexins in sweet potato r,
ae and its involvement in rot of sweet potato. Plant Cell Physiol. 15:1093-1098.
iol. Pit, Pathol. 17:145-55. 13.KOJIMA, M. I. and I. URITANI. 1975. Possible
SL. T., L. KUHNERT, B. J. WILSON and volvement of furanoterpenoid phytoalexin in e
[. HARRIS. 1977. Biogenesis of lung-toxic blishing host-parasite specificity between sv
s produced during microbial infection of n,.* A. ,r, .... ; ....; r.--f rr*.... fm,..-


WELL, B. C. 1978. Cassava (Manihot esculenta
atz.) as feed for pigs and poultry: a review.
p. Agr. Trinidad 55: 273-282.
S, H. R. 1959. The effect of plant bed tempe-
res and fungicide treatments on the occurence
ava black rot of sweet potato sprouts. Phyto-
ology 49:253-254.
AY, R. F. and G. G. DIVINAGRACIA. 1986.
ening sweet potato roots for resistance to Java
k rot. Paper presented in 17th Pest Control
acil of the Philippines. Iloilo City. 10 p.
LGRACIA, G. G. 1975. Diseases of root crops
he Philippines. Unpublished. NSDB Annual
art. 16 p.
ER, L. L., T. L. WEIMER and J.M.R. ADAMS.
8. Sweet potato storage rots. J. Agr. Res. 15:
.268.
), H., I. URITANI and S. AKAI. 1969. Produc-
of furanoterpenoids and other compounds in
,t potato root in response to infection by
)us isolates of Ceratocystis fimbriata. Phytopa-
SZ. 65:332-340.
N., H. IMASEKI, N. NAKASHIMA and I.
TANI. 1971. Structure of a new sesquiterpe-


1/. Lompounas accumulating in p
-.-- r- i- a- A me~ --A. 0 T


U te, J. iy
after infe
1-.l 1t -l


dazole as sweet potato seed treatment fungil
Plant Dis. Reptr. 56:219-223.
MENANCIO, D. 1981. Biochemical basis of resist
to Cercospora leaf spot in Vigna radiata L. Wil
var. radiata. MS Thesis. University of the Pt
pines at Los Banos, College, Laguna. 73 p.
MINAMIKAWA, ., T. AKAZAWA and I. URIT
1963. Analytical study of umbelliferone and
poletin synthesis in sweet potato roots infe
by Ceratocystis fimbriata. Plant Physiol. 38:
497.
OGUNI, I. and I. URITANI. 1973 Isolation of i
droipomeamarone, a new sesquiterpenoid fron
black rot fungus infected sweet potato root ti:
and its relation to the biosynthesis of ipome
rone. Phytochemistry 13:521-522.
PALOMAR, M. K.,A. D. SOLIS and H. S. BAND/
1980. Sweet potato tuber ror disease in the P1
pines. Annals of Tropical Research 111-121.
REYES, G. M. 1920. Storage-rots caused by Dipli
Phil Am~ 1 -' 15.7


coum










factors affecting


nicity of Diplodia tube- FYnt Stltnn


AHMANN, M. A., B. G. CLARE and W. WOOD- gamon Press Ltd. Oxford. p. 29-63.
BURY. 1966. Increased disease resistance and en- 27.URITANI, I., K. OBA, A. TAKEUCHI, K.
zyme activity induced by ethylene production by INOUE, R. ITO and I. TIO. 1981. Bioche
black rot infected sweet potato tissue. Plant Phy- furanoterpene produced in mold damaE
siol. 41:1505-1512. potatoes. In Ocy (ed.). Antifungal ani
EINBAUER, C. E. and L. J. KUSHMAN. 1971. toxicants in foods. Food and Nutrition I
Sweet potato culture and diseases. Agr. Hdbk. No. Westport, Connecticut. 508 p.
388. p 1-3. 28.VILLAREAL, R. L. and S. C. TSOU. 191
CEUCHI, A., i. OGUNI, K. OBA, M. KOJIMA and potato tips as vegetables. Hortscience 14:4
L URITANI. 1978. Interactions between diseased 29.ZUCKER, M. and J. F. AHRENS. 1958. Qu
sweet potato terpenoids and Ceratocystis fimbriata. assay of chlorogenic acid and its pattern
Agr. Biol. Chem. 42:935-939. bution within tobacco leaves. Plant Ph]
LITANI, I.1963. Symposium on natural biochemical 246-249.
resistance to diseases in plants. Connecticut Agric.










nhfr*l ff Ralrant a lie


Avelita M. Rosales, F. L

respectively, Research Assistant, Assistant S
Research Institute (IRRI), Los Bafios, Lagus



ABST

he effect of beneficial bacteria on control of baka-
aused by Fusarium moniiforme was studied. Sixty
rnt of the 139 ricefield bacterial isolates inhibited
nycelial growth of F. moniliforme in vitro. In
house experiment using naturally-infected IR42
soaked in individual bacterial suspension of 9
:es, bakanae infection was reduced by 1.9 to 77%.
edbed experiment using IR58 seeds soaked sepa-
r in suspensions of 18 bacterial isolates, bakanae


INTROL

mnae or foot rot of rice has recently gained
lic importance due to commercial cultiva-
susceptible cultivars IR42 and IR36 since
Fhe pathogen, Fusarium moniliforme Shel-
luces seedling elongation due to gibberel-
it rot or seedling rot effected by fusaric
ain sterility and discoloration.
nae was first noted in Japan in 1828 (6)
the Philippines in 1934 (19). It had been
d in many rice growing countries like Aus-
3angladesh, China, Korea, India, Thailand
her countries (16). The disease was ob-
in the provinces of Laguna, Camarines
Albay, Iloilo, and Zamboanga in 1978 and
.4). Local epidemics in some regions where
cultivated are still observed at present.
t figures on yield losses are scanty. Reports
that yield losses amounted to 20 percent
k (6); 15 percent in Thailand (7) and Uttar
,India (17), and 70 percent due to foot rot
r maturing cultivars in Northern Australia
he Philippines specifically in Laguna prov-
ange of 1 to 13 percent yield loss was es-
on variety IR42 (14).
pathogen is seedborne (13, 20) and soil-
25). Seedborne inoculum could provide ini-
for further infection. Under favorable envi-


que and T. W. Mew

tist and Department Head, The Internationi
hilippines.



T

idence and disease control ranged from 0.9 t
i% and 71.7% to 96.3%, respectively, in treated
Ids. In farmer's field test, naturally-infected IR4
ds bacterized with isolates In-b-150 F, In-b-59
7, In-b-17 NF and in-b-24 F had bakanae incident
18-20% comparable to 17% of the benomyl trea
;nt. Disease intensities in treated and untreated
its were 2.24.5% and 13.5%, respectively.



'ION

a that subsequently infect proximate hei
ants which results in tremendous yield k
te disease has been effectively controlled
emical seed treatment (8).
Bakanae disease could be controlled by th
resistant varieties. However, breeding for I
.e resistant varieties is complicated by the
nce of races or strains of F. moniliforme v
ve been reported to be very variable (15,
kewise systemic and non-systemic fungicide
ntrol the disease. However, there are econ
d technical constraints in the use of fungic
Effectively manage this disease an approp
ernative is the use of biological antagonists.
Biological control of plant pathogens ha:
ived increased attention due to public cor
environmental pollution. The application:
mt growth promoting rhizobacteria to pc
ed pieces prior to planting reduced signifii
the population of Erwinia carotovora in
als (10). Seed treatment with fluorescent
ria suppressed take-all disease of wheat (26)
at work using fluorescent and non-fluores
cteria for bacterization of rice seeds showed
session of sheath blight development and pri
in of plant from infection (11). As bakan
ansmitted primarily through seedborne in
n, seed treatment with antagonistic bac















MATERIALS AND METHODS

Culture and preparation of bacteria.

Total of 139 bacterial isolates previously
ed effective in controlling sheath blight w
m in this study. These were grown on pept(
ose agar plants (PSA) for 24 hours at 28
bacterial suspension prepared from th
-s was adjusted to a concentration of app
itely 1 x 109 cells/ml.

Culture and preparation of
F. moniliforme inoculum.

.moniliforme was isolated from natural
cted IR42 plants by the monospore is4
technique. Cultures were maintained on pol
:rose agar (PDA) for routine tests. For gre
se experiments, the inoculum was prepa
g rice hull-rice grain substrates (3 parts 1
: 1 part rice grain in 200 ml water). The n
was packed in 500-ml culture bottles (e
little) and autoclaved at 15 PSI at 121 C
e hours. The pathogen was transferred as
ly to the substrate and incubated for 7 day
n temperature (28 C). Inoculum was addec
previously sterilized continuously for 8 he
eedboxes (28 x 11 x 11 cm.) at a 1:20 (v
). The infested soil was covered with pla
and incubated for two days.

Test of antagonistic activity
in vitro.

bacterial isolates were tested for their anti
ic activity against a virulent isolate of
liliforme (isolate F-24) by spot plate met]
PDA. One ml spore suspension (50,000 spo
of the pathogen was added and spread on e
plate. A loopful of bacterial suspension (
cells/ml) was placed at the center of e
e. Four replicates were made for each isol
incubated at 28 C for one week. Subsequen
bition zone was measured.
, bioassay method using IR42 was also d
ed to evaluate the efficiency of the bacte:
Ltes. Artificially-infected IR42 seeds w


Grenhouse Test

Nine isolates of bacteria were teste
greenhouse. Seeds of cultivar IR42 wei
with bacteria as previously described
soaking them in bacterial suspension (1 x
ml) at a 1:10 (w/v) for 12 hr. Bacteriu
seeds were sown in seedboxes previously
with F. moniliforme. Seeds soaked in st
tilled water was used as check while Be:
the rate of one g/l/kg of seed was util
standard chemical.

Seedbed Evaluation

A seedbed (25 x 1.5 m) was prepared
rally-infested field soil. Fifty-five bacteria
were screened for their effectiveness ag
kanae. Two hundred fifty g IR 58 se
soaked separately in each bacterial suspe
12 hrs then sown in seedbed. Disease i
was observed two weeks after sowing.



Field Evaluation

Field plots were established at the farn
with previous history of bakanae infect
1978. Naturally-infected IR42 seeds wei
with bacteria (109 cells/ml) as previously c
The seedlings were separately raised
beds in the greenhouse then transplanted
(5.5 x 3.5 m) at 20 x 20 cm spacing. Fiv
untreated seedlings were planted between
prevent bacterial contamination from
to another. The farmer's practices of
application, weeding and insect control
lowed. The treatments were 1) seed I
with fluorescent bacterium, In-b-24, 2) s
ment with fluorescent bacterium, In-t
seed treatment with nonflourescent bactc
b-17, 4) seed treatment with nonfluoresc
590, 5) seed treatment with Benomyl
a.i./l of water/kg seeds, 6) without ba
fungicide treatment, 7) farmer's plot
treatment. Treatments were replicated f<
in randomized complete block design. I
.. -- __ _ l- 1 U 1 H.. ,-* ___ --


- I l- -- __


- - - 4- -k -1.+. -;+1k ,
















Treatment



erial isolates
.149
.24
157
.147
.150
17
.151
591
148
)myl (Standard Chemical)
:rol (Sterile distilled water)

Means of 3 replications with 25 plants/replicate. M
1.05) by Duncan's Multiple Range Test.
Percentage disease control = Control Treatme
Control


























Figure 1. IR58 seedlings from bacteria
and dark green leaves. Seedlin
incidence and yellowish leaves


Bakane
incidence




51.0 c
48.0 bc
39.0 bc
38.0 bc
36.0 b
32.0 b
31.0 b
24.0 b
12.0 a
23.0 b
52.0

followed by a common letter are not significantly

x 100



























'ted seeds (right) have low bakanae infection
rom untreated seeds (left) have higher disease


_ _


1

















RESULTS AND DISCUSSION


lixty percent of 139 isolates inhibited myce
vth of F. moniliforme while fifty percent w
ctive in suppressing bakanae based on seedl
;ermination tests. Some of these isolates w
effective in reducing bakanae incidence
'icially-infested soil in the greenhouse (Ta
Disease incidence was reduced by 1.9 to 7
g bacterium-treated seeds. In seedbed eval
, 18 out of 55 isolates reduced bakanae
ion (Table 2). Bakanae incidence ranged fr,
to 6.6 percent and 1.0 to 6.8 percent wl
Is were treated with fluorescent and nonfli
ent bacteria, respectively. Percentage dise
action ranged from 72.5 to 87.9 percent
clings from seeds treated with fluoresci
:eria and 71.7 to 96.3% in seedlings gro
a nonfluorescent bacterium-treated see
its from bacterium-treated seeds were health
had more tillers than those from untrea
s (Fig. 1). The present results corroboral
findings obtained by Mew and Rosales (1
.e working on bacterization of rice plants
.th blight control. Similarly, Burr et al.
irted that strains of fluorescent Pseudon
* applied to potato seed pieces increased yi
eld trials. The foregoing results of Burr, et
were further confirmed by Kloepper et al (1
beneficial effect of bacterization on crops 1
rth-promotion was demonstrated in sugarb
, in radish and other crops (23).
hen plants from IR42 seeds treated with ani
stic bacteria were grown in the farmer's fie]
ression of bakanae was effectively obtain'
le 3). Bacterization reduced bakanaeinciden
0.4 to 74.6% comparable to 76.1% with ben
treatment when compared to disease in,
: in farmer's field plot. Based on the disea
ence in the control using distilled water t
Incidence was reduced by 58-64%. Disea
sities in treated and untreated plots were 2.
and 13.5%, respectively.
disease incidence and intensity of the chei
differed significantly from those of the fi


those of the farmer was grown in natural
ted field. Since F. moniliforme is a soilboc
gen, it was able to survive as saprophyte
debris (25). The build-up of inoculum in
together with the inoculum present in
seeds contributed to increase bakanae infi
dapog seedlings (27). Visual examination
dapog seedlings used by the farmer duri
planting time showed that majority hao
discolorations in the roots and bases of tl
Thus, disease incidence and intensity wei
in the farmer's field. These observations
red with the findings of Ito and Kimura
the pathogen became systemic multiplyin
the vascular tissue particularly in large pi
sels and lacunae of the xylem with browl
in roots and stems and of seedlings grove
turally infested soil. Disease incidence ar
sity of the rice plants were affected by the
of inoculum present in the vicinity of the i
The effectiveness of bacteria in baka
pression is similar to take-all decline by
cent Pseudomonas (26). These workers
that siderophores and antibiotics were meo
responsible for effectiveness of bacteria
seeds with fluorescent Pseudomonas. In
sent study, the effect on bakanae contr
be attributed to other unknown mec
since the plants from treated seeds were I
greener, and had more tillers than plan
from nontreated seeds. According to Bri
suppression of diseases by bacteria can i
to improved yields of crops. An inocul
either antagonizes or competes with the I
for colonization sites on the roots, and at 1
time produces stimulatory growth substai
improve plant growth and consequently
yield. Further investigation should be t
determine the mechanisms involved in
suppression by the antagonistic bacteria.
This study demonstrated the applical
biological control under greenhouse and fi
editions and the utilization of naturally-o
beneficial bacteria for bakanae control.
plicability of such biological control
which is still in its incipient stage merits
investigation to evaluate its efficacy, u:
verse environments, on rice grain yield
that could be attributed to disease supi
The vital impact of these beneficial bac





ment



riall isolates

ourescent isolates2
-b-266
-b-108
-b-242
-b-772
-b-784
-b-24
-b-150

nfluorescent isolates

b-157
b-715


Bakanae
incidence
(O)





2.9
3.5
3.5
5.8
6.0
6.6
6.6



0.9


4.5
5.5
5.7
5.9
6.4
6.8
ater) 24.0







Philippine Phytopathology


Table 3. Effect of bacterization of IR42 seeds grown in farmer's field naturally infested with Fusarium
moniliforme on bakanae incidence.


