Front Cover
 Front Matter
 Abstracts of papers presented at...
 Effect of flooding on pot populations...
 Relative susceptability, resistance...
 Nematodes in cropping patterns....
 Nematodes in cropping patterns....
 Variability in colletotrichum...
 Effect of fungicide and insecticide...
 Evaluation of selected fungicides...
 Pathogenicity and cultural characteristics...
 Phytopathological note: Pathologic...
 Back Matter
 Back Cover

Group Title: Journal of Tropical Plant Pathology
Title: Journal of tropical plant pathology
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00090520/00018
 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 1976
Frequency: semiannual
Subject: Plant diseases -- Periodicals -- Philippines   ( lcsh )
Plants, Protection of -- Periodicals -- Philippines   ( lcsh )
Genre: periodical   ( marcgt )
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: VID00018
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
    Front Matter
        Front Matter 1
        Front Matter 2
    Abstracts of papers presented at the thirteenth annual meeting of the Philippines phytopathological society, inc., Cagayan de oro City, 5-7 May 1976
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
    Effect of flooding on pot populations of rotylenchus reniformis and meloidogyne incognita
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
    Relative susceptability, resistance and tolerance of selected crops to inoculation with meloidogyne spp. in pots
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
    Nematodes in cropping patterns. IV. Populations of plant parasitic nematodes associated with cropping patternes under different rice-growing enviroments in Manaoag, Pangasinan
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
    Nematodes in cropping patterns. V. Populations of plant parasitic nematodes associated with different land forms and cropping patterns in Iloilo
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
    Variability in colletotrichum musae
        Page 40
        Page 41
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
    Effect of fungicide and insecticide sprays on mango fruit setting and post-harvest rots.
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
    Evaluation of selected fungicides for the control of grape downy mildew
        Page 60
        Page 61
        Page 62
        Page 63
        Page 64
        Page 65
    Pathogenicity and cultural characteristics of botryodiplodia spp. causing fruit rots
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
        Page 71
        Page 72
        Page 73
        Page 74
    Phytopathological note: Pathologic reactions of cowpea to the reniform nematode at varying levels of inoculation
        Page 75
        Page 76
        Page 77
    Back Matter
        Page 78
        Page 79
        Page 80
    Back Cover
        Page 81
        Page 82
Full Text





Abstracts of Papers Presented at the Th
Phytopathological Society, Inc., Caga'

Effect of flooding on pot populations o
incognita M. B. Castillo, M. S. Alejai

Relative susceptibility, resistance and tole
Meloidogyne spp. in pots M. B. Cast

Nematodes in cropping patterns. IV. Pop
ciated with cropping patterns unc
Manaoag, Pangasinan M. B. Castillo,

Nematodes in cropping patterns. V. Pop
cited with different land forms and
M. B. Arceo and J. A. Litsinger ....

Variability in Colletotrichum musae (Ber
chemical control T. H. Quimio .

Effect of fungicide and insecticide sprays o
A. N. Pordesimo and F. C. Barredo ..

Evaluation of selected fungicides for the
Pordesimo ................ .

Pathogenicity and cultural characteristics
M. T. Lantican and T. H. Quimio .

nematode at varying levels of inoculati



E, 1976 NUMBERS 1 AND 2


-nth Annual Meeting of the Philippine
le Oro City, 5-7 May, 1976 .. .......

otylenchus reniformis and- Meloidogyne
I R. R. Harwood ..................

e of selected crops to inoculation with
. .. . . . . . . . . . . . . ..

ions of plant parasitic nematodes asso-
different rice-growing environments in
3. Arceo and J. A. Litsinger ..........

ons of plant parasitic nematodes asso-
pping patterns in Iloilo M. B. Castillo,

t Curt.) v. Arx and its significance in
. . . . . . . . . . . .. . ... .

ango fruit setting and post-harvest rots. -

itrol of grape downy mildew A. N.
. ... . . .. .. . . . . . . . ..

lotryodiplodia spp. causing fruit rots -

reactions of cowpea to the reniform
- L. M. Villanueva and M. B. Castillo ....

Organ of
*Hnl nrlirAl cnr-iFrTV IMP



President D. A. BENIGNO, I
Vice President P. M. HALOS, UPL
Secretary A. N. PORDESIMC
Treasurer T. T. REYES, UPL
Auditor O. R. EXCONDE,
Board Members K. C. LING, IRRI,


American Cyanamid Company, Princet(

Bayer Philippines, Inc. 622 Shaw Blvd.,

Canlubang Sugar Estate, Canlubang, Cal

Hoechst Philippines, Inc., Corner Pionei

Macondray & Co., Inc., Filipinas Life B

Philippine Sugar Institute, West Avenue

Shell Chemical Company (Philippines),
Metro Manila

Tarlac Development Corporation, Hacie

Twin Rivers Research Center, Twin Riv
del Norte

Union Carbide (Philippines), Inc., P. O.
Metro Manila

Victorias Milling Co., Inc., Victorias, N(

Warner Barnes & Co., Ltd., 2900 Farad,
Metro Manila

Plant Quarantine Officers Club, BPI, Sal

October 1962

RS 1976-1977

I, College, Laguna
college, Laguna
'LB, College, Laguna
Dllege, Laguna
3, College, Laguna
age, Laguna
San Andres, Metro Manila
ivao City
IC, Madaum, Tagum, Davao del Norte
as Agricultural Trading, Cubao, Quezon Cit


ew Jersey, U.S.A.

daluyong, Metro Manila

a, Laguna

Reliance Sts., Mandaluyong, Metro Manila

Ayala Avenue, Makati, Metro Manila

man, Quezon City

Shell House, 1330 Roxas Blvd.,

Luisita, San Miguel, Tarlac

lantation, Inc., Madaum, Tagum, Davao

56, Commercial Center Post Office, Makati


., Corner South Expressway, Makati,

dres, Manila



Official Organ of the Philipg


P. M. HALOS, Editor-in-Chi
UPLB, College, Lagun

L. L. I LAG, Associate Editc

M. B. CASTILLO, Associati


D. A. BENIGNO, Business I

Subscriptions: Communications sho
of Plant Pathology, UPLB, College, Laguni
(January and June), is the official organ
free to members in good standing and t(
P12.50 per copy (domestic) and $25 per '
in advance. Membership in the Philippin
membership will be supplied by the Secrel
the right to charge some authors a presel
payment capabilities of their research proj
be secured from the Business Manager. N
tisements is assumed by this Journal or by 1

Ipin^e artaent




3artment of Plant Pathology

.B, College, Laguna

r, UPLB, College, Laguna


r, UPLB, College, Laguna

addressed to the Treasurer, P. P. S. c/o Departr
Philippine Phytopathology, published semi-annL
'hilippine Phytopathological Society, Inc. It is
ning Associates. For others, it is P25 per yei
;12.50 per copy elsewhere, postage free and pay
pathological Society, Inc.: Information regar
in request. Page Charge: The editorial board resi
it for each published page commensurate upor
supporting institutions. Advertisements: Rates
rsement of any statement of claims made .in a
ppine Phytopathological Society, Inc.


(Arranged alphabetical]

Quantitative and qualitative resists
to rice blast. S. W. Ahn and S. H.
A total of 3,515 monoconidial iso.
have been inoculated to 12 Philippine
8 international race differential varie
and more than 240 Philippine races
been identified at IRRI. The reaction
18 varieties that composed the Philip
and international differential varietif
being the same) to 242 races have 1
recorded and the relative resistance
each variety was calculated in percent
i. e., percentage of resistance to the
races. These 18 varieties were expose
the blast nursery under very condi
conditions for disease development.
days after exposure, the number o
sions were counted. The results she
that varieties which are resistant to n
pathogenic races have lesser number
lesions. This indicates that there are 1
races in the blast nursery and that vari
with higher percentage of resistance
races (qualitative) are more resistant (
titatively. Varieties with very high
centage of resistance to races will be
to maintain the resistance or will be 1
Two varieties and 3 lines derived
generally susceptible parents in the
nursery have lesser number of lesions
any of the parents. Artificial inocul:
showed that several isolates infecting
of the parents did not infect variety
lines derived from them. This exy
why these varieties or lines are
resistant than the parents. This also
gests that the resistant genes in
parents act complementarily as expr
in the new varieties or lines.

-7 MAY 1976

cording to first author's surname)

A survey of higher plants for fungicid
activity of their extracts against He
minthosporium oryzae Breda de Hao
and Pyricularia oryzae Cav. E. E. D
mancas and D. B. Lapis. UPLB.

Ninety three plants were screened f<
fungicidal activity of their extracts again
H. oryzae and P. oryzae, the causal org
nisms of brown spot and blast of ric
respectively, Of these, 47 plants hE
extracts that were inhibitory to the growl
of the test fungi.
Among the 47 plant extracts, 9 we
further assayed against H. oryzae and
against P. oryzae for activity of the d
ferent dilutions, the supernatant liqui
and precipitates of the extracts, and tl
effect of aging. In most cases, the e
tracts were active at 1:10 aqueous sol
tion; only Impatien balsamina extra<
were found active at 1:1,000 dilutic
The precipitates were significantly mc
active than the supernatant liquids wi
the exception of Pseudocalymna alliaceu
extracts wherein the supernatant liqu
was significantly more active than
precipitate. Generally, the activity of t
plant extracts decreased with time.
I. balsamina, P. alliaceum, Allium sa
vum, and Tagetes erecta extracts w(
further evaluated in in vivo assays i
activity as protectant, therapeutant
both; and for the influence of sprayi
intervals on the effectivity of the extrac
I. balsamina extracts had both the
peutic and protective effects while t
other three plant extracts were the
peutic only. The spray interval of eig
days was necessary to obtain the pi
tective effect of I. balsamina extra

Philippine Phytopathology

against P. oryzae.
There were no significant differences
among the 1, 2, 4 and 8-day spray inter-
vals of the crude extracts on rice against
H. oryzae.
7Te role of dew period on blast
disease incidence. M. I. El Refaei and
S. H. Ou. IRRI.
Under controlled conditions in the
Phytotron, a dew period of 8-9 hours
was necessary for the sprayed spores of
Pyricularia oryzae to infect the rice leaves;
longer dew periods up to 24 hours in-
creased the number of lesions at all tem-
peratures studied.
Under lowland conditions, spacing be-
tween hills affected the dew period on
the rice leaves. Closer spacing of plants
increased the dew period. There were 13
nights of the dew period reaching 10
hours or more in closer spacing (10 x 10
cm), 5 nights in 20 x 20 cm spacing and
only 2 nights in wider spacing' (40 x 40
cm) in a one month period during the
seedling stage. Accordingly, the number
of lesions on leaves in 10 x 10 cm spacing
was more numerous than in 20 x 20 cm
spacing and least in the 40 x 40 cm
In the blast nursery, the dew period
may be manipulated by covering the
seedlings with plastic sheet to increase
dew period. The dew period can be
reduced by placing a layer of bamboo
mat on the seedlings. The blast lesions
developed very early and were numerous
under plastic covering which had 14 hours
of dew every night. Plants that received
normal dew had lesser number of lesions
which also developed later. Plants with
bamboo mat covering had very few le-
Early experiments showed that dew
played a very important role in conidial
release and germination. We believe that

dew is the most important climatic factor
in blast development.
Inhibition of respiration in Pythium
species by ethazoL P. M. Halos and
O. C Huisman. UPLB and UC Berkeley.
Ethazol (5-ethoxy-3-(trichloromethyl)
1,2,4-thiadiazole) concentrations that in-
hibited growth also proportionately de-
creased respiration in Pythium debarya-
num. P. ultimum, P. sylvaticum and P.
vexans. Time course studies revealed that
18 /uM of the chemical inhibited growth
in culture by 50% after 4 h. While glucose
and acetate oxidations were relatively in-
sensitive, those of succinate and malate
were inhibited 50% after only 3 h of
Since the uncoupler dinitrophenol did
not release ethazol inhibition, the fungi-
cide does not interfere with oxidative
phosphorylation. Evidence was obtained
suggesting a block in the electron trans-
port system. Tetramethyl-p-phenylene
diamine released the inhibition indicating
that the site of ethazol inhibition is be-
tween cytochromes b and c. Cysteine and
ascorbic acid also released ethazol inhi-
bition of oxygen uptake.
The site of ethazol action was verified
in isolated mitochondria from Pythium
species. In P. ultimum, ethazol (18 /jM)
reduced NADH and succinate oxidations
by 50% after 1 min. The proximity or
identity with the antimycin inhibited site
was demonstrated in Pythium species and
beef heart mitochondria.
Mitochondrial respiration in Fusarium
oxysporum f. sp. vasinfectum, pinto bean
and beef heart was much more resistant
to ethazol inhibition than those in Py-
thium species. Differential sensitivity to
respiratory inhibition may therefore ac-
count for selectivity of ethazol.

Aflatoxin formation in sorghum grains

Vol. 12

Jan. & June, 1976

as affected by temperature and length c
incubation L. L. lag, L. S. F. Madan
ba, E. M. Luis and F M. Rodrigue
Preliminary results showed that A
pergillus flavus Link ex Fries synthesize
aflatoxin in sorghum grains incubated :
30 C, 20 C and at ambient room ter
perature (21-30 C). Toxin was not former
at 10 C. Formation of the toxin started
earlier and was found in greater quantitii
in the autoclaved grains than in the ra
Aflatoxin was formed earliest and w;
produced in largest quantities in grail
incubated at 30 C. Detectable amoun
of the toxin were first noted in the aut
claved grains within 48 hours after inoc
nation with A. flavus.
The maximum amount of aflatoxc
formed at 30 C was 34,800 ppb of E
which was observed on the 17th day i
incubation; at 20 C, the maximum w
3,300 ppb B1 formed on the 8th day

The role of liquid fertilizer in the ir
provement and tolerance of tobacco plan
against bacterial wilt. J. Z. de Jesu
Tobacco seedlings with early sympton
of wilt disease were studied for the agr
nomic characteristics using liquid fer
lizer. The fertilized plants were compare
with the non-treated plants for the
resistance against the wilt disease. Whf
sprayed only with the fungicide and i
secticide, the plants exhibited small at
thin leaves. However, when also spray(
4 times with the liquid fertilizer, tl
plants showed marked recovery and t
lerance against bacterial wilt. The fe
tilizer used was Complesal, 12-4-6 NP
while the tobacco variety used was tl
cigar filler, Simmaba type.

Experimental epidemiology of rice tu


gro disease (I and II). K. C Ling. IRR
The effects of several factors on ri
tungro incidence inf terms of percent
infected Taichung Native 1 (TN1) see
lings were studied by a cage method in
greenhouse. Unless specified otherwi:
180 virus-free Nephotettix virescens we
introduced into the cages containing 31
test seedlings in 12 pots plus four pots
diseased plants as virus sources and we
confined for 7 days threat.
The percentage of infected seedlir
(Y) increased with an increasing numt
of adult insects (X) by I = 100 1I
(1 + aX + bX2), where a and b valid
varied according to the mortality of t
insects during the test period.
When the insects were confined foi
number of days (X) in the cage, the p4
centage of infected seedlings (Y) increase
as the duration of confinement lengthen.
by Y = 100 (1 e-0,1368x), whe
e = 2.718.
Based on the percentage of infect
seedlings, the adult insects appeared to 1
about three times more efficient in sprea
ing tungro disease.
The percentage of infected seedlin
(Y) increased as the percentage of pots
diseased plants (X) that acted as vir
sources increased by V = a+bX (6.25
50 percent) and by Y = ax b/x-wh(
zero infection was included for no
diseased plants and 100 percent infectic
for all diseased plants. The a and b valu
varied according to the growth stage i
the insect.
Based on the distance travelled by 1
cincticeps and tungro virus retentic
period, it was estimated that a disease
plant at a distance greater than 250
m could no longer be a direct sour(
of tungro virus for the healthy plant. Th
distance is suspected to be longer, pa
ticularly when the insect travels passive
by strong wind.

4 Philippine Ph

When diseased plants of TN1 or IR2
were used as virus sources, the percentage
of infected seedlings were significantly
higher than when diseased plants c
C4-63G or IR20 were used. Consequently
diseased plants of different varieties wer
not identical in quality as sources c
tungro virus.

Effect of temperature on the tran
mission of rice tungro virus by Nephc
tettix virescens. K. C Ling and E. R
Tiongco. IRRI
The retention period of rice tungr
virus by adult N. virescens at 13 and 32
was determined under controlled condi
tions. The longest retention period ol
served was 22 days after acquisition
feeding for the 4,378 insects kept at 13
and only 6 days for the 2,517 insects a
32 C. The retention period could b
longer had more numerous viruliferou
insects been tested under lower tem
peratures which are more favorable fo
virus retention by the insect vector. How
ever, at both tested temperatures, th
infectivity decreased gradually with tim
after acquisition feeding.
The retention period is a major cr
terion for grouping insect-borne viruses
Persistent viruses survive in their vector
for long periods, sometimes for weeks o
months. Non-persistent viruses survive i
their vectors only for a short period.
The rice tungro virus was previous
categorized in the non-persistent grou
Based on the condition that "short" refer

.ytopathology Vol. 1:

2 Therefore, we propose a new term -
s "transitory" for tungro virus and those
y leafhopper-bome viruses with similar
>f virus-vector interaction while other leal
r, hopper-borne viruses could remain in th
e persistent group. Hence, the leafhoppel
if borne viruses could now be categorize
as transitory and persistent rather tha
non-persistent, semi-persistent, and pel
s- sistent as applied to the aphid-born
- viruses.
Some cytological observations on PI
ricularia oryzae Cav. K. Manibhushat
o rao and S. H. Ou. IRRL
For nuclear staining of conidia an
mycelium ofP. oryzae, a modified cell
phane method of Hrushovertz (1956) wE
C successfully used. Two square cm of cellt
t lose tubing were sterilized in boiling di
tilled water for 20-30 min and wer
transferred aseptically on the surface o
the prune extract agar medium. Th
r plated petri dishes were inoculated nea
the sides of the bits and were incubated
at 28 C for 4-6 days. The cellulose square
e with the grown up mycelium and conidi
were gently removed and fixed in Car
noy's fluid for 10 min. Acid hydrolysi
i- in 1 N HCI at 63-65 C for 8-10 min wa
. followed by staining with Giemsa at 28
s 30 C.
The nuclei in the cells of conidia, coni
diophores and mycelium were uniformnl
stained as reddish-purple. Most of thi
y cells were uninucleate, confirming the
P results of Yamasaki and Niizeki (1965)
* r .. -- -_. ._1 -- - -- -11- -- l ...

