Jo- /0 etoI
VOLUME 4 JANUARY AND JUNE, 1968 NUMBERS 1 AND 2
Official Organ of
The Philippine Phytopathological Society
Abstracts of Papers Accepted for Presentation at the Fifth Annual Meet-
ing of the Philippine Phytopathological Society, Davao City,
May 10, 11, 12, 1968 ..... ..... .. . ..... .... 1
Mechanism of Tungro-Resistance in Rice
K. C. Ling ....... .. ....... ........ . 21
Cultural Characteristics and Pathogenicity of Ustilago maydis
O. R. Exconde, G. M. Lopez, and S. A. Raymundo . 39
Pathologic Reactions of Field and Fiber Crops to Three Isolates of
* D. T. Begornia and R G. Davide . ... ... .. 52
The Effect of Chicken Manure on the Incidence of Sclerotium Disease
V M. Mercado and A. N. Pordesimo .. 75
S A Bacterial Leaf Blight of Coconut
J. B. Tunac and Ma. Salome del Rosario ............ 88
A Helicotylenchus Species Parasitic on Coconut and African
.. Oil Palm
A. C. Pizarro ............. ........... 91
, *A.'-*: 2 t<
-- -:-: f'^ ,. ,, ;. ,, ., ,*......... .: .... ........ ...,,,.,,, ..,. -" i ,,` ;
Founded on 10 October 1962
The P.P.S. Council 1968-1969
'resident, A. V. PALO, Bureau of Plant Industry, San Andres, Manila
retiring President, MA. SALOME DEL ROSARIO, UPCA, College, Laguna
lice-President, R. F. P. QUEMADO, Union Carbide Phil., Inc., P.O. Box 677, Manila
secretary, R. G. DAVIDE, UPCA, College, Laguna
treasurer T. T. REYES, UPCA, College, Laguna
Editor-in-Chief, A. N. PORDESIMO, UPCA, College, Laguna
Newsletter Editor, G. G. DIVINAGRACIA, UPCA, College, Laguna
business Manager, R. F. P. QUEMADO, Union Garbide Phil., Inc., P. O. Box 677,
Luditor, C. A. BANIQUED, Bureau of Plant Industry, San Andres, Manila
F. C. QUEBRAL, UPCA, College, Laguna (Luzon)
C. F. LUCERO. Bureau of Plant Industry, Cebu City (Visayas)
A. L. ELOJA, Bureau of Plant Industry, Davao City (Mindanao)
The P.P.S. Council 1969-1970
'resident, R. F. P. QUEMADO, Union Carbide Phil., Inc., P.O. Box 677. Manila
Retiring President, A. V. PALO, Bureau of Plant Industry, San Andres, Manila
'ice-President Elect, R. G. DAVIDE, UPCA, College, Laguna
secretary, G. G. DIVINAGRACIA, UPCA, College, Laguna
treasurer T. T. REYES, UPCA, College, Laguna
Editor-in-Chief, A. N. PORDESIMO, UPCA, College, Laguna
Newsletter Editor, G. G DIVINAGRACIA, UPCA, College Laguna
business Manager, C. A. BANIQUED, Bureau of Plant Industry, San Andres, Manila
Luditor, F. L. NUQUE. Plant Protection Division, IRRI, College, Laguna
F. C. QUEBRAL, UPCA, College, Laguna (Luzon)
J. R. RIVERA, Phil. Sugar Inst., Bacolod City (Visayas)
A. L. ELOJA, Bureau of Plant Industry, Davao City (Mindanao)
VELSICOL CHEMICAL CO., Makati, Rizal
ABSTRACTS OF PAPERS ACCEPTED FOR PRESENTATION
AT THE FIFTH ANNUAL MEETING OF THE PHILIPPINE
PHYTOPATHOLOGICAL SOCIETY, DAVAO CITY
MAY 10, 11, 12, 1968
(Arranged alphabetically according to first author's surname)
Coffee rust on rejuvenated kona arabica. C. A. Alaban. During
wet months and with abundant tree foliage coffee rust incidence becomes
high. Severe infection causes premature leaf fall and with continuous
partial defoliation the tree may eventually die. Protection against cof-
fee rust becomes necessary to maintain a healthy tree and the desired
cherry production. Copper fungicide has been a standard protective spray
and a year-round monthly spray has offered good protection. Some car-
bamates have proven to be very good substitutes for copper materials.
Heart rot and butt rot of newly set pineapple plants. C. A. Ala-
ban. Under favorable conditions, heart rot and butt rot primarily occur
in areas planted to crowns. Heart rot is caused by Phytophthora para-
sitica, a soil-borne phycomycetous fungus, while butt rot is caused by
Thielaviopsis paradoxa which is a wound parasite that occurs everywhere
and persist in soil. Phytophthora infection occurs most frequently and
severely in low or poorly drained spots and in areas where soil pH is
relatively high. Invasion of both roots and soft stem tips results in death
of the plants. Thielaviopsis infection occurs only through relatively
fresh wounds and affects primarily the older basal stem tissues but ii
can cause complete collapse. At Polomolok, South Cotabato, infection
by these fungi frequently occurs in the same area and causes severe loss
in stand of plants. Dip treatment of planting materials proved superior
to spray application after planting. Captan, Dexon, Difolatan, and Viti-
.gran Blue gave reasonably good control. Vitigran Blue and other copper
fungicides were effective but were slightly to seriously phytotoxic.
Some plant parasitic nematodes found in the vicinities of General
Santos and Davao, Mindanao. E. J. Anderson and C. A. Alaban. -
Soil and root extractions from a limited number of samples collected in
uncultivated areas or soils recently planted to pineapple, banana, or
vegetables yielded a wide variety of plant parasitic nematodes of the
sub-families Tylenchinae, Hoplolaiminae, Pratylenchinae, Criconematinae
r.te..ndpnn 7npioi n-f' M
valent- and abundant in certain samples. Radopholus was found in sam-
ples from banana and abaca plantings in Davao and General Santos. The
earlier cropping histories of-the soils could not be determined. Pratylen-
chus, Criconemoides, Helicotylenchus and occasionally Meloidogyne larvae
and Tylenchorhynchus were found in presently uncultivated soils. The
diversity of plant parasitic forms suggests much movement of infected
plants and infested soil. Actual or potential nematode induced disease
problems in a wide variety of crops.
Reaction of promising soybean hybrids and standard varieties to
rust Progress report. -.F. B. Ballon, and B. M, Legaspi. Rust, caused
by Uromyces sojae Sydow., is one of the most destructive diseases of
soybean in Los Bafios, Laguna. The disease is most severe on the dry
season crop, especially when planted in. October, reducing bean yield by
30 to 80%.