Bakanae Disease4 Diseases
Treatments1 incidence2 control (%) intensity
(%) Cl C2 (%)

Bacterial isolate
In-b-150-F 21.0 c3 70.4 58.0 2.2 c
In-b-590-NF 20.0 c 71.8 60.0 2.4 c
In-b-17-NF 19.0 c 73.2 62.0 2.3 c
In-b-24-F 18.0 c 74.6 64.0 2.2 c
Benomyl 17.0 c 76.1 66.0 1.0 c
Control 1 (Farmer's field) 71.0 a 13.5 a
Control 2 (Sterile distilled water) 49.5 b 4.5 a


IPlant treated with bacterial antagonists, Benomyl and control 2 were Dapog-raised in
transplanted on farmer's field. Control 1 is untreated seeds raised in farmers fields.


the greenhouse and


2Incidence = Number of hills infected x 100
Total number of hills

3Means of 3 replications. Means followed by a common letter are not significantly different (P = 0.05) by Dun-
can's Multiple Range Test.

4Percentage disease control = Control Treatment x 100
Control
Cl is the percentage disease control based on control 1
C2 is the percentage disease control based on control 2

SDisease intensity = Total number of tillers/hill No. of bakanae infected tillers/hill x 100
Total number of tillers/hill


Vol. 22











LITERATURE CITED


IROWN, M. E. 1974. Seed and root bacterization. Ass. 35:121-144.
Annu. Rev. PhytopathoL 12:181-197. 14.NUQUE, F. L., VERGEL DE DIOS, I.T.,
IURR, T. J., SCHROTH, M. N. and SUSLOW, T. L. M., BANDONG, J. M. and CRILL,
1978. Increased potato yields by treatments of Studies on the etiology, epidemiology
seedpieces with specific strains of Pseudomonas of the bakanae disease of rice in the
fluorescens and P. putida. Phytopathology 68: Phil. Phytopath. 16:1-2.
1377-1383. 15.NUQUE, F. L., T. V. DE DIOS, and J.
JARRET, S. D. 1963. Soil fungi and soil fertility. 1981. Pathogenic races of Fusarium I
The MacMillan Co. New York. 165 p. in the Philippines. Phil. Phytopath. 198
IEATON, J. B. and MORSCHEL, J. R. 1965. A 16.OU, S. H. 1972. Rice Diseases. Londol
foot rot disease of rice variety Bluebonnet, in wealth Agric. Bur. England. 368 p.
northern territory, Australia, caused by F. moni- 17.PAVGI, M. S. and SINGH, J. I. 1964. E
liforme Sheldon. Trop. Sci. 7:116-121. foot rot of rice in Uttar Pradesh, Indii
IOWELL, C. R. and STIPANOVIC, R. D. 1980. Reptr. 48:340-342.
Suppression of Pythium ultimum-induced damp- 18. PHINEY, B. 0. and WEST, C. A. 1960. G:
ing-off of cotton seedlings by Pseudomonas fluo- native plant regulators. Ann. Res. PI
rescens and its antibiotic, pyolutiorin. Phytopa- 11:411-436.
thology 70:712-715. 19.REYES, G. M. 1934. A new or little kn
TO, S. and KIMURA, J. 1931. Studies on the baka- occurring in the Philippines. Phil. J. A
nae disease of the rice plants. Rep. Hokkaido Exp. 142.
Stn. 27:1-95+5. 20. SANTOS, L. G. 1957. A survey of the seec
KANJANASOON, P. 1961. Seed dressing campaign of rice. Unpublished B. S. Thesis. (
on elongation disease of rice. IRC/RPP/W.P. 88. UPLB.
CAWASE, J. 1975. Effect of thiram-benomyl mix- 21.SCHER, F. M. and BAKER, R. 1982. Eff
ture for seed disinfection of bakanae disease. Chu- domonas putida and a synthetic iron
goku Natl. Agric. Exp. Stn. Rep. Crop Res. Kinki- induction of soil suppressiveness to FR
Chugoku Re. 6:58-65. pathogens. Phytopathology 72:1567-15
CLOEPPER, J. W. and SCHROTH, M. N. 1978. Plant 22. SCHROTH, M. N. and HANCOCK, J. G.
growth-promoting rhizobacteria on radishes. Pages ted topics in biological control. Annu.
879-882 in Proc. Int. Conf. Plant Pathog. Bacter. biol. 35:453.476.
4th Vol 2, Angers, France. 23. SCHROTH, M. N. and HANCOCK, J. G. 19


1978-1982.
dEW, T. W. and ROSALES, A. M. 1986. Bacte
tion of rice plants for sheath blight control.
topathology 76 (In Press).
MIAH, S. A. and ZAMAN, M. Q. 1973. Studies or
reaction of high yielding dwarf to foot rot
bakanae in Bangladesh. Bangladesh J. Bot. 2:72
MATH, R,, NEERGAARD, P. and MATHEW, i
1970. Identification of Fusarium species on s
as they occur in blotter test. P roc It. Seed


reducing crop growth. Phytopathology 7
25.THOMAS, K. M. 1931.A new paddy diseasE
Agric. J. 19:34-36.
26.WELLER, D. M. and COOk, R. J. 1983.
of take-all of wheat by seed treatment
recent pseudomonads. Phytopatholol
469.
27.YU, and SUN. 1976. Ascospore liberation o
fufikuroi and its contamination of rice
Protection Bull., Taiwan 18:319-329.






Philippine Phytopathological Society, Inc.
1986 Phil. Phytopath. 22: 3641


Biological Control ofRadopholus Similis on Banana
With Three Nematophagous Fungi



Lourdes C. Generalao and R. G. Davide

Respectively, Instructor, College of Agriculture, University of Southeastern Philippines, Apokon,
Tagum, Davao del Norte and Professor, Dept. of Plant Pathology, College of Agriculture, Univer-
sity of the Philippines at Los Bafios, (UPLB) College, Laguna, Philippines. 3720.

Portion of M. S. thesis of the senior author submitted to UPLB.



ABSTRACT


The potentials of Paecylomyces lilacimus, Penicil-
lium anatolicum and Arthrobotrys cladodes as biolo-
gical control agents against Radopholus similis nema-
todes on Cavendish banana were demonstrated under
laboratory and greenhouse experiments. Based on
mortality and infectivity tests, P. lilacinus was more
effective and proved comparable with those of nemati-
cide Nemacur 10G at 200 ppm. Generally, the three
fungi significantly reduced the nematode population
in the soil and roots of Cavendish banana as compared
with the control. The fungi cultured in ipil-ipil leaves,
rice hulls and banana leaves and leaf sheaths were
more effective against the nematode than when used


directly as spores and mycelial suspension applied as
soil drench; the substrates supported abundant growth
of the fungi except P. anatolicum which did not grow
well in rice hulls.
In the mortality test, P. lilacinus spores were ob-
served parasitizing the tail region of R. similis. Penicil-
lium anatolicum showed no direct parasitism but the
nematode was killed by the toxic substances appa-
rently secreted by the fungus. Arthrobotrys cladodes
which was supposed to trap nematodes was not ob-
served producing the trap mechanisms while in water
suspension resulting in very low nematode mortality
which was comparable with the control.


INTRODUCTION


Radopholus similis (Cobb) Thorne is a major
nematode pest of Cavendish banana in the coun-
try. Banana companies spend over 50 million
pesos annually for the chemical control of the
nematodes. However, the banning of highly ef-
fective nematicides like DBCP, EDB and Aldicarb
and the government restriction on the use of ne-
maticides by small farmers due to high levels of
toxicity and hazards to human health have greatly
affected our effort to effectively control the nema-
todes. Alternative control measures which could
be safer, cheaper and more-practical to apply in
the soil than the chemicals should be developed.
The potential of microorganisms for biological
control of nematodes have long been recognized
(4, 5) but not much has been known for their
practical application in the field. Recently, reports
indicate that such soil fungi as Paecilomyces lila-
cinus (Thom.) Samson (3) and Arthrobotrys cla-
dodes Drechs. can effectively control root-knot
Snematodes and potato cyst nematodes in the
Philippines (2, 7). However, it is not clearly
known whether they can also control R. similis


on banana. Another fungus, Penicillium anatoli-
cum Stolk, isolated in Peru by Jatala (Per. Com.)
but has not been tested on R. similis has been
found recently to produce toxins that are lethal
to plant parasitic nematodes (6).
This study, therefore, was conducted primarily
to evaluate the biocontrol effectiveness of P. lila-
cinus, cladodes and P. anatolicum against R.
similis on Cavendish banana using different sub-
strates as compared with a standard nematicide.


MATERIALS AND METHODS


Test of different su bstratesforfungal growth and
sporulation. The following substrates, namely;
dried ipil-ipil leaves, chopped banana leaves and
leaf sheaths, rice hulls with one g grains/400 g rice
hulls, were tested for growth of P. lilacinus, P.
anatolicum and A. cladodes. Five g. of each sub-
strate were separately placed in Petri dish and four
replicates were made. In addition, 100 of each
substrate were placed in dextrose bottles (1 liter






. Biological Control of Radophotus similis on Banana


cap) for mass production. The Petri dishes and
bottles containing the different substrates were
first sterilized in autoclave for one hour at 121.C
before inoculating with the test fungi. Each test
fungus was separately inoculated to the different
substrates in bottles and Petri dishes using four
replications per substrate. Every bottle of substrates
was seeded aseptically with 50 ml of the spores
and mycelial suspension in sterile distilled water
while each Petri dish with substrate was seeded
with a 4 mm mycelial disc placed at the center.
The test fungi were allowed to grow under room
temperature (20-25C) for seven days. The growth
rate of each fungus in different substrates was
evaluated using the following growth index; 1 = no
growth, 2 = poor growth, 3 = moderate growth,
4 = abundant growth, 5 = very abundant growth.
Mortality test on R. similis Seven-day old cul-
tures of the three test fungi grown in oat meal agar
slants in test tubes were used for the test. Spore
suspension of each fungus was separately made in
sterile distilled water placed in 100 ml flask. Using
a haemacytometer, the spores were counted and
calibrated at 250,000 spores/ml. Then pure popu-
lation of R. similis originally taken from roots of
Cavendish banana and cultured on carrot discs in
the laboratory as described by Boncato and Davide
(1) was prepared in a suspension with sterile dis-
tilled water and added with a drop of 1000 ppm
streptomycin sulfate to prevent bacterial conta-
mination. Approximately 500 R. similis indivi-
duals per ml suspension were added to each Petri
plate (50 x 15 mm) containing 3 ml of the fungal
spores suspension. The same number of nematodes
as placed in the Petri plates containing 3 ml of
200 ppm Nemacur 10G nematicide and to the
control plates which contained only 3 ml sterile
distilled water. For each treatment 3 replicate
plates were assigned. All treated plates were ar-
ranged separately on the laboratory table and kept
for 72 hours under room temperature (20-25 C).
The nematode mortality was obtained by count-
ing the dead and live individuals after 24, 48 and
72 hours, using the following formula:
DT DC x 100
% mortality =- C x

where DT = dead nematodes in the treatment
IP = initial nematode population
DC = dead nematodes in the control
plates
ICP = initial nematode population in
control plates

Test on Cavendish banana plants infected with


R. similis. To determine the biocontrol effec-
tiveness of P. lilacinus, A. cladodes, and P. anato-
licum against R. similis on banana, the experiment
was conducted using Cavendish variety as test
plants under greenhouse conditions. Each fungus
species was applied as soil incorporation after
being grown for two weeks on ipil-ipil leaves and
rice hull substrates and through soil drench using
spores and mycelial suspension. A nematicide
treatment was included using 200 ppm Nemacur
10G applied as soil mix. For the control, sterile
water was used to serve as basis for comparison
with the bio-control and nematicide treatments.
Non-infected Cavendish banana suckers were
planted in clay pots (17.78 cm diam.), filled with
sterilized soil. One month later, plants with uni-
form height were selected and used in the test.
Each potted plant was inoculated with approxi-
mately 2,000 individuals of P. similis previously
cultured in carrot discs through small holes 2
inches deep near the base of the plant. Five days
after inoculation the different bio-control treat-
ments together with the nematicide and control
treatments were separately applied using 5 repli-
cations per treatment. For the fungal treatments
using substrates ipil-ipil leaves and rice hulls, 5 g of
each were added per pot and for the soil drench
application, 200 ml of the spore and mycelial
suspension of each fungus species (grown in oat
meal agar medium) which contained 250,000
spores/ml was drenched or poured over the soil
surface of each potted plant. For the nematicide
treatment, 200 ml of 200 ppm Nemacur 10G was
incorporated into the soil per pot.
All treated plants were arranged in a complete-
ly randomized design on the cement floor of the
greenhouse and were allowed to grow for 11
weeks. At the end of the experiment, the plants
were carefully removed from the pots and root
system were thoroughly washed with tap water.
Then the root lesion index ratings and the number
of nematodes recovered from the roots and soil
were determined. The following root lesion index
developed by Wehunt and Hutchinson (8) was
used in evaluating the degree of nematode infec-
tion in roots of the test plants; 0 = no lesion; 1
= slight infection, few lesions, 1 mm or less in dia-
meter; 2 = moderate infection, many lesions 1
mm or less or a few lesions larger than 1 mm; 3 =
severe infection, many lesions larger than 1 mm
in diameter, a few coalesced into areas greater than
1 mm in diameter; and 4 = very severe infection,
many lesions greater than 3 mm. The soil samples
were analyzed for nematodes using the sieving and
Baermann funnel methods.