Jan. & June, 1976 ABSTRACTS 5

after 36 hours of conidial germination. When the two isolates from Davao and
However, the frequency of these multi- Isabela were used to test 153 varieties
nucleate cells was very low. for varietal resistance, the reaction on
Influence of herbicides and insecti- Nakhi was quite distinct. The Isabela
cides on the susceptibility of rice plant to isolate produced- an R reaction, while
leaf blast, bacterial leaf blight, and sheath the isolate from Davao produced MS
blight. C E. Manila and D. B. Lapis. reaction on Nakhi.
UPLB. A test of 83 isolates on three rice
Two herbicides and two insecticides varieties, IR8, IR20 and IR1545 which
were tested for their effect on the deve- carry no gene, a dominant gene, Xa4,
lopment of bacterial leaf blight, leaf blast, and a recessive gene, xa5, for resistance,
and sheath blight on some recommended respectively, suggested that there were
rice varieties, distinct differential interactions. At least
4 pathogenic groups of the isolates were
Analysis of individual responses of the observed. It is evident that the patho-
varieties showed that of the 12 varieties, genic variability of X. oryzae did not
Agroxone 4 decreased bacterial leaf blight only reflect differences in virulence, but
severity on IR-28 and TKM 6. The se- also in pathogenicity. A set of differen-
verity of blast infection was increased by tial varieties under our current evaluation
Mipcin on IR-5, C-22, IR-20, IR-1561, will be used to classify the Philippine
IR-1330, IR-1487, C4-63G and C4-137 isolates into pathogenic races.
while 2,4-D, Agroxone 4, and Azodrin
168 did not alter rate of disease develop- Yield losses due to sheath blight di-
ment. The sheath blight was not affected sease of rice. S. H. Ou and J M Ban-
by the chemical treatments. dong. IRRI
The combined effects of Agroxone 4 This study was conducted during the
and 2,4-D reduced severity of bacterial dry and wet planting seasons in 1975
leaf blight while Azodrin 168 and Mip- at IRRI, using a moderately susceptible
cin appeared to predispose rice plants variety IR26 and a highly susceptible line,
to blast. The development of sheath IR1487-372-1 at three levels of disease
blight was not altered by the chemicals. intensity (1/10, 1/5, and 1/2 hills inocu-

Pathogenic variability of Xanthomonas lated) under two levels of nitrogen fer-
oryzae. T. W. Mew, A. G. dela Rosa utilization (0 and 100 kg N/ha.).
and C. C. Magpantay. IRRI. The plants were grown in 2.6 x 4.6 m
During the 1975 wet season, IR30, plots at a distance of 20 cm between
which carries the dominant gene for bac- hills. One half of the total amount of
trial blight resistance, was found sus- nitrogen fertilizer requirement was ap-
ceptible in Iloilo and Davao. Pathogeni- plied about a week after transplanting
city studies indicated that the isolates of and the other half at the booting stage
X. oryzae from these areas were similar of plant growth. Inoculation was done
to that of the Isabela strain in attacking by using grain inoculum at the booting
IR20 and IR30. However, varieties con- stage. Final disease reading was taken at
veying a recessive gene for resistance was the ripening stage of the plants.
not overcome by these isolates in the On IR26, the percent yield reductions
greenhouse. per unit of disease rating are 2.7 in the

6 Philippine Phytopathology Vol. 12

zero N-level plots and 2.3 in the 100-N- In the foliar experiment, the majority
level of fertilizer per hectare. However, of the chemicals gave good protection
they are not significant up to the highest against leaf blast one week after spraying.
level of disease incidence in higher level Benlate, Fi, Hoe 17411, Hoe 22843,
of nitrogen fertilization during the dry Hoe 25985, Homai, LS 65255, Saprol,
season trial and at both N-levels in wet Topsin M, and others controlled the
season. On IR1487, the percent yield disease. However, it was noted that two
reductions per unit of disease rating are weeks after spraying, the general re-
4.4 in the zero N-plots and 4.3 in the actions of both sprayed and unsprayed
100-N-level. There are statistically sig- plants were almost similar, indicating
nificant differences between the levels that protection by foliar spray'is short-
of disease incidence in both nitrogen lived under heavy disease pressure.
levels. The highest percentages of yield Of the nine chemicals sprayed at 7-day
losses are about 13 percent for IR26 and intervals 3 times starting from the boot-
23 percent for IR1487.
23 percent for R1487. ing stage onwards to test their compara-
tive effectiveness against neck blast, Ben-
Chemical control of blast, sheath late, EL 291,F,Hoe 17411,LS72.1828,
blight, and Cercospora leaf spot diseases NF 48, Panoctine and Topsin M, reduced
of rice. S. H. Ou, F L. Nuque and J. M. occurrence of neck rots. This resulted in
Bandong. IRRI. higher yields in the treated than the con-
Sixteen chemicals were used in the trols.
experiments for controlling rice blast and For sheath blight control, 8 chemicals
eight for sheath blight. The chemicals
were sprayed thrice at weekly intervals
were used as foliar spray, seed and soilooting stage on plants pr
starting at booting stage on plants pre-
treatments for blast control and spray viously inoculated with the causal or-
viously inoculated with the causal or-
for sheath blight and Cercospora diseases. i. r
ganism. The average disease ratings of
The results of seed treatment experi- chemically-treated plants were lower than
ments showed that the chemicals gave an those of the control. Benlate, Hoe 22843,
effective control of leaf blast under very Hoe 25985, Neoazocin, Topsin M, Vali-
conducive conditions for disease develop- dacin dust, Validacin microgranules and
ment compared with the non-treated in Validacin solution gave effective control
the blast nursery. Benlate, Fi, Hoe of the disease. There were also differences
22843, Hoe 22845, Hoe 25985, Homai, in the yield between the chemically
MKS, Saprol, Topsin M and other treated treated and the control plants but not
plants had fewer lesions than the control. among those treated chemically.
Of the 13 chemicals used in the soil treat- In the evaluation of different chem-
ment experiment, Benlate, Homai, Hoe icals for their effectiveness against neck
17411, Hoe 22843, Hoe 22845, Hoe blast and sheath blight, some plots were
25985, and Topsin M gave equal pro- likewise relatively free from Cercospora
tection against leaf blast. No lesions were leaf spots. The number of spots from 20
observed on the leaves of plants grown flag leaves were taken at random in each
in plots treated with these chemicals. of the sprayed plots to determine their
Other chemicals were not as effective in effectiveness. Plants sprayed with Ben-
the control of the disease. There were late, Hoe 17411,Hoe 22883, Roe 25985,
significant differences between treated NF 48, Panoctine, Saprol and Topsin M
and control and also among treatments. have remarkably lower number of lesions

han untreated plants. Chemically treated two crosses exhibited high levels of
plantss have lower number of lesions than resistance to both undet field conditions.
Insprayed plants. Likewise, differences The two crosses are IR 9560 (IR83///
vere noted among the treatments. IRs/Carreon//IR$FTetep) which was in-
tended for increasing blast resistance
Pathogenic races ofPyricularia oryzae from different sources and the other,
n the blast nursery. S. H. Ou, F. L. IR4497 (IR24//Zenith/Malagkit Sunsong)
Vuque and S. F. Ebron. IRRI, intended to increase the spectrum of re-
The races occurring monthly in the distance to bacterial blight. Several single
The races occurring monthly in the
RRI blast nurserywas monitored for a plants from these crosses were selected.
RRI blast nurserywas monitored for a
eriod of 10 months starting from April, They were grown separately in pots in the
,eriod of 10 months starting from April, .
974 to January, 1975. A total of 519 greenhouse and were artificially inocu-
974 to January, 1975. A total of 519
slates were inoculated to both Philip- lated with grassy stunt two weeks after
olates were inoculated to both Philip-Majority of the selec-
,,i r. r... . sowing in the F4. Majority of the selec-

nine for IR4497 lines. Since only one
If these, a number of new races were
determined. The most prevalent races source of resistance to grassy stunt, Ory-
,ere P8 followed by P17, P20, P21 and zae nivara, is known so far, these new
68. Other races have one or few isolates sources are very valuable alternative
nly. Races P8 and P17 appeared for 10 sources in breeding for grassy stunt re-
nd 9 months, respectively. Other races sistance. All parents of the two crosses
'ere present periodically. Thirty six are susceptible to grassy stunt. The genes
ices were detected only once indicating involved in these resistant lines are being
iat they were rare races. investigated.
The isolates were classified into 37 Little leaf disease of cowpea (Vigna
ices according to the standard inter- unguiculata (L.) Walp) its nature and
national race numbers. Of these races, control. L. L. Paje, D. A. Benigno and
ie most prevalent were IA-110, IA-109 M. A. Favali-Hedayat. UPLB.
nd IA-126. They were detected in 10,
and 9 months, respectively. Other A new and unreported viral disease of
aces occurred periodically and 15 races cowpea, Vigna unguiculata (L.)Walp. (V.
appeared once during the period of study. sinensis (L) Savi ex Hassk., V. cylindrica
[any races were present at the same time (L.) Skeels), named cowpea "little leaf"
i the field thus confirming previous was studied. The virus was isolated from
ndings. Philippine-developed cowpea cultivars.
Once the plants are attacked, little or no
Two possible new sources of resistance pods are produced resulting in decreased
against grassy stunt disease of rice. production.
H. Ou, F. L. Nuque, K. C. Ling and V. The cowpea little leaf virus is a rigid
guiero. IRRI. rod-like particle measuring about 330 nm.
In 1973, a very severe outbreak of It can be transmitted by Aphis craccivora
rown hopper and grassy stunt disease Koch. but not by A. gossypii Glov., A.
f rice. occurred in Laguna including glycines Mats., Longuinguis sacchari
te IRRI farm. Several hybrid lines from Zenht., Rhopalosiphum maidis Fitch.,

Philippine Phytopathology

and sap transmission. However, seed
transmission was observed from as low
as 5% to as high as 75% depending upon
the variety.
Only V. unguiculata and V. sinensis x
V. sesquipedalis were found susceptible
to the virus. Other plant species like
Gomphrena globosa L., Arachis hypogea
L., Centrosema pubescens Benth., Gly-
cine max (L.) Merr. Phaseolus aureus
Roxb., Nicotiana glutinosa L. and N.
tabacum L. were not infected.
Systemic and contact insecticides
tested did not decrease yield loss. Use
of virus-free seeds and roguing are there-
fore recommended as control measures.

The effect of fungicide treatment on
germination and seed rot of cotton. -
A. N. Pordesimo and V. R. Daquioag.
Laboratory tests of seed-treatment
chemicals by brining undelinted cotton
seeds were conducted to evaluate their
influence on germination and effective-
ness against seed rot and to explore their
possibility for use in the field. The seeds
were soaked for 5 and 10 min. in HgCl2
(at 1:500 and 1:1,000), Agrosan 5 W (at
2.5 g/1 and 3 g/l) and Vitavax (at 1 g/
100 ml and 2 g/100 ml). Untreated seeds
and seeds immersed for the same period
in tap water served as control. Triplicate
plates with 25 seeds each were used for
each treatment. Two trials each for the
aged and newly-harvested seeds were
Old or recently-harvested seeds treated
with HgC2l and Agrosan 5 W at either
dosages and periods of exposure gave
higher germination over the other treat-
ments. Vitavax-treated seeds had the
least percentage of germination. Seed rot
was primarily responsible for the low ger-
mination. Seed rot was primarily respon-
sible for the low germination in all treat-

Species of Aspergillus and Rhizopus
were commonly observed on seeds soaked
in water and untreated seeds. Rotting,
exhibited by discolored radicle and ooz-
ing, were common on untreated seeds.
Bacterial isolates were obtained from
such ooze and discolored radicles.

A rapid inoculation technique for to-
mato bacterial wilt'screening. A. J.
Quimio and F R. Prado. UPLB.
Four weeks old wilt-susceptible 2029
and Tropi-red tomatoes were used to
study 6 inoculation techniques for screen-
ing tomatoes against bacterial wilt caused
by Pseudomonas solanacearum. The tech-
niques were scissored petiole, scalpeled
petiole, pricked petiole, cut roots, in-
jured stem, and pricked stem. The first
two methods were rapid, consistent, and
could be adopted easily for massive wilt
screening tests.
The inoculum levels that could be used
to differentiate between wilt-susceptible
and resistant reactions were determined
using four weeks old 2029 and VC 1169
tomatoes as test plants. The assay plants
were inoculated with the bacterium by
the scalpeled petiole technique. The sus-
ceptible but not the resistant reaction
could be demonstrated with clarity
among plants grown in soil. However,
both reactions could be detected easily
in plants grown in sand cultures. With the
isolate used in the experiments, inoculum
concentrations equivalent to 1/200-1/400
x 50% T (425 nm) appeared to be the
desired levels for wilt resistance evalua-
Tomato bacterial wilt screening could
therefore be done easily and rapidly with
minimum space and time requirements
using scalpeled petiole inoculation tech-
nique on 4 week-old plants grown in sand

Vol. 12

Survey of plant parasitic nematodes inefficient as in chicken manure and
associated with sugarcane roots in the fungus or fungus and triazophos combina-
'hilippines. T T. Reyes and E. D. tions.
eguico. UPLB. Yield was relatively higher when
Sixteen genera of plant parasitic nema- chicken manure was applied either alone
)des were found associated with sugar- or in combination with any of the fungus,
ane roots collected from 152 localities Tagetes, and triazophos. Chicken manure
1 83 towns and cities in 16 provinces of had some beneficial effects on the host
ie Philippines. These were Tylencho- plant.
iynchus, Pratylenchus, Helicotylenchus, As a pre-plant treatment, T. patula
.otylenchus, Hemicriconemoides, Meloi- almost completely rid the soil of M.
ogyne, Paratylenchus, Scutellonema, He- incognita but stimulated the tremendous
zicycliophora, Xiphinema, Hoplolaimus, rise in the populations of Rotylenchus,
'richodorus, Longidorus, Rotylenchulus, Aphelenchus, and three free-living nema-

country. Ine rest were utiusmouLU uniy 1. paluta on ne tropical rrunppme in.
>oradically and in low population densi- incognita can be easily offset by the
es. planting of a susceptible tomato plant.

Integrated biological and chemical Triazophos when used alone at the
control of Meloidogyne incognita on rate of 0.25 gm/tomato plant in granular
)mato. J. S. Ruelo and R. G. Davide. form was ineffective in controlling
PLB. M. incognita. However, this rate was suf-
ficient when used in combination with
Integration of chemical and biological ficient when used in combination with
methods against M. incognita on tomato either Tagetes or chicken manure, or with
lethods against M. incognita on tomato
under field conditions was found effec- any combination of chicken manure,
ve. The sixteen treatment combina- fungus, and Tagetes.
ons utilized triazophos (Hostathion 5G) Laboratory, greenhouse bag and pot,
applied at 0.25 gm/tomato plant; Arthro- and field experiments revealed that an
otrys oligospora, a nematode-trapping integration of chemical and biological
ingus; Tagetes patula L. var. hiliput methods effectively controlled M. incog-
mkist, a marigold plant; and chicken nita on tomato.
lanure applied at 1,200 cc/tomato plant.
High levels of control ranging from Symptom pattes of Philippine corn
3.31%-97.30% were attained with the downy mildew under controlled environ-
lowing integrated control measures: mental conditions. J. A. Singh and 0.
allowing integrated control measures:
riazophos, chicken manure, and fungus; R. Exconde. UPLB.
riazophos, chicken manure, fungus, and Conidia of six isolates of Sclerospora
'agetes: triazophos, chicken manure and philippinensis Weston collected from
'agetes; fungus, chicken manure, and Bukidnon and some Southern Luzon
'agetes; triazophus, fungus, and Tagetes. provinces were studied for their gross
Control obtained when triazophos, Ta- morphology and aggressiveness under
etes, or A. oligospora were used alone controlled environmental conditions
r in treatment combinations were as using "KOITOTRON" Growth Chamber.

nce of early systemic infectior

dieting the capability of the isolates to most common on grasses and affected
incite systemic infection. Appearance of about 25%, 18% and 17% of the hosts,
systemic symptom in susceptible varieties respectively. Rhizoctonia, which is serious
and inbred lines was faster than in re- during the rainy season, infected about
sistant varieties and inbred lines. Ag- 48% of the legumes, followed by Cercos-
gressiveness of isolates in invading the pora (11%). Many of these diseases were
growing point from the site of inocula- widespread and severe and could cause
tion differed with the test materials, problems as more lots are planted to
pasture crops. Except for the rusts and
Fungal diseases of pasture grasses and the smuts, the other causal fungi have
legumes in the Philippines. R. B. Val- been isolated and tested for pathogeni-
dez and G. B. Rosario. UPLB. city.
A survey for the occurrence of diseases Tests for seed-borne fungi in four cul-
attacking both introduced and native tivars of imported Stylosanthes seeds
pasture grasses and legumes in the Philip- showed the presence of Helminthospo-
pines revealed the predominance of rium, Curvularia, Botrytis, Penicillium
fungal diseases. The survey which covered and Aspergillus species.
29 localities in 13 provinces in Luzon,

Phil. Phytopathol. 12:11-16
Jan. & June, 1976



Assistant Professor, Department of Plant Pathology, U.P. at Los Bafios, College of
of Agriculture, Research Assistant and Head, Multiple Cropping Program, The Inter-
national Rice Research Institute, Los Bafios, Laguna, Philippines.
This study was a part of the UPLB-IRRI Cooperative Nematology Research Project.

Pots with plugged holes and containing soil inoculated with 500 nema-
tode larvae each were used. Flooding was done at 10 and 30 days after ino-
culation of mung bean roots with R. reniformis and at 10 and 50 days after
inoculation of tomato roots with M. incognita. Unplanted pots were also
flooded at 10 days after inoculation. Nematode recoveries from flooded and
unflooded pots showed that populations of both nematodes were reduced by
flooding for 1, 4 and 7 days, with no significant differences (lsd .05) in effect
among flooding durations. When flooding was done at the 10th day, no nema-
todes were recovered from soil in both unplanted and planted pots, while 20
to 33 R. reniformis and 20 to 60 M. incognita were recovered from soil in
unflooded, unplanted and planted pots. Reduction in nematode counts from
roots ranged from 25% to 75% for R. reniformis and 47% to 72% for M.
incognita. When flooding was done at the 30th day, reductions in soil counts
of R. reniformis ranged from 80% to 95% and in root counts from 53% to
73%. Flooding at the 50th day reduced .soil counts of M. incognita by 59%
to 86% and root counts by 51% to 73%. Time of flooding did not seem to
influence nematode control in the roots.