In a series of soybean breeding work at the BPI Economic Garden,
several improved strains developed at the station and selected introduced
standard varieties were subjected to rust infections,and screened rigid-
ly. Results showed that most of the standard varieties succumbed to in-
fection except variety Sankuo, of Taiwan origin, which exhibited a high
degree of resistance to the disease. Some hybrids, progenies of improved
strains crossed to Sankuo, likewise showed resistance to rust. Such pro-
mising hybrids are L114, L1080 and L51 from the, cross between C-364
x Sankuo; 1-113, 1-117, 1-243. from EG1 x Sankuo; K-465, K-489 and
K-87 from B-256 x Sankuo; and J-212, J-243 and J,24 from E.G.-2 x
Sankuo. The yield and the desired agronomic characters of these hybrids,
are not much affected by rust.
'Chemical control -of powdery mildew and downy mildew of cucumber.
- C A. Baniqued, D. S. Isidro, and V. L. Domingo. Four fungicides,
viz., Dupont Fungicide 1991, Karathane, Manzate D, and Dithane M45
were tested against powdery mildew and downy mildew of cucumber
caused by. Erysiphe cichoracearum DC. and Pseudoperonospora cubensis
(Berk..and Curt.) Rostow., respectively. Manzate D and Dithane M-45
were applied at 2 lb/100 gal, KKrathane at 8 oz/100 gal, and. Dupont
Fungicide 1991 at 4 and 8 oz/100 gal. A spray .combination of Mnzate
D at 2 lb and Dupont Fungicide 1991 at .4 oz/100 gal was .lso tested,.
The experiment consisted of 7 treatments including check, each re-
plicated 3 times. The first spray was applied 1 week after seedling
emergence and subsequent sprays were applied at weekly intervals for
8 weeks. Blanket applications of insecticides were employed to control
insect pests The effectiveness of the test fungicides was evaluated on
the 'bases of lesion counts and speed of spread from the oldest to the
youngest leaves after the 4th, 6th, and 8th spray applications.
The spray combination of Manzate D and Fungicide 1991, Manzate
D arone, and Dithane M-45 gave significant protection to the crop. Fun-
gicide 1991 alone and Karathane did not give .significant. protection
against downy mildew. Plants sprayed, with the spray combination were
generally robust followed by plants sprayed with Manzate D,.and Dithane
M-45, in that order. The vegetative growth of sprayed plants was pro-
longed by almost 1 month thereby increasing the number of harvest from
14 to 20 times.
Growth and reproduction of Aphelenchus avenue on- plant patho-
genic fungi in corn meal agar.- R. V. Cortado and R. G. Davide. -
Aphelenchus avenue Bastian, a nematode with doubtful parasitism on
higher plants, is one of thosefound 'in our survey to be constantly asso-
ciated with tobacco plants.' A test on its pathogenicity revealed that
this particular nematode is not parasitic on tobacco plants as shown by
their failure to survive and reproduce.
Attempts were made to study the growth and reproduction: of A.
avenae on various species of plant pathogenic fungi in vitro.
Eleven 'soil-borne fungi, most of which are plant pathogenic, viz.,
Pythiuni debaryiauim;: Alternaria brassicicola, Rhizoctonid soldni, Cera-
tocystis paradox, Fusarium oxysporum. f. lycopersici, Aspergillus niger,
Phytophthora palmivor~, Sclerotium rolfsii, Saccharomyces cerevisiae,
and Penicillium sp. were tested as possible sources of nutrition of the
nematodes. Each fungus, was grown in triplicate plates of corn meal
agar. Three plates of corn meal agar without any test fungus served as
control. Subsequently, 5 female nematodes dipped in 0.1% streptomycin
sulfate suspension were introduced into each petri dish. These nematode
cultures ,were kept at room temperature throughout the study. The rate
of reproduction of the nematodes was determined, at 10 and 20 days after.
their introduction into the medium.
The results indicate that the nematodes grew and reproduced rapid-
ly in the presence of any of the fungous species on corn meal agar. The
failure of the nematodes to survive in the agar medium without a fungus
surgests that A. avenae is a fungal feeder. Their failure to survive in
agar plates seeded with S. rolfsii and S. cerevisiae coupled with the ap-
)arent influence of the kind of fungus on their rate of reproduction sug-
rests that A. avenue has preferential tendency for certain fungi as
source of nourishment.
Ten days after introducing the nematodes in the fungal cultures, 6
'ungi appeared to favor their reproduction as reflected by population
:ount. The mean nematode population was 669.9 in A. brassicae, 178.3
n P. palmivora, 137 in P. debaryanum, 108.6 in R. solani, 78.6 in F. oxy-
porum f. lycopersici, and 56 in Penicillium sp. Twenty days after intro-
luction, the mean population count was 2,293 in A. brassicae, 1,837.3 in
P. palmivora, 1,075 in F. oxysporum f. lycopersici, 417 in Penicillium sp.,
!36 in P. debaryanum, and 161.6 in R. solani.
The fact that the nematodes reproduced in the absence of males in-
licates that A. avenae is either parthenogenetic or hermaphroditic, or
Nematode-trapping fungi in the Philippines. R. V. Cortado and
1. G. Davide. The presence of nematode-trapping fungi in the Philip-
)ines is reported for the first time. This "friendly" group of fungi was
isolated from cow dung and compost from rice hay. Isolation was done
>y planting small bits of dung and compost in plated corn meal agar.
Ten adult nematodes (Rhabditis sp.) were introduced into each..late
culture to induce the growth of the fungi. Cultures were kept at room
temperature and examined periodically under the binocular and com-
ound microscope for the appearance of nematode-trapping fungi.
The nematode-trapping fungi were observed in the plate cultures
within 3 weeks. Their presence were unmistakably manifested by the
numerous nematodes actually trapped and killed. Two distinct types of
ungi were noted based on the manner by which they held the nematodes
n captivity. The more aggressive one (possibly DactyleUa sp., or Ar-
hrobotrys sp.) formed many hyphal rings or loops that squeezed the
nematode once it passes through. The less aggressive (possibly Harpos-
)orium sp.) formed no rings but its hyphae penetrated the body of the
nematode. Cow dung yielded both the ring and non-ring former while
he compost yielded only the latter.
Histopathology of stems and leaves of eggplant infected by Pho-
nopsis vexans. Gil G. Divinagracia. Pycnidiospores of Phomopsis
'exans (Sacc. & Syd.) Harter germinated after 6 hr and entered the
-ij. L_ _- r 4A-4 + Akjl 4-1.- c+,nmO+--o TIa
fungus can infect all tissues, possibly including the vascular elements
It spreads inside the suscept intra- and inter-cellularly. It is evidently
a parasitic pathogen (facultative saprophyte) since it does not kill cells
in advance of the hyphae. Staining tests suggest breakdown of pectic
and cellulosic components of the host cell walls.
The variety Florida Market which was used in the study responded
to infection by division of cells adjacent to and away from infected tis.
sues. The fungus in most instances was stopped from further penetra,
tion. In very young tissues, this histogenic defense reaction was nol
evident. Cells in these tissues were easily killed and very little to no
divisions occurred near infected cells.
The influence of nitrogen level on the degree of infection of rice
bacterial leaf blight.-T. S. Eugenio and F. M. Olivares, Jr.-The
effect of nitrogen level on the degree of infection of bacterial leaf blighl
of rice was determined during the 1968 regular crop season using var.