Jan. & June 1986















effects of different substrates on fungal grow
ilomyces lilacinus showed a growth index ol
eating very abundant growth on the thr
rates tested, i.e. ipil-ipil leaves, rice hulls, a
na leaves and leaf sheaths (Table 1). On t
r hand, P. anatolicum gave a growth index rE
or abundant growth on ipilipil leaves a3
na leaves and leaf sheaths but gave poor
rate growth on rice hulls. However, A. c
s showed very abundant growth on ipil-i]
s, moderate on banana leaves and leaf sheat
abundant growth on rice hulls. These resu
irmed findings in previous study (7).
effects of nematophagous fungi on R. simi
nmersion tests. All the three nematophago
i killed R. similis with 72 hrs. after immersi,
Le suspension. The effects of P. lilacinus *
,arable with Nemacur 10G (Table 2). Ho-
P. anatolicum and A. cladodes were inferior
acinuss. Spores of P. lilacinus were cluster,
ad the tail region of dead P. similis larvae ai
:s (Fig. 1).
ecilomyces lilacinus, although an egg parasit
Iso found parasitizing larvae and adults of 1
s. Its spores were observed adhering outsic
inside the nematode body within 48 hrs. i
Ispension. The spores in clusters were initih
and parasitizing the tail region of the nem
On the other hand, no nematodes were tra


1. Growth index ratings of nematophagous

TREATMENT

acinus +_,ipil-ipil leaves
acinus + rice hulls
acinus + banana leaves and leaf sheaths
atolicum + ipil-ipil leaves
atolicum + rice hulls
atolicum + banana leaves and leaf sheaths
adodes + ipil ipil leaves
adodes + rice hulls
zdodes + banana leaves and leaf sheaths


1Growth index: 1 = no gorwth; 2 = poor grove
nt growth;


ped by A. cladodes in the suspension as the
to develop the trap mechanism in water susf
However, in P. anatolicum suspension the
no indications of spores adhering or parasiti
the nematodes but they appeared dark, bri
dead which could be the result of the toxic
of the fungal secretions. This observatic
firmed the report of Molina and Davide (
the fungus does produce toxic compounds I
nematodes.
Effects of nematophagous fungi on R. si
Cavendish banana plants. Based on le
dex ratings, P. lilacinus grown in rice hulls
the lowest nematode infection among tre:
with an index of 1.25. However, when
soil drench with spore and mycelial sus
(grown in oat meal agar medium) alone tt
was raised to 2.25 indicating moderate i
(Table 3). Compared with P. anatolicum
cladodes regardless of substrates used, P.
gave better control of the nematodes wi
ficantly lower lesion index. In P. anatoli
use of substrates did not seem to imp
control efficiency against the nematodes.
it had lower effectiveness in rice hull s
with 3.75 lesion index compared to 2.7!
spore and mycelia suspension or soil dren<
cation. On the other hand, A. cladodes in
leaves significantly improved its control ef


gi in various substrates'

MEAN2

5.00 a
5.00 a
5.00 a
4.00 ab
2.75 b
4.00 ab
5.00 a
4.00 ab
3.00 b


S= moderate growth; 4 = abundant growth; and






Biological Control of Rodopholus similis on Banana


Table 2. Mortality of Radapholus similis 72 hours after immersion into fungal suspension compared with
a nematicide treatment.

NEMATODE COUNTS1
PERCENT
TREATMENT Initial Dead nematodes MORTALITY

P. lilacinus Suspension 372.3 61.3 13.10
P. anatolicum Suspension 396.0 44.7 7.91
A. cladodes Suspension 384.0 31.7 4.89
Nemacur 10G 200 ppm 404.3 62.7 12.14
Control 396.3 13.3 3.36

1Data are means of 3 replications.


Figure 1. Mate and female tails of R. similis showing clusters of spores of Paecilomyces
licinus parasitizing the nematodes.


the nematodes as shown by a lesion index of 1.75.
The use of spore and mycelial suspension alone as
soil drench application for P. lilacinus and A. cla-
dodes gave lower effectiveness against the nema-
todes than when applied with substrates of ipfl-
ipil, rice hulls, and banana leaves and leaf sheaths.
Comparing the effects of P. lilacinus, P. anatoli-
cum and A. cladodes with that of the nematicide
Nemacur 10G applied at 200 ppm, the lesion
index was relatively higher in the biocontrol
treatments but not significantly different with P.
lilacinus in different substrates and that of A. cla-
dodes in ipil-ipil substrate. In other treatments,
however, the nematicide has significantly greater
effectiveness against the nematodes. Compared


with the control, some of the fungal treatments
gave no significant difference like those of P
anatolicum in rice hulls and A. cladodes in spore
and mycelial suspension. However, all the treat-
ments of P. lilacinus gave significant reduction of
lesions compared with the control treatment.
Effects of nematophagous fungi on R. similis
population density in soil and roots of Cavendish
banana plants. The results revealed that P. lila-
cinus, P. anatolicum, and A. cladodes significantly
reduced the nematode population in soil and roots
of the test plants as compared with the control.
Again, P. lilacinus, regardless of substrates used,
proved more effective in controlling the nematodes
which showed 82 87% and 86-88% reduction in


Jan. & June 1986














'MENT MEAN INDEX RATING2

nus
1-ipil leaves 1.75 ef
e hulls 1.25 f
nana leaves and leaf sheaths 1.50 ef
re and mycelial suspension 2.25 de

ilicum
1-ipil leaves 2.75 cd
e hulls 3.75 ab
nana leaves and leaf sheaths 2.75 cd
*e and mycelial suspension 2.75 cd

odes
i-ipil leaves 1.75 ef
:e hulls 2.75 cd
nana leaves and leaf sheaths 3.00 bed
re and mycelial suspension 3.25 abc
Lacur 100 (200 ppm) 0.75 f
trol 4.00 a

ion index ratings 75 days after treatment: 0 = no lesion, 1 = few lesions or slight infection: 2 = many le
e infection; 3 = many large lesions greater than 1 mm diameter or severe infection; 4= many large
han 3 mm or very severe infection.
in of 4 replications; numbers followed by the same letters in a column are not significantly different at '


il and root samples examined respectively
4). P. anatolicum gave 43-64% and 41-7891
on and A. cladodes 56-68% and 54-679
on in soil and root samples, respectively
red with the nematicide Nemacur 10G all the
treatments gave lower percentage reduction
iatodes but statistically showed no signifi
fference when compared with the effect o:
'inus and some treatments of P. anatolicur
cladodes.
lerally, the application of spores and my
suspension of the fungus as soil drencl
d lower percentage reduction of the nema
population in soil and roots of the plants a


effectiveness varies considerably. P. ii
)roved more effective and can compare wi
effects of nematicide. However, how effect
hey against the nematodes under field cor
remains to be determined and a field study
follow. Likewise, the possibility of combine
ilication of these three fungi using favorab]
trates to further improve their effect
against the nematodes may deserve a study.














MEAN NEMATODE COUNTS1
EATMENT Soil per Percent Root
400 cc Reduction Samples (15 gm) R


lilacinus
+ ipil-ipil leaves 4.4 cde 86.5 4.3 de
+ rice hulls 4.8 cde 85.5 4.5 de
+ banana leaves and
leaf sheaths 5.7 cde 82.5 4.6 cde
Spores and mycelial
suspension 6.0 cde 81.8 4.6 de

anatolicum
+ ipil-ipil leaves 16.3 bc 50.5 12.1 bcde
+ rice hulls 11.8 bcde 64.2 8.5 bcde
+ banana leaves and
leaf sheaths 15.9 bc 41.7 16.4 bed
Spore and mycelial
suspension 18.7 b 43.3 17.8 b

cladodes
+ ipil-ipil leaves 12.4 bcde 62.3 16.99 bc
+ rice hulls 13.8 bcd 47.9 12.14 bcde
+ banana leaves and
leaf sheaths 10.6 bcde 67.9 13.29 bcde
Spore and mycelial
suspension 14.4 bc 56.3 13.73 bcde
macur 10G (200 ppm) 1.0 e 96.7 1.76 e
introl 32.9 a 36.6 a

Mean of 4 replications; means followed by the same letters in a column are not significantly different
IT. Data taken 75 days after treatment.




LITERATURE CITED

)ONCATO, A.A. and R. G. DAVIDE 1980. Radopho- new approach to the eelworm problem
lus similis on Cavendish banana in Davao del Norte: Faber and Faber Ltd., London.
111. Laboratory and field evaluation of nematodes 5. LINFORD, M. S. 1937. Stimulated activity
for R. similis control. Phil. Agric. 63:147-155. enemies of nematodes. Science 85:123-1
6. MOLINA, G. and R. G. DAVIDE. 1986.
)AVIDE, R. G. and R. A. ZORILLA. 1983. Biological of microbial extracts for nematicid
and chemical control studies of the potato cyst against plant parasitic nematodes M
nematode found in Madaymen, Buguias, Benguet. incognita and Radopholus similis.
Phil. Phytopathology 19: 28-35. Agric. 67: 361-371.
[ATALA, P., A.J. DEVAUX and M. BOCANGEL. 8. WEHUNT, B. S., D. J. HUTCHINSON
10'70 inloieA -nntrnl of Mplnidno ne incogni- EDWARDS. 1980. Reaction of banana










rntrol of Tvlenchulus S


Irma C. Tandin


Respectively, Instructor, Dept of Plant Pai
itabato, and Professor, Dept. of Plant Pa
ilippines at Los Bafios (UPLB) College, Lagt
Portion of M.S. Thesis of the senior author


Al

Application of Paeciomyces lilacinus and Penicilli
tatolicum either as soil drench or soil-substrate (i
ills rice bran) mix significantly controlled the cit
ematodes Tylenchulus semipenetrans under grei
)use conditions. They were also effective against I
)pholus similis on banana. Their effects were in m.
ises comparable with those of nematicide phenai
los (Nemacur 10G) at 100 ppm. The effects of the
ngi against the nematodes varied with the methods
iplication. On T. semipenetrans, the soil-substr
ix P. lilacinus and P. anatolicum proved more eff
re than the soil drench. On the other hand, the r(
n ma+hnA n.o m-- nr aff-ranr +than th- n- ,lr A-,


and R. G. Davide


igy, University of Southern Mindanao, Kaba
ogy, College of Agriculture, University of
Philippines, 3720.
nitted to UPLB.



LACT

treatments than those in the roots, whereas mo
matodes were controlled in the roots than in th
in the nematicide treatment.
Generally, P. lilacinus was more effective th
anatolicum. The combination of both fungi dii
increase their effectiveness. They showed antago
effects. On citrus plants, there was significant imi
ment of plant growth as a result of the nematod(
trol but on the banana plants no significant diffe
was observed among the treatments. Micros
examination of nematodes parasitized by P. lik
clearly showed mycelial growth around the insic
body. However, P. anatolicum did not parasite













n.. /min.itann on.l_ the 6-month old


r 10g) application, and 8) non-treated check, duals of R. similus previously obtained I
r the soil drench application, two-week old fected roots of Cavendish banana and cult
e of P. lilacinus and P. anatolicum, separate- 6 weeks on carrot dishes in 1% water agar
wn in coconut water broth in dextrose bot- plates. The drenching application of P.
vere used. The spore and mycelial suspen- and P. anatolicum was similar to the exp
)f each fungus was prepared by macerating on citrus except that the amount used was
ingal mat from the coconut water medium fungal suspension per plant containing 2!
Faring blender for 2-3 minutes in 200 ml dis- spores per ml. For the combination of bol
water. The suspension of P. lilacinus con- a 1:1 ratio of the suspension was used, tl
70 x 106 spores per ml while P. anatolicum ml of P. lilacinus plus 50 ml of P. anatolio
vision had 10 x 106 spores per ml. Each test drenched into each plant. On the other h:
was drenched with 200 ml of each suspen- root dip application of both fungi was
removing the test plants from the pots anc
the for 10 minutes in each of the fungal su,
r the soil-substrate mix treatment, two-
old cultures of P. lilacinus and P. anatoli- containing 25 x 104 sporesml. The treated
separately grown in 1:1 rice hull-rice bran were then planted in 17.5 cm. diam clay p
sterilize sandy loam soil.
ate in dextrose bottles were used. They ste ze sandy loam so
removed from the bottles and 20 g were The same procedure was done for the n
I with the soil around each plant. dal treatment that is, the test plants were
the combined treatment of P. lilacinus plus in 100 ppm suspension of phenamip
10 minutes and were then planted in p(
itolicum, the same sources of cultures were 1 mites d ere then planted in p1
sterilized soil. For the soil drench, 100
and the proportion was 1:1 whether applied poured round each plant. One da later
Sdrench or soilsubstrate mix. poured around each plant. One day later
root-dip treated plants and the non-treate
r the nematicidal treatment, 100 ml of 100 plants were inoculated with about 1,000 R
phenamiphos suspension was drenched into individuals per plant. As in the first test
potted plant. The check plants did not re- inoculated plants were arranged randon
any treatment, except that each was spaced apart on the concrete floor in th
ted with 100 ml distilled water, house to avoid crosscontamination. The
the 8 treatments were applied on 6-month were allowed to grow for 6 weeks and t
trus seedlings. Each test plant was inoculated effectiveness of the different treatments
urs after treatment with nematode contain- the nematodes was evaluated based on
out 2,000 larvae of T. semipenetrans through centage reduction of the nematode po]
e holes near the base of the plant. All treated inside the roots and in soil samples. The
including the checks were arranged random- of the treatments on plant growth was also
the cement floor of the greenhouse. The ted based on plant height and weight of t
were allowed to grow for 16 weeks. Evalua- roots.
)f the effectiveness of each treatment was
on reduction of the nematode population in RESULTS AND DISCUSSION
and soil samples and increase in plant growth.
ntrol of R. similis on banana. The experi- Effects of the biocontrol fungi and nen
was also conducted under greenhouse condi- treatment on T. semipenetrans. Based
using seedlings of banana (Musa balbisiana nematode counts in roots and soil of the
grown in 17.5 cm diam clay pots filled with ted plants, P. lilacinus and P. anatolicum i
red soil. The following treatments with 4 nificantly controlled T. semipenetrans ei
ition each were used 1) P. lilacinus soil lied alone or in combination (Table 1). H
1, 2) P. lilacinus root dip, 3) P. anatolicum the soil substrate mix with rice hull-rice b
Irench, 4) P. anatolicum root dip, 5) P. better control results than the soil drenc
us plus P. anatolicum combination soil pared with the nematicidal treatment,
1, 6) P. lilacinus plus P. anatolicum com- drench application gave significantly lower











e 1. Nematode counts and percentage reduction of Tylenchulus semipenetrans o
rhizopheres after different fungal and nematicidal treatments1