Most nematode species are adversely (Thames, 1952; Hollis and Johnston,
affected by high soil moisture. In satu- 1957). Brown (1933) reported that a
rated soils, the air spaces are reduced and four-month flooding killed the root-
so lack of aeration probably reduces knot nematode larvae, but it took 12
nematode activity, since the organism to 22-1/2 months of flooding to make
appears to be well adapted to living in the tomato plants subsequently grown
the soil pores (Wallace, 1963). Besides in the flooded soil free of root galls. In a
aeration, reduction in nematode popula- naturally occurring infestation, root-knot
tions in flooded soil may be caused by nematode larvae did not survive two to
toxic chemicals (Hollis and Rodriguez- five days at 10.7 per cent of field capa-
Kabana, 1966; Wallace, 1963). Hirshman- city and a considerable reduction in
niella oryzae and Ditylenchus angustus, number resulted at field capacity (Pea-
which are parasitic on rice roots in paddy cock, 1957).
fields, are probably more tolerant of sa- Populations of Rotylenchulus reni-
turated conditions. Wallace (1963) be- forms and Meloidogyne incognita vary
lives that somewhere between the ex- considerably among growing seasons even
tremes, each nematode species has an in soil and roots ofmonocultured crops.
optimum soil moisture for activity. Variations appear to be more pronounced
Control of plant parasitic nematodes in areas with poor drainage conditions
has been achieved through flooding where a few days of flooding occurs


alter neavy rams. wnemer sou saturauon jormis, nooumg was mauc Iu aiVu Ju
is responsible for the unexplained shifts days after inoculation; on M. incognita
in nematode populations is not known. 10 and 50 days after inoculation. Ten
This study was conducted to determine days after inoculation was selected be-
the effect of flooding on populations of cause it was believed that at this stage,
D --A Alf '*u^_u'^ mr~ct namaf hald alpral\ infprffrl thp

Pots and test plants used. Clay pots
(25-cm diameter) with their holes plugged
with cement were prepared. Each wa,
filled up to about 8 cm from the rim witt
baked clay loam soil. Two separate
groups of pots were prepared. One grout
was planted with mung bean (MG 50
10A) seeds and the other, with tomato
(VC 11-1) seeds. After one week, the
seedlings were thinned to only three pei
pot. Two separate groups of unplantec
pots were also provided.
Nematodes tested and inoculation pro
cedures. R. reniformis (a semi-endo
parasite) and M. incognita (an endo
parasite) were used as test nematodes ir
two separate experiments. In both cases
a suspension containing approximately
500 active larvae, freshly hatched frorr
egg masses, was added to each pot. Ir
planted pots, the nematodes were ino
culated by pouring the suspension on the
exposed roots of one-month old seed.
lings. R. reniformis was inoculated or
mung bean while M. incognita was ino
culated on tomato. In unplanted pots,
inoculations were done at the same time
as the planted pots by pouring the nema-
tode suspensions into the holes made al
the center of the pots and then covered
with soil.
Flooding schedules and durations. -
Flooding was made by saturating the soil
in the pot with water and maintaining
the level of the water up to about 3 cm
from the rim. In planted pots, two
flooding schedules were tested on each
of the two nematode species. On R. reni-

I JVLO. .l^/ Allv I V l- J ulu J .-u u ir
inoculation for R. reniformis and M. in
cognita, respectively, was based on the
assumption that at these stages, mosi
nematodes had already reproduced oi
completed their life cycles. In unplantec
pots, flooding was done only 10 day!
after inoculation for both nematodes
Three durations of flooding per schedule
were selected, namely, 1, 4 and 7 days
The different combinations of scheduk
and duration were replicated three times
For each combination in the planted pol
group, an unflooded planted pot wa,
provided as check; an unflooded unplant
ed pot was likewise provided for eact
combination of schedule and duration it
the unplanted pot group also as check
The experimental pots were placed or
saucers and randomly arranged inside the
Care and maintenance of experiment
plants. Fertilization by band applica
tion of 1 g of complete (14-14-14) fer
tilizer at one week after planting and 1 I
at one month thereafter was made on al
pots. Ordinary watering was done on al
unflooded pots, either planted or un
planted. Control of insect pests anc
diseases was done by bi-weekly spraying
with a combination of Thiodan an<
Ditane M-45.
Collection of data. At the end o:
each flooding duration, the population
in soil and roots of each pot of the nema
tode species under investigation wa
determined. Nematodes from the soi
were extracted by the combination o
the sieving (No. 50 and 325 sieves) an<
Baermann funnel (24-hr settling period

techniques Nematodes in the roots were
mountedd after staining in acid fuchsin
md clearing in lactophenol.


The average number of nematodes
recoveredd from each flooded and un-
looded pot containing soil previously
noculated with 500 nematode larvae was
determined. Per cent reduction due to
flooding was computed, based on com-
>arisons of nematode counts from the
flooded and unflooded pots.
Table 1 shows the effect of flooding
an population of R. reniformis. When
flooding was done at 10 days after inocu-
ation, no nematodes were recovered
rom the soil in both unplanted and
planted pots after 1-, 4- and 7-day flood-
ng, while nematodes ranging from 20
o 33 were recovered from the soil in
inplanted and planted pots which were
lot flooded. Nematode recoveries from
nung bean roots in planted pots were
educed by 25%, 67% and 75%, while
otal nematode recoveries were reduced
>y 53%, 78% and 82%, due to flooding
or 1, 4 and 7 days, respectively. Al-
hough a trend towards greater reduction
vith prolonged flooding duration was
loted, significant differences in per-
entage reductions among durations were
lot observed. When flooding was done
It 30 days after inoculation, a few nema-
odes were recovered from soil in planted
iots after 1-, 4- and 7-day flooding.
nematode counts from the soil in un-
looded pots indicated reductions of 81%,
10% and 95% due to flooding for 1, 4 and
' days respectively, while 53%, 53% and
'4% reductions were indicated by nema-
ode counts from roots. Total nematode
ounts from unflooded pots indicated
deductions of 64%, 62% and 89% due to
flooding for 1, 4 and 7 days, respectively.

reductions among flooding durations
were not significant (LSD .05).
The effect of flooding on M. incognita,
shown in Table 2, somewhat parallels that
on R. reniformis. When flooding was
lone at 10 days after inoculation, no ne-
natodes were recovered from the soil in
)oth unplanted and planted pots after
1-, 4- and 7-day flooding, while nema-
:odes ranging from 20 to 60 were re-
:overed from the soil in unplanted and
wantedd pots which were not flooded.
nematode recoveries from roots in
planted pots were reduced by 72%; 47%
nd 64%, while total nematode recoveries
vere reduced by 79%, 77% and 76%, due
o flooding for 1, 4 and 7 days, respec-
ively. In both cases, differences in per-
entage reductions among flooding dura-
ions were insignificant. When flooding
vas done at 50 days after inoculation,
percentage reductions due to flooding for
, 4 and 7 days were, respectively, 59%,
'7% and 84% in nematode recoveries
rom soil, 53%, 73% and 51% in nema-
ode recoveries from soil, 53%, 73% and
1% in nematode recoveries from the
oots and 53%, 74% and 68% in total
nematode recoveries. Likewise, no signi-
icant differences in percentage reduc-
ions among flooding durations were

Reactions of R. reniformis and M.
ncognita to flooding were similar. Pot
populationss of both nematodes were
educed by flooding for 1, 4 and 7 days.
this observation concurs with that of
'eacock (1957). Effect of flooding on
nematode eggs, however, was not de-
ermined. A trend towards greater reduc-
ion with prolonged soil saturation was
toted in R. reniformis population, but
statistical analyses of R. reniformis and
f. incognita recoveries showed no sig-

1 -- - .


Flooding Time
and Duration Floodei


Inplanted pots
1-day flooding 0
4-day flooding 0
7-day flooding 0

ots planted to mungbean
1-day flooding 0
4-day flooding 0
7-day flooding 0


ots planted to mungbean
1-day flooding 7
4-day flooding 7
7-day flooding 7

aData are averages of three replicates.
bAverages of the three replicates and n

Soil Root

Unflooded Per cent Flooded Unflood
(Check) reduction (check

27 100a -
20 100a -
20 100a -

27 100a 28 42
33 100a 17 56
27 100a 19 74

40 81a 42 88
27 80a 13 26
200 95a 21 80

Based on the values indicated. Similar letter

_ __

ne incognita recovered from

Flooding Time
and Duration Flooded


planted pots
1-day flooding 0
4-day flooding 0
7-day flooding 0

its planted to tomato
1-day flooding 0
4-day flooding 0
7-day flooding 0


its planted to tomato
1-day flooding 280
4-day flooding 113
7-day flooding 150

aData are averages of three replicates.
bAverages of the three replicates and not

nflooded Per cent Flooded Unflooded
(check) reductionb (check)

20 100a -
60 lOOa -
20 lOOa -

20 lOOa 12 44
40 lOOa 16 31
20 100a 11 30

1,493 59a 3,058 20,945
933 77a 1,366 5,659
3,020 84a 2,631 5,366

based on the values indicated. Similar letters ii


tions among the durations of flooding
Flooding appears to be more effects
against nematodes in soil than those i
mung bean or tomato roots, as evidence
by the consistently greater percentage
reductions observed in the former than i
the later. This suggests better nematode
control by pre-plant flooding than b
flooding when plants are established an
nematodes have already invaded th
roots. It is probable that either the tox:


BROWN, L. N. 1933. Flooding to con
HOLLIS, J. P. and T. JOHNSTON. 195
tions in water saturated soils. Phyt
soil. Phytopathology 56:1015-101
JENKINS, W. R. 1960. Control of nem
Sasser and E. R. Jenkins (eds). Nei
PEACOCK, F. C. 1957. Studies on roi
Gold Coast. Part 2. Nematologica :
THAMES, W. H. 1952. The benefits of
Sci. Fla. 76: 77.
WALLACE, H. R. 1963. The biology o
London. 280 p.

chemicals, if any, resulting from saturate
condition were not absorbed by the roo
or the nematodes in roots were provide
by oxygen from the intercellular space
of the roots.
Length of flooding time in plante
pots, either at 10 or 30 days after inoci
lation with R. reniformis and either at 1
or 50 days after inoculation with A
incognita, did not seem to influence
nematode control.


Al root-knot nematodes. J. Agr. Res. 47:8

Microbiological reduction of nematode pop
)athology 47:16 (Abstr.)
ANA. 1966. Rapid kill of nematodes in floo

odes by physical methods, pp. 44-446. In J
itology. The Univ. North Carolina Press, Cha

-knot nematodes of the genus Meloidogyru
ooding in the control of nematodes. Proc. I

plant parasitic nematodes. Edward Arnold L



Assistant Professor, Department of I
of Agriculture, College, Laguna.
This study was partly supported by i
No. 2.275-28B.
The author acknowledges the suggest
:able in this paper.


Root-knot nematodes collected
for their ability to cause damage on
were found associated in the field and
experiments using varied numbers of n
root gall ratings, nematode reproduce
weight and/or yield, the susceptibility
bean (Henderson), celery (Utah 52-70
(Apollo) to M. incognita; of cowpea (
purple), hyacinth bean (Morado), mui
soybean (Clark 63) to M. acrita; anc
(Tainung S 3) and strawberry (Miss
On the other hand, the resistance of cc
and pigeon pea (Native) to M. incogn
naria; and of black pepper (trioicum)
season), Ginger (Hawaiian), soybean (
exhibited tolerant reactions to inocu
M. incognita, 200 egg masses of M. in
and 100 egg masses of M. javanica per ]

Root-knot nematodes, Meloidogyne
pp., are prevalently associated with a
variety of economic crops in the Philip-
ines. They have very wide host ranges
Valdez, 1968) and are believed to play
significant role in limiting production
If the susceptible crops. Generally legu-
linous and solanaceous crops and also
lie cucurbits and crucifers appear to be
iost commonly attacked (Castillo, Reyes
nd Davide, 1974).
Because of host specificity, the patho-
enicity of root-knot nematodes differs
among nematode and crop species. Varia-
ions in infectivity among nematode iso-



mt Pathology, U.P. at Los Bafios, Colleg

RCP Project No. I.E.-41 and NSDB Projeci

on of Prof. A.N. Pordesimo concerning th<


throughout the Philippines were tested
he respective crops with which they
a other crops through pot inoculation
natode egg masses or larvae. Based on
mns and percentage reductions in top
of Baguio bean (Red kidney), bush
), mung bean (MG-50 10 A) and Rose
U1 season), eggplant (Dumaguete long
bean (Accessions 304 and 432), and
of black pepper (trioicum), soybean
nery) to M. javanica were apparent.
;on (Deltapine 16), peanut (CES 101)
a, M. acrita, M. javanica, and M. are-
SM. acrita was observed. Cowpea (All
lark 63) and strawberry (Missionery)
tions with up to 250 egg masses of
ognita, 200 egg masses of M. arenaria
it, respectively.

sites or races and in susceptibility among
rop varieties have also been reported
Martin, 1954). Among the susceptible
rops, some appear more severely affect-
d by a given nematode species than
others. On the other hand, tolerant crops
row normally and produce normal yields
despite heavy nematode infections. Root-
not nematode species also differ not
nly in crops that they attack, but also in
ie severity of the disease they cause on a
iven crop.
This study was conducted to deter-
line the susceptibility, resistance or
Alerance of selected crops to root-knot


nematode species and to learn the potei
tial damage that a given nematode speci
may cause under a certain inoculu:
level. Information that will be derived
useful in the formulation of a crop rot
tion scheme to control root-knot nem


A single egg mass culture of each roo
knot nematode isolate collected in 197
to 1974 from soil and/or roots of selected
crops throughout the Philippines was ii
creased on potted tomato (VC 11-1
plants for three to six months. The di
ferent nematode species were identified
with consultations from Dr. A.L. Taylo
Chief of Nematology, Florida, Depar
ment of Agriculture and Consumer Se
vice, Gainesville. Four species were idei
tified, namely M. acrita, M. arenarii
M. incognita, and M. javanica. The roo
knot nematode previously identified i
M. incognita var. acrita was elevated t
species level, M. acrita, based on the di
scriptions recently provided by Esse
Perry and Taylor (1976).
Through inoculation experiments, th
different root-knot nematode isolate
were tested for their ability to caus
damage on the respective crops wit
which they were found associated in th
field. In addition, the following isolate
were also tested on other crops: M. acril
from hyacinth bean on cowpea, blac
pepper, pigeon pea, cotton, and peanu
M. incognita from lima bean on mun
bean (MG-50 10A) and cowpea; M javi
nica from mung bean on soybean;M. ar
naria from ginger on cotton and peanu
M. incognita from celery on cotton an
peanut; and M. javanica from black pe]
per on cotton and peanut. Except th
simultaneous experiments on cotton
mung bean accessions 304 and 432, pe:
nut, and pigeon pea, the experiments o

the different crops were conducted
s different times.
n The inoculation experiments consists
s of introducing counted nematode e
S masses or newly-hatched larvae arour
Exposed roots of one to four two-wei
old seedlings (one-to two-month o
cuttings in the case of black pepper ai
rose) grown in 15-to 23-cm dia. pc
containing baked soil. Each inoculu
Level was replicated four to six time
The materials used in each experimei
were uniform. In each case, an adequa
number of non-inoculated seedlings w
S provided as checks. When egg mass
were used as inocula, the relative number
of eggs per egg mass were determine
from 20 randomly-obtained egg masse
before each inoculation experiment. TI
general average numbers of eggs per el
mass were, respectivley, 517, 475, 42
and 341 for M. acrita, M. arenaria, A
incognita, and M. javanica.
The experimental pots were place
on top of hollow blocks and randomly
arranged outside the greenhouse. Tl
plants were protected from foliar pests b
regular spraying with recommended pest
cides. The effects of nematode inocua
tion were determined at last harvest, i
the case of the early maturing crops, (
at least three months after inoculation
in the case of the late maturing crop
SData collected consisted of root ga
rating, root weight, top weight, yiel<
and namatode reproduction. Root ga
Ratings were based on relative percentage
Sof galled portions of root systems dete
Smined as follows: 1.0% (none); 2.(
S1-25% (light); 3.0, 26-50% (moderate
S4.0, 51-75% (severe); and 5.0, over 759
(very severe). Nematode reproductio
was determined based on the presence c
Absence of nematode egg masses a
Sustained 1 g root sample obtained fror
-inoculated plants in each pot.


Crops' Responses to Me


The relative susceptibility, resistance
ir tolerance df a particular crop species/
variety to a given nematode species and
he virulence of a particular nematode
species to a given crop species/variety are
parent (Table 1).
Effect of nematode inoculation on
got weight. Only Baguio bean (Red
idney), black pepper (trioicum), celery
Utah 52-70 H) inoculated with, res-
ectively, M. incognita, M. javanica and
I. incognita, exhibited significant reduc-
ions in root weight. In some cases, root
eight increases were even noted in other
rops inoculated with nematodes. This
Consistency is believed to be at least
artly attributable to the increase in root
lass due to the formation of galls, which
complicated the determination of the
ematode effect on root weight. The
ature of the variations in root weight
deductions due to root-knot nematode
loculations among crop species is not
tell understood. It is apparent, however,
[at root weight is not a good criterion
or determining the crops' susceptibility
ir resistance to root-knot nematodes.
Crops susceptible to root-knot nema-
odes. Based on gall ratings, nematode
-production and percentage reductions
i top weight and yield, the susceptibility
f Baguio bean (Red kidney), bush bean
Henderson), celery (Utah 52-70 H),
lung bean (MG-50 10A) and rose (Apol-
o) to M. incognita; of cowpea (All
:ason), eggplant (Dumaguete long pur-
le), hyacinth bean (Morado), mung bean
Accessions 304 and 432), and soybean
'lark 63) to M. acrita; and of black
epper (trioicum), soybean (Tainung # 3)
nd strawberry (Missionery) to M. javani-
a were apparent. The minimum effective
loculum levels observed for each species
nd the corresponding percentage reduc-
ons in top weight and yield reflect the

larive aegree or crop suscepuoulty ana
ie potential damage that the nematode
an cause on the crops.
The mung bean accessions 304 and
34 from the Department of Agronomy,
University of the Philippines, College
f Agriculture at Los Bafios, which were
ested simultaneously against M. acrita,
somewhat differed in susceptibility to the
ematode. Based on minimum effective
loculum levels observed, the former
appears to be more susceptible to the
ematode than the latter.
Crops resistant to root-knot nema-
odes. Based on similar criteria used in
etermining crop susceptibility, the re-
istance of cotton (Deltapine 16), peanut
CES 101) and pigeon pea (Native) to
1. incognita, M. acrita, M. javanica, and
f. arenaria; and of black pepper (trioi-
um) to M. acrita was observed. On black
epper, only light root galling was ob-
erved on plants inoculated with up to
:00 M. acrita egg-masses per plant. Only
ew nematode egg masses were observed
n the roots of inoculated plants at the
termination of the experiment. This
resistance of black pepper to M. acrita
nd its susceptibility to M. javanica re-
[uire further investigations. On cotton,
'eanut and pegion pea, no galls (rating of
.0) formed on roots inoculated with the
different nematode species; none of the
ess than one nematode recovered per
ram of roots at the termination of the
experiment had reached even the adult
tage. Inoculum levels of up to 1,000 and
:,000 larvae per plant for peanut and cot-
on, respectively, and up to 300 egg
lasses per plant for pigeon pea did not
ause significant reductions in either top
eight or yield. These observations indi-
ate the high degrees of resistance of the
rops to the isolates of the nematode
species tested. Presley (1954) reported
he susceptibility of cotton to Meloi-
nnInof mcn ln. I-rar ...nn ...n ral lt-.n -,


Table 1. Reactions of selected crops to Meloidogyne spp. inoculations at different levels

Inoculum Maximum Minimum effective inoculum level observed
level gall Nematode and percentage reduction Crop
Crop/nematode species used rating Reproduction Top weight % Yield % Categoryc

Baguio bean (Red Kidney)
M. incognita
Black pepper (trioicum)
M. acrita
M. javanica
Bush bean (Henderson)
M. incognita
Celery (Utah. 52-70H)
M. incognita
Cotton (Deltapine 16)
M. acrita
M. arenaria
M. incognita
M. javanica
Cowpea (All season)
M. acrita
M. incognita
Eggplant (Dumaguete long purple)
M. acrita
Ginger (Hawaiian)
M. incognita
Hyacinth bean (Morado)
M. acrita
Mung bean (MG-50 10 A)
M. incognita