IR-8 as indicator. The rates of application tried were 40, 60, 80, 10(
and 120 kg N per hectare. Observations were made on representative
flag leaves gathered at random from the different treatment plots. A
disease index was devised to record numerically the degree of infection
of samples from the various treatments.
The application of 60, 80, 100 and 120 kg N per hectare slightly
increased the degree of infection but statistical analysis showed no
significant increase in the degree of infection corresponding to the in-
creasing level of nitrogen.
Dextran yields ,of four Leuconostoc mesenteroides isolates in coconut
water and pineapple juice. P. M. Halos and M. O. San Juan.- Pure
cultures of bacteria were isolated from fermenting cabbage (Brassica
oleracea L. var. capitata), mustard (B. nigra Kock), and pechay [B.
pekinensis (Lour.) Gagn.]. Like Leuconostoc mesenteroides strain NRRL
B-742, the isolates yielded crude dextran when grown separately under
laboratory conditions in either coconut water or pineapple juice.
The isolates differed in dextran yields. In coconut water-sucrose
medium, strain NRRL B-742 gave the highest yield followed in descend-
ing order by the isolates from pechay (B-102), cabbage (A-101), and
mustard (C-103). In pineapple juice-sucrose medium, isolate B-102 gave
the highest yield followed by strain NRRL B-742, isolate A-101, and
isolate C-103 in that order.
concentration, incubation temperature, and other stimulatory factors.
Morphological; cultural and biochemical properties of the isolates
fr6m local sources showed that they were identical with Leuconostoe
mesenteroides (Cienkowski). -van Tieghem.
A proposal to standardize the international race numbers of Pyricu-
laria oryzae.- The International Rice Research Institute.--In 1967,
Atkins,. et al. proposed that the following comprise an international set
or rice varieties for differentiating races of P. oryzae, A-Raminad Str.
3, B-Zenith, C--NP-125, D-Usen, E--Dular, F-Kanto 51; G-Sha-
tiao-tsae (S), and H-Caloro. They also suggested that the races dif-
ferentiated by the international set be called international races.
The races are prefixed by the letter "I" followed by the group letter
A, B, C, D,. E, F, G, and H, according to the susceptibility of the key
variety.' The arabic numeral following the group letter indicates the
race number and completes the race designation. Only 32 races were
Because more isolates of P. oryzae have been collected and more.
races. identified, the number of races need to be standardized in order to
lessen the confusion.
,Based on 8. differentials, only a maximum of-256. races can be dif-
ferentiated. The pathogenicity pattern for each race can be standardized
by pre-designating. their numbers. Therefore, the international race
numbers are from IA-1 to IA-128, IB-1 to IB-64, IC-1 to IC-32, ID-1 to
ID-16, IE-1 to IE-8, IF-1 to IF-4, IG-1 to IG-2, IH-1 and II-1.
Since the reaction of a variety to a race may. be neither susceptible-
nor resistant but intermediate, the use of small letters, a,b,c,d,e,f,g,- and
h after the. race numbers are suggested in distinguishing the races if
Further studies on the nonpersistence of the rice tungro virus in its
vector. K. C. Ling. The following evidences have proven the non-
persistence of the rice tungrd virus in Nephotettix impicticeps: 1) a
gradual decrease in vector infectivity with time, 2) the longest retention:
period is less than a week, 3) the absence of any demonstrable incuba-
tion period in the insect, 4) the existence of a daily consecutive trans-.;
mission pattern, 5) the increase in infectivity by a prolonged acquisition.
feeding period, 6) the loss of infectivity after molting, and 7) the re-
j- !n *! j- rt-P *I-P/\,*'<--iT^r Vhfr mn~nr/fiTo'-'-I/\v fnPoQ/Hn f
*tddies on the effect of the vitus bn the insect indicated that there
were no significant differences in life span, fecundity, and egg hatching
'ate between viiuliferous and virus-fiee insects. '
Studies on the inactivation of viruliferous insects by chemical treat-
nent. through the feeding technique revealed that the -percentage of in-
ective insects decreased when the viruliferous insects' ere treated with
formalin. The reduction was highly correlated with both the concentra-
ion of formaldehyde in the solution used for treating the virufiferous
insects and' the duration" of the treatment. Consequently, the results
seemed to indicate that tungro virus-laden insects can be inactivated and
that formalin is an effective inactivator. Formalin did not, however,
dter the ability of the insect to transmit 'the virus; the percentage of
infective insects treated with formalin 4 hr before acquisition feeding
was the same as those treated" ith water.
These results serve as circumstantial evidences that the rice tungro
virus is stylet-borne.
Rice tiungro resistance in Pankhari '203. K. C. Ling.-- Pankhari
O03 is highly resistant to fungro. Based on the artificial inoculation 6f
riore than 4,000 seedlings, the average percentage of infected seedling.
of this variety was 4.61 whereas that'of Taichung (Native) 1 [T(N)1]
which served as a susceptible check was 79 to 98.
: An anatomical study showed that there is a sclerenchyma cap on
;he top of the vascular bundle in the.cross section;of the leaf sheath of
'ankhari 203, but the sclerenchyma cap is not wide enough to prevent
bhe insect stylet from reaching the vascular bundles.
:. Studies .on the infectivity of about 2,300. viruliferous insects using
bhe top of the vascular bundle in thp cross section pf the leaf sheath f 9
infective insects after feeding on Pankhari 203. was 34.26,. whereas on
' (N) 1, it was 40,97. The difference of 5.31% was statistically signifi-
ant.. It.could, be suspected that the smaller. percentage of infective in-.
;ee,'t after feeding on Pankhari 203 might, have. resulted from, the in-
Ictivitation of the viruliferous insects during feeing by a certian sub-
stance present ,on, Pankhari: 03. Since. the rate -of inactivitation was.
ow,- it. could Ibe postulated that.the mechanism of tungro resistance in
Rankhari 203 is .due to the inhibitipn of; .multiplicati~ n of the virus rather
;han the. inactivation f thle -virus .by ac substance :p. -. substances present
A method for screening grassy stunt-repistti.n vri.etie,. .-'K: .
A method for screening grassy stunt-resistan t viaietie: -*K: 0.
PUTT TlDIDTMV VkTFn-CD A'rXZ^ T
Ling and V. M. Aguiero. The development of a screening method fc
varietal resistance became necessary because a high incidence-f -grass
stunt, transmitted by Nilaparvata lugens, occurred recently at the IRR
Experimental results indicated that: 1) about 30% of the inse(
population were active transmitters, 2) the infective insects transmitted
the disease almost until death and the intermittent transmission patter
occurred in some cases, 3) seedlings inoculated for 24 hr showed a high
percentage of infection than those inoculated for 6, 8, 16, and 18 hr, an,
4) there was no significant differences in percentage of infection be
tween seedlings inoculated at 11-13 and 20 days after sowing. A method
for screening varieties resistant to grassy stunt involved breeding anm
selecting an active colony, mass rearing and virulifying the insects, ir
oculating 32 entries (608 seedlings) daily and observing the infected
seedlings one month after inocula ion.