ROOT S

ATMENT Nematode Percent Nematode
Count Reduction Count


Drench

Slitacinus 270.0 c 63.7 21.2 ab
.anatolicum 413.5 cd 44.4 6.8 ab
.lilacinus + 563.5 d 24.2 39.5 b
P. anatolicum

..nhatratp Miy


. lilacinus 0.2 a 101
. anatolicum 0.8 a 91
. lilacinus + 0.5 a 91
P. anatolicum


1.8 a
1.5 a
0.8 a


1UU ppm) iuu.eo D 0.t 3z.o

trol 743.0 e 383.5 c

IData which are means of four replicates were collected 16 weeks after treatment. Means followed
r are not significantly different with DMRT at P = 0.05.

the soil-substrate mix application proved more Further observation ofP. lilacinus a
:tive than the nematicide. On the other hand, licum effects on T. semipenetrans in
combinedd use of P. lilacinus and P. anatolicum water agar containing adult females of
te soil drench application proved less effective trans in infected roots, actual parasitis
when applied singly indicating on antagonis- cinus was observed on the nematode.
effect. vaded the nematode body which ap
effects of the biological control and nematici- veiled and deformed (Fig. 2). The egg,


gave varying effects
Generally, the P. lilaci
rowth increase based
inared with P. anatoli,


re high- and killed the nematode indica
weights duces toxic substances which are
aticidal observation confirmed the findih
it only study (6).
Jt -Aiinr LC'/T-.*. -P*!, L .- ^ ---I


er hand in the soil-substrate mix the plants in dicate that both P. lilacinus and P. anc







Jan. & June 1986 Biological Control of Tylenchulus Semipenetrans on Citrus 45


Table 2. Height, root and top weights of citrus plants infected with Tylenchulus semipenetrans
from the different fungal and nematicide treatments.1


HEIGHT TOP ROOT
INCREMENT (cm) WEIGHT (g) WEIGHT (g)
Percent Percent Percent
Treatment Mean Increase Mean Increase Mean Increase


Soil Drench
P. lilacinus 4.8 ab 27.1 2.0 a 56.1 1.0 a 56.9
P. anatolicum 3.2 b 0.0 1.4 a 39.6 0.9 ab 50.6
P. lilacinus + 3.3 b 0.0 1.2 a 29.3 0.5 a 13.7
P. anatolicum


Soil-Substrate Mix

P. lilacinus 5.6 ab 36.9 2.0 a 56.9 0.6 bc 27.9
P. anatolicum 4.9 ab 28.6 1.4 a 35.6 0.5 c 10.2
P. lilacinus + 6.1 a 42.4 1.7 a 48.5 0.5 c 17.0
P. anatolicum

Phenamiphos (100 ppm) 4.5 ab 22.6 1.1 a 19.4 0.5 c 4.4

Control 3.5 b 0.9 a 0.4 c -

1Data which are means of four replicates were collected 16 weeks after treatment. Means followed by a common
letter are not significantly different with DMRT at P = 0.05.



















Fig. 1. Effects ofP. lilacinus, P. anatolicum and a nematicide phenamiphos treatments on top
growth of citrus plants as a result of the nematode control.
a = P. lilacinus soil-substrate mix e = Phenamiphos
b = P. lilacinus + P. anatolicum soil-substrate mix f = P. lilacinus soil drench
c = P. anatolicum soil-substrate mix g = non-treated check
d = P. anatolicum soil drench h = P. lilacinus + P. anatolicum soil drench







46 Philippine Phytopathology VoL 22


plants. For instance, in soil drench application
both fungi were more effective in reducing the ne-
matode population in the soil than in the roots
(Table 3). This effect was higher, but not signifi-
r" rcantly different from the nematicidal treatment.
Likewise. in the root-din avplication, the funeal


-* matode population in the soil than in th
-a On the other hand, the nematicidal tr
'. - was more effective in reducing the nema


Generally, r. luacinus was more elective man
P. anatolicum in controlling the nematodes in the
r soil. However, the combination of both fungi did
not show any significant advantage. In some cases
the combined effects of both was lower than its
Adult female of T. semipenetrans parasi- single treatment which again indicates that they
ized by P. lilacinus. Note the mycelial may have some antagonistic effects when grown
growth around the body. together. Compared with the nematicide, P. lila-

SMean counts and percentage reductions of R. similis in banana roots and soils from the different
ingal and nematicide treatments1

ROOT COUNT SOIL COUNT
MENT Percent Percent
Mean Reduction Mean Reduction


inch

rcinus 23.2 a 72.3 109.5 a 90.2
atolicum 122.2 b 0.0 116.5 a 89.6
icinus + 69.8 ab 17.0 105.0 a 90.6
anatolicum

iphos (100 ppm) 26.8 a 68.2 352.0 a 68.6

34.0 ab 1,121.0 b

[p
rcinus 24.5 a 60.8 37.0 a 85.9
atolicum 40.0 b 36.0 63.5 a 75.7
rcinus + 23.2 a 62.8 71.0 a 72.9
anatolicum

iphos (100 ppm) 3.8 a 94.0 89.0 a 66.0


Snot significantly different with DMRT.






























1 of nematodes in the soil


lively control R. similis on banana (4). Micro- with combined P. lilacinus and P. and
examination of the nematodes parasitized showed generally lower growth than the
lilacinus clearly indicate the presence of my- plants which may be due to the antagor
growth around and inside the body (Fig. 3). fects of both fungi when applied together
ects of the biocontrol and nematicidal 4).

4. Height and top weight of banana plants with R. similis from the different fungal and n
dal treatments.1
HEIGHT (cm) TOP WEIG
TMENT Mean Mea

)rench


ilacinus 25.8 189.4
wnatolicum 26.7 187.9
ilacinus + P. anatolicum 21.2 193.1
namiphos 30.9 200.6
>l 29.9 188.1

Dip

lilacinus 36.8 135.5
inatolicum 31.4 116.3
ilacinus + P. anatolicum 24.8 159.1
mnamiphos 29.8 123.8
ntrol 34.8 142.4



'ata which are means of four replicates were taken 6 weeks after treatment Statistical analysis of the dal


ents on plant











ents on plant


~o*-~-:







Phlippine Phytopathology



LITERATURE CITED


R. G. DAVIDE. 1980. Rado- gical control efficiency
avendish banana in Davao del fungi in different subst
ution and density as compared Radopholus similis The


3. DAVIDE, R. G. and R. A. ZORILLA. 1983. Evalua-
tion of a fungus Paecilomyces lilacinus for the
biological control of potato cyst nematode Glo-
bodera rostochiensis as compared with some ne-
maticides. Phil. Agr. 66:397-404.
4. GENERALAO, L. C. 1985. Evaluation of the biolo-


as biological control agents against selected plant
pathogens.Ph.D. Thesis,U.P. at Los Bafios,151 p.
7. VILLANUEVA, L.M. and R. G. DAVIDE. 1984.
Evaluation of several soil fungi for biological con-
trol of root-knot nematodes. Phil. Agr. 67:361-371.





Effects of Various Cul
and Weather Factoi
Sorghum Stal


Naomi G. Tangonm


Respectively, Assistant Dean, College of A
can, Cotabato, and Associate Professor, Depi
University of the Philippines at Los Bafios (UP
Portion of the Ph.D. Dissertation of the senr



AB

Two sorghum croppings, a main crop and a ratoc
were used to determine the effects of various culture
management practices and prevailing weather condo
tions on the occurence and development of sorghul
stalk rot.
Results show that except for lesion length, r
other disease parameter was significantly influence
by tillage practice. Deep plowing the field and weedir
apparently limited the size of lesions or severity of ii
fection on sorghum plants regardless of NPK levels al
plied and population density maintained. Conversel.
minimum tillage without weeding resulted to muc
larger lesion size. Grain yield of sorghum in both crol
pings was higher where a maximum tillage supplemei
ted with hand weeding was employed.
NPK fertilizers applied at higher rates resulted in




INTR

The National Research System listed sorghur
together with corn second in 12 commodities. Thi
crop research program is streamlined along th
five-year development plan of the National Econc
mic Development Authority (NEDA) and the prc
gram of the Ministry of Agriculture (MA). The re
searches are prioritized based on these major
thrusts such as the development of energy resom
ces and alternatives, self-sufficiency in food an,
better nutrition, development of export product
and import substitutes, improvement of the social
and economic well-being of the people, and env.
ronmental and ecological consideration. Research
on sorghum needs to be strengthened to support
the existing programs of the government in feed
grain and to utilize alternative sources of energy
Despite the fact that Mindanao is engaged i


ural Management Practices
s on the Development of
k Rot in Mindanao


i and Tricita H. Quimio


riculture, University of Southern Mindanao, Kaba-
rtment of Plant Pathology, College of Agriculture,
.B) College, Laguna, Philippines, 3720
or author submitted to UPLB.



TRACT

i significantly higher percentage infection of stalk rot
I in both main crop and ratoon sorghum. However, no
- significant effect on the rate of infection was noted.
I Plant population density did not have any signi-
ficant effect on both percentage and rate of infection
o of stalk rot. Lesion length, on the other hind, was sig-
I nificantly influenced by higher population density.
g Closer planting of sorghum promoted the increase in
lesion size.
The effect of weather factors showed that high
, temperature slows down infection rate; high relative
h humidity increases infection rate but not beyond an
optimum level; high rainfall exerts a depressive effect
on infection rate while longer sunshine duration acce-
lerates it.
a




)DUCTION

Southern Mindanao Agricultural Research Cent(
(SMARC) at the University of Southern Mindi
nao (USM) is considered the national research
center for sorghum, limited studies if not entire
ly wanting, has been done on diseases of sorghur
particularly sorghum stalk rot, a very severe an
endemic disease.
An earlier paper (5) showed that three fungi
pathogens were consistently associated with th
stalk rot complex. These were Colletrotrichut
graminicola (Cesati) Wilson, causing a "red rot
. symptom in sorghum stalks, Fusarium monil
forme Sheldon and Macrophomina phaseolin
(Tassi) Gold (= Rhizoctonia bataticola (Taub
. Butler for causing the charcoal rot of sorghum. Be
cause of their synergistic relationship, their corr
bined effect resulted to an etiological phenom






Philippine Phytopathology


MATERIALS AND METHODS

Experimental Area

The SMARC experimental area utilized for this
study is located in the northeastern side of the
USM campus near the University Hospital, at
Kabacan, North Cotabato.


Experimental Design

A three-factor factorial split plot design in a
randomized complete block with four replicates
was used.The areas was thoroughly prepared follow-
ing standard field procedure of one plowing and
two harrowings furrowed at 75 cm distance.
The main plot was 1,666 sq m with sub-subplots
measuring 4.5 x 7 m. A one meter alley separated
one subplot from the other. One set on opposite
fields was laid out to make a total of four repli-
cates.


Treatments

The mainplots were maximum tillage I (non-
conventional practice, deep plowed at 36-15 cm
supplemented with handweeding) and minimum
tillage II (conventional practice, plowed at 18-22
cm and no supplemental weeding).
The sub-subplots were 50-00 NPK kg/ha, 100-
25-25 NPK kg/ha, and 150-50-50 NPK kg/ha.
Half of the total amount of nitrogen (urea)
together with all the phosphorous (solophos) and
potassium (muriate of potash) were applied basally
on furrows and covered with a think layer of soil
(2-3 cc). The other half of the nitrogen was side-
dressed 28 days after planting (DAP).
The Sub-sub-subplots were population densi-
ties of 250,000 plts/ha, 350,000 pits/ha, and
450,000 pits/ha. Seeds of the IPB Hybrid variety
were drilled on furrows and after two weeks,
thinned out to one plant per hill following treat-
ment population densities. Off-bearing and hilling-
up were accomplished when the plants were about
1.5 feet tall or 28-30 DAP.
No artificial inoculation was performed because
the area was previously planted to sorghum where
the incidence of stalk rot was seemingly high. No
pesticides were applied on the sorghum plants
during the experiment. Buffer rows were main-
tained at the surroundings of the experimental
areas.