4.3 with


5.0 with

5.0 with




5.0 with

200 47

None 0
50 42

None 0

10 59.4




50 47

200 48 S

- R
- S

25 58 S

- S


100 66
None 0

-- --
None 0 T

- S

25-300 4.7 with None

0 100 93 S

M. acrita 25-'
Mung bean (Acc. 432)
M. acrita 25-'
Peanut (CES 101)
M. acrita 1,(
M. arenaria 1,1
M. incognita 1,1
M. javanica 1,1
Pigeon pea (Native)
M. arenaria 25-:
M. acrita 25-:
M. incognita 20-:
M. javanica 25-!
Rose (Apollo)
M. incognita 1,1
Soybean (Clark 63)
M. acrita 25-
M. arenaria 25-
Soybean (Tainung // 3)
M. javanica 10-
Strawberry (Missionery)
M. javanica 25-

aNumber of egg masses per pot, excel

bReductions were significant at P =
due to inoculations with M. incognita, M. ja
CBased on reactions to the inoculum i

5 5.0 with

5 5.0 with

) 1.0 without
3 1.0 without
3 1.0 without
3 1.0 without

D 1.0 without
0 1.0 without
D 1.0 without
0 1.0 without

0 5.0 with

0 5.0 with
0 4.2 with

5 5.0 with

0 4.0 with

; figures on cotton, peanut and rose, whicI

i with DMRT. Only Baguio bean, black pep
nica and M. arenaria, respectively;-, no dat
Ad; S, susceptible; R, resistant; T, tolerant.

ained from inoculations of Meloidogyne
pp. on cotton have been reported (Val-
lez, 1968; Begonia and Davide, 1968;
"oledo and Davide, 1969). Sasser (1954)
reported the susceptibility of peanut to
4. arenaria. These inconsistencies indi-
ate the variabilities in pathogenicity
among isolates of the same root-knot
nematode species, similar to that reported
iy Sasser and Nausbaum (1955).
The relative resistance of radish (Ja-
'anese radish) to M. incognita isolate
rom celery and of radish and asparagus
o field populations of Meloidogyne
pp. were also indicated in earlier studies
Castillo and Bulag, 1974; Castillo, Alejar
nd Litsinger, 1977).
Crops tolerant to root-knot nema-
odes. The lack of significant reduc-
ions in top weight and/or yield of cow-
ea (All season), ginger (Hawaiian), soy-


EGONIA, D. T. and R. G. DAVIDE. 1968.
to three isolates of Meloidogyne incogn
patterns. III. Composition and popular
cropping patterns of Batangas. Phil. Agi
ASTILLO, M. B. and V. B. BULAG. 1974.

ean (Clark 63) and strawberry (Mis-
onery), inoculated with up to 250 egg
lasses of M. incognita, 200 egg masses of
. incognita, 200 egg masses of M. are-
aria and 100 egg masses of M. javanica
er pot respectively, despite the moderate
n cases of cowpea, ginger and straw-
erry) to severe (in case of soybean)
ailing of infected roots indicates the
)lerance of the crops to the nematodes
: the different inoculum levels used. Just
ce the reported (Castillo and Maranan
974) tolerance of cassava (Golden) to
. arenaria and of sweet potato (BNAS)
SM. acrita, at per plant inoculum levels
f 175 and 200 egg masses, respectively,
would be interesting to determine the
asibility of growing these varieties in
eld soils infested with root-knot nema-


athologic reactions of field and fiber crops
!. Phil. Phytopathol. 4:52-73.
ITSINGER. 1977. Nematodes in cropping
ns of plant parasitic nematodes in selected

[an. & June, 1976 Crops' Responses to Meloidogyne spp. 23

root-knot nematode populations in two-year tobacco rotation plots. Phytopatho-
logy 45:540-545.
'OLEDO, R. and R. G. DAVIDE. 1969. Reactions of different vegetable and field crops
to infection by Meloidogyne javanica. Phil. Phytopathol. 5:45-51.
TALDEZ, R. B. 1968. Survey, identification and host-parasite relationships of root-knot
nematodes occurring in some parts of the Philippines. Phil. Agr. 51:802-824.



Assistant Professor, Department of
at Los Bafos, College, Laguna 3720 and,
Entomologist, Department of Entomolog
Laguna 3720.
This study was part of the UPL


Plant parasitic nematode popt
terns under different rice-growing
Field legumes and vegetables were t1
todes were extracted from soil and r
lenchulus spp. predominated over t
ferences in nematode populations at
duration of flooding. The highest p
upland fields. Isolated paddies in d
had surprisingly low populations.
undergoes two to three months of
to control the nematodes, although
would be a source of reinfestation
farmers periodically flood their fie
ciencies in the soil. Although populi
populations were observed in this i
rice is cultivated under three month
of nematodes. Rice-based cropping
populations in the flooded environn
dominant factor influencing nemat
areas, flooding is more determinat

The effect of crop species and crop-
ping sequence on composition and po-
pulation density of plant parasitic nema-
todes is well documented (Oostenbrink,
1960; Ferris and Bernard, 1967; Mukho-
padyaya and Prasad, 1968; Castillo, Bajet
and Harwood, 1976; Castillo, Alejar and
Harwood, 1976; Castillo, Alejar and
Litsinger, 1977).
In well-drained rainfed upland areas of
Batangas, cropping of leguminous and so-
lanaceous vegetables favored the build



'lant Pathology, College of Agriculture, U.
respectively, Research Assistant and Associa
, Cropping Systems Program, IRRI, Colleg

'A-IRRI Cooperative Nematology Researc


itions were determined in cropping pat-
environments in Manaoag, Pangasinan.
standing crops at sampling time. Nema-
At samples. Meloidogyne spp. and Roty-
e other plant parasitic nematodes. Dif-
ong environments were associated with
mulations were detected in non-flooded
inage ways among these upland fields
these areas, one crop of paddy rice
ooding. This was apparently sufficient
soil erosion from surrounding slopes
ach rainy season. In one lowland area,
Is to alleviate the iron and zinc defi-
ions were still reduced, relatively higher
!a. The normal rainfed paddies, where
of flooding, harbored the least number
pattems did not affect the nematode
nts. While cropping pattern may be the
le populations in non-flooded upland
a in the flooded rice-growing environ-

up in populations of plant parasitic nema-
todes, particularly the predominant Me-
loidogyne spp. and Rotylenchulus spp.,
while cropping of rice and corn sup-
pressed the populations (Castillo, Alejar
and Litsinger, 1977). The effect of mo-
noculture, rotation and mixed cropping
on nematode populations was likewise
dependent on the crop species and crop-
ping sequence. Thus crop rotation is an
important means of reducing nematode
populations in these areas.


Nematodes in Cropping Patterns. IV

In rainfed lowland rice areas where
nematode-susceptible upland crops are
often grown after rice, various factors
may influence nematode populations in
the soil. Some of these factors are crop
species, cropping pattern, length ol
cropping season, duration of flooding,
and length of dry fallow. For instance,
in Manaoag, Pangasinan, different rice-
growing environments exist. These envi-
Sronments determine to a large extent the
potential for crop intensification. It
would be interesting to determine how
these environments influence plant para-
sitic nematode populations and how their
effects compare with that of cropping


In March, 1976, a survey was conduct-
ed to determine the populations of plant
parasitic nematodes in cropping patterns
under different rice-growing environ.
ments of upland and lowland areas ol
Manaoag, Pangasinan. The municipality
has an average of six consecutive dry
months with less than 100 mm of rair
and four consecutive wet months with
more than 200 mm of rain of which al
least one month has rain exceeding 50C
mm. The average rainfall is 1980 mm pei

Descriptions of the Different Rice-
Growing Environments
Normal rainfed paddies. These are
located in the lowland areas surrounding
the village of Caaringayan, a nearly level
plain with a very high water table. Soils
are calcareous clay loam with pH 7.5.
The basic soils are believed to be respon-
sible for the deficiency of iron at the
aerobic (oxidized) state and that of zinc
at the anaerobic (reduced) state or when
the field is flooded. Because of the very
higl water table and poor drainage,

these areas get inundated early and fre-
quently during the wet season. One crop
of paddy rice normally undergoes three
months of flooding.
Intermittently flooded paddies. -
These are located in the partly irrigated
lowland areas of the village of Pao, a
nearly level plateau with a low water
table. Soils are calcareous clay loam,
moderately well-drained and with pH
7.3. Iron and zinc deficiencies in the soil
are also found in these areas. To alleviate
these deficiencies farmers periodically
flood and drain their fields. Paddy fields
here are incompletely bunded. Only
temporary bunds are constructed across
the slope when rice is grown. When the
paddy field is irrigated, the water stays
only for a short time on the land. Gen-
erally little effort is exerted by farmers
to impound water for the rice due to the
soil problem.
Non-flooded upland fields These
are located in the more elevated upland
areas of the villages of Caaringayan and
Pugaro. Soils in these areas range from
silty clay loam to clay loam, non-cal-
careous, well-drained, and with pH
ranging from 6.5 to 7.2. They are un-
suitable for flooded rice although upland
rice may be grown. Crops in these areas
are strictly rainfed.
Isolated paddies in drainage ways
among upland fields. These are located
in the upland areas of the villages of
Pugaro and Babassit. Because of the very
low elevation of the paddies, the sur-
rounding slopes provide water during the
rainy season. Two to three months of
flooding a year normally occurs here.
Selection of cropping patterns. -
Cropping patterns were determined
through interviews with the farmers.
Areas in which soil treatments with
nematicides, e.g. carbofuran, were applied

Jan. & June, 1976

were avoided. Only cropping patterns McBeth, Taylor and Smith (1941). Each
of three-year duration and with known soil sample was sieved twice with the
nematode-susceptible crops (as far as 60-mesh screen. Nematodes were identi-
Meloidogyne spp. and Rotylenchulus spp. fled and quantified with the aid of stereo-
are concerned), namely, mungbean, cow- scopic and dissecting microscopes, res-
pea, bottle gourd, bitter gourd, and egg- pectively.
plant, as standing crops were selected.
The crops were either ready for harvest
or already harvested but still possessed RESULTS AND DISCUSSION
live roots when sampled. To compare the
nematode complexes, representative crop- Table 1 shows the populations of
ping patterns in each of the different Meloidoyne spp., Rotylenchulus spp.
rice-growing environments were selected. nematodes in
and other plant parasitic nematodes in
In environments where the desired crop- cropping patterns under different rice-
ping patterns could not be found, the growing environments in Manaoag, Panga-
dominant ones were considered instead. ofBatangas
sinan. As in the upland areas of Batangas
Sampling for nematodes. Sampling (Castillo, Alejar and Litsinger, 1977),
for nematodes in each plot was done Meloidogyne spp. and Rotylenchulus spp.
by collecting approximately 50 cc soil predominated over the other plant para-
containing pieces of feeder roots from sitic nematodes, namely, Criconemoides,
the root zone of each of 28 to 40 ran- Helicotylenchus, Hoplolaimus, Pratylen-
domly-selected plants. Samples from 7 chus, and Tylenchorhynchus, in soil and
to 10 plants were placed in each plastic roots of the nematode-susceptible field
bag. Thus four composite samples were legumes and vegetables. In earlier experi-
collected per plot. Whenever possible, ments, the yield of mungbean grown in
sampling from each cropping pattern in soils initially infested with 90 M. acrita

Table 1. Populations ofMeloidogyne spp., Rotylenchulus spp. and other plant parasitic nematodes in cropping patterns under different
rice-growing environments in Manaoag, Pangasinan

Cropping No. of
period plots No. of nematodes observed1
Environment Cropping Pattern (No. of yrs.) sampled Mel. Rot. Others Total

upland fields Rice-field legume-fallow 3 2 268 b 44 b 54 d 367 c

Isolated paddies
in drainage
ways among
upland fields Rice-field legume-fallow 3 4 0 a 2 a 11 bcd 13 ab
Rice-vegetable-fallow 3 3 15 a 0 a 2 ab 17 ab
Corn-rice-field legume-fallow 3 3 0 a 0 a 13 cd 13 ab

flooded paddies Rice-field legume-fallow 3 1 4 a 0 a 8 abcd 12 ab
Corn-rice-field legume-fallow 3 4 4 a 1 a 36 d 41 b

Normal rainfed
paddies Rice-field legume-fallow 3 2 0 a 1 a 1 a 1 a
Rice-vegetable-fallow 3 1 1 a 0 a 5 abcd 6 a
Rice-field legume-fallow 2 3 0 a 0 a 1 a 1 a
-rice-rice-field legume 1
Corn-rice-field legume-fallow 2 2 0 a 1 a 3 abc 4 a
-rice-rice-field legume 1

1Data are means per composite sample (200 cc soil and 1 g roots), replicated four times in each of the plots sampled. Among all
cropping patterns in the different environments, similar letters indicate no difference at 5% level with DMRT. Mel. Meloidogyne; Rot.
Rotylenchulus; Others Criconemoides, Helicotylenchus, Hoplolaimus, Pratylenchus, and Tylenchorhynchus.

28 Philippine Phytopathology Vol. 12

ments with comparable cropping pat- This precluded the determination of the
terns, e.g. rice-field legume-fallow, rice- effect of cropping pattern on nematode
vegetable-fallow and corn-rice-field le- populations in these fields.
gume, generally harbored statistically si- The present findings indicate that
milar npmatnlp nrnilatlinne ...

numbers in these paddies could probably duration of flooding. The effect of the
be attributed to the combined effects non-susceptibility of the rice plant to
of flooding and drvine of the soil. which Meloidosvne son. and Rotvlenchulus son.

in nematode p
related with
though not n(
. .

a (Castillo, Baj<
Batangas (Ca,
er, 1977), floc
ve in the flooi
gasinan. The :
ding on popi
atodes (Brown

fields. Isolated padi
among these uplan(
crop of paddy ric

Xlwxly low po auuiia, kou
i."'i~ U U~ LU "iU

season. Although I
still reduced, relative
were observed .in

ie nerr

attacks on the succeeding
eptible upland crops, with

,Research Assistant, Research Aide and
borer, IRRI Cropping Systems Pro-
am, for their assistance in the labora-
iry works; Mr. R.D. Alcos, laborer,


IOWN, L. N. 1933. Flooding to control roi
ASTILLO, M. B., M. S. ALEJAR and J. A.
patterns. III. Composition and populat
cropping patterns in Batangas. Phil. Agr
ASTILLO. M. B.. M. S. ALEJAR and J. A. i

distance in the soil sampling; and Dr. M.
. Vega, IRRI Assistant Director, for pro-
ding funds to support the study.


knot nematodes. J. Agr. Res. 47:883-888.
ITSINGER. 1977. Nematodes in cropping
as of plant parasitic nematodes in selected
^ .noQ nnn

imersuogyne acru u. rn. ADgr. z-z. .
ASTILLO, M. B., M. S. ALEJAR and R. R. HARWOOD. 1976. Nematodes in cropping
patterns. II. Control of Meloidogyne incognita through cropping patterns and cul-
tural practices. Phil. Agr. 59:295-312.
ASTILLO, M. B., M. S. ALEJAR and R. R. HARWOOD. 1976. Effect of flooding on
pot populations of Rotylenchulus reniformis and Meloidogyne incognita. Phil.
Phytopathol. 12:11-16.
ASTILLO, M. B., N. B. BAJET and R. R. HARWOOD. 1976. Nematodes in cropping
patterns. I. Population of Rotylenchulus reniformis on successively monocultured
crops. Phil. Agr. 59:288-294.
ERRIS, V. R. and R. L. BERNARD. 1967. Population dynamics of nematodes in
fields planted to soybeans and crops grown in rotation with soybeans. I. The genus
Pratylenchus (Nemata: Tylenchida). J. Econ. Entomol. 60:405-410.
cBETH, C. W., A. L. TAYLOR, and A. L. SMITH. 1941. Note on staining nematodes
in root tissues. Helminthol. Soc. Wash. Proc. 8:26.
UKHOPADYAYA, M. C. and S. K. PRASAD. 1968. Population dynamics of Tylencho-
rhynchus. Nematologica 14:404-418.



Phil. Phytopathol. 12:30-39
Jan. & June, 1976



Assistant Professor, Department of Plant Pathology, College of Agriculture, U.I
at Los Baiios, College, Laguna 3720 and, respectively, Research Assistant and Associat
Entomologist, Department of Entomology, Cropping Systems Program, IRRI, Colleg4
Laguna 3720.
This study was part of the UPLBCA-IRRI Cooperative Nematology Researc


A survey was conducted to determine the populations of plant parasitic
nematodes in different land forms and cropping patterns of rainfed upland
and lowland areas in Oton, Tigbauan and Leon, Iloilo. Soil texture ranges
from clay to clay loam and pH, from 6 to 7.2. Only cropping patterns of
three-year duration and with legumes or other non-graminaceous upland
crops as standing crops were considered. Nematodes were extracted from
replicated composite samples (300 cc soil and 1 g roots) by the sieving-
Baermann funnel technique; those in the roots were stained in acid fuchsin-
lactophenol. Meloidogyne spp. and Rotylenchulus spp. predominated over
the other plant parasitic nematodes. From the most to the least nematode-
infested, the land forms were as follow: unbunded river levee; unbunded sum-
mit; bunded summit and bunded river levee; plain, plateau and slope; and
drainage way. The effect of land form was evidently related with duration of
flooding. Lowland rice cropping was associated with reduced nematode
populations. Apparently, one crop of lowland rice was sufficient to effectively
control the nematodes in the flooded lowland areas. In the non-flooded areas,
high populations resulted from continuous planting of upland crops. Dis-
semination of nematodes from the more elevated to the less elevated land

In rainfed upland areas of Batanga!
cropping pattern appeared to be the d(
minant factor influencing the population
of plant parasitic nematodes, particularly
the root-knot nematodes (Meloidogyn
spp.) and Rotylenchulus spp., on nor
graminaceous annual crops (Castillc
Alejar and Litsinger, 1977). Generally
cropping patterns involving mostly th
nematode-susceptible vegetables or field
legumes had higher nematode popular
tions than those involving mostly th
nematode-resistant rice or corn. Rice o

corn cropping tended to reduce nematod
populations on the succeeding vegetabi
or field legume, with the suppressive
effect generally increasing with the nun
ber of croppings of the preceding n
sistant crop.

A different situation was observed i
cropping patterns under varied ric
growing environments in Manaoag, Pang
sinan (Castillo, Arceo and Litsinge
1976). Duration of flooding appeared t
be a more dominant factor in reducing

iNematoaes in uropping

nematode populations than cropping pat-
ern. For instance, while the cropping
>attern rice-field legume-fallow yielded
'ery high populations of Meloidogyne
pp. and Rotylenchulus spp. in non-
looded upland fields, reduced nematode
populations were consistently observed in
similar cropping pattern in other environ-
nents, viz, isolated paddies in drainage
vays among upland fields, intermittently
flooded paddies and normal rainfed
Rainfed agricultural areas of Iloilo
ire characterized by a diversified topo-
;raphy distinguished by different land
brms, each possessing distinct qualities
n relation to the water table, water
ource, drainage characteristics and soil
ype. Cropping patterns and cropping
>attern potentials in these land forms
reflect these different qualities. Both
upland and lowland cropping patterns
ire found in these land forms. Thus, a
purely rainfed area of Iloilo was selected
is a suitable laboratory for confirming
>ur earlier observations and determining
he influence, if any, of land form on
plantt parasitic nematode populations. Thi
Nhis study also seeks to identify the land
forms with greater capacity to reduce
nematode infestation and, therefore, bet-
er potential for growing the nematode-
usceptible upland crops in rice rotations.