A blank test consisting of about 6,000 seedlings of Taichung (Na
tive) 1 in 320 pots indicated that the percentage of infected seedling
varied from 35.7 to 100%, or an average of 75.8%. Replication of sam
ples is necessary for increasing accuracy of results. A modification o
the method is now being emphasized to minimize variations in the re
suits. A total of 1,117 varieties and lines have been tested. Of these
315 showed an infection rating ranging from 0 to 60%, and the res
showed more than 60% infection. Varieties and lines with less thai
30% infection are being confirmed.
Relationship between cultural characteristics and pathogenicity o
Pyricularia oryzae A preliminary study. K. C. Ling and PriscillH
Chinte -Sanchez. Pure cultures of different isolates of the rice bias
fungus showed a wide variation in their cultural characteristics. To de
termine the pathogenicity of isolates with different cul rural characters
tics, 28 stable isolates conveniently grouped in o 4 cultural types wer
selected and tested. These cultural types were tentatively designate(
and described as follows: A-white, fluffy aerial mycelium; B-gral
with powdery-like aerial mycelium; C-gray without aerial mycelium
and D-gray with cotton-like aerial mycelium. The isolates were cul
tured in steamed water hyacinth stem. Spore suspensions obtained fron
these cultures were inoculated separately on international and Philippinm
differential rice varieties. The degree of pathogenicity of each isolate
was determined by the lesion type formation on leaves of varieties ir
J.enI Jcuaint a1wU cu a, ULrei z ULn ueiween tme cuiLurai cnaracteris-
ties and pathogenicity. The pathogenicity index [ (NR + 3 NM + 5 NS) /
(NR. + NM + NS) where NR, NM, and NS are numbers of resistant,
intermediate and susceptible reactions, respectively, on 18 differentials
to an isolate] revealed the degree of pathogenicity of the tested isolates
asD > C >B >A.
The control of root-knot nematode in wrapper tobacco seedbeds using
granular formulations. C. P. Madamba and C. G. Goseco. Three out
of 6 granular nematocides reduced significantly root-knot nematode in-
fes'ation in wrapper tobacco (var. Viscaya) seedbeds. But none of them
were comparable to the efficiency of ethylene dibromide soil fumigant.
The percentage of root-knot infestation in control beds and in those
treated with Basudin 10G at 400 kg, Solvirex 5G at 60 kg and Lannate
90Wd at 12.2 kg/hectare was 79.5, 21.4,,50.2 and 56.8, respectively. In-
festation in seedbeds treated with ethylene dibromide at 28.8 gal/hectare
was 2.7%. The average galling per seedling was 0.29, 1.85, and 2.68
for Basudin, Solvirex, and LannaW:e, respectively; galling was almost nil
(0.006) in ethylene dibromide-treated beds.
There were no significant differences in seedling heights between
treated seedlings and the controls. But the treated seedlings have well
developed and almost gall-free root systems.
Plant parasitic nematodes on ramie and their control by soil fumi-
tion. --C. P. Madamba, R. G. Davide, and R. K. Palis. Studies on the
identification and distribution of plant parasitic nematodes associated
with ramie [Boehmeria nivea (L.) Gaud.] grown in Cotabato revealed
the presence of at least 10 genera. The most predominant genera isolated
from soils collected at the KENRAM (Phil.), INC. plantation in Isulan
were Trichodorus, Xiphinema, Dorylaimus and Meloidogyne larvae. Res-
pectively, they occur in 82.4, 69.0, 52.9 and 45.6% of 150 soil samples
collected from 25 randomly selected lots. The same nematode genera
were frequently isolated from 74 soil samples obtained from the Ramie
Corporation of the Philippines (RAMCOR) farm at Buluan. Unlike in
the former plantation, Xiphinema occurred in 40.5% of the soil samples
followed by Meloidogyne larvae, 31.1% ; Dorylaimus, 20.3% and Tricho-
Root-knot nematode infestation at both plantations showed that 58%
or 14 out of 24 randomly surveyed lots at KENRAM and 57.1% or 12
out of 21 lots at RAMCOR were severely infested with the nematode.
trace to moderate. None of the lots in both farms was nematode-free.
Analyses of the data gathered from both farms showed that lower slalk
characteristics, notably stalk heights and population densities, Were cor-
related with severe root-knot infestation. Additional surveys in several
ramie farms at Davao failed to show the presence of root-knot nematode
in that area.
Soil fumigation of established ramie beds in the field resulted in
effective con rol of the nematodes and in subsequent increase of fiber
yields. Nemagon 75EC, applied either as drench in furrows or injected
into the soil with tractor-drawn equipment at 3.4 gal/hectare resulted
in increase in yield of dry fiber corresponding to 28.46 and 19.6 kg/
hectare per harvest over the controls, respectively. Nemagon 20G used
at 116 kg per hectare gave 18.98 kg/hectare increase. Fumazone 70E
applied by hand-injectors at 8.5 gal/hectare gave an increase of 24.03
Other tests indicate that Temik 2G and Temik 10G applied at 25
and 5 kg/hectare resulted in yield increases corresponding to 37.95 and
9.48 kg/hectare per harvest over the control, respectively. Likewise,
Nemafos 10G used at 34 kg/hectare gave an increase of 31.21 kg/hec-
tare over the control.
Preliminary studies on the banana mosaic virus in the Philippines.
-Lydia Velasco-Magnaye and A. L. Eloja.- The banana mosaic virus
(BMV) affecting the Giant Cavendish banana of the Standard Fruit
Corporation in General Santos, Cotabato, is sap transmitted and is also
vectored in a non-persistent manner by the cotton aphid (Aphis gossypii
Glover) and by the corn aphid [Rhopalosiphum maidis (Fitch.)].
BMV has been transmitted in the laboratory to Amas, Sefiorita,
Suay-baguio, Bongolan, Latundan, Lacatan, Saba, and Cardaba varieties
of banana. On Saba and Cardaba which appear to be tolerant to in-
fection, only a few and small yellowish to whitish markings may appear
on a leaf about 7 days after inoculation. These markings may either
persist or fade after a few weeks. Other leaves may be symptomless.
On other varieties, the yellowish markings on the leaf blades are many,
usually larger and, therefore, more conspicuous. Only a few leaves may
Infected'plants of all varieties undergo a stage whereby the leaves,
formed after' infection has set in, have difficulty in'unfolding that te-
suits in the characteristic bunchy appearance. The leaf formed imme-
diately after the bunching,stage is usually much reduced in size but the
succeeding ones are progressively larger. The third to the fifth leaves
may be as big as the corresponding leaves of healthy plants.