Disease Development

Percentage and rate of Infection
The percentage infection of sorghum stalk rot
was taken by the formula:


total rotted plants
total number of plants


x 100


Weekly counts were done beginning at the first
appearance of the characteristic diagnostic symp-
tom of stalk rot (Fig. 1) until physiological ma-


Fig. 1. Diagnostic external symptom of sorg-
hum stalk rot in natural field infection.


turity of the sorghum plant, i.e., from 49-91 DAP
for the main crop and from 35-77 DAR for the
ratoon crop. The rate of infection was also compu-
ted by transforming the percentage infection
values to its logit form and regressed with time.
The slope taken after regression analysis was the
apparent rate of infection. The simple regression
equation developed by Zadoks and Shein (7) was


Vol. 22






Jan. & June 1986



used as follows:


log e


Xt
xt = r.t. +c
1- xt


where:

r = rate of infection, per unit/day; t = time,
day and c = constant.

Severity of Infection
The severity of infection of stalk rot was assessed
by measuring the extent of rotting (lesion length,
cm) on sorghum stalks opened lengthwise (Fig. 2).


Agronomic Characters

Data on some agronomic characters of sorghum
were also gathered. These were:
1. Days to flowering the number of days to
flowering when 50% of the sorghum was in
bloom.
2. Plant height measured from the base of
the plant to the tip of the penicle head at
physiological maturity.
3. Grain yield weight of the sorghum grains
at 14% moisture content.
In all cases, sample plants were taken from the
three middle rows of each subplot.


Fig. 2. Characteristic external and internal symptom expressions of sorghum stalk rot
complex caused by various pathogens.


Ratoon Sorghum
Immediately after harvest of the main crop or
first cropping, the sorghum stalks were cut at
about an inch from the ground level. Plowing was
done on the same day following the same treat-
ments of the main crop. Data gathered were es-
sentially similar as the main crop in addition to
counting the number of tillers produced.


Weather Factors

Readings on weather conditions, namely: tem-
perature, rainfall, relative humidity, and sunshine
duration during the conduct of the field experi-
ment were taken from the USM SMARC PAGA-
SA Agromet Station. A correlation analysis on
the above factors plotted against the incidence or


Effects of Various Cultural Management Practices










The application of varying levels of NPK fertili-
zers particularly at higher rates tended to favor a
higher infection of stalk rot. At 150-50-50 kg/ha,
infection was significant at 26% over 100-25-25
and 50-0-0 kg/ha with 23 and 22% infection, res-
pectively, for the main crop. Similarly, the ratoon
crop had means of 41, 38 and 39% infection at
150-50-50, 100-25-25 and 50-0-0 kg/ha with NPK
rate significantly different over the others.

Rate of Infection (r)
As shown in Table 2, it appears that the main
crop had a greater r (= 0.068 and 0.063 per unit
day) for minimum tillage than the ratoon crop
(r = 0.018 and 0.017 per unit per day) for mini-
mum and maximum tillage, respectively. Differ-
ences between each treatment in either cropping
was, however, not statistically significant.

Table 2. Effects of tillage practices, NPK fertil-
iezers and population densities on rate
of infection of stalk-rot infected main
crop and ratoon sorghum, USM-SMARC,
Kabacan, North Cotabato.

RATE OF INFECTION1
(Per Unit Per Day)
TREATMENTS Main Corp Ratoon Crop

Tillage practice

Minimum 0.068 0.018
Maximum 0.063 0.017

NPK fertilizer level

50-0-0 : 0.067 0.019
100-25-25 0.65 0.018
150-50-50 0.65 0.019

Population density

250,000 0.068 0.017
350,000 0.067 0.018
450,000 0.062 0.018


percentage infection and severity of infection
(lesion length) of stalk rot of sorghum was made.
Analysis of variance for all data was done using
the General Linear Model (GLM). Test of signifi-
cance among means for all factors with signifi-
cantly different effects was made using Duncan's
Multiple Range Test (DMRT). Processing of data
was performed at the Agricultural Resource Cen-
ter, INC. (ARC), UPLB, College, Laguna.


RESULTS

Effects of Tillage Practices, NPK Fertilizer Levels
and Population Densities

Percentage Infection
Where tillage is concerned, Table 1 shows there
was no significant difference noted in percentage
infection between minimum 24% and maximum
24% treatments for both main crop (MC) and
ratoon crop (RC).
Table 1. Effects of tillage practices. NPK fertil-
izers and population densities on per-
cent infection rot-infected main crop
and ratoon, sorghum (IPB Hybrid)
USM-SMARC, Kabacan, North Cota-
bato, 1983-84.

% INFECTION 2
TREATMENTS Main Crop Ratoon Crop

Tillage practice

Minimum 24a 40a
Maximum 23a 39a

NPK fertilizer level

50-0-0 22b 30b
100-25-25 23b 38b
150-50-50 26a 41a

Population density

250,000 23a 39a
350,000 24a 39a
450,000 23a 40a

1Figures represent the mean of 4 replicates; means
with a column followed by a common letter are not
significantly different (= 0.05, DMRT).
2Taken 91 days after planting (DAP) and 77 days
after ratooning (DAR) for main crop (MC) nnd ratoon
crop (RC), respectively.


Philippine Phytopathology


Vol. 22


1No significant difference in
DMRT at 5% level of significance


all treatments using


NPK fertilization in varying levels had no signi-
ficant differences among each other. At the rate
of 100-25-25 and 150-50-50, the rate of infection
was not significantly different from the other two
treatments of the main crop. The highest and










lowest rate of NPK fertilizers for the ratoc
showed the same rate of 0.019 and therefore, we
not significantly different from each other.

Lesion Length (cm)

The severity of infection was assessed by me
during the lesion length (cm) of infected sorghu
stalks. Table 3 presents the effect of tillage, NP
fertilizer and population density on mean lesic
length of sorghum stalk rot-infected main crc
and ratoon sorghum. Minimum tillage signii
cantly increased lesion length for both croppin
with means of 40.22 cm and 73.75 cm for tl
main crop and ratoon sorghum, respectively:
Lesion length with maximum tillage had means i
35.10 cms for main crop and 61.50 cms for tl
ratoon crop.
NPK application at all levels in both cropping
showed significantly larger lesions with increasir
levels of NPK fertilizers. For the main crop, mea
lesion lengths were 29.12, 38.33, and 45.53 cm
50-0-, 100-25-25 and 150-50-50, respectively
Lesion length with the ratoon crop significant]
differed from each other with means of 60.62 ft
NPK rate of 50-0-0, 67.54 for 100-25-25 and 7,
71 cm for 150-50-50.
Population densities also had significant diffe
ences in all treatments for both main crop an
ratoon crop. Increasing population density result
to increasing lesion lengths. The lesion length fc
main crop were 24.24 cm for 250,000 plts/hi
32.28 cm for 350,000 and 56.45 for 450,000 pit!
ha. The ratoon crop in increasing order of trea
ments had means of 55.12, 68.79 and 78.96 cm
Grain Yield

Table 4 shows the effect of tillage practice
NPK fertilizer levels and population densities o
grain yield of sorghum. In both main crop an
ratoon crop a significant difference was note
between minimum tillage. Yields of 5,680 an
4,800 kg/ha were obtained in the main and rn
toon crops, respectively, when grown under min
mum tillage while 10,450 and 5,380 kg/ha wei
obtained under tillage for the main and ratoo
crops, respectively.
In the main crop, no significant effect we
exerted by both NPK fertilizer rates and popul;
tion densities on grain yield of sorghum. NPI
levels at 50-0-0, 100-25-25 and 150-50-50 ha
mean yields of 8,130, 7,970 and 8,090 kg/hi
respectively, while population density at 250,000
350,000 and 450,000 had mean yields of 8,27(


STable 3. Lesion length (cm) of stalk rot infected
: main crop and ratoon sorghum taken at
harvests as affected by tillage practices,
NPK fertilizers and population densities,
USM, SMARC, Kabacan, North Cota.
bato, 1983-841
MEAN LESION LENGTH
TREATMENTS Main Crop Ratoon Sorghu
STillage practice
Minimum 40.22a 73.75a
Maximum 35.10b 61.50b
NPK levels (kg/ha)
50-0-0 29.12c 60.62c
S 100-25-25 38.33b 67.54b
150-50-50 45.53a 74.71c
Population density (plts/ha)
250,000 24.24c 55.12c
S 350,000 32.28b 68.79b.
450,000 56.45a 78.96a
'Figures represent the mean of 4 replicates; mear
within a column followed by a common letter are nc
significantly different ( = 0.05, DMRT).
2Taken 95 DAP and 80 DAR for main crop and ri
toon sorghum, respectively.
Table 4. Effects of tillage practices, NPK fertili.
zers levels and population densities on
grain yield of stalk rot infected sorghum
(IPB Hybrid), USM-SMARC, Kabacan,
North Cotabato, 1983-84.1

GRAIN YIELD (kg/ha)2
TREATMENTS Main Crop Ratoon Sorghu:

Tillage practice

Minimum 5680a 4800a
Maximum 10450b 5380b

NPK level
50-0-0 8130a 4680b
100-25-25 7970a 5550a
150-50-50 8090a 5040a
Population density
250,000 8270a 4970b
350,000 7910a 5190a
450,000 8010a 5120a

1Figures represent the mean of 4 replicates; meat
within a column followed by a common letter are nc
significantly different (= 0.05, DMRT).
2Taken 95 DAP and 80 DAR for main crop and r










The ratoon crop had mean yields of 4,680,
5,550 and 5,040 kg/ha in increasing order of NPK
fertilizer levels. Significantly higher yields were
obtained in the ratoon crop when fertilizer level
was increased to 100-25-25 but was not signifi-
cantly better when fertilization was increased to
150-50-50.
Analysis of variance shows tillage was the only
treatment with a significant effect on grain yield
in the main crop. All other treatments had no
significant effects. Neither was there any signifi-
cant effect on the interactions of all other treat-
ments. The analysis of variance for the ratoon
crop however, shows tillage and fertilizer as having
significant effect on grain yield.

Number of Days to Flowering

The effects of tillage practices, NPK fertilizers
and population densities on some agronomic char-



Table 5. Effects of tillage practices, NPK fertilizer
characters of stalk rot-infected main crop


DAYS TO
SOURCESOF FLOWERING2
VARIATION Main Ratoon
Crop Crop


Tillage practice

Minimum 57.55a 32.38a
Maximum 51.46b 31.69b

NPK levels

50.0-0 52.28c 31.33b
100-25-25 54.45b 31.58b
150-50-50 56.79a 33.20a

Population density

250,000 53.00c 31.49a
350,000 54.25b 31.96ab
450,000 56.28a 32.28a

IFigures represent the mean of 4 replicates; means
significantly different (a = 0.05, DMRT).
2Taken when 50% of the plant population has folio
3Taken 90 DAP and 75 DAR for main (MC) and ra


acters of stalk rot infected main crop and ratoon
sorghum is presented in Table 5. Days to flower.
ing was significantly affected by tillage practices
with means of 57.55 and 51.47 days for minimum
and maximum treatments, respectively, for the
main crop. The same was true with the ratoon
crop with means of 32.38 and 31.69 days for mini-
mum and maximum tillage, respectively. NPK fer.
tilizer applications at different levels were also
significantly different from each other in the main
crop with means of 52.28, 54.45 and 56.79 days
for 50-0-0, 100-25-25 and 150-50-50, respectively.
Higher NPK seemed to prolong the number of
days to flowering. In the ratoon, on the other
hand, only the highest level of 150-50-50 NPK
significantly prolonged the number of days to flo.
wearing (33.20 days) with the other treatment
levels having no significant differences from each
other, the means being 31.33 days for 50-0-0 and
31.58 days for 100-25-25 NPK.



levels, and population densities on some agronomic
nd ratoon sorghum.1


PLANT HEIGHTS3 TILLERING4
(cm) CAPACITY
Main Ratoon Ratoon
Crop Crop Crop





208.05a 191.61a 85.41a
212.52b 193.02a 107.19b



210.53a 192.99a 57.71c
210.13a 190.57a 91.54b
210.20a 193.38a 109.66a



209.91a 192.17a 79.62c
210.45a 192.44a 97.42b
210.49a 192.34a 111.87a

within a column followed by a common letter are not

ved.
son crop (RC), respectively.










Plant Height

Table 5 also presents the effects of tillage pra
tice, NPK fertilizers and population densities c
plant height for both the main crop and ratoc
crop. Interestingly, only tillage practices for tl
main crop was significantly different to each othi
with means of 208.05 and 212.52 cm for mir
mum treatments, respectively. NPK fertilizer a]
plication in all levels were not significantly di
ferent from one another with means of 210.5:
210.13 and 210.20 cm for 50-0-0, 100-25-25 an
150-50-50, respectively.

Tillering Capacity
(Ratoon Sorghum)
Data for tillering capacity of ratoon sorghui
is also included in Table 5. A significantly high
number of tillers was produced in plants wit
maximum tillage with a mean of 107-19 tille:
was produced in plants with maximum tillaj
with a mean of 107.19 tillers compared to ti
minimum tillage mean of 85.41 tillers. The high:
NPK fertilizer level of 150-50-50 produced tl
significantly highest number of tillers with a mea
of 10966; the other rates which were also sign
ficantly different to each other with means (
57.71 and 9.54 tillers, respectively, were tl
treatment at 50-0-0 and 100-25-25. The trea
ments of varying population densities were als
significantly different to each other with meai
of 79.62, 97.42 and 111.87 tillers for 250,001
350-,000 and 450,000 plants/ha, respectively]
All treatments including the interactions between
tillage and fertilizers were highly significant.