A survey was conducted to determine
the populations of plant parasitic nema-
todes in different land forms and crop-
ping patterns of upland and lowland
areas of three municipalities in Iloilo,
namely, Oton, Tigbauan and Leon. Crop-
ping patterns in each land form were de-
termined through interviews with farm-
:rs. Only those that had been repeated on
the same plots during the last three years
md with nematode-susceptible crops, e.g.

iiu1iir,1Cin, LUwl w au lumall U, 4U1 V5"
plant, as standing crops were considered.
Graminaceous upland crops, particularly
rice and corn, were avoided because our
preliminary investigations showed that
they are resistant to Meloidogyne spp.
and Rotylenchulus spp., the two nema-
tode groups that we believe to be the
most important nematode pests of non-
graminaceous annual upland crops in the
Philippines. Crops were at least in the
flowering stage when sampled. Two
sampling trips were made in 1977, one in
January and another in February.
Descriptions of the different land
forms. Figure 1 shows a cross section
of the generalized toposequence showing
relative positions of land forms in relation
to the water table in the rainfed rice pro-
duction complex of Iloilo. Table 1 gives
the descriptions of the physical charac-
teristics of the different land forms. From
these, it is apparent that the land forms
have varied water supply and retention
capacity and, therefore, also have varied
potential for intensive lowland rice crop-
ping. In the order of increasing capacity
to hold water, the land forms can be
arranged as follows: summit, river levee,
slope, plateau, plain, and drainage way.
Despite the high water table, the river
levee has relatively short flooding dura-
tion because its soils are newly deposited
and, therefore, loose. The longest dura-
tion of flooding in the drainage way is
attributable to its very low elevation,
very high water table and very poor
Generalized cropping pattern in the
different land forms. Since water is
quickly drained from the summit and
river levee, these land forms are best
suited for a wide variety of upland crops.
Surprisingly, however, some farmers, in
the summit bund their fields, particularly
the less sloping plots, during the rainy


F---- 9r-S



Figure 1. Cross section of a generalized toposequence showing relative positions of land forms in a rainfed rice production complex.

Table 1. Physical characteristics of the various land forms in Iloilo
Land Form Water Table Water Source Lateral

Summit Very low Rain Very rapid

Platmn l LoTw Rain. low lateral Moderate

34 Philippine Phytopathology Vol. 12

the river levee maybe bunded or un- Plant Pathology, University of the Philip-
bunded. The former represents the fields pines at Los Baios, College of Agricul-
closest to the river where puddling of ture.
soil for lowland rice can be done after Processing of samples and quantifica-
heavy rains. The latter represents the tion of nematodes. Within a week from
typical upland cropping area. collection, each composite sample was
One cropping of lowland rice followed thoroughly mixed and a 300 cc soil and
by a field legume is the dominant crop- 1 g root sample was processed for nema-
ping pattern in the slope and plateau todes. Nematodes were extracted from
areas. Two lowland rice croppings a year the soil by the combination of the
are practiced by some farmers. Plains sieving (using 60- and 325-mesh screens)
are potentially two lowland rice crop and Baermann funnel techniques de-
areas. Some farmers prefer to follow low- scribed by Thorne (1961); nematodes
land rice with a field legume. Drainage in the roots were stained in acid fuchsin-
ways are best suited for two or even three lactophenol following the procedure of
lowland rice croppings a year, depending McBeth, Taylor and Smith (1941). Each
on the extent of the rainy season. For soil sample was sieved twice with the
some reasons, a few farmers grow only 60-mesh screen. Nematodes were identi-
one crop of lowland rice. In the dif- fled and quantified with the aid of
ferent lowland rice areas, farmers some- stereoscopic and dissecting microscopes,
times either ratoon their rice crops or fal- respectively.
low their fields until the heavy rains
cease before sowing field legumes. For R TS A
nematode assay, the ratoon and fallow
environments are considered alike since
during fallow, the stubbles of the pre- In the differet land forms and cp-
ceding rice crop, which still possess live ping pattems of Iloio, Meloidogyne spp.
roots, are left in the field. Fields sown and Rotylenchulus spp. predominated
to field legumes following rice are not over the other plant parasitic nematodes,
weeded. namely, Helicotylenchus, Hemicricone-
moides, Hemicycliophora, Hoplolaimus,
Sampling for nematodes. A com- Pratylenchus, Scutellonema, and Tylen-
bination of fixed and random sampling chnrhvnrhuws Onlv Mplnidnomnp enn ind

WIui a pac1iuu.iu UoUppig paU iL was
divided into five subplots. From each
subplot, a composite soil and root sample
from 10 randomly selected plant hills
were collected close to plant roots by
means of a trowel. Thus five composite
samples representing 50 plant hills were
collected per plot. Sampling from each
cropping pattern of the different land
forms was replicated in four different
plots, situated either in the same or dif-
ferent localities. The samples were placed
b -1l1A U-~I --n A nl-l,---A +1-

reeamg positions m roots ot the crops
sampled. Roots infected by Meloidogyne
showed the galling symptom of root-
knot; those infected by large numbers of
Rotylenchulus were usually necrotic. No
correlation on the occurrence or popula-
tion of any of the other plant parasitic
nematodes with a particular land form or
cropping pattern was observed. These
nematodes, therefore, are believed to be
of minor importance and perhaps feed
mainly on the roots of weeds associated

cularly Meloidoyne spp. and Rotylen-
chulus spp., are presented hereafter.
Effect of land form in each of the
different cropping patterns. The ef-
fects of the land forms slope, plateau,
plain, and drainage way on populations
of Meloidogyne spp. and Rotylenchulus
spp. were not indicated either in rice-
legume, rice-fallow/ratoon-legume or rice-
rice-legume cropping pattern (Table 2).
The effects of these land forms on the
populations of the nematodes in each of
the cropping patterns cited were statis-
tically similar. The inconsistent results
obtained concerning the populations of
plant parasitic nematodes other than
Meloidogyne spp. and Rotylenchulus spp.

Table 2. Effect of land form on populat
spp. and other plant parasitic i
Iloilo, 1977

No. of nemi
Cropping Pattern2 Land Form

Rice-legume Slope
Drainage way

legume Slope
Drainage way

Rice-rice-legume Slope
Drainage way

SData are means of 20 composite sa
ples/locality. Among land forms within a
significant difference at 5% level with DM.
Others = Helicotylenchus, Hemicriconem
lenchus, Scutellonema, and Tylenchorhynci
2All rices are lowland varieties, bunde

taken as a whole could not be explained.
It is interesting to note, however, that in
all cropping patterns, total nematode
populations were numerically lowest, al-
though not necessarily statistically dif-
ferent, in the drainage way.
Effect of cropping pattern in each of
the different land forms. The in-
fluences of the cropping patterns rice-
legume, rice-fallow/ratoon-legume and
rice-rice-legume on populations ofMeloi-
dogyne spp. and Rotylenchulus spp.
were not indicated either in the slope,
plateau, plain, and drainage way (Table
3). The effects of these cropping patterns
on the populations of the nematodes in
each of the land forms cited were statis-

ons of Meloidogyne spp. and Rotylenchulu
nematodes in different cropping patterns o

odes observed/300 cc soil and 1 g roots'
Mel Rot. Others Total

9 a 2 a 34 ab 45 be
la 2a 86 b 89 c
0 a 1a 23 ab 24 abc
la la 5a 7a

la 4a 90a 95 c
1a 9 a 21 a 31 be
32 a 12 a 84 a 128 c
Oa la 21 a 22 ab

0a a 14 a 15 a
Oa la 35a 36 a
Oa la 24 a 25 a
Oa Oa 5a 5a

Lples collected from four localities, five sarr
cropping pattern, similar letters indicate n
T. Mel.=Meloidogyne; Rot. Rotylenchulus
ides, Hemicycliophora, Hoplolaimus, Prat)

Vru rrr-r)


rnilppine rnytopatnology

Table 3. Effect of cropping pattern on p
spp. and other plant parasitic n,

No. of nematc
Land Form Cropping Pattern2

Slope Rice-legume

Plateau Rice-legume
Rice-fallow/ratoon leg

Plain Rice-legume

Drainage way Rice-legume

SData are means of 20 composite s
ples/locality. Among cropping patterns
significant difference at 5% level with DM
Others = Helicotylenchus, Hemicriconer
lenchus, Scutellonema, and Tylenchorhyn
2 All rices are lowland varieties, bur
nongraminaceous upland crops.

tically similar. Even the rice-rice-ratoon-
legume cropping pattern had similar ef-
fect as that of the less intensive rice
croppings in the drainage way. In each
of the land forms, except the slope, the
effects of the aforementioned cropping
patterns on populations of plant para-
sitic nematodes other than Meloidogyne
spp. and Rotylenchulus spp. and also of
all plant parasitic nematodes taken as
a whole, were likewise similar. Although
statistically significant only in the slope,
generally higher total nematode popula-
tions were observed in the rice-fallow/
ratoon-legume cropping pattern than in
either the rice-legume or rice-rice-legume.
Tt:l.4 :- --.-,1--.1.1. 4 . +^ m -rr.

pulations ofMeloidogyne spp., Rotylenchuh
wtodes in different land forms of lloilo, 197

es observed/300 cc soil and 1 g roots'
Mel. Rot. Others Tota

9 a 2 a 34 ab 45 a
ne la 4 a 90 b 95 b
Oa la 14a 15a

la 2a 86 a 89a
ne la 9 a 21 a 31 a
Oa la 35a 36a

0 a la 23 a 24 a
ne 32 a 12 a 84 a 128 a
Oa la 22a 23a

la la 5a 7a
ne 0 a la 21 a 22 a
Oa Oa 5a 5a
Oa Oa 4a 4a

nples collected from four localities, five san
thin a land form, similar letters indicate n
T. Mel. = Meloidogyne; Rot. = Rotylenchulu
)ides, Hemicycliophora, Hoplolaimus, Prat:
ed; legume = mung bean or cowpea; NGUC

weedy environment in the rice-fallow/
ratoon-legume cropping pattern, since
less land preparation was involved.

Effect of land form over all cropping
patterns. From the most to the least
nematode-infested, the land forms can be
arranged as follows: unbunded river
levee; unbunded summit; bunded summit
and bunded river levee; plain, plateau and
slope; and drainage way (Table 4). The ef-
fect of land form on nematode infesta-
tion was evidently related with duration
of flooding. Generally lower nematode
populations were found in land forms
with longer duration of flooding, namely
.n1- nl-.+.- l nion .nrd rlianop W-

vol. 1i

Jan. & June, 1976 Nematodes in Cropping Patterns. V 37

Table 4. Populations of Meloidogyne spp., Rotylenchulus spp. and other plant parasitic
nematodes in different land forms over all cropping patterns in Iloilo, 1977

No. of No. of nematodes observed/300 cc soil
Generalized Plots and 1 g roots
Land Form Cropping Pattern2 Sampled Mel. Rot. Others Total

a) Bunded Lowland rice-NGUC 4 5 a 274 c 25 b 304 cd
b) Unbunded Continuous NGUC 4 41 b 587 cd 22 b 650 d

Slope 1 to 2 croppings
of lowland rice-
legume 12 3 a 2 a 46 b 51 b

Plateau ditto 12 1 a 4 a 47 b 52 b

Plain ditto 12 11 a 5 a 44 b 60b

Drainage way 1 to 3 croppings
of lowland rice-
legume 16 la la 12a 14 a

River levee
a) Bunded Lowland rice-NGUC-
corn 4 108 b 28 bc 64 b 200 cd
b) Unbunded Corn-fallow-NGUC 3 1,427 c 1,219 d 65 b 2,711 e

1Data are means of composite samples, five from each plot; among land forms over

Philinnina Phvtonatholnrv

form and cropping pattern. This suggests
that in bunded plots with relatively iden-
tical flooding durations, the influence of
land form and the particular cropping
patterns cited is insignificant. Despite the
more nematode-favorable cropping pat-
tern (continuous NGUC) in the unbunded
summit than in the unbunded river levee
(corn-fallow-NGUC), the populations of
all plant parasitic nematodes were signi-
ficantly higher in the latter than in the
former. This is probably attributable to
nematode dissemination from the more
elevated to the less elevated land form
through erosion. However, only further
investigations can resolve this. The dif-
ference in soil pH between summit (6.0)
and river levee (7.2) is perhaps unimpor-
tant, since reports -(Wallace, 1963) on the
influence ofpH on nematode populations
are either conflicting or negative.
In our pot experiment (Castillo, Ale-
jar and Harwood, 1976), flooding signi-
ficantly controlled the populations of
M. incognita and R. reniformis in soil and
roots of susceptible crops. The present
findings support our observation in the
lowland areas of Manaoag, Pangasinan
(Castillo, Arceo and Litsinger, 1976) that
in rice-based cropping patterns, flooding
is more dominant in reducing populations
of plant parasitic nematodes, particularly
Meloidogyne spp. and Rotylenchulus
spp., than crop rotation. The reverse is
probably true in the well-drained upland
areas. In land forms with longer flooding
durations, the effect of cropping pattern,
if any, was believed to be masked by that


AYALA, A. and C. T. RAMIREZ. 1964
the reniform nematode, Rotylenchu
Rico. J. Agr. Univ. Puerto Rico 48: 1
pot populations of Rotylenchulus

of flooding. Apparently, one crop of low-
land rice was sufficient to effectively
control the nematodes in these land
forms. Other than the probable influence
on nematode dissemination through soil
erosion, no indication of the effect of
land form on plant parasitic nematode
populations was obtained. This observa-
tion concurs with those of Krusberg and
Hirschmann (1958) and Ayala and Ra-
mirez (1964). The association of low
nematode populations in certain land
forms and of high populations in others
are evidently related with duration of
flooding and, perhaps, with host distri-
bution. As far as nematode control is
concerned, the land forms with longer
flooding durations, namely drainage way,
plain, plateau, and slope, in this order,
have better potential for intensive crop-
ping with nematode susceptible crops.


The authors are indebted to the fol-
lowing personnel of IRRI: Mr. M. D. Lu-
maban, Research Assistant, for his as-
sistance during the survey: Dr. R. L.
Tinsley, Agronomist and Dr. M. E. Ray-
mundo, Post-doctoral Fellow, for the
illustration and descriptions of the land
forms; Mrs. S. P. Milagrosa, Research
Assistant, Mr. R. C. Maligalig, Research
Aide and Mr. C. T. Perez, Jr., Laborer,
for their assistance in the laboratory
works; and Dr. M. R. Vega, Assistant
Director, for providing funds to support
the study.


Host range, distribution and bibliography (
s reniformis, with special reference to Puert
R. HARWOOD. 1976. Effect of flooding o
eniformis and Meloidogyne incognita. Phi

Vol. 12

CASTILLO, M. B., M. S. ALEJAR, and J. i
patterns. III. Populations of plant par
in Batangas. Phil. Agr. 60: 285-292.
patterns. IV. Populations of plant I
rice-growing environments in Manaoag
in Peru. Plant Dis. Reptr. 42:599-608.
McBETH, C. W., A. L. TAYLOR and A. L.
root tissues. Helminthol. Soc. Wash. P
THORNE, G. 1961. Principles of nematol
553 p.
WALLACE, H. R. 1963. The influence ol
(ed.) The Biology of plant parasitic

SLITSINGER. 1977. Nematodes in croppin
sitic nematodes in selected cropping pattern

LITSINGER. 1976. Nematodes in croppin
rasitic nematodes associated with different
Pangasinan. Phil. Phytopathol. 12:24-29.
1958. A survey of plant parasitic nematode

MITH. 1941. Note on staining nematodes i
)c. 8:26.
gy. McGraw-Hill Book, Co. Inc. New York

the environment, p. 47-100. In H. Wallac
ematodes. Edward Arnold (Publishers) Ltd

~~ II.___~~_~II Il

-T_ L- A T B 1 EQi

SrrujcbL ouppjurEIu uy rlln-u

tented evidences on the variability of Colletotrichum
sm of banana anthracnose, in terms of spore sizes and
.acteristics, reaction to chemicals, and pathogenicity.
is of the organism were detected from the 10 isolates
ed area in Luzon.

bananas throughout the world. The or- elections into 3 strains. In India, Vamo-

Jan. & June, 1976 Variability and Control of C. n

tissues on potato dextrose agar plates was sterilized 5-mm di
used in the isolation of the organism. advancing margin
Single spores from stock plates or tube cultures of the 1
cultures of each isolate were used in were dipped in the
transferring the organism to culture 10 minutes, dripped
media plates for subsequent studies, and then transfer
The culture plates were incubated under previously prepare
standardized temperature of 30C unless dipped in sterile w
otherwise indicated. The plates were ini
Variability Studies hours and resulting
Pathogenicity Test for pathogenicity For spore gen
was made for each isolate on Bungulan were scraped froi
and Latundan banana fruits using ripe plates with a ste
pin-pricked fruits. Inoculations were placed or dipped
made by placing a drop of the spore sus- tion (1000 ppm)
S. 1 ... fungal snore cone

rr -- -1 n4 +_ 1 -In5

0 ihnl

n the
n for
of a
or 48

K. oorer Iroi
-4 day old
plates. The
lical solution
r for 30 sec
the center
)A plates.
served as coi
:d at 300C f
'th was reco
ion test, s]
orulating cu
lat needle,
e chemical
10 minutes.
tion was in

Table 1. Sources of Colletotrichum musae isc

slatee No. Variety

20 Latundan

22 Latundan

24 Latundan

26 Lacatan

28 Bungulan

32 Saba

34 Latundan

38 Latundan

60 Latundan

62 Latundan

able 2. Comparative virulence of the 10 isol

solates Bw

20 X

22 X




32 X



60 XX

62 XX

SIncubated for 4 days
2 Disease index
X = slight infection
XX = moderate infection
XXX = severe infection

ates used in the present study.