Other suscepts of BMV that have been found so far in the labora-
tory are abaca, corn, cucumber, tomato, tobacco, Nicotiana glutinosa,
Canna indica, Commelina benghalensis, Gomphrena globosa, Physalis sp.,
Datura sp., Plantago major, and Chenopodium amaranticolor which is a
The effect of chicken manure on the incidence of Sclerotium disease
on selected vegetables. V. M. Mercado and A. N. Pordesimo. The ef-
fect of increasing levels of chicken manure on the incidence of Sclero-
tium disease was studied using pechay, cabbage, cauliflower, tomato,
cucumber, and squash as indicator plants and Sclerotium rolfsii as test
Observation on the rate of emergence showed an appreciable delay
in the emergence of seedlings in treatments containing manure. Cruci-
fers and tomato seemed to be more sensitive to chicken manure treat-
ments; their emergence on manure-treated seedflats was completed on
the 12th day after sowing, whereas the emergence of cucumber and
squash was completed on the 10th day. All test vegetables gave the
highest emergence on baked soil. At 2 and 3 kg manure levels, cucumber
and squash had more or less 50% seedling emergence but pechay, cab-
bage, cauliflower, and tomato had none. At 2 and 3 kg levels, the effect
of the chicken dung was lethal to small-seeded vegetables.
A consistent picture of increased incidence of damping-off was evi-
dent with heavier application of chicken dung. Infested soil treated with
0.5 kg chicken dung showed a marked increase in damping-off over the
infested soil alone. This held true for all vegetables. Isolations that
were made in vitro cultures showed that S. rolfsii was predominantly
associated with the damped-off seedlings.
After emergence, no apparent phytotoxic effect was noted on young
seedlings in manure-treated flats.
A report on the 1966 and 1967 Philippine uniform blast nurseries.
- S. H. Ou, K. C. Ling, F. L. Nuque, T. T. Ebron, Jr., and J. P. Silva. -
To identify varieties with a broad spectrum of resistance to the rice
blast fungus (Pyricularia oryzae Cav.), repeated tests were conducted
in various locations in the Philippines: San Mateo, Isabela; Mufioz, Nue-
va Ecija; Santa Barbara, Iloilo; Musuan, Bukidnon; Midsayap, Cota-
bato; Pili, Camarines Sur; and IRRI, Los Bafios, Laguna.
Two sets of selected varieties were sent to the above cooperating
stations for testing. One set, called the International Blast Nursery
(IBN), consisted of 258 varieties, while the other set, the Blast Resis'ant
World Collection Varieties (BRWCV), consisted of 321 varieties. The
latter se: consisted of selections from the world collection of more than
8,000 varieties after repeated tests for blast resistance at the IRRI Blast
In the 1966 "and 1967 Uniform Blast Nursery tests, about 4 and
14% of the varieties in the IBN and BIWCV sets, respectively, showed
resistant reactions. These are potential sources of genes for resistance
to blast in breeding programs. Repeated testing is suggested to deter-
mine their possible breakdown in resistance.
Effect of bacterial leaf blight on grain yield ,of rice. S. H. Ou, F.
L. Nuque, and J. P. Silva. The economic importance of bacterial leaf
blight is usually not realized unless its damage to the crop is known. To
determine the over-all loss in grain yield caused by this disease, IR8
and Tainan 8, a susceptible and an intermediate variety, respectively,
were grown in pots and then inoculated with B15 at the following growth
stages: 30, 60, 30 + 60 days after sowing, booting, 60 + booting, flower-
ing, and 60 + flowering. The single needle prick method of inoculation
was used for the 30 and 60-day growth stages while the multiple needle
prick method was employed at booting and flowering (flag leaf) stages.
The results showed that the disease could cause very heavy losses.
Based on filled grain weight, the average loss for infected IR8 and Tainan
8 as compared to the control were 74.9 and 46.9%, respectively. The
average losses from 1000-grain weight on the above varieties were 22.0
and 9.3%, respectively. Early and double infection up to 60 days on
IR8 and early and double infection up to booting on Tainan 8 resulted
in a serious loss. Infection during the later growth stages of both varie-
ties did no' affect the yield significantly.
The loss is generally higher on a susceptible than on an interme-
New susceptsg of Xanthomonas oryzae in the Philippines. S. H.
Ou, F. L. Nuque, J. M. Bandong and J; P. Silva.--In studying suscept
range of X. oryzae, 31 gramineous and 5 cyperaceous plants were artifi-
ciallv inoculated with B6. a virulent strain, by the single needle prick
method. Two species of Leptochloa afid one of Zizania were infected.
The early symptoms produced 7 days after inoculation on Leptochloa
chinensis (L.) Nees, L. pwaicea (Retz) Ohwi, and Zizania aquatica were
yellow to light orange lesions around the point of inoculation.
These lesions gradually extended longitudinally to the healthy regions
down to the leafsheath. About 3 weeks after inoculation the leaves dried
up. The bacterium was reisolated from Leptochloa sp. and inoculated
to rice var. BPI-76; the inoculated leaves showed typical blight symp-
toms. Since no naturally-infected Leptochloa has yet been found, the
role of these weeds in the life cycle of this bacterium in the field remains
Pathogenic races of Pyricularia oryzae in different regions of the
Philippines. S. H. Ou, P. L. Nuque, T. T. Ebron, Jr., Sonia P. Ebron,
and J. M. Bandong. In investigating the distribution of pathogenic
races of the rice blast fungus (Pyricularia 'oryzae Cav.) in the Philip-
pines, 776 isolates obtained from 7 different regions were inoculated
to the Philippine differentials composed of 12 rice varieties from 1962
to 1967. Based on the pathologic reactions of the differential varieties,
the isolates were grouped into 88 races. Apparently, only a few of these
races are distributed throughout the country; the others are found only
in certain regions.
The total number of races found so far in each region are: Northern
Luzon, 17; Central Luzon, 15; Southern Luzon, 69; Bicol Region, 20;
Western Visayas, 31; Eastern Visayas, 6; and Mindanao, 24. The com-
mon races are P9, P11, and P15 in Northern Luzon,; P25, P8, P21, and
P29 in Central Luzon; P8, P12, P16, P30 and P57 in Southerni Luzon;
P21, P25, P31, P84, and P85 in the Bicol Region; P11, P13, anld .P23 in
Western Visayas; P8 and P18 in Eastern Visayas, and P9 aind P25 in
P8 is the only race found in all regions. Races P9, P20, P23, and
P30 were found in all regions except Eastern Visayas. Some, races were
found only in certain region, e.g., P2, P45, P47. to P87, and P88 in
Southern Luzon; P37, P39, P84, P85, and P86 in the Bicol region; P4,
P40, P41,' and P42 in Western Visayas; and P3; P27, P33, P34, and
P35 in Mindanao.
Effect of drying soils prior to treatment with Zinophos for the con-
tol. .of the root-knot nehnatode. A, V. Palo, R. H. 'Calinga and M. T.
diethyl 0-2 pyrazinyl phosphorothiotate) for controlling the root-knot
nematode (Meloidogyne incognita Chitwood) was investigated. Soil with
a moisture content of about 21% was artificially infested with nematodes
and divided into 2 lots (not dried, and air-dried to about 11% moisture
content). The chemical was used at 2, 4, 8, 16 and 32 ppm, each repli-
cated three times. For control, no chemical was applied. Tomato was
used as the test plant.