Effect of Weather Factors on Stalk Rot-infecte
Main Crop and Ratoon Sorghum

Correlation Between Percentage
Infection of Stalk Rot-Infected


Table 6. Linear correlation coefficients of percei
toon sorghum with respect to weather di


WEATHER PARAMETER


Maximum Temp., OC
Minimum Temp., C
(Maximum-Minimum), OC
Average humidity, %
Rainfall, mm


Main Crop and Ratoon Sorghum and
Prevailing Weather Conditions

S Table 6 indicates the linear correlation coeff
client matrix for weather factors of percentage iT
Section of stalk rot-infected main crop and ratoo
r sorghum. For the main crop, percentage infection
was directly or positively correlated to maximum
(+ 0.13865), minimum (+ 0.40431) and average
[-
(0.43212) temperatures. It is interesting to not
That only temperature of all the weather variable
showed a significant effect on percentage infection
of sorghum stalk rot-infected main crop. All othe
weather parameters like relative humidity, rainfall
sunshine duration and including the difference
between maximum and minimum temperature
had negative correlations with percentage infect
Stion in that there was an inverse relationship.
s For the ratoon sorghum, however, maximun
e minimum, and temperature gradient showed
Negative linear correlation coefficients with pe
t centage infections of 0.21580, 0.47140, an
: 0.34335, respectively. This implies that an
Increase in the above weather parameters meal
a corresponding decrease in percentage infe
f tion or vice versa. All other parameters like ti
Temperature gradient such as specified in th
Case, relative humidity, rainfall and sunshine dur
Stion had positive values of + 0.04976, + 0.2135:
s + 0.56189 and + 0.15432, respectively, andthei
fore any increase in them meant a correspondir
decrease in percentage infection of stalk rot i
Sratoon sorghum.


r DISCUSSION

Findings show that the kind of tillage pracl
ces employed on sorghum main crop and ratoc
had a very significant effect on severity of infe


tage infection of stalk rot infected main crop and r
ta. USM, SMARC, Kabacan, North Cotabato, 1983-8.


MAIN CROP RATOON SORGHU


+0.13865 -0.21580
+0.40431 -0.47140
-0.21122 +0.04970
-0.43578 +0.21353
-0.22797 +0.65189
n ina; +0.15432










tion or lesion length of stalk rot. Deep plowing
supplemented with handweeding (maximum til-
lage) resulted in a very much reduced lesion
length on sorghum plants. Seemingly, this may be
due to the longer-term influence on sorghum
growth of tillage especially on continuous crop-
pings such as ratoon. Statistically, this may be
seen as a carry-over effect of the relatively large
individual variation of tillage and population.
In contrast, minimum tillage without deep
plowing and no handweeding promoted the dev-
elopment of markedly bigger lesions or a more
severe stalk rot infection. This corroborates with
a previous study made (1) in that cultivating the
soil somehow promoted stalk rot in corn regard.
less of wehther the pathogen was fungus or a
bacterium.
Interestingly, however, other disease para-
meters in this study, like percentage infection and
rate of infection, were not significantly affected
by the kind of tillage employed. This means that
tillage as cultural practice may be dispensed with
as it does not seriously predispose or infect sorg.
hum in the field.
The results of this study also point to the favor-
able effects of high rates of NPK fertilization in
minimizing stalk rot damage and the apparent ag-
gravating effects of phosphorous and potassium
application as well as low soil fertility. Wardlaw
(6) found that sorghum had the ability to use
considerable amount of soil moisture during its
growing period. Moreover, sorghum roots contain
large quantities of sugar which stimulate the
rapid multiplication of soil microorganisms. They
in turn absorb considerable nitrogen making it
unavailable to the succeeding crop.
The results also indicate that the influence of
higher population density on yield of stalk rot-
infected sorghum is an increasing trend because of
the competitive nature of crops. Sorghum has a
marked capability to compensate for variation in
plant population and planting arrangement; that
is, in higher plant population, the number of grain
per panicle for instance is reduced but yields are
obtained because of the increase in the number of
panicles per unit area (Karchi and Rudich, 3). Ex-
periments to test row spacing of from 10 to 40
inches on indicated that higher grain yields were
obtained at a population density of 150,000 tc
200,000 plants per hectare provided nutrition,


light and moisture are not limiting (4). The opti-
mum plant population density depends on cer-
tain conditions such as variety and other environ-
mental factors. In the Philippines, a plant popula-
tion of 200,000 plants/ha is recommended to
obtain high grain yields using the recommended
varieties and approved cultural practices (2).
The main crop periods (growth and sampling)
may be said to be hotter, more humid and with
more rainfall. The crop period for the cotton
sorghum was comparative drier, with more sun-
shine and lesser rainfall.
Correlation analysis revealed that there appeared
to be a certain element of compensatory effects.
For example a positive correlation was found for
the gradient air temperature vs. % infection in the
main crop but was exactly the opposite for the
ratoon crop. This was the general pattern observed
in this study. The results did not sufficiently justi-
fy making any other inference firstly, because of
the characteristics of the above-mentioned observa-
tions and secondly, because of the low values
(even among the different agromet weather varia-
bles, correlation coefficient were low).
The percentage infection was actually a mea
sure of the number of plants infected at a giver
time and was not indicative of how fast it dev
eloped or progressed. Therefore, it may have beei
affected more by endogenous and host-relatec
factors and was influenced by agrometeorologica
factors only in a very indirect way. The compensa
tory rule evident in those results suggested that if
certain agromet or weather factor was below the
threshold limit for optimum disease development
the usual trend was reversed so that there was i
balance established. When taken in the context o
the whole set of agromet or weather factors, thi
accounted for the "shortage" or the "surplus" a
the case may be.
In very general terms, the implications are: high
temperature slowed down the rate of infection; a
higher temperature gradient (difference between
maximum and minimum air temperature) accelera
ted the rate of infection but did not go beyond the
optimal level. Higher rainfall exerted a depressive
effect on the rate of infection. Longer sunshine
on the other hand, accelerated the rate of infec
tion, probably because it was associated with a
theoretical decrease in rainfall which some claim
to be acidic.










LITERA

1. BAYACAG, TERESITA C. 1983. Control of stalk rc
of corn through cultural practices, SMARC Am
Report 1982. Univ. of Southern Mindanao, Kab;
can, North Cotabato. p. 11.
2. GOMEZ, A. A. and A. C. MERCADO, Jr. 1968. Ho'
to grown grain sorghum. UPCA, College, Lagun;
p. 15.
3. KARCHI, Z. and Y. RUDICH. 1966. Effects of roy
width and seedling spacing on yield and its con
ponents in grain sorghum under dryland cond
tions. Agron. J. 58: 602.
4. STICKLER, F. G, and G. E. FAIRBANK. 196.


WURE CITED


: Grain sorghum stand and yields as affected b
tillage and use of press wheels. Agron. J. 57:18'
* 5. TANGONAN, N. and T. H. QUIMIO. 1985. Etiolog
of Sorghum stalk rot complex in Mindanao. Phi
Phytopathology. 21: 20-27.
6. WARDLAW, I. F. 1967. The effect of water stress c
translocation in relation to photosynthesis an
growth. Aust. J. Biol. Sci. 20: 25.
7. ZADOKS, J. C. and R. D. SCHEIN. 1979. Epidemic
logy and Plant disease management. New Yoi
Univ. Press, 427 p.


TURE CITED

t Grain sorghum stand and yields as affected b
tillage and use of press wheels. Agron. J. 57:18'
- 5. TANGONAN, N, and T. H. QUIMIO. 1985. Etiolog
of Sorghum stalk rot complex in Mindanao. Phi
v Phytopathology. 21: 20-27.
6. WARDLAW, I F. 1967. The effect of water stress c
translocation in relation to photosynthesis an
, growth. Aust. J. Biol. Sci. 20: 25.
- 7. ZADOKS, J. C, and R. D. SCHE1N. 1 79. Epidemic
- logy and Plant disease management. New YoI
Univ. Press, 427 p.










Optimum Dose of I
Prevention an

G. Bhaktavatsala




Division of Plant Pathology, Central Rice Re


AB

In order to determine the optimum dose of deltE
methrin for efficient management of tungro disease
through vector control, different concentrations wer
evaluated both under greenhouse and field condition;
Cypermethrin (100 g ai/ha) and carbofuran (2 k
ai/ha) were included as check insecticides. Based o:
these trials, it was concluded that 12 g ai/ha for delta
methrin in susceptible cultivar Taichung Native 1, an,
6 g ai/ha of deltamethrin in tolerant cultivar Ratn
were the lowest possible critical doses for efficient

INTRi

Carbofuran has been reported as one of the in
secticides to control tungro vector and to reduce
disease incidence (3, 5,6). A search has been mad(
for alternative insecticides to reduce disease inci
dence by controlling the vector. Satapathy anc
Anjaneyulu (4) reported cypermethrin, a synthe
tic pyrenthroid, as a powerful insecticide to kil
the insect vectors and to reduce disease incidence
remarkably. Subsequently, deltamethrin, another
synthetic pyrenthroid, has been reported to kil
the tungro vector to prevent tungro infection ii
greenhouse trials (2). The optimum dose of thi

MATERIAL

The persistent effect of deltamethrin in pre
venting tungro infection in a greenhouse was de
termined with different dilutions. Different dilu
tions of the insecticide were sprayed on 35-day olI
healthy Taichung Native 1 plants. The treated anm
untreated plants were inoculated individually a
different intervals i.e. 3,6, 9, 12, and 15 days afte
spraying by two viruliferous insects per plant
The leafhoppers were made viruliferous by feedin,
them on 45-day Taichung Native 1 diseased plant
for -48 h. There were three replications for eaci
treatment, each having 20 plants. A similar
number of inoculated untreated plants served a


eltamethrin for Tungro
I Vector Control

i and A. Anjaneyulu



search Institute Cuttack 753 006, Orissa, India.


TRACT

management of tungro disease under field conditions.
Cypermethrin equalled to 25 g ai/ha of deltamethrin
in the cultivar Taichung Native 1, whereas in Ratnam
carbofuran, cypermethrin and a low dose of deltame-
thrin (6 g ai/ha) were on par. There was strong posi-
tive correlation between rate of of tungro infection
and grain yields indicating that higher grain yield in
insecticide treated plots was due to tungro disease in
the present experiment.



IDUCTION

insecticide for tungro prevention and vector con
trol has not yet been reported. We tested diffe
rent dilutions of deltamethrin both under green
house and field conditions in order to determine
the optimum dose to be used by rice growers. W4
have also compared these dilutions with effective
concentrations of cypermethrin and carbofurai
which had been reported effective in reducing th<
disease incidence by controlling the vector (4, 6)
The preliminary results have been published it
IRRN 11 (5): 20-21.


1 AND METHODS

days after inoculation based on typical symptom
of orange discoloration and stunting and vecto
mortality 48 h after release of insects into cages
The vector mortality counts were adjusted usinj
Abbott's formula (1). The values of tungro pre
vention were calculated based on formula suggest
ted by Satapathy and Anjaneyulu (4). Analysis o
variance was conducted by statistical method
after transofrming percent values into angula
values. The treatments were compared by Dun
can's Multiple Range Test (DMRT). The relation
ship between concentration of deltamethrin an<
percent prevention and vector mortality was cor










Different dilutions of deltamethrin were field
evaluated using 'Taichung Native 1' (susceptible)
and 'Ratna' (tolerant) as test cultivars. The diffe-
rent dilutions used were 200, 100, 50, 25, 12 and
6 g ai/ha. Cypermethrin (100 g ai/ha) and carbo-
furan (2 kg ai/ha) were included in the trial as
check insecticides. Cypermethrin and deltameth-
rin were applied as foliar spray while carbofuran
was applied as granules by broadcast method,
Different concentrations of deltamethrin and
check cypermethrin were applied at 10-day inter.
vals i.e. 15, 25, 35, and 45 days after transplant
ing (DT), whereas carbofuran was applied three
times as broadcast application at 15, 30, and 45
DT. The other experimental details regarding
design, spacing, a plot size, fertilizer schedule
date of sowing and transplanting and method ol
simulating tungro epiphytotic condition were
the same as described by Satapathy and Anja
neyulu (4).
Disease incidence was monitored at weekly

RESULTS A

Persistency studies of deltamethrin with dif.
ferent dilutions under greenhouse conditions re-
vealed that there was a gradual decrease of per
cent prevention with gradual decrease of concen-
trations from 200 to 6 ppm at all days after treat-
ments. Similarly there was gradual decrease in
per cent prevention along with time lapse (Table
1). More than 50% reduction was observed upto



Table 1. Persistence of deltamethrin for prevent
virescens in greenhouse tests.

Concentration % Prevent
Insecticide (ppm) 3 DAT

Deltamethrin 200 100 a2
Deltamethrin 100 100 a
Deltamethrin 50 84 b
Deltamethrin 25 77 c
Deltamethrin 12 43 d
Deltamethrin 6 27 e
Cypermethrin 100 78 c
Carbofuran 1 kg ai/ha 43 d

IAdjusted values by Abbott's formula.
2In each column, the values followed by the same letti
Duncan's multiple range test at P 0.05.


intervals starting 28 DT. The adult and nymph vec-
tor populations were monitored at 30 and 42 DT,
The sampling procedures for vector and disease in-
cidence described by Satapathy and Anjaneyulu
(5) were used in the present experiment. Plant
height, panicle number per plant and grain yield
were recorded at harvest. The sampling for plant
height and panicle number per plant was 1 m2
whereas grain yield was determined based on har.
vest of entire plot.
Rate of infection (r) in each treatment was cal-
culated using the formula of Van Der Plank (7).
The data were analyzed by randomized block
design and treatments were compared by DMRT.
The differences between two treatments were se-
parated out by alphabets The functional rela-
tionships between concentration of deltameth.
rin and rate of tungro infection, rate of tungro in-
fection and grain yield, concentration of delta-
methrin and disease incidence were computed by
regression analysis.