Place Date Collected

Laguna Nov. 13, 1972

Batangas Dec. 1, 1972

Cavite Dec. 18, 1972

Cavite Dec. 22, 1972

Cavite Dec. 22, 1972

Laguna Jan. 5, 1973

Aparri Jan. 8, 1973

La Union Feb. 9, 1973

Zambales Feb. 9, 1973

La Union Feb. 9, 1973

tes of Colletotrichum musae on banana1

Degree of Infection2
gulan Latundan












seem to be more virulent to both banana
varieties than the rest of the isolates
which either showed differential viru-
ence (32, 34, 38, 60) or not-so-virulent
reaction (24, 26, 28) to the 2 varieties
f the bananas.
Cultural, morphological, and physio-
'ogical characteristics When grown on
3 different media, the 10 isolates showed
variable colony characteristics (Fig. 1).
Relative sizes (Table 3) and shapes of the
conidia (Fig. 2) provided further evidence
on the variability of the 10 isolates.
Figure 3 shows the variable reaction
of some of the isolates of C. musae to
different light conditions. Isolates 20,
26, 32, 34, .38, 60 and 62 did not differ
- -+n. f r artil^h lnrlr ,liffPrPnt lioht

were enhanced by continuous light,
others were enhanced by alternating light
and darkness.
Figs. 5 and 6 show the variability ex-
hibited by the different isolates under
different temperatures in terms of growth
and sporulation. All of them showed
20-300C as their optimum temperature
for growth. Isolate 24 had a narrower
range of temperature for growth (20-

reduced growth under continuous light;
isolate 24 had more growth under CL and
CD than RC and ALD while the growth
of isolate 28 was reduced at CL and ALD.
Variability was further substantiated by
the data on sporulation of the different
isolates at different light conditions (Fig.
4). While sporulation of some isolates A

Fig. 1. Colonies of C. musae isolates grown on 3 culture Media: A. Cook's Medium,
B. Czapek's Medium, C. Yeast Extract Agar. The numbers are isolate code num-
I ~- T- w . *-,- 17 J_- -l4 Onont- --- - ^_

TI~ B. R aN 10'7i C

I~r:n~:l:~r r~rl P~nklrl ~F ~ mrmo

Philippine PhytonatholoYv

Table 3. Spore measurements of the different isolates of Colletotrichum musae'

Isolate No. Range Average

20 10.2-- 30.6 x 3.4 -6.8 /u 16.1 x 5.1 /u

22 10.2 20.4 x 4.25 6.8 u 15.61x 5.2 /u

24 10.2- 20.4 x 3.4 6.8 u 12.65 x 4.9 /u

26 10.2 17.0 x 4.24 -- 6.8 u 14.89x 4.93 u

28 6.8 37.4 x 3.4 5.1 u 15.88 x 4.42/u

32 10.2 -- 34.0 x 3.4 5.95 u 18.73 x 4.83 u

34 10.2- 23.8 x 3.4 5.95 /u 15.2 x 5.03 u

38 10.2 34.0 x 3.4 6.8 u 15.2 x 5.1 /u

60 8.5 -- 23.8 x 3.4 5.95 u 14.6 x 4.9 /u

62 8.5 20.4 x 3.4 5.95 /u 15.03 x 4.8 u

'Average spore measurements of 100 conidia.




Fig. 2. Photomicrographs of conidia of
isolates of C. musae from Yeast
extract agar culture representing
3 different strains. A. Strain I
(62) B. Strain 2 (24) C. Strain
3 (28). X800.

Vnl 19

g. 3. Growth of C. musae at different light conditions: continuous light (CL), continuous d
light and dark (ALD). Grown in Yeast extract agar plates and incubated for 7 days at

rnuippine rnywopamnoiogy

1400 *
1100 *
1000 .
S 900

2( 22 *


Fig. 4. Effect of different light conditii
agar plate and incubated for 7 di

300C). The isolates exhibited quite a wide
range of variability in sporulation at dif-
ferent temperatures.
Reaction to chemical

In-vitro test Table 4 shows that my-
celial growth of isolates 20, 24, 26, and
28 was resistant to 1000 ppm benomyl
while spore germination of the above 4
isolates with the exception of 20 was
highly resistant to the chemical.
In-vivo test When the resistant
isolate 28 was inoculated on the green
Bungulan and Latundan fruits, and
treated with 100, 200, 400, 600 and 800
ppm benlate, the isolate exhibited re-

SCtinuous Light
SCtln0 uoui Dayrln
oc Conditin
i Altomating Light ad D~ar

32 34


as on the sporulation of C. musoe. Grown

tion to chemicals and in their patho-
genicity. Species of Colletotrichum are
among the pathogens that exhibit wide
variability. One of the obvious reasons
why many groups of fungi are in a re-
latively confused taxonomic state is that
we do not know the total range of varia-
tion within the group and are not certain
what characters are the more valid ones
to use in separating them. The occur-
rence of the fungus on different hosts
and the variation of an organism which
in reality are only strains or races within
the species most often lead to the crea-
tion and multiplication of specific names.

LcPL1UIV laulati, UL, WIU iA a lUw da IUU LuzoI Islaniu1 iI me rullppines, me
ppm. author detected 3 possible strains among
the 10 isolates: 20, 22, 32, 34, 38, 60
DISCUSSION and 62 belonging to one strain, 24 to
another strain and 26 and 28 to a third
Many pathogens show wide variations strain. These were considered separate
in cultural characteristics, in their reac- strains based on their cultural character-

V U1. 1A

48 Philippine Phytopathology Vol.




2 26 28 32 3, 3 60 62

tract agar plates under complete darkness

Table 4. Action of benomyl on the 10 isoi

Isolate No. % Germin
% Germina

20 26

22 30.

24 93

26 93

28 98

32 20

34 38

38 62

60 44

62 26

(f)* Mycelial growth slightly inhibi
+ No inhibition
5 (-) Mycelial growth completely in

r 7 days.

es ofColletotrichum musae.

BENOMYL (1000 ppm)
)n Mycelial Growth (mm

32 (-)*


18 (+)*

30 (+)*

42 ()





5 (-)



ariability and Control of C. musae

tics, morphology, virulence 'and dit-
erences in their reaction to fungicide
enomyl. Whether these variations had
een due to heterokaryosis and other
mnetic factors as suggested for other
ingi (Suzuki, 1965), is not known
nd would need further studies. The
variability of C gloeosporioides, causal
rganism of many tropical fruit anthrac-
ose, is as far known, the result ofmuta-
ons which occur easily and regularly
Von Arx, 1957). Likewise, variants
observed in C destructivum are believed
3 arise as mutants (Chilton, 1943).
ytogenetic studies will determine whe-
ier variability of C musae is also due to
On the practical aspects, benomyl is
sed to control banana anthracnose
Meredith, 1971; Eckert and Sommer,
967). It is a benzimidazole derivative
nd behaves as systemic fungicide. Its


ASHBY, S. F. 1931. Gloeosporium strains. I
3URGER, O. F. 1921. Variations in Colleto
3HILTON, S. J. P. 1943. Variations in spon
destructivum. Mycologia 35:13-20.
on the disease. J. Madras Univ. Sect. B
ECKERT, J. W. and N. F. SOMMER. 1967
by postharvest treatment. Annu. Rev.
3AVARRA, M. 1973. Preliminary study or
use of benomyl and thiabendazole. Un
MEREDITH, B. S. 1971. Transport and stole
Trop. Agric. (Trin.) 48:35-50.
MISRA, A. P. and K. K. DUTTA. 1962. St
study of 2 isolates of Colletotrichum
pathol. 15: 74-85.
RAMAKRISHNAN, T. S. 1946. Studies oq
Acad. Sci. 25:15-26.
SUZUKI, H. 1965. Origin of variation in I
Proc. of Int. Rice Research Inst. Symp
rORO, R. A. 1922. Studies on banana at
VI, 1-23.

action together witn otner oenzlmiaazole
derivatives like thiabendazole (TBZ) has
been described as both preventive and
In-vitro tests revealed differential reac-
tions of C. musae isolates to benomyl.
Therefore, while benomyl must have
already been officially recommended for
the control of banana fruit rots (Wardlaw,
1972), it should not be expected to
work in all attempts to control banana
anthracnose. In the Philippines, as shown
in this study, it is caused by different
strains of C Musae which are variably
affected by the chemical. This may partly
explain unsuccessful trials of dipping Bun-
gulan bananas in up to 800 ppm benomyl
to control natural infection (Gavarra,
1973 unpublished report). The results
strongly indicate involvement of resistant
strains on naturally infected bungulan.


-op. Agric. (Trin.) 8:322-325.
trichum gloeosporioides. Jour. Agr. Res. 20:

lation of different isolates of Colletotrichum

N. 1963. Anthracnose of banana. I. Studies
Control of diseases of fruits and vegetables
hytopathol. 5:391-432.
the control of banana anthracnose with the
publishedd term paper.
age diseases of bananas: Biology and control.

dies in anthracnose fungi. III. A comparative
apsici (Syd.) Butler and Bisby. Indian Phyto-

the genus Colletotrichum. III. Proc. Indian

ricularia oryzae. In; The Rice Blast Disease,
ssium. 1965.
thracnose. Jour. Dept. Agric., Puerto Rico.

in. & June, 1976

Minn. 239 p.
VON ARX, J. A. 1957. Die arten der gattung Colletotrichum Cda. Phytopath. Z. 29:413-
WARDLAW, C. W. 1972. Banana diseases including plantain and abaca. 2nd ed. Longman
Group Ltd. London. 878 p.

Phil: Phytopathol. 12:51-59
Jan. & June, 1976



Assistant Professor and Instructor, Department of Plant Pathology, College of
Agriculture, U.P. at Los Bafios, College, Laguna; junior author's present address is VIC-
MICO, Victorias, Negros Occidental.
Grateful appreciation is due Messrs. Servillano Yuson and Romeo Javier for the
use of the mango orchards and facilities in Jaen, Nueva Ecija, and in Calumpang, San
Miguel, Bulacan, respectively.
Early part of the study was funded by U.P. 5460 and by FAR 017 in the later part.
In field test conducted on full grown 45-year old trees at Yuson's Farm
in Jaen, Nueva Ecija in November 1971, mancozeb + Karathane + Thiodan
improved fruit setting of smudged and irrigated mango cv. 'Carabao' to pro-
duce off-season fruits. In a separate trial, the application of fungicide-insecti-
cide sprays as pre-bloom, bloom, and post-bloom sprays minimized incidence
of anthracnose and Diplodia basal rot on fruits harvested from sprayed trees.
In the 1973 field trial at Calumpang, San Miguel, Bulacan, conducted
on 8 to 10-year old grafted mango cv. 'Carabao' trees, fungicides and insecti-
cides, applied separately or in combination, as bloom sprays at weekly inter-
vals improved fruit setting. Mancozeb and copper oxychloride were superior
than Captan, zineb, and mancozeb + Karathane. Imidan excelled five other
insecticides in improving fruit setting.
Spray applications with fungicides in combination with insecticides
during flower initiation, nectar stage, and fruit development did not show
any marked effect on fruit setting in the 1974 field trials. But the carry-
over protection of three applications against post-harvest rots was manifested
in lesser number of rotted fruits two weeks after harvest under ordinary
room conditions.

It is not uncommon to see mango
trees in commercial orchards, along
roadsides and national highways, parks,
or even in the backyards with only a few
fruits that have set after they have
profusely bloomed. This deplorable situa-
tion has ever since been the major prob-
lem of mango growers. Obviously, this
problem will become even more im-
portant to those who desire to produce
off-season fruits by either smudging or
the recently developed chemical sprays
both of which are undoubtedly expensive
orchard operations. If artificially-induced
flowers can be made to set a substantial
number of fruits during off-season or at a
time when mango fruits command a

better market price, then our local mango
growers can be ascertained a reliably good
source of income.
By and large, all Philippine varieties
of mango (Mangifera indica L.) are sus-
ceptible to three major fungal diseases,
viz., anthracnose, powdery mildew, and
Diplodia stem-end or basal rot.
Anthracnose caused by Colletotrichum
gloeosporioides Penz. is the most impor-
tant disease of flowers and young fruits.
It may be directly responsible for the
impairment of fruit set where leafhoppers
(Idioscyrus spp. or Chunroceus spp.) are
not a problem. It can cause excessive
shelling after bloom, cracking, stunting

Philippine Phytopathology

of young fruits, and latent fruit infection effects on incidence of fruit rots in
prior to harvest that result in the typical storage.
black spot development during transit or This paper presents results of field
ripening in storage. experiments conducted at Yuson's Farm
Powdery mildew caused by Oidium in Jaen, Nueva Ecija, and at Javier's
mangiferae Berthel attacks the bloom Farm in Calumpang, San Miguel, Bula-
and can actually reduce the yield of any can within the period November 1971 up
given tree to zero. This causal fungus to May 1974.
infects the new bloom, thus greatly re-
ducing fruit set. MATERIALS AND METHODS
The stem-end or basal rot caused by In all experiments, the Philippine
Diplodia natalensis Pole-Evans is essen- mango (Mangifera indica L. cv. 'Carabao')
tially a disease of mango fruits in storage. was used as test plant. Four single-tree
Affected fruits result in extensive rotting replicates per treatment in a randomized
(Alicbusan & Schafer, 1958; Halos & complete block design was invariably
Divinagracia, 1970). used.
Protection against these maladies must Two types of power sprayers were em-
start right in the field if exportable quali- played. A tractor-drawn John Bean Mo-
ty mango is desired. The proper kind and del 55 A with 50-gal tank capacity, 300-
amount of chemicals to use, and the pre- 400 psi, 5 gal spray/min output (San
cise time and number of spray applica- Jose, Calif.) was employed at Jaen,
tions must be determined. Nueva Ecija. In San Miguel, Bulacan, a
In an earlier experiment, Pordesimo, mounted bucket-type Birchmeier, Bimoto
Imperio, and Halos (1972) have tested Meteor I, 500 psi, 20 liters/min output
five fungicides applied as pre-harvest was used.
spray three weeks before harvest at Yu- The test chemicals, time, and number
son's Farm in Jaen, Nueva Ecija and as of applications, varied among the experi-
post-harvest dip for the control of an- ments, depending upon the specific ob-
thracnose and rotting of mango fruits. jectives of each test. The choice of the
Results of their experiment suggested a test materials was also dependent upon
need to protect fruits starting from the their availability and quantity sufficient
field and immediately after harvest par- to run the test. The concentration of each
ticularly against anthracnose and other test material was based closely on the
fruit rots. manufacturer's recommended dosage ex-
Although custom spraying of mango pressed in either weight or volume of the
Although custom spraying of mango
trees with insecticides is really not a new product per 100 liters dilute spray.
orchard practice, there has indeed been Fruit set was determined by actual
very limited studies along this line under count of fruits that set per inflorescence
Philippine conditions. Moreover, fungi- and based on 100 inflorences per single-
cides have seldom or never been used in tree replicate. Fruits harvested from each
custom spraying operations in mango experimental tree and the control were

Vol. 12

The number of fruit set per inflorescence fungicides were Captan (N-trichlorome-
-_-- n r ......... ---- n .-- thvl thin-4-cvlnhexene-l .2 dicarbo-

The percentage of fruits affected by
.. anthracnose and Diplodia basal rot in-

Treatment" 1U00 ters Average
dilution range

ancozeb 80% WP 210 g 2-16 5.4
+ Karathane WD (22.5%) 30 g
+ Thiodan 35% EC 80 ml

copper oxychloride (58%) 480 g 0-2 0.4

?vin 85% WP 240 g 0-8 2.0

nsprayed Control 0 0.0

aTwo applications on 45-year old trees; one at flower initiation (11/5/71) and the
other one week later (11/12/71). Intermittent rainfall occurred within the period.
bTriton B-1956 at 30 ml/100 liters was added to the spray mixture.
CNumber of fruits that set based on 20 inflorescences on each of 4 sides and center
r each single-tree replicate.

able 2. Carry-over effects of pre-bloom, bloom, and post-bloom sprays on incidence of
mango fruit diseases in ordinary storage (Yuson's Farm, Jaen, Nueva Ecija-1972)

Amount per Days Percentagec
reatmentb 100 liters in
dilution storage Anthracnose Diplodia rot Clean fruit
in grams

enomyl 50% WP 116 7 6.0 3.3 87.1
14 6.0 3.3 86.6
7 2.2 6.6 87.7
;ineb 75% WP 240 7 2.2 6.6 87.7
14 7.8 12.2 68.8

7 1.7 1.7 96.5
lancozeb 80% WP 240 1 1.7 96.5
14 12.3 15.7 68.4

:opper oxychloride 7 1.6 3.3 93.0
(58%) 480 14 5.0 5.0 83.3

lancozeb 80% WP 210 7 1.6 1.6 90.0
+ Karathane WD 30 14 3.3 8.3 76.6
(22.5%) 7 8.8 5.8 85.3
e o~ P 240 14 14.7 14.7 52.9

aData represents average of 4 single-tree replicates per treatment.
bSevin at 240 g and Triton B-1956 at 30 ml/100 liters was added to all treatments.
CBased on actual count at indicated storage period.

V'~"'C~U Yt~'OJP V Il~11~V


can perhaps be extended further by ii
proved storage facilities such as ref
geration or atmospheric storage; this
another phase of study which has 1
ceived little attention and which still 1
mains untapped for Philippine mang
Field Trials at Javier's Farm,
Calumpang, San Miguel, Bulacan
Fruit setting on fungicide- and insec
cide-sprayed trees differed among the t(
materials (Table 3 & 4). The 1973 fie
tests have shown that either fungicide
insecticide sprayed alone helped to ii
prove fruit setting of mango. Among t]
test fungicides, copper oxychloride am
mancozeb have demonstrated satisfacto
performance during the dry season n
tural flowering period. Among the sevw
insecticides, Imidan 50 WP and Imida
malathion 1-1E have given satisfactol
performance. Results of this experimel

suggest that both insecticide and fungi
cide sprays provide beneficial effects or
fruit setting under the conditions of the
The five insecticide-fungicide combina-
tion sprays tested in 1974 yielded nc
appreciable differences in fruit setting
among treatments and among number of
spray applications. But the incidence of
rotting on fruits harvested from trees
sprayed 3 times with Captan + Imidan-
malathion 1-1E, Captan + Imidan 50, and
Mancozeb + Imidan-malathion 1-1E was
minimal (Table 5). These results suggest
that a well timed single-spray application
of any of the spray combinations can
help sustain a desirable degree of fruit
setting during natural flowering in the
dry season and in cases where leafhopper
population is low and unfavorable periods
fnr anthrorno lnT i nmant nrnva;l Thb

Bulacan 1973)

Amount per Mean numb
Treatment 100 liters of fruits pe
dilution inflorescene

Captan 50% WP 300 g 1.7

Zineb 75% WP 240 g 3.2

Mancozeb 80% WP 240 g 5.4

Copper oxychloride (58%) 360 g 5.8

Mancozeb 80% WP 210 g 1.6
+ Karathane WD (22.5%) 30 g

Thiodan 35% EC (Control) 80 ml 4.8

Unsprayed Control 1.4

LSD 0.05 -3.8

aBased on a total of 100 flower cluster per single-tree replicate, 4 reps per treat-
ment; 25 clusters on each of 4 sides of tree.
bTriton B-1956 at 30 ml/100 liters was added to each treatment.
CAvaraco nf A rpnlioatia


;I;-n;nn D1.,r\~nl~~l.\n

Chemical Sprays on Mango

Table 4. Fruit settingaoon insecticide-sprayed mango trees
Bulacan 1973)

(Calumpang, San Miguel,

Mean number
Amount per of fruits per
Treatment 100 liters inflorescencec

Imidan 50% WP 120 g 5.9

Imidan 50% WP 180 g 4.5

Imidan-malathion 1-1E 198 ml 4.8

Trithion 25% WP 240 g 3.2

Thiodan 35% EC 80 ml 2.3

Sevin 85% WP 240 g 2.5

Malathion 57% EC 198 ml 3.5

Thiodan 35% EC 80 ml
+ Mancozeb 80% WP 210 g 4.4
+ Karathane WD (22.5%) 30 g

Unsprayed Control 1.4
LSD 0.05 . . . 2.1
0.01 . . 2.9

aBased on a total of 100 flower clusters per single-tree
each of 4 sides of tree; 4 reps per treatment.

replicate, 25 clusters on

bTriton B-1956 at 30 ml/100 liters was added to each treatment.