Drying the soil before applying Zinophos has influenced the effi-
ciency of the chemical in the control of the nematodes. Both air-dried and
non-dried soil yielded gall-free root systems in the 32-ppm treatment. At
16 ppm trace infestation was noted in the non-dried soil. All root systems
of plants grown in air-dried soil were gall-free. Drying the soil prior to
the chemical treatment of 8 ppm gave significant results. The root systems
of plants in soil that had been dried had trace galling while those in the
non-dried soil had moderate infestation. The root systems in the un-
treated soil and those treated with 2 and 4 ppm had severe infestation
in both lots. Under drier soil condition Zinophos even at lower dosage
level can still provide adequate control of the nematodes.
Yield losses due to rice grassy stunt infection. M. K. Palomar and
K.C. Ling. Plants of IR8, Taichung (Native) 1, and BPI-76 were
artificially inoculated at different ages with grassy stunt virus using
Nilaparvata lugens Stal. as vector. The reductions in height of the in-
fected IR8 plants inoculated at 15, 30, 45, 60, and 75 days of age were
55, 43, 15, 10, and 1%, respectively, while those of the Taichung (Native)
1 plants were 64, 59, 14, 2 and 4%, respectively. The BPI-76 plants
showed-59, 52, and 1% height reductions for the corresponding ages of
10, 30Q, and 60 days. In all cases, plants inoculated at 10, 15, and 30
days of age produced more leaves and tillers than their respective con-
There was no yield when plants were inoculated at 15 and 30 days
old. Inoculations at 45 days old gave yield indices of 31 and 23% for
IR8 and Taichung (Native) 1, respectively; yield index of 0.3% for
inoculations at 10 and 30 days old was recorded for BPI-76. Plants
inoculated at 60 and 75 days old did not develop characteristic symptoms
before harvest and their yields did not decrease. The grains from the
infected plants were lighter, smaller and dark brown.
The severity of rice grassy stunt decreased with increasing plant
Diseases of rambutan in Oriental Mindoro.-A. N. Pordisimo. -
In late September 1967 unreported diseases of Rambutan (Nephelium
lappaceum L.) were found to occur on bearing trees in a commercial
planting in Oriental Mindoro. Affected trees exhibit symptoms diagnos-
tic of viral infection.
Swollen trunk in characterized by swelling or bulging of the trunk.
Fruit production is very much reduced. In some instances, scaling of
bark and presence of chlorotic ring spots on leaves constitute the symp-
tom complex indicating the presence of a primary causal complex.
Scaly bark is characterized by presence of dried bark scales on the
trunk. In more advanced cases, defoliation results; soon this is fol-
lowed by production of numerous water sprouts. This symptom complex
resembles that of a "quick decline" effect which also suggests the exis-
tence of a viral complex.
Transmission of the disease is still unknown. The history of the
disease is obscure and the authentic sources of original planting stocks
could not be ascertained.
A study on the shifting of races of Pyricularia oryzae at the IRRI
blast nursery. Md. Quamaruzzaman and S. H. Ou. To determine the
seasonal shift of races of Pyricularia oryzae 'Cav. and their populations
under natural conditions, a total of 268 monoconidial cultures of P. oryzae
were isolated monthly from lesions produced on leaves of rice varieties
at the IRRI blast nursery from August 1966 to December 1967. All the
isolates were tested for their pathogenic patterns on the 12 Philippine
and 8 international differential varieties. Based on the pathologic re-
actions of the differentials, the isolates could be classified into 49 and
27 race groups by Philippine and international differentials, respec-
SThe results indicated that races of P. oryzae at the IRRI blast nur-
sery varied monthly while the number of races ranged from 3 to 13 by
Philippine differentials and from 2-to 10 by -international 'differentials.
No race group occurred, every month. Some of the races were present in
a few consecutive months while others appeared periodically.
The races of P. oryzae at the IRRI blast nursery were, therefore,
shifting during the period of this. study and the most common races
were P8 and IA-69. .
Field spraying with'Du Pont Fungicide 1991 against leaf mold on
rain-tolerant Tomato Strain 2029.- F. C. Quebral and R. L. Villareal.
--A field experiment with Dupont Fungicide 1991 used at the rate of
2, 4, and 8 oz/100 gal of water and applied 4 times at weekly interval
against leaf mold of tomato during the wet season was conducted at the
UPCA Experiment Station from August to October 1967. The rain-
tolerant Tomato strain 2029 was used as test plant.
Experimental plots consisted of 2 replicates, each having 4 subplots
measuring 3.5 x 5 m. Each treatment plot had a total stand of 50 plants.
The degree of infection, number, and weight of marketable tomato
fruits were the criteria used in evaluating the efficiency of the chemical.
Fungicide 1991 applied at 8 oz/100 gal of water produced no phyto-
toxic effects; it provided adequate protection to tomato plants against
severe damage by leaf mold. Plants under this treatment had an aver-
age infection index of 27% and a total yield of 482 marketable fruits
with a total weight of 10.04 kg or an increase of more than 100% over
those of the control which had an infection index of 87% and a total
yield of 146 fruits that weighed only 2.23 kg.
Transmission of rice tungro virus by a new vector, Nephotettix
apicalis. C. T. Rivera and K. C. Ling. Greenhouse studies were con-
ducted in 1967 and 1968 at the International Rice Research Institute to
determine whether or not the rice green leafhopper, Nephotettix apicalis
(Motsch.) can transmit the rice tunrro virus.
.solates are ni
U 1i e llp Linu ill peL ull llull y U
reduced long before it was es
us was still able to manifest
re neutralized by the presence
us concentration of Y. When
hlier than G, symptoms of G r
nore invassive than Y. In simi
lated yellow blotches and the ih
s introduced earlier, i.e., 6, 12,
s partially suppressed, although
er time. This phenomenon ca
Soaking the seeds for 30 min
I 10% clorox was effective in i
I 1 ^W -f-_-_ -- _T_ "m -- --- _3
ory that these 2
vladamba.- Stuales on tne post-in
ncognita Chitwood in ramie [Boeh%
seisen showed that under greenhouse
m (G) further strengthened the
Aely related. Both isolates multi-
other. Even if Y or G had been
led in the plant, the challenged
The lethal characteristics of Y
., indicating a reduction of the
s introduced 6 hr or even 24 hr
sted earlier which shows that G
'us infection, Y appeared as small
ion period was delayed. When G
4 hr earlier, the appearance of Y
manifested in isolated spots at a
consideredd as partial suppression
9 parts HSSO,, 1:100 parts HNO0
sting the virus while 75% alcohol
)und to be infected even after 2
acted plants gave 15.3% infection
on. The percentage of Y and G
ise the 2 viruses occurred simul-
'adang-cadang affected palms on
,ods.--Ma. Salome del Rosario,
o. Two methods of purifying
phate buffer method, good infec-
ied while with the borate buffer,
t step. Further purification in-
['he "virus zone" measuring 5 cm
>paque bluish-green on the upper
lysis of the "virus zone" revealed
illimicron with their correspond-
de in ramie, with a consideration
ina. J. J. Walawala and C. P.
iter. On the average, the females reached egg-laying stage 19.8
days after inoculation.
cond stage larvae became sexually differentiated as males and
3 5.7 , 0.45 and 6.7 0.17 days after entry into roots, respec-
The third and fourth larval stages were both observed 8.9 +
iys after penetration for males and 11.8 0.21 days for females.
ty was attained by males and females 16.9 0.48 and 14.8 --
.ays after inoculation, respectively. Some males exhibited two
suLrresting that sex reversals may have occurred.