ID DISCUSSION

15 DAT in 100 and 200 ppm, upto 9 DAT with
25 and 50 ppm and 9 DAT with cypermethrin
There was no significant difference between 12
ppm deltamethrin and carbofuran at all interval,
of testing, while 25 ppm and above of deltameth
rin were significantly superior. Carbofuran was sig
nificantly inferior to cypermethrin. Vector mortal
ity also gradually decreased with decrease in dilu



in of tungro virus infection and mortality of N.


on of infection % Vector Mortality1
9 DAT 15 DAT 3 DAT 9 DAT 15 DAT

89 a 56 a 100 a 97 a 70 a
80 b 51 ab 100 a 84 b 63 b
65 c 44 be 87 b 62 c 35 c
50 d 29 d 80 c 54 c 24 d
27 e 8e 44 d 22 d Oe
5f Of 16e Oe Oe
57 cd 37 cd 82 c 56 c 27 d
27 e 5e 41 d 23 d Oe


r do not differ significantly according to










tion of deltamethrin and also with time lapse.
More than 50% of vector mortality was observed
with 100 and 200 ppm of deltamethrin until 15
DAT and 25 and 50 ppm upto 9 DAT. As in per-
cent prevention, cypermethrin almost equalled to
25 ppm deltamethrin. Carbofuran was inferior to
cypermethrin and equalled to 12 ppm of delta-
methrin.

Table 2. Percent tungro disease incidence in Taichu
methrin at different concentrations.

Dose
Insecticide (g a.i/ha)
T

Deltamethrin 200 0.0 a
Deltamethrin 100 0.0 a
Deltamethrin 50 0.0 a
Deltamethrin 25 0.0 a
Deltamethrin 12 0.0 a
Deltamethrin 6 0.3 a
Cypermethrin** 100 0.0 a
Carbofuran 2 kg 0.0 a
Control 0.5 a

*In each column values followed by the same letter do
**Check insecticides


Table 3. Rate of tungro infection (1) and per cent i
treated with deltamethrin at different con


Insecticide Concentration
(g a.i./ha)

Deltamethrin 200
Deltamethrin 100
Deltamethrin 50
Deltamethrin 25
Deltamethrin 12
Deltamethrin 6
Cypermethrin* 100
Carbofuran* 2 kg
Control

*Check insecticides

of deltamethrin. The disease incidence in carbo
furan was significantly higher than 12 g a.i./ha of
deltamethrin, and also cypermethrin. However
all the insecticide treated plots had significantly
less disease incidence when compared to control


In field trials, although there were significant
differences in maximum disease incidence in cul-
tivar Taichung Native 1 among 200, 100, 50, 25
and 12 g ai/ha, the disease incidence was less than
10%0 in all these treatments. The disease incidence
was very high (80.9%) in treatment 6 g a.i./ ha of
deltamethrin (Table 2). The disease incidence in
cypermethrin was on par with 50 and 25 g ai./ha

ig Native 1 (T) and Ratna (R) rice treated with delta-


Days after transplanting (DT)*
28 49
R T R

0.0 a 2.9 a 1.7 a
0.0 a 3.7 a 1.9 a
0.0 a 4.8 ab 3.7 b
0.0 a 6.2 b 4.5 bc
0.0 a 9.5 c 4.7 bc
0.0 a 80,9 e 5.2 c
0.0 a 6.3 b 2.1 a
0.0 a 19.3 d 11.6 d
0.1 a 100.0 f 43.6 e

not differ significantly according to DMRT at P = 0.05



disease control (2) in Taichung Native 1 and Ratna rice
:entrations.

TN 1 Ratna
1 2 1 2


).152 97 0.129 96
).165 96 0.131 96
).177 95 0.154 92
),190 95 0.175 90
1.211 91 0.177 89
).330 19 0.181 88
),191 94 0.136 96
).248 81 0.221 73
).603 0.285



90% even in 12 g a.i./ha of deltamethrin and also
cypermethrin. The rate of tungro infection wa:
remarkably less in all the concentrations of delta
methrin except 6 g.a.i./ha when compared to con
trol (Table 3).










than 6% in all concentrations of cypermethrin an(
deltamethrin (table 2). Thus disease control wa
more than 94 in all these treatments (Table 3)
The insecticide, carbofuran was significantly in
ferior when compared to above treatments. Thi
disease incidence in all the later observations il
treated plots was sginificantly less than control
There was not much variation in rate of tungr<
infection among the insecticide treatments, the
same being high in control.

The plant height, panicle number per plant an
grain yield were significantly superior in insect

Table 4. Plant height, panicle number and grain yi
deltamethrin at different concentrations


TN
Dose Height Pan
Insecticide (g a.i./ha) (cm) numl
(per pl

Deltamethrin 200 75.5 f* 10.3
Deltamethrin 100 72.3 9.4
Deltamethrin 50 71.0 de 8.8
Deltamethrin 25 68.4 cd 8.6
Deltamethrin 12 65.5 c 8.4
Deltamethrin 6 46.1 a 4.3
Cypermethrin** 100 71.8 e 9.2
Carbofuran** 2 kg 62.1 6.8
Control 45.2 a 3.2

*In each column, the values followed by the same let
range test at P = 0.05.
**Check insecticides
In cultivar Ratna, the grain yields of all insect
cide treated plots were significantly greater tha:
control (Table 4). Among the treatments, their
was no significant difference among carbofurar
cypermethrin, 6, 12 and 25 g ai./ha of delta
methrin. Once again, there Was no significant dil
ference between 200 and 100g. a.i./ha of delt
methrin. Once again, therewas no significant
difference between 200 and 100 g. a.i./ha and als
50 and 25 g a.i./ha of deltamethrin.
The insect population was remarkably less i
all the insecticide treated plots than the contre
(Table 5). There was not much variation among
symthetic pyrethroids in both the cultivars. Hov
ever, the insect population in 6 g ai./ha of delti
methrin, especially in cultivar Taichung Native I
In cultivar Ratna, there was no such difference
There was a strong negative correlation between


cide-treated plots in cultivar Taichung Native
when compared to control except 6 g a.i./ha o
deltamethrin with regard to plant height ani
panicle number (Table 4). These yield bearin;
parameters and grain yield in 12 g.a./ha was mud
better (significantly superior) than 6 g a.i./ha o
deltamethrin. There was no significant different
in grain yield between 200 and 100 g a.i./ha of del
tamethrin and among 50, 25 and 12 g a.i./ha o
deltamethrin. Cypermethrin paralleled to 50, 25
12 g a.i./ha of deltamethrin. Carbofuran was in
ferior to cypermethrin and 12 g a.i./ha of delta
methrin.

Id in Taichung Native 1 and Ratna rice treated with



Ratna
le Grain Height Panicle Grain
er yield (cm) number yield
it) (kg/ha) (per plant) (kg/ha)

3342 e 73.5 d 11.6 b 4734 e
d 3100 e 72.7 cd 11.6 b 4329 de
cd 2614 d 68.1 bcd 10.6 ab 4036 cd
cd 2418 d 67.3 bc 10.6 ab 3813 bcd
c 2362 d 66.6 ab 10.7 ab 3405 b
664 b 65.0 ab 10.2 a 3355 b
d 2572 d 68.0 bcd 10.6 ab 3572 bc
1362 c 68.1 bcd 10.7 ab 3547 bc
209 a 61.2 a 10.3 a 2937 a

er do not differ significantly according to Duncan's multiple


number per plant and grain yields indicating th,
reduced yields in control plots are primarily dul
to tungro disease (Table 6). A positive correlation
was observed among plant height, panicle number
per plant and grain yields. Also there was strong
positive correlation between insect population an(
rate of tungro infection which indicates that thi
disease is primarily spread by Nephotettix vire
scens. The relationships between highly corre
lated characters were shown in figures 1 to 6. li
all the cases, the relationships follow exponentia
model.
Based on data presented above, it can be con
cluded that all concentrations of deltamethrij
except 6 g a.i./ha in Taichung Native 1 was mud
better than carbofuran. However, cypermethri
has equal effect as that of 25g a.i./ha of delta
methrin in Cultivar Taichung Native 1. In Cultiva










cypermethrin and carbofuran. Hence, we conclude
that 12 g a.i./ha of deltamethrin in susceptible cul-
tivar Taichung Native 1 and 6 g aj/ha of delta-
methrin in tolerant cultivar Ratna for efficient
management of tungro disease in order to get

Table 5. Adult and nymph population of Nephot
treated with deltamethrin at different conci


Dose
Insecticide (g a../ha) Taich
Native

Deltamethrin 200 3.3
Deltamethrin 100 5.0
Deltamethrin 50 4.7
Deltamethrin 25 7.3
Deltamethrin 12 7.7
Deltamethrin 6 16.4
Cypermethrin** 100 3.0
Carbofuran** 2 kg 9.3
Control 50.7

*Average values of 2 observations recorded at 30 and 4;
**Check insecticides


Table 6. Interrelationships between maximum dise
(3), panicle number (4), adult (5), nymi
Native 1 and Ratna rice treated with delta

Correlation ci
1 2 3

1 0.923 -0.952
2 0.889 .0.867
3 0.592 -0.694 -
4 -0.254 -325 0.553
5 0.931 0.921 -0.678
6. 0.931 0.913 -0.532
7 .0.706 -0.752 0.684


Significant value of 'r' for 25 d. f. at 5% = 0.381
Significant value of 'r' for 25 d. f. at 1% = 0.487


satisfactory yields. These extreme low doses of
deltamethrin were well under the purview of
farmers' budget when compared to yield figures
and cost of input, as far as disease protection is
concerned.

ttix virescens in Taichung Native 1 and Ratna rice
ntrations

Adult population Nymphal population
per 20 hills* per 20 hills
ng Ratna Taichung Ratna.
1 Native 1

1.4 0.3 0.0
1.3 1.6 0.3
4.7 3.0 0.7
6.3 4.4 0.6
8.3 4.0 1.6
6.7 13.3 3.7
2.0 2.0 1.3
13.0 22.3 34.0
42.7 151.6 103.7

days after transplantation.



ise incidence (1), rate of tungro infection (2), height
hal population (6) grain yield and (7) in Taichung
lethrin

efficient Taichung Native 1
4 5 6 7

-0.919 0.907 0.826 0.712
-0.866 0.969 0.950 -0.589
0.932 -0.778 -0.778 0.806
-0.862 -0.817 0.779
-0.350 0.953 -0.593
-0.260 0.892 0.562
-0.390 0.732 -0.680 -









Jan. & June 1986


Optimum Dose of Deltamethrin for Tungro


Fig. 1. Relationship between concentration of Fig. 2. Relationship between concentration of
deltamethrin and vector mortality deltamethrin and prevention of tungro
infection.


Fig. 3. Relationship between concentration of
deltamethrin and disease incidence in the
rice cultivars TNI and Ratna.


Groin nob I Kg/tb)


Groin yield( Kg/Ho)
50001- ---

4500 ,--' ..R.0

4000 rf' 0 yi00 i.
150 H* o095"






1500

1000

500


o a0 4o o a o 10 2 140 1 o IWo zoo L2
ConcentlrOtOn(GA I /Hoa)


Fig. 5. Relationship between concentration of del- Fig. 6.
tamethrin and grain yield in the rice culti-
vars TN1 and Ratna.


Rot of infelonn

060
0.55

0.50

0.45

040

035

0.30

025


0.15 -

0 20 1 O 1 I 18 0 20
ConcantmrlK (G.A.I /Ho)


Fig. 4. Relationship between concentration of
deltamethrin and rate of tungro infection
in the rice cultivars TNI and Ratna.


Grain yield (Kg/Ho)
5000

4500 -

4000

3500- RodI o0,
I 50 ISt i I

2500 I
2500

2000

1500 TNI o1
V 104.4 "
1000 0

500-

015 0.25 0.35 045 0.55
Rote of infection


Relationship between rate of tungro in-
fection and grain yield in the rice cultivars
TNI and Ratna.











LITER,

1. ABBOTT, W. S. 1925. A method of computing th
effectiveness of an insecticide. J. Econ. Entomol
18: 265-267.
2. BHAKTAVATSALAM, G. and A. ANJANEYULU
1984. Greenhouse evaluation of synthetic py
rethroids for tungro prevention. Int. Rice Res
Newslett. 9(2): 15.
3. RAO, G. M. and A. ANJANEYULU. 1979. Carbofu
ran prevents rice tungro virus infection. Curr. Sci
48: 116-117.
4. SATAPATHY, M.K. and A. ANJANEYULU. 1984
Use of cypermethrin, a synthetic pyrethroid,





ACKNOI

The authors wish to t
Central Rice Research Insi
Head, Division of Plant P,
ties and to Mr. S. Rawlo fR


IURE CITED

in the control of rice tungro virus disease and its
vector. Trop. Pest Management. 30:170-178.
5. SATAPATHY, M. K. and A. ANJANEYULU. 1986.
Prevention of rice tungro virus disease and control
of the vector with granular insecticides. Ann. Appl.
Biol. 108: 503-510.
6. SHUKLA, V. D. and A. ANJANEYULU. 1980. Evalua-
tion of systemic insecticides for control of rice
tungro. Plant Dis. 64: 790-792.
7. VAN DER PLANK, J. E. 1963. Plant diseases; Epide-
mics and Control. Academic Press, New York.





LEDGMENT

mk Dr. H. K. Pande,Director,
ute and Dr. S. Gangopadhyay,
lology for providing the facili-
his help in Statiscal analysis.







Philippine Phytopathological Society, Inc.
1986 Phil Phytopath. 22: 65-67


Phytopathological Note: Occurrence of
Race 7 of Xanthomonas campestris
pv malvacearum (Smith) Dye
in the Philippines


Teodora O. Dizon and T. T. Reyes



Science Research Specialist and Associate Professor, respectively, Institute of Plant Breeding
and Department of Plant Pathology, College of Agriculture, University of the Philippines at Los
Bafios, College, Laguna, Philippines, 3720.


ABSTRACT

The occurrence of race 7 of Xanthomonas campes-
tris pv malvacearum, a bacterium causing bacterial
blight, black arm and bacterial boll rot in cotton was
reported for the first time in the Philippines.