CAverage of 4 replicates.

low number of fruits that set on all treat-
ments including the control may be at-
tributable to the early and prolonged dry
spell and to sporadic outburst of gusty
winds that mutilated the tender fruit
clusters, thereby thinning the fruits that
have set to almost a uniform number.
Inadequate irrigation after the fruits have
already set impaired subsequent fruit
The value of fungicide and insecticide
sprays has been reflected in the number
of fruits that set and in minimizing fruit
rots after harvest. Besides this beneficial
effect, we have also noted the reduction
of damage by twig borers (Niphonuclea

spp.) and fruit flies. Similarly, the in-
cidence of leaf anthracnose and sooty
mold (Capnodium sp.) concomittant with
that of homopterous insects was con-
siderably reduced.
In the light of the results of our study,
it appears that fruit setting of off-season
flowers can be assured by fungicide-insec-
ticide sprays applied at floral initiation
and one week thereafter. This period may
be regarded as the critical stage for an-
thracnose development especially during
periods of high humidity and prolonged
wetting. Without protective sprays, off-
season flowers did not set fruits. Applica-
tion of insecticides is equally beneficial

Jan. & June, 1976

3 Philippine Phytopathology Vol. 12

ible 5. Influence of fungicide-insecticide spray combination and number of applications
on fruit set and fruit rot in storage (Calumpang, San Miguel, Bulacan 1974)

Amount per Number
Treatment 100 liters of Fruit Fru
lilutinn anrave t8 ta

Jan. & June, 1976 Chemical Sprays on Mango 59


ALICBUSAN, R. V., & L. A. SCHAFER. 1958. Diplodia rot of mango. Phil. Agr. 42:
HALOS, P. M., & G. G. DIVINAGRACIA. 1970. Histopathology of mango fruits infected
by Diplodia natalensis. Philippine Phytopathol. 6: 14-28.
PORDESIMO, A. N., E. N. IMPERIO, & P. M. HALOS. 1972. Pre-harvest spray and post-
harvest dip of mango fruits against anthracnose and fruit rots. Proc. 3rd Natl. Pest
Control Council Conf., 16-18 April 1972. Teachers' Camp, Baguio City. p. 8 (Abstr.)


Jan. & June, 1976


A. N. P(

Assistant Professor, Department of I
.Los Bafios, College, Laguna 3720.
This study was funded by FAR 01
the later part.
Grateful appreciation is due Mr. Ju
Batangas; Messrs. Rodolfo Jauregue and I
B. Unson of Balayan, Batangas, for the use


Field tests during the wet seas(
tions in Rosario and Sto. Tomas, B
applications with Mancozeb effect
Home-made Bordeaux mixture 4-4-1
toxic to leaves, flowers, and young de
against downy mildew.
In the dry season of 1975, the
grape downy mildew control was d
where epiphytotic conditions prevail
of the test fungicides. In this test s
of Mancozeb in controlling downy n
or alternate for Mancozeb in spray pi
in Philippine vineyards.

Downy mildew caused by Plasmopara
viticola (Berk. & Curt.) Berl. & de T. is
specially destructive where grapes are
grown under exceptionally humid condi-
tions; it can cause severe epiphytotics
year after year. When weather is favorable
for disease development and no protec-
tive control measure against the disease is
employed, downy mildew can easily ruin
the crop in one season. This malady has
posed a serious threat to the developing
grape industry in the Philippines.
The common practice among the local
vineyard growers to minimize damage by
this disease has been the spray application
of a wide variety of fungicides of uncer-
tain effectivity that are available in their
locality. The grower's choice of spray
chemicals to apply has been practically



int Pathology, College of Agriculture, U.P. al

during the early part and by F.C. 28218 ir

iniano Tumambing, Provincial Agriculturist
igido Marajas of Sto. Tomas, and Mr. Cesai
'their vineyards.


of 1974 were conducted at three loca-
angas. In the three sites, weekly spray
*ly controlled grape downy mildew.
was just as effective but was phyto-
iloping fruits. Captan was less effective

effect of protectant fungicide spray on
nonstrated only in Rosario, Batangas
I that permitted a more effective assay
e, Grapefun excelled the performance
dew; this fungicide can be a substitute
grams for grape downy-mildew control

based on foreign literature, salesmens
preference, or simply guesswork due
mainly to the absence of local recom-
mendations. This sad situation may be
attributed to the lack of experimental evi-
dence although there has already been an
earlier attempt to evaluate fungicides
against foliar diseases of grapes under Los
Bafios, Laguna conditions (Pordesimo &
Valmayor, 1972).
In countries where grapes are well
established, fungicides for grape downy-
mildew control are evaluated periodically.
El-Rifai (1970) found Bordeaux, copper
oxychloride and zineb to be effective
against Plasmopara viticola in Cairo.
Champagnol (1973) regarded Bordeaux as
still the best fungicide for the control of
P. viticola. Sinha, Jeyrajan, and Kapoor

applications of Bordeaux and of aureo-
Fungin at 20 ppm were the best for Cer-
:ospora viticola.
The present study was aimed at de-
termining the performance of selected
fungicides applied at weekly intervals
during the wet and dry seasons; and
obtaining experimental evidence as basis
in the formulation of chemical control
recommendation against grape downy
mildew and as reference point for con-
ducting further field trials.


In all experiments, var. Red Cardinal
was used in all test sites. A knapsack
sprayer, Birchmeier Senior (Kunten,
Switzerland) was invariably used. The
test fungicides were applied at weekly
intervals starting immediately after prun-
ing except in the dry season trial at
Rosario, Batangas where the first spray
was applied 3 weeks after pruning or
when the shoots were about 15 to 25 cm
long. All experiments were conducted
in a randomized complete block design.
Downy mildew incidence was rated as
number of infected leaves per shoot ir-
respective of lesion size.
Wet season trial. Six fungicides were
tested at Sto. Tomas and Rosario, Batan-
gas during the wet season (14 August to
16 October 1974). To prevent insects and
mites from interfering with the experi-
ments, each of these was combined with
an insecticide of known pesticidal activity
and compatibility. The test fungicides
were Captan 50-WP (N-trichloromethyl-
thio 4 cyclohexene 1, 2- dicarboximide,
50%), fixed copper (58% copper oxy-
chloride), mancozeb (a coordination pro-
duct of zinc ion and manganese ethylene
bisdithio-carbamate, 80%), and home-
made Bordeaux mixture 4-4-50 (the first

in pounds; the second is lime in pounds;
and the third figure is water in gallons).
The insecticides selected among ade-
quately available materials were Thio-
dan endosulfann [hexachlorobicyclohep-
tene bisoxymethylene sulfite, 35%]),
Trithion 4E (s-p-chlorophenylthiome-
thyl-O, O-diethyl phosphoro-dithioate,
45.2%) and Imidan-malathion l-l-E (an
emulsifiable concentrate composed of
Imidan (N-mercaptomethyl-phthalimide
S(O-O-dimethylphosphorodithioate) and
Malathion (O, O-dimethyl dithio-phos-
phate of diethylmercaptosuccinic acid).-
On account of the compatibility fac-
tor of the test fungicides and the insec-
ticides, six spray combinations were made
out. These were Captan + Thiodan, Cap-
tan + Imidan-malathion 1-1E, Bordeaux
mixture 4-4-50 + Trithion, Copper oxy-
chloride + Imidan-malathion 1-1E, Man-
cozeb + Thiodan, and Mancozeb +
Imidan-malathion 1-1E. Shell Tenac
sticker was added to each spray combina-
tion, except Bordeaux mixture 4-4-50
+ Trithion.
In a separate test, Captan + Imidan-
malathion 1-1E and Mancozeb + Imidan-
malathion 1-1E were compared with
home-made Bordeaux mixture 44-50 +
Trithion to find out the effect on fruit
set and degree of downy-mildew control.
Likewise, Shell Tenac sticker was added
to each spray combination except Bor-
deaux mixture + Trithion.
In all the trials, the amount of each
test material was based closely on the
manufacturer's recommended dosage ex-
pressed in either weight or volume of the
product per 100 liters dilute spray (Tables
I & 2).
Dry season trial. Six fungicides were
tested in Rosario and Balayan, Batangas
during the dry season (25 January to 7


Table 1. 1974 Wet season grape fungicide evaluation (Rosario a
tan.n l

Amount per % downy mildew controld
Treatmentb 100 liters
dilution Rosario Sto. Tomas

Captan 50% WP 240 g 88 52
+ Thiodan 35% EC 80 ml

Captan 50% WP 240 g 83 56
+ Imidan-malathion 1-1E 198 ml

Bordeaux mixture 4-4-50c 100 74
+ Trithion 45.2% EC 125 ml

Copper oxychloride 58% 360 g 98 72
S+ Imidan malathion 1-1E 198 ml

Mancozeb 80% WP 240 g 100 82
+ Thiodan 35% EC 80 ml

aWeekly applications beginning 8/14/74 until 10/16/74 during which typhoons
were prevalent.
bShell Tenac sticker at 132 ml/100 liters was added to all treatments except Bor-
deaux mixture.

CThe formula represents 4 lb copper sulfate, 4 lb lime in 50 gal water which is
equivalent to 960 g copper sulfate, 960 g lime in 100 liters water.
dCalculated from the average of 2 plants per replicate (4 replicates in Rosario;
3 replicates in Sto. Tomas) based on number of infected leaves of 10 randomly selected
shoots per plant.

March 1975). These were Captan 50-WP, cozeb.
Daconil W-75 (tetrachlorisophthalni- As in the wet season trials, the amount
trile, 75%), benomyl (methyl 1-butyl- of each test material was essentially based
carbamoyl)2-benzimidazole carbamate, on the manufacturer's recommended
50%), home-made Bordeaux mixture dosage. The desired amount of each was
3-5-50, mancozeb, and Grapefun (9% calculated in terms of weight or volume
copper, 32% maneb, 7% carbaten, 51% of the product per 100 liters dilute spray
inert). To each of these was combined (Table 3).
Imidan-malathion 1-1E merely to pre- Evaluation of the test fungicides was
vent interference by insects. Shell Tenac based mainly on percentage of infection.
sticker was added to the spray mixture Infection percentage was based on total

~ n-_ mi~__ n

igicides for Grape Downy M

"able 2. 1974 Wet season grape fungicide ev,

Amount per
Treatment 100 liters

;aptan 50% WP 240 g

fancozeb 80% WP 240 g

lordeaux mixture 4-4-50 e

Jnsprayed Control

aWeekly applications from 9/4/74 tc
talent Figures are based on average of 4
plants of var. Red Cardinal.
bImidan-malathion 1-1E at 198 ml
vere combined with captain and mancozeb;
vith Bordeaux mixture.

rationa (Sto. Tomas, Batangas)

Average % % Downy
No. of Fruit mildew
bunches setc controld

9.5 62.7 25

5.2 56.3 81

1.3 4.9 81

3.2 15.5 0

0/30/74 during which typhoons were pre-
ps per treatment, each rep with duplicate

id Shell Tenac sticker at 132 ml/100 liters
ithion at 125 ml/100 liters was combined

dCalculated from the average of 2 plants per rep bas

- -_ ,-- n 0 :-_ fM-A

eThe formula represents 4 lb copper sulfate, 4 lb lime in 50 gal water which is equi-
valent to 960 g copper sulfate, 960 g lime in 100 liters water.

of all the vines in a replicate. A leaf was control may be seen in Table 1. It can be
counted as infected regardless of lesion noted that Captan was inferior to the rest
size. of the test fungicides in the control of
grape downy mildew. Mancozeb ranks
RESULTS AND DISCUSSION superior among them in either location.
Home-made Bordeaux mixture 4-4-50
Wet season trial. At all test sites, all ranked equal to mancozeb at Rosario,
the unsprayed (control) plants became Batangas where copper oxychloride per-
defoliated at the termination of the formed satisfactorily. But the two copper
experiment. The sprayed plants had fungicides have imparted slight spray
intact leaves but with varying degrees of injury to foliage. In Sto. Tomas, the per-
infection that very well served as a visual formance of the test fungicides does not
gauge of the comparative efficiency of compare favorably with that in Rosario,
the test fungicides. Batangas. The discrepancy in the per-
The performance of the test fungi- formance of the same fungicides at the
cides differed with the test sites. The two test sites may be attributable to the
effectivity of the test materials reckoned difference in the density of the foliage
in terms of percentage of downy mildew which retained rain water longer in Sto.



able 3. 1975 Dry season grape fungicide evaluation (Rosari(

Percentage Infectionc
Amount per
Treatment 100 liters Downy mildew Cercoepora leaf spot
(grams) Rosario Balayan Rosario Balayan

;aptan 50% WP 240 56.4 0 0 0.4
)aconil 75% WP 240 52.3 0 0 1.5
3enomyl 50% WP 116 84.0 0 0 0.2
3ordeaux mixture 3-5-50 d 38.9 0 0 3.9
rrapefune 420 27.1 0 0 0.2
4ancozeb 80% WP 240 31.0 0 0 0.4
Jnsprayed Control 100.0 0 Defoliated 0.6

aWeekly spray applications started 1/25/75 until 3/7/75.
bShell Tenac sticker at 132 ml/100 liters was added to Captan, Grapefun, and
nancozeb; Imidan 1-1E at 198 ml/100 liters was combined with all the test fungicides.

CAverage of 4 reps, each rep with 2 plants in Rosario, and with 5 plants in Unson's
rarm in Balayan, based on total leaf count of randomly selected shoots.
dThe formula represents 3 lb copper sulfate, lb lime in 50 gal water which is equi-
alent to 711 g copper sulfate, 1200 g lime in 100 liters water.

iraue name oi rungiciae contaimnng e7o copper, azwo ma
1% inert.

ieD, o7o caroaTen, ana

In Rosario, the foliar canopy was during the wet season. R

nake leaves dry faster. The prolonged
vetting period that prevailed in Sto.
romas decidedly favored downy mildew.
furthermore the thickness of the vines
nd foliage that interfered with spray-
Iroplet deposition and prevented tho-
ough coverage of infection courts must
ave appreciably contributed to the less
effective performance of the fungicides.
Under the conditions of both test
ites, the occurrence of grape downy
mildew in epiphytotic proportion which
ias brought about by typhoons in week-
y succession has enabled me to identify
lancozeb as the most effective fungicide
or protection against down mildew

lating chemical control recommendation
for field application and as bench-mark
information for conducting subsequent
field trials with the use of new and im-
proved fungicides.
In another trial where captain, man-
cozeb, and home-made Bordeaux mix-
ture 4-4-50 were tested, similar results
were obtained (Table 2). Likewise, man-
cozeb gave good control of downy
mildew. Bordeaux mixture 44-50 was
comparable in effectiveness. Captan gave
poor control but it helped improve fruit
set better than did mancozeb. Bordeaux
mixture 44-50 appeared phytotoxic to
mfl--... Eo maflaa.,I n hA tl nPrrPfntac


-4 D-7-- D-*---.1nnn~

jzciues ior rapee LDowny ivi

or Iruts mat set. plications ot ettecuve protectant ungi-
Dry season trial. Results of this cide sprays have appreciably provided
test are presented in Table 3. It may be adequate protection against downy mil-
noted that Rosario and Balayan, Ba- dew. But in Balayan where no downy
tangas presented two contrasting pic- mildew epiphytotics prevailed, the results
tures of grape disease situation. In Ro- of the test did not show any difference
sario, downy mildew was in epiphytotic in disease rating among sprayed and un-
form while it was practically absent in sprayed vines. Severity of disease is in-
Balayan where Cercospora leaf spot was deed essential in the evaluation of fungi-
sporadic. Among the six test fungicides, cides in field trials.
Grapefun gave better control of downy The existence of abundant inocula
mildew than did mancozeb which was when favorable meteorological conditions
used as the standard fungicide on ac- such as high humidity and prolonged
count of its superior performance during wetting periods prevail was certainly a
the preceding wet-season .trial. With its vital factor for downy mildew epiphyto-
desireable performance against downy tics. It has brought about a condition
mildew, Grapefun can now be considered ideal for evaluating the performance
in formulating chemical control pro of protectant fungicides under severe
grams for Philippine vineyards. Bordeaux disease situations. This has enabled me
mixture 3-5-50 ranked third in efficacy. to compare the performance of the test
As in the previous tests, the unsprayed fungicides and identify the promising
(control) plants became defoliated at the ones for use in conducting subsequent
termination of the experiment in Rosario field trials and possibly in formulating
but in Balayan, the sprayed and the recommendations for the control of
unsprayed plants remained unaffected by grape downy mildew in Philippine vine-
downy mildew. In the former location yards.
where epiphytotics prevailed, weekly ap-


abortion). Progress Agricole et Vit
53: 41)
EL-RIFAI, I.F. 1970. Studies on the con
grape with fungicides. Agr. Res. R
Pathol. 51:95)
the control of foliage diseases of gr
16-18 April 1972. Baguio City. p. 8

le 90 (3): 51-59. (Abstr. Rev. Flant Yath

Al of powdery mildew and downy mildew
., Cairo 48 (3): 1-9. (Abstr. from Rev. Pla

)R. 1972. Evaluation of four fungicides I
es. Proc. 3rd Natl. Pest Control Council Coi


_r 1111. -r 1 jJfCIllU.



Research Assistant and Assistant Professor, respectively, Department of Plant
Pathology, University of the Philippines at Los Bafios, College, Laguna.
Thesis presented for graduation by the senior author for the degree of Bachelor

Jan. & June, 1976 Characteristics of Botryodiplodia spp. 67

and sapodilla (Srivastava and Tandon, thod. The first utilized mycelial plugs as
1968) and soft rot of mango (Rao, 1966). described above or by directly placing a
Grapes have not been reported as host of drop of the spore suspension on the
Botryoiiplodia theobromae and this is pricked area, while in non-wounding
the first time that the fungus was iso- method, the mycelial disc and the drop
lated from and shown to cause fruit rot of spore suspension were directly placed
of grapes, on the marked intact surface of the host.
This experiment was conducted in the Host range. Several fruits were
laboratory of the Department of Plant artificially inoculated with the three
Pathology, U.P. at Los Bafios from isolates under study and incubated in-
November, 1974 to March, 1975 to side moist plastic bags.
study the pathogenicity and cultural
characteristics of Botryodiplodia spp.
isolated from banana, grape and papaya Cultural Studies
fruits and determine whether the isolate
frdm grapes is identical with those of Effect of various agar media on my-
banana and papaya and hence be identi- celial growth and pycnidial production.
fled as Botryodiplodia theobromae. The 3 isolates of Botryodiplodia were
cultivated on different agar media, viz.,
MATERIALS AND METHODS Corn meal agar (CMA), Cook's medium
(CM), Difco potato dextrose agar (DPDA),
Isolation and inoculation Czapeck's agar (CZAP), Richard's me-
Isolation and Inoculation
dium (RM), V-8 juice agar (V-8), Sa-
The organism was isolated from bouraud's agar .(SA) and Yeast extract
agar (YEA). See Tuite (1969) for the
diseased banana, grape and papaya fruits agar (YEA). See Tuite (1969) for the
~ .. ... r- n Phn; "Mu f nlttn composition of these media. A mycelial

on its original host and checking proof of
its pathogenicity, one isolate each from
banana, papaya and grapes were sub-
sequently grown on plain PDA for use on
all succeeding experiments. All inocula-
tions, unless otherwise indicated, were
done by placing a mycelial disc cut with a
sterile cork borer from a 3-5 day old
PDA plate culture, on the surface of a
pricked area of the host. This was the
wounding method. The inoculated
hosts were incubated inside moist plastic
bags at 30C.