Ilphoxyethyl thiophosphate) used as dips for root-kno
1 ramie rootstocks for 10 and 15 min, respectively
rolled the nematodes, regardless of dosages used. Phy
f the chemicals were evident up to 4 weeks afte
after recovery was observed in rhizomes treated wit]
ive ingredient Fumazone 70E and 2.5 and 5.0%0 active
-stox. Ten weeks after planting, the stalk characters
inder this treatment were significantly superior thai
-I-"Kr - -- 4-1-- ---4- "" "-4- -F-n- wnA--
[etasystox stunted the plants.
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Il@ I rilmlITe INi FIa r" ll IRIlP lllr M
MECHANISM OF TUNGRO-RESISTANCE IN RICE
VARIETY PANKHARI 203
K. C. LING
Associate Plant Pathologist, International Rice Research Institute,
Los Bafios, Laguna.
The author wishes to thank Mr. M. K. Palomar, Research Assis-
tant, IRRI, for his help in preparing paraffin sections, and Dr. Kwan-
chai A. Gomez, Associate Statistician, and Miss Rosalinda C. Alicbu-
san, Research Assistant, IRRI, for their help in the statistical analysis.
Based on the mass screening technique for testing varietal resist-
ance to tungro, rice variety Pankhari 203 from India was found high-
ly resistant to the disease while variety Taichung (Native) 1 from
Taiwan was highly susceptible.
The feeding behavior of the leafhopper vector, Nephotettix impic-
ticeps was similar on both varieties; the size, distribution, and number
of feeding punctures and of feeding tracks terminating at vascular bundle
were the same. Adult insects confined on seedlings of Pankhari 203
had a shorter life span than those on Taichung (Native) 1.
The sclerenchyma cap on the abaxial side of the vascular bundle in
a cross section of the Pankhari 203 leaf sheath was not wide enough to
prevent the insertion of stylet or prevent it from reaching the vascular
bundle. The mechanism of tungro-resistance in Pankhari 203 cannot
be attributed to the inability of the vector to feed on this variety.
The percentage of infective insects following feeding on Pankhari
203 seedlings was statistically lower than that of insects fed on Taichung
(Native) 1 seedlings serving as controls. This difference in percentage
of infective insects appears to be due to inactivation of the viruliferous
insects while feeding on Pankhari 203. Since the rate of inactivation
was low, it is postulated that the mechanism of tungro-resistance in
Pankhari 203 is suppression of establishment of the virus resulting from
either the inactivation of the virus or the inhibition of virus multiplica-
tion by a substance or substances present in the plant.
Number of entries
Total number of seedlings
(%) infection mean
- Pankhari 203
hari 203 T(N)I
I 0.1-4.0 1 8.1-2.0- I 16.1-20.0I
0 4.1-8.0 12.1-16.0 20.7
I 801-4.01 88.1-92.01 96.1-99
76.9-80.0 84J-88.0 92.1-96.0 100
Infected Seedlings (%)
Fig. 1. Frequency distribution of entries of Pankhari 203 and Taichung
(Native) 1 by the percentage of tungro-diseased seedlings tested
by the mass screening method.
140 .- 100
\ Average life span (days)
120 Experiment 1 I Il I V Meon
SOn T(N)I 1415 1017 9.13 720 12.08 10.64 80
S _0- \ \ On Pankhari 3.10 1.80 330 2.25 3.53 297
0 1 L.S.D. 1% 820 8.14 3.78 515 4.73 2.39
60 --On Taichung (N)t
\ \ 40
0 \-On Pankhari 203
0 --- 0
5 10 15 20 25 30 35
Days on Seedlings
Fig. 2. Life span of adult Nephotettix impicticeps when fed on Taichung
(Native) 1 and Pankhari 203 seedlings in test tubes.
LING: TUNGRO-RESISTANCE IN RICE
In breeding for disease resistance, methods have been developed for
identifying and testing resistant varieties. The methods for testing re-
sistance to leafhopper-borne viruses have involved insect inoculation
(Gidding, 1937; Larson, 1945; Lamey, 1969; Ling, 1967, 1969; Sakurai,
1969). Rice varieties resistant to leafhopper-borne viruses have al-
ready been reported (Lamey, 1969; Ling, 1969; Sakurai, 1969; Toriya-
In animals, the mechanism of resistance to viral infection, or the
ability to resist infection, seems dependent on the presence of protective
antibodies (Baron, 1963). In plants, resistance may involve escape
from infection despite inoculation. It may also involve prompt death of
invaded tissues, with or without limitations on virus movement, and
rapid inactivation of virus. It may be characterized by a tendency to
inhibit the expression of disease symptoms due to partial suppression
of viral multiplication and/or suppression of systemic spread (Holmes,
The transmission of the rice tungro by Nephotettix impicticeps
Ishihara was reported in 1965 (Rivera and Ou, 1965). Based on the
mass screening method for testing tungro resistance (Ling, 1967, 1969),
Pankhari 203 consistently showed a lower percentage of infected seed-
lings than the susceptible variety Taichung (Native) 1 (Fig. 1). Be-
cause the inoculation was done by viruliferous N. impicticeps, the low
percentage of infection might have been due to the vector's inability to
feed on Pankhari 203 and/or the resistance of this variety to the virus.
The present work attempted to compare the feeding behavior of this
leafhopper vector on Pankhari 203 and Taichung (Native) 1, and de-
termine the mechanism of tungro-resistance in Pankhari 203. Abstracts
of part of this work have been published (Ling, 1968a; Ling and Palo-
MATERIALS AND METHODS
A virus-free stock of the rice green leafhopper, N. impicticeps, was
reared on healthy rice plants in large wooden cages covered with nylon
screen. The maximum age difference among insects within a colony was
2 days. Only adult insects were used in experiments; they were made
viruliferous by confining them on tungro-affected plants of rice variety
Taichung (Native) 1.