INTRODUCTION


MATERIALS AND METHOD


Isolation of Bacterium

The bacterium was isolated from leaf lesions
a susceptible cotton line, Deltapine 16, planted
the greenhouse of the Institute of Plant Breedinj
April, 1986 using the streak plating technique
n+r i + ana-r i;nalp mlnnnipc nf thp. hactprillm


mean


causes a serious disease of cotton commonly re
ferred to as bacterial blight, angular leafspot oi
vein blight, black arm and bacterial boll rot
These symptoms are common in almost all cotton
growing areas of the world. An estimated yield
loss of more than 50 percent in susceptible cotton
cultivars in the United States of America was re
ported by Simpson (6) and about 30 percent ir
the Philippines (5). Serious occurrence of th(
disease in the Philippines was first reported by Re
inking (4). In November, 1980, outbreak of bac
trial blight occurred in Cagayan province.
Xanthomonas campestris pv malvacearum is
rod-shaped, motile with single polar flagellurr
and Gram-negative. On culture agar media, the
bacterium produces yellow pigment being non
water soluble carotenoid (1) and has a very nar
row host range.
So far, 18 races of X. campestris pv malva
cearum from various parts of the world have beei
identified based on reactions on differentia
varieties (2).
This study reports the occurrence and identi
--C -- '7 -f V bot. v l


terium was tested on Deltapine 16, the susceptible
cotton line from where the bacterium was isolated


Inoculum Preparation and Inoculation Method

A loopful of the pure culture of each of the 1C
isolates (Isolates 1, 2, 3, 4, 5, 6, 7, 8,9 and 10) i
sterile distilled water was streaked on slants and in
cubated at 28 to 30 C for 48 hr. Sterile distilled
water was aseptically added to the culture tubt
and stirred with sterile wire loop to suspend the
organism. The number of bacterial cells in the sus
pension was adjusted to 0.90 absorbance on Spec
trophotometer (Bausch and Lomb Spectronic 20:
with a red filter at 620 nm. The cell suspension
contained approximately 5 x 107 cells per ml ol
water.
Thirty-day old cotton seedlings of the different
tial hosts were inoculated by spraying both lea
surfaces with the prepared bacterial suspension
fl-- 4nnf nT in,,+ia nlandc liran an










Differ

The cotton lines used as differential hosts
were 101-102B, 1-10B, 20-3, Acala 44, Mebane
B-l, Stoneville 20 and Stoneville 2B-S9. The seed!
were sown in No. 7 clay pots containing sterile
soil and kept in the greenhouse. Five plants ol































1 No visible lesion or
pinpoint lesion

2 Small lesion, drying
rapidly
3 Larger lesion, slowly
drying

4 Large, water-soaked
lesion that turned
black when dry


itial Host

each line were inoculated. Reactions of the inocu
lated plants were evaluated 10 days after inocula
tion based on the following rating scale (Fig. 1
developed by Hunter et al., (2):

























3 4






Immune or
Resistant

ReResistant
Resistant

Susceptible

susceptible

Susceptible











RE




Pathogenicity Test

The isolates of the bacterium produced typical
bacterial blight symptoms when inoculated or
leaves of the susceptible cotton line.

Reaction of Diffential Hosts

The seven cotton lines showed varying reaction

Table 1. Lesion size and characteristics and readc
isolates of Xanthomonas campestris pv m



Lesion s
Line (Isc

Stoneville 20 pinpoint
101-102B small (1
3 to 4 di
Stoneville 2B-S9 larger (3
6 to 7 di
Mebane B-l larger (3
6 to 8 di
1-10B larger (4
7 to 9 di
Acala 44 large (5 1
turned b
20-3 large (5 1
turned b


iULTS




to X. campestris pv malvacearum (Table 1). Only
two lines, namely: Stoneville 20 and 101-1021
showed resistant reactions. Other cotton lines ex
hibited susceptible reaction to the bacterium.
Based on the reaction of the different cotton
lines, all isolates of X. campestris pv malvacearum
were identified as race 7.



ons of the cotton lines inoculated with the different
Ivacearum 10 days after inoculation.



,e/characteristics
ates 1 10) Reaction

lesions resistant
o 2 mm), dried
ys resistant
to 4 mm), dried
ys susceptible
to 4 mm), dried
ys susceptible
to 5 mm), dried
ys susceptible
im or more),
ack when dry susceptible
im or more),
ack when dry susceptible


LITERATURE CITED

1.DYE, D. W. 1962. The inadequacy for the usual fungal and bacterial diseases. IPB-CRDI Res. Proj
determinative tests for the identification of Xan- Annual Rept. 24 p.
thomonas spp. New Zealand J. Sci. 5:393- 6.Simpson, D. M. 1956. Strains of cotton resistant t
416. bacterial blight. P1. Dis. Reptr. 40:549-555.
2.HUNTER, R. E., L. A. Brinkerhoff and L. S. Bird.
1968. The development of a set of upland cot-
ton lines for differentiating races of Xantho-
monas malvacearum. Phytopathology 58:830. ACKNOWLEDGEMENTS
3.KELMAN, A. 1954. The relationship of pathoge-


lll a 1U1ii Ulitllll b. oL. I
appearance on a tetrazolium medium. Phyto- & M University, Texas, USA for
pathology 44:696-695. tial hosts and to the National P
4. REINKING, O.A. 1918. Philippine Economic Plant Laboratory (NPGRL). Institute of
Diseases. Phil. J. Sci. 13: 165-170. College, Laguna for procuring the (
5.REYES, T. T. and T. O. Dizon. 1983. Screening of


n~r\l~r;~nl hTrr~s ~M-rs~n


nv --n---- -
rwifiina +11







Philippine Phytopathological Society, Inc.
1986 Phil. Phytopath. 22: 68-69

Phytopathological Note: Occurrence of
Sclerotium Boll Rot of Cotton
in the Philippines



Teodora O. Dizon and Tiburcio T. Reyes

Respectively; Science Research Specialist, Institute of Plant Breeding and Associate Profes-
sor, Department of Plant Pathology, College of Agriculture, University of the Philippines at Los
Bafios, College, Laguna, Philippines, 3720.


ABSTRACT
The occurrence of cotton boll rot caused by Scle-
rotium rolfsii is reported for the first time in the
Philippines.


INTRODUCTION

In November, 1985, an unusual disease of cot-
ton boll was observed on lines Deltapine 16, JPM
782-488-1, 425, 82-N-56, 82-N-60, 82-N-66 and
82-N-70 planted in the Cotton Disease Nursery at
the University of the Philippines at Los Baiios,
College, Laguna. Infected bolls were brown, dried
with abundant sclerotia on the surface of the car-
pel tissue and in between locules.


MATERIALS AND METHODS

Isolation and Identification of the Pathogen

The fungus was isolated by planting carpel tis-
sues and sclerotia from infected boll. Sclerotia
were directly placed on plated potato dextrose
agar (PDA). Infected carpel tissues were cut into
small sections, disinfected with 10% NaOCI for
10 min, rinsed twice with sterile distilled water,
blotted dry and then planted on plated PDA. The
agar plates were incubated at 27 to 30 C under
continuous light until growth of the fungus was
observed. The fungus was identified based on
growth characteristics and morphology of mycelia
and sclerotial bodies.

Pathogenicity Tests

Seven-day old pure cultures of 7 isolates of the
fungus from PDA plate were inoculated to healthy
bolls of cotton line Deltapine 16, one of the lines
from where the fungus was isolated.


Inoculation Method


The fungus was inoculated into wounded and
unwounded bolls. Before inoculation, the bracts
were removed, disinfected with 10% NaOCI for
20 min and rinsed twice with sterile distilled
water. For wounded boll inoculation, the carpel
wall was pricked with sharp sterile scalpel, while
for unwounded boll inoculation,no injury was made
to the boll. The inoculum, 7 mm diameter my-
celial agar disc, was placed on the on the wounded
and unwounded areas of the boll and held in place
with a tape. The inoculated bolls were enclosed
in moistened plastic bag for 72 hr. The age of the
bolls used were 10, 15, 20, 25, 30 and 35 days
after anthesis. Three bolls were used for each age
level. Wounded and unwounded bolls not inocu-
lated with the fungus served as control.
RESULTS AND DISCUSSION

Disease Symptoms


In the field, the symptoms first appear as light
brown spots on the carpel. The spots enlarge ra-
pidly and turn brown causing drying of the whole
carpel tissue, spreading to the peduncle and the
leaf petiole (Fig. 1). White feathery-like mycelia
were produced on the surface of the boll. Later,
numerous round to irregular, white to light brown
sclerotia were produced. When an affected boll is
split open, white cottony mycelial growth and
sclerotia of the fungus were observed in the lo-
cules, lint and seeds. The inner tissues became dry
and turned brown and the lint discolored and dis-
integrated. Seeds became rotted.

The Pathogen

Isolations of carpel tissues and sclerotia from






pathological Note: Occurrence of Sclerotium Boll 1


infected boll yielded Sclerotium rolfsii Sacc. The infected carpel tissues. The morphological chai
pathogen grew very well on PDA forming scarse acteristics of the isolated fungus were similar t
white mycelia and round, white turning light S. rolfsii causing seedling diseases (1,3,4) and bo
brown sclerotia 2 to 4 days after plating. The size rot as reported by Lyle, and cited by Watkini
of the sclerotia ranged from 0.5 to 2.0 mm in dia- (5) in cotton.
meter. No other fungal species were isolated from















Figure 1. Boll rot of cotton caused by Sclerotium rolfsii Sacc.

Pathogenicity Tests

All isolates of the fungus produced the disease disease. Generally, symptoms on infected bol
both on inoculated wounded and unwounded found in the field and bolls inoculated with is<
bolls at all age levels. The fungus grew rapidly on lated fungus were similar.
the inoculated bolls producing white mycelia and The pathogen is a major soilborne-seedlinj
brown lesions 3 to 4 days after inoculation on disease causing organism. In cotton Aycock (1
wounded bolls and 6 to 9 days on unwounded believed that the fungus usually attack plar
bolls. From the boll, infection spreads to the pe- parts in contact with the soil or near the ai
duncle and leaf petiole. Later, the infected bolls, soil interface. In seedling diseases, the nature (
peduncle and leaf petiole turned brown and dried spread of the pathogen and the mechanism <
with abundant mycelia and sclerotia on the sur- pathogenicity were explained in detail by Boyl
face. Inoculated immature bolls (10 to 20 days (2) and Watkins (5). When soil moisture is abui
old) failed to open. When split open, the inner dant, growth of the fungus may extend into tl
walls of the carpel of affected locules and stylar stem few inches above the ground surface. Sine
canal were brown and dried. The lint turned bolls are located a foot or more above the so
gray to reddish brown. Numerous sclerotia were level, further investigations on the nature of tt
also observed. Bolls 25 to 35 days old opened at spread of the pathogen and the development (
the carpel tip exposing the white to light brown, infection on bolls have to be undertaken. Their
compacted locks. Locks at the locular sutures in would somehow explain why under field condo
between carpels were stained. Seeds of immature tions only mature bolls were affected but und
bolls had wrinkled, brown and soft seedcoat. greenhouse inoculation tests both the immatu
-i,, .U11- ,-a A.A nh an, mrn amrmntnm of the and mature bolls succumb to infection.


Jan. & June 1!








































al order and with number
tnote. Biological Abstr
- consulted in abbrevia
lipp. Entomol., Philipp


, and each typed on a
Id be understandable w
re to be used for footn<
re Cited and should be


ending of the paper. Tl
, and photographs) she
amposite cuts when po
figure reference, using


ers. Do not cite un-
acts' 1968 List of
ting the names of
. Phytopathol., J


i.e. after Literatur


separate page. The3
without reference t(
)tes to tables. Page:
numbered accord


ie size and arrange
)uld correspond t(


11. See latest journal of Philippine Phytopathology for more details on the format of
papers to be submitted to the journal.

12. Articles published are not paid but authors foot the bill for reprints


tion should
k; it should
title Abbrei
nples of al
it Dis. Rept

nents should


be number,
;criptive he;
er case sup(
iles should


I add clear]
res (graphs
Combine il
correspond


erials with
)urnals. E:
[ol. Biol., I

Wcknowled;
ited.

'ables shot
nust have
he text. LA
containing
agly.

figuress sho
nents of f
journal pal
ach unit 1
II -- fl. I


:xt) under lil

: in alphabet
appear as f
tions must
reviation: P
J. Agr. Res.

be placed a


consecutive
ings and shi
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How Literat


to an under
ine, drawin
stations in
rith the tex


1T-TT 1KT H rTT 1T A WT T L / TkT T TTI T T




























































.4





rE7WMAL CROP C iROP .
U.P. AT LOS : .,
COLLEGE, L,-IGUNA 3
DHILIPPINES
Republic of the Philippines
Department of Public Works, Transportation and Communication
BUREAU OF POSTS
Manila



SWORN STATEMENT
(Required by Act 2580)



The undersigned, ARCADIO J. QUIMIO, editor of PHILIPPINE
PHYTOPATHOLOGY published semi-annually in English, in College,
Laguna, after having been duly sworn in accordance with law,
hereby submits the following statement of ownership, management,
circulation, etc., which is required by Act 2580, as amended by
Commonwealth Act No. 201.




Editor: ARCADIO J. QUIMIO
Business Manager: CEFERINO A. BANIQUED
Owner: PHIL. PHYTOPATHOLOGICAL SOCIETY,
INC.
Printer: PDM Press Inc.
Office of Publication: DEPT. OF PLANT
PATHOLOGY

In case of publication other than daily, total number of copies
printed and circulated of the last issue date June 1985.

1. Sent to paid subscribers ...... 120
2. Sent to others than paid
subscribers ............... 380
TOTAL 500



SGD. ARCADIO J. QUIMIO
Editor-in-Chief

SUBSCRIBED AND SWORN to before me this day of May 1987
at College, Laguna, the Affiant exhibiting his Residence Certificate
No. 1467112 issued at Los Baflos, Laguna on January 31, 1987.

Doc. No. 44
Page No. 10 SGD. ATTY. LORENZO C. MENESES, JR.
Book No. 3 Until Dec. 31, 1987
Series of 1987 PTR No. 1174223
Issued on 1-2-87
Los Banos, Laguna

NOTE: This form is exempt from the payment of documentary stamp tax.






































































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