Method of penetration. To check if
the pathogen directly or indirectly enters
thA hnrt I mIthnfA nf innAllnn -m,;..

oorer irom me auvancmg margin o0
2-day old colonies on PDA was planted
centrally on each medium and incubated
at 30C with light.
Effect of temperature. Mycelial
discs were planted centrally on plated
DPDA and incubated with light at dif-
ferent temperatures which ranged from
10t to 40t at 10C intervals.

Effect of light. The different isolates
on plated DPDA were exposed to dif-
ferent light conditions at 30t: conti-
nuous light (CL), continuous darkness
(CD) and alternate light and dark (ALD).
Effect of pH. DPDA plates pre-
viously adjusted to pH ranging from 3 to
9 after autoclaving were planted centrally
uith nnp mirfplial ldie pneh nf thf thrpA

Philippine Phytopathology

In all of the above experiments, co-
lony diameters and photographs were
taken after 3 days incubation. Replicate
plates were further incubated for another
30 days with light as indicated above
for pycnidial counts.
Morphology of the spores. Using an
ocular micrometer, conidial sizes of the
three Botryodiplodia isolates were meas-
ured, photographed and compared.


Method of host penetration. In-
fection occurred only when the surface
was wounded, showing that the or-
ganism enters the host only through

studies showed that the three isolates
could positively cross-inoculate although
the banana isolate seemed to be only
slightly virulent on grape and ,papaya
Host range. Of the three isolates,
grape and papaya isolates were found to
be more virulent than the banana isolate,
infecting 12 of the 17 hosts tested. The
banana isolate was able to infect only 8
hosts. Results are presented in Table 1.


Effect of various agar media on my-
celial growth and pycnidial production.
- Corn meal agar supported least while

Cross-inoculation. Cross-inoculation

Table 1. Host range of Botryodiplodia isolates from banana, grape and

Botryodiplodia isolates from
Banana (BB) Grape (GB) Papaya (PB)

APPLE (Malus sylvestris Mill.) + + +
BALIMBING (Averrhoa balimbi) + + +
CARROT (Daucus carota L.) -
CHICO (Achras zapota L.) + + +
CHAYOTE (Sechium edule (Jacq.) Sw. -
CITRUS (Citrus sp.) + + +
EGGPLANT (Solanum melongena L.) + +
GREEN PAPPER (Capsicum sp.) -
GUAVA Psidium guajava L.) + + +
MUSK MELON (Cucumis melo L.) + + +
PATOLA (Luffa cylindrica Roem.) + + +
POTATOES (Solanum tuberosum L.) + +
RADISH (Raphanus sativus L.) + +
STAR APPLE (Chrysophyllum cainito L.) -
TIESA (Lacum nervosa) + + +
TOMATOES (Lycopersicum esculentum Mill.) + + +
WATER MELON (Citrullus vulgaris Schrad.) -

- = No infection; + = Infected. The
at 300C in a moist condition.

hosts were all incubated for 2 to 5 days


Vol. 12

Fig. 1. Mycelial

growth of Banana (BB), Grape (GB) and
!odia incubated for 3 days on different agar n


Philippine Phytopathology

Vol. 12

Fig. 2. Mycelial growth of Botryodiplodia isolates incubated

Fig. 3. Mycelial growth of Botryodij
under different light condition

odia isolates incubated for 3 days
t 300C.

Characteristics of Botryodiplodia spp.

V-8 supported best the mycelial growth
of the three isolates (Table 2 and Fig. I).
Except for Sabouraud's agar which
changed color from brownish to reddish-
pink, the other media retained their
colors. It took 3 days to cover up the 9
cm petri dishes with grayish-green my-
celium which could either be very scarce
as in corn meal agar, slightly dense as in
Difco potato dextrose agar and Sabou-
raud's agar or dense as in the rest of the

concentric circles. Small, scattered pycni-
dia developed on the other media.
Effect of temperature on mycelial
growth and pycnidial production. -
Botryodiplodia isolates grew best at
30C, followed by 200C and 40'C. No
growth was observed at 10C (Figure 2).
Pycnidia were absent at 10C, 20C and
40C while some developed on plates in-
cubated at 30t.
Effect of light on mycelial growth and

Table 2. Effect of various agar media on pycnidial
Botryodiplodia theobromae isolatesa

production of

No. of pycnidialb
Media BB GB PB

COOK'S 5 5 13
V-8 JUICE AGAR 5 8 18

aBB banana isolate; GB grape isolate; PB papaya isolate

bTaken after 30 days incubation under continuous light.

After 30 days of incubation, pycnidial
production could be observed first as
large, columnar stroma developing on the
surface, and later, on each of these stro-
ma an ostiole was produced. Potato dex-
trose agar gave the maximum number of
pycnidial bodies after 30 days of incu-
bation while CMA gave the minimum
number (Table 2). Pycnidia produced
on Czapeck's agar were found to be big
and clustered while those on V-8 were
smaller. On yeast extract agar, clustered
pycnidia were almost the same in size as
those on V-8 but they were arranged in

pycnidial production. Differences in
mycelial growth between the three iso-
lates grown under three light conditions
were not very significant as shown in
Fig. 3, indicating that different light con-
ditions have no influence on 3-day old
mycelial growth of Botryodiplodia iso-
lates. Cultures grown under continuous
light and alternate light and darkness (12
hr. light 12 hr. dark) formed pycnidia
on the surface of the plates after an addi-
tional incubation period of 30 days at
3(fC (Table 3).

Jan. & June, 1976

Philippine Phytopathology

Table 3. Effect of light on mycelial growth and pycnidial
of Botryodiplodia theobromae isolates.

Colony diam. (mm)a No. of pycnidiab
Light conditions BB GB PB BB GB PB

Continuous light 89.0 83.3 90.0 40 65 75
Continuous darkness86.7 81.7 90.0 0 0 0
Alternate light and
darkness 89.3 86.7 90.0 13 24 20

taken after 3 days of incubation at 300C
taken after 30 days of incubation at 300C

C12 hours light-12 hours dark

Effect of pH on mycelial growth and
pycnidial production. Table 4 shows
that pH 6 to 8 favored best the growth of
Botryodiplodia mycelium. Below pH 6
and above pH 8, growth was minimized
and arranged from scarce to slightly
dense. Few pycnidia were produced on
plates with pH 6 and 7 and none on
plates with pH 3, 4, 5, 8, and 9.


Conidial sizes of the Botryodiplodia

isolate from banana gave an average size
of 26.28 x 15.57.u, the grape and papaya
isolates differing slightly (Table 5). They
are all oval-shaped, the protoplasm slight-
ly colored and double-walled (Fig. 4).
While young conidia are non-septate,
mature 2-3 week old spores show longi-
tudinal striations plus characteristic cross-
wall at the midpoint.


Botryodiplodia theobromae Pat. infec-

Table 4. Effect of pH levels on mycelial growth and pycnidial production
of Botryodiplodia theobromae isolates.

s Colony diam. (mm)a No. of pycnidiab

3 41.6 45.0 43.2 0 0 0
4 65.5 71.6 69.7 0 0 0
5 74.4 75.8 73.4 0 0 0
6 82.0 85.8 85.0 12 18 14
7 86.2 89.0 88.1 41 59 73
8 83.3 84.5 80.1 0 0 0
9 70.8 76.3 74.2 0 0 0

taken after 3 days incubation with light at 300C.

taken after 30 days incubation with light at 300C.


Vol. 12

Characteristics of Botryodiplodia app.

Table 5. Conidial sizes of Banana (BB), Grape (GB) and
Botryodiplodia isolates.

Papaya (PB)

Botryodiplodla Range (p) Average (u)

BB 25.11-27.00 x 15.12-16.11 26.28 x 15.57
GB 25.94-27.00 x 13.50-15.75 25.95 x 14.59
PB 26.28-27.81 x 14.94-16.29 26.67 x 15.93

tion causes brownish discoloration and
eventually soft-rotting of the fruit. As
the disease advances the whitish to
grayish-green mycelium form into dense
stroma and ultimately into flask-shaped
pycnidia which can either be separate or
grouped together, situated superficially,

Fig. 4. Photomicrographs showing co-
nidia of Banana (upper) Grape
(middle) and Papaya (bottom)
Botryodiplodia isolates.

and ostiolated.

It is evident from the morphological
studies that conidial sizes of the three
isolates vary slightly. Shreemali and
Bilgrami (1968) reported variations in the
morphology of the conidia and pycnidia
of the different isolates of B. theobromae.

Results on cultural studies show that
there is not much difference in the my-
celial growth on all the culture media
except on cor meal agar which showed
very thin and sparce surface mycelial
growth. Wardlaw (1972) reported that
B. theobromae can grow rapidly on high
concentrations of starch and sucrose
which probably could not be provided
by the percentage of corn meal in the
medium. Moreover, corn meal agar gave
the least number of pycnidia while potato
dextrose agar and Czapeck's agar gave the
highest. A study on pycnidial production
conducted by Ekundayo and Haskins
(1969a) showed that synthetic medium
made up of components of Czapeck's
agar supported the greatest amount of
pycnidial production compared to other
four media they used, thus supporting
the results found in the present study.

The present study showed that light
has no influence on the mycelial growth
of Botryodiplodia but is necessary for
pycnidial production. This confirms the
reports of Ekundayo and Haskins (1969)

Jan. & June, 1976

Philippine Phytopathology

who found that while light has no effect sapodilla although when citrus fruits ex-
on the vegetative growth of B. theobro- posed to this temperature were trans-
mae, it is however essential for pycnidium ferred to room condition, the rate of
production. decay was more or less enhanced.
Botryocdplodia theobromae, like other Although slight differences in cultural
tropical plant pathogenic fungi, exhibited characteristics were observed on banana,
maximum growth at 300C. This coincides grape and papaya Botryodiplodia iso-
with the results of Verma and Singh lates, results of cross-inoculation studies,
(1971) and Goos et al. (1961). At 100C, host range studies, and morphological
mycelial growth was greatly suppressed. characteristics gave proofs for the iden-
This temperature, therefore, can be used tity of Botryodiplodia theobromae.
in storage of fruits without danger of Hence, the species isolated from and
soft-rotting caused by B theobromae causing fruit rot of grapes is identified
Srivastava and Tandon (1968) reported as Botryodiplodia theobromae, the same
that incubation at 100C was found to species infecting banana and papaya.
check Botryodiplodia rot of citrus and


EKUNDAYO, J. A. and R. H. HASKINS. 1969. Pycnidium production by Botryo-
diplodia theobromae. L The relation of light to the induction of pycnidia.
Can. J. Bot. 47(7): 1153-1156.
GOOS, R. D., E. A. COX, and STOTZKY. 1961. Botryodiplodia theobromae and its
association with Musa species. Mycologia 53: 262-277.
HUNTER, J. E., L N. BUDDENHAGEN and E. S. KOJIMA. 1969. Efficacy of fungicides,
hot-water, and common-irradiation for control of postharvest fruit rots of papaya.
PL. Dis. Reptr. 53: 279-283.

of different isolate; of Botryodif
21(4): 357-360.
TUITE, J. A. 1969. Plant pathological m
Co. Minn. 239 p.
VERMA, O. P. and R. D. SINGH. 1971
Botryodiplodia theobromae Pat. Indi
WARDLAW, C. W. 1931. Banana Disease
rot of the banana. Trop. Agric. 8(9):
1972. Banana diseases, includir
diplodia theobromae Pat. causing f:

968. Range of variations in the morpholog.
iia theobromae Pat. Indian Phytopatho

ods: Fungi and bacteria. Burgess Publishinl

:pidemiology of mango dieback caused b]
J. Agric. Sci. 40(9) 813-818.
I. Observations on the Botryodiplodia fruil
plantains and abaca. London. 878 pp.
165. Some pathological studies on Botryo
t rot. Mycopath. et Mycol. Applicata 29:


Phytopathol. 12:75-77
Jan. & June, 1976




Former Research Assistant and Assistant Professor, respectively, Department of
Plant Pathology, UPLB-CA, College, Laguna.
This study was supported by UPLBCA-NRCP Cooperative Nematology Research
Project No. I.E.-41.

The reniform nematode, Rotylenchu-
lus reniformis, was first reported infecting
cowpea roots in Hawaii (Linford and
Yap 1940). The nematode was subse-
quently reported attacking the crop in
California (Konicek, 1963), India (Das
gupta and Seshadri, 1971), and England
(Razak and Evans, 1976). In the Philip-
pines, Rotylenchulus spp. have been ob-
served widely distributed in fields grown
to cowpea (Castillo, 1974 a and b). The
feeding of large numbers of gravid fe-
males of the nematodes was frequently
observed associated with the decline of
the crop.
Under controlled conditions, the pa-
thologic effects of R. reniformis inocula-
tions on coffee (Valdez, 1968) and on
mung bean, soybean and peanut (Bajet
and Castillo, 1974) have already been
determined. This study was conducted
to determine if the same effects could be
observed on cowpea.


The R. reniformis population used in
this study was obtained from around
banana roots in College, Laguna and in-
creased on Siratro for six months. The
nematode inocula used were extracted
from the soil by the routine extraction
method, consisting of the sieving Baer-
mann funnel technique. Nematodes other
than R. reniformis found in the sus-

pensions from the funnels were hand-
picked and discarded.

All season variety of cowpea was
used as test plant. Three seeds were
planted in each of 18-cm diameter clay
pots containing baked soil. Seven days
after planting, the seedlings were thinned
to two per pot. Their roots were partly
exposed by removing some of the soil
and then aliquot suspensions containing
known numbers of active R. reniformis
were carefully poured around the seed-
lings, after which the roots were covered
with soil. The inoculum levels used,
replicated five times, were approximately
1,000, 2,500, 5,000, 7,500 and 10,000
per pot. Five pots containing nematode-
free seedlings were provided as checks.
The experimental plants were randomly
arranged on top of hollow blocks placed
Two months after inoculation, the
reactions of the test plants to nematode
inoculations were evaluated based on the
following: degree of root necrosis,.root
weight, top weight and yield (dried
seeds). The build-up in nematode popula-
tion in the soil and roots during the ex-
perimental period was also determined.
All the soil contained in each pot, in-
cluding the check pots, were processed
for nematodes. The presence of infecting
nematodes were determined by staining
the whole root systems of the two plants

Philippine Phytopathology

in each pot in acid fuchsinlactophenol.


Examination of stained inoculated
roots showed numerous females in feed-
ing position (Fig. 1). However, no ap-
parent differences in necrosis were ob-
served between inoculated and non-
inoculated plants. Thus, root necrosis
as a pathologic effect of the nematode
on the crop was disregarded. It is pro-
bable, however, that histological studies
on infected roots will reveal cell disinte-
gration and discoloration, similar to that
observed by Rebois, Epps and Hartig
(1970) in soybean roots infected with
R. reniformis.
Nematode inoculations did not cause
significant reductions in top weight
(Table 1). However, inoculations with
5,000, 7,500 and 10,000 nematodes
significantly reduced the root weight

by 45.6%, 58.1% and 54.4%, respective-
ly. In yield (dried seeds), significant re-
ductions of 47.8% and 60.9% resulted at
7,500 and 10,000 levels respectively.
The initial inocula of 1,000, 2,500,
5,000, 7,500 and 10,000 nematodes per
pot had increased by, respectively, 3.7 X,
6.1 X, 4.1 X, 2.3 X, and 2.6 X at the
termination of the experiment (Table 1).
The abrupt decline in rates of increases
at the 7,500 and 10,000 inoculum levels
was probably due to competition for
food and space as the population densi-
ties increased.
The present findings demonstrated the
susceptibility of cowpea to R. reniformis.
Since this nematode is widely distributed
in fields grown to cowpea in the Philip-
pines (Castillo, 1974 a and b), it is pro-
bable that this pest is exacting a heavy
yet hidden toll to our local fanners. Thus,
control measures should be employed to
increase the production of the crop.

Fig. 1. Photomicrograph of a cowpea root showing Rotylenchulus reniformis females
in feeding positions.

Vol. 12

Reniform Nematode

Table 1. Reactions of cowpea to varying levels of inoculation with Rotylenchulus ren:
forms and nematode build-up two months after inoculation

Inoculum level
(No. of nematodes/ Plant weight (g)y Rate of nematod
pot) Root Top Yieldz build up

0 (check) 32.9 b 81.2 a 28.9 b 0

1,000 23.0 ab 68.9 a 18.3 ab 3.7 X

2,500 23.3 ab 72.4 a 17.4 ab 6.1 X

5,000 17.9 a 69.9 a 23.6 ab 4.1 X

7,500 13.8 a 68.2 a 15.1 a 2.3 X
(58.1) (47.8)

10,000 15.0 a 55.7 a 11.3 a 2.6 X
(54.4) (60.9)

XData are means of five replicates.
YSimilar letters indicate no significant differences at P = 0.05 with DMRT. Nos
in parentheses are per cent decreases compared with the check.
ZDried seeds.


tstSAJ ASJL4UL, Sn. u. a .I~' a. ,.czInat..aICUa aU
eggplant, and celery in Benguet, I
CASTILLO, M. B. 1974 b. Survey and
pepper, beans, peas, eggplant, and
adaptation in physiological races 4
formis. Indian J. Nematol. 1:128-14
KONICEK, D. E. 1963. A plant parasitic
California. Phytopathology 53:1141
LINFORD, M. B. and F. YAP. 1940. E
Hawaii. Helminthol. Soc. Wash. Pro
RAZAK. A. R. and A. A. EVANS. 1976.
Rotylenchulus reniformis on cowpe
REBOIS, R. V., J. M. EPPS and E. E. H
bean to Heterodera glycine and i
VALDEZ, R. B. 1968. Stubby roots of
formis. Phil. Agr. 51:672-679.

ngas, Laguna, and Camarines Sur. Phil. Af

mnomy of nematodes attacking ginger, bla(
ery in the Philippines. NRCP Res. Bul. 2!

1971. Reproduction, hybridization and ho
ie reniform nematode, Rotylenchulus rer

matode of the genus Rotylenchulus found
e host plants of the reniform nematode
intracellular tube associated with feeding I
lot. Nematologica 22:182-189.
TIG. 1970. Correlation of resistance in so
vlenchulus reniformis. Phytopathology. 61

'fee seedlings caused by Rotylenchulus rer

e7 l

rAN ~

Republic of the Philippines
t of Public Works, Transportation and Communications

(Required by Act 2580)

ied semi-annually in English, College, Laguna, after having been
nce with law, hereby submits the following statement of ownership,
on, etc., which is required by Act 2580, as amended by Common-


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