Adaiu; I UniKU-ia Sl1TANHE l
r ~vsng punccurs of iv. mupwtcceps. ine eeaing punctures oi nv
impicticeps on leaves of Taichung (Native) 1 and Pankhari 203 are
shown in Fig. 5. The presence of insect punctures on Pankhari 202
rAVPnlIdr thna AT iVnAm.nti..'na wra Rhla +n innprf ita vtvl n intn tha 1]pn
m JW WillMWP j
::: i:;: ::
*i -. i:i:i~__ :,ii;*ri:-:l~i : :::::::
i:i;-:::-:--:- --;:::: :;-I::::::!--- -i'-;-::-:::' :::
,;: ,, *
:~-i': :-: : ::~- ---::::::"
i::-: :: :
: ";: : i --6,~-i .-.
:: : : : :
i :-:::::: -
:::::;':-: : :::::: :::::::: ::r ::i~~a6i
W '` Ioabrum
0M --4 -- -.0 ---4-: -.0 --1-
.. "," . m. axilla
s. A 'fl. ..a..4-t...LS, ~A -. . .. 1TL-S SS!
immediately after puncturing was smaller than the diameter of tl
needle, and it was even smaller when measured 10 min later.
Number of feeding punctures. The average number of puncture
made by an insect in 1 hr on the leaf blade of Taichung (Native)
was almost identical to that made on Pankhari 203 (Table 1). Th
number indicated the frequency of insect feeding which may be relate
to the frequency of virus inoculation by the vector.
Duration of single feeding of N. impicticeps. The incidence of virt
inoculation was related to the duration of insect feeding. The duratic
of a single feeding of N. impicticeps on leaves of Taichung (Native)
varied appreciably, the shortest being about 1 min and the longest, moi
than 366 min (Table 2). Previous starvation of the insect might hai
been one of the factors which affected the duration of individual fee4
ings. Since the duration of individual feedings varied greatly even c
the same variety, the difference between durations of individual fee<
ings on both varieties was expected to be insignificant in a small san
pling. The actual duration of individual feeding of insects on Pankha.
203 was not determined. But by casual observation the duration of a
individual feeding of the insect on Pankhari 203 was apparently n<
shorter than that on Taichung (Native) 1. Naito and Masaki (1967b
pointed out that in the case of N. cincticeps the average actual feedki
time was 84.97% of a given time period.
Shortest duration of inoculation feeding. The minimum time re
quired by the vector to introduce the virus into the host tissue detel
mines the possibility for transmission of the virus by its vector in ec
perimental feedings. The results (Fig. 6) showed that none of the 4
viruliferous insects that has a single inoculation feeding of 1 to 6 mi
transmitted the virus. But an insect with a single inoculation feeding
of 7 or more minutes transmitted the virus. Seven minutes was n<
necessarily the minimum duration for positive transmission but it wa
the shortest duration of positive inoculation feeding. This result ind
cated that if a single probing was longer than 7 min, there was enough
time for a viruliferous insect to transmit the virus to the seedling.
Feeding behavior of N. impicticeps. The examination of the feei
ing tracks of N. impicticeps in the cross sections of leaf blades of bot
varieties revealed that regardless of variety, the feeding track terminate
':** :: j4. .
TABLE 1. Number of feeding punctures by Nephotettix impicticeps per insect per
hour on leaf blades of Taichung (Native) 1 and Pankhari 203.a
Variety Male adult Female adult Mean
Taichung (Native) 1 2.56 2.88 2.72
Pankhari 203 3.01 2.91 2.96
a 10 insects, 2 to 10 p.m., 2 replicates each.
TABLE 2. Duration of a single feeding of Nephotettix impicticeps on leaf blade
of Taichung (Native) 1.
Single feeding duration
Starvation No. of insects tested (minutes)
0- 62 20 1 20 5.3
6- 29 10 1 85a 23.0b
10- 45 15 1 63a 16.9b-
40 100 30 1.5 366a 77.9b
120 140 20 5 233a 39.1b
Total/mean 95 1 366a 39.0b
a Insects were still continuously feeding on the leaf when the data were taken.
b Averaged from the readings.
TABLE 3. Frequency of feeding tracks of Nephotettix impicticeps terminating at
indicated leaf blade tissues.
No. of Percentage of tracks terminating at
Variety tracks Phloem Phloem Paren- Across
examined oem xylema chyma leaf blade
'Taichung (Native) 1 177 80 7 12 1
SPankhari 203 186 77. 7 7 9
Total 363 78 7 9 5
a It might not be terminated- at the xylem, however, the xylem was plugged with
LING: TUNGO0-RESISTANCE IN RICE
I 2 3 4 5 6 7 8 9 10 II 12 13 14 15
Purdfion of Single Irioculation Probing (minutes)
6. Transmission of tungro virus by viruliferous adults of Nepho-
tettix impicticeps allowed single, natural probes not longer than
15 min on Taichung (Native) 1 seedlings.
S.Insect did. not transmit the virus
Insect transmitted the virus
rnILtIirP r Yi1.r IIUY~Al~l LAJU
the tracks terminated at the phloem and more than 80o of the tracks
examined reached the vascular bundles of the leaf blade. The feeding
tracks usually curved from the entrance toward the vascular bundle and
this curve may be regarded as evidence that N. impicticeps preferred
that tissue. The length of feeding tracks varied depending on the dis-
tance between the point of entrance and the vascular bundle. However,
the insect stylet was long enough to reach either of the two adjacent
vascular bundles from any point on the leaf blade when the feeding
track was perpendicular to the vascular bundle.
The feeding tracks of N. impicticeps in cross sections of leaves of
Taichung (Native) 1 and Pankhari 203 are shown in Fig. 7. No appa-
rent difference in the feeding tracks and the tissues damaged by the
insect was noted between the two varieties. The feeding tracks on leaves
of Pankhari 203 showed that the insect was able to insert its stylet into
the vascular bundle; in cross section, the sclerenchyma cap on the abaxial
Fide of the vascular bundle in the leaf sheath was not wide enough to
prevent the insertion of the insect's stylet or to prevent it from reach-
ing the vascular bundle. Furthermore, no striking difference in percent-
age of feeding tracks terminating in various tissues was observed
between the 2 varieties (Table 3), hence, the feeding behavior of N.
impicticeps on these varieties seemed similar.
Infectivity of viruliferous N. impicticeps after feeding on Pankhari
203. The results of a total of 29 tests involving about 2,300 viruliferous
insects are summarized in Fig. 8. Nine out of 29 tests showed 1 to 10%
(average 4.9%) more infective insects among those fed on Pankhari
203 than among those fed on Taichung (Native) 1. Nineteen out of 29
tests showed 1 to 34% (average 10.4%) more infective insects among
those fed on Taichung (Native) 1 than among those fed on Pankhari
203. The result of one remaining test did not show any difference. The
average percentage of infective insects after feeding on Taichung (Na-
tive) 1 was 40.07%; that of infective insects fed on Pankhari 203 was
34.76%. The difference of 5.31% of the total of 29 tests was statis-
tically significant. The number of infective insects fed on Pankhari 203
was about 87% of those fed on Taichung (Native) 1.
The difference in percentage of infective insects was not highly
correlated to the duration of insect feeding on Pankhari 203. Further-
more, the difference in the percentage of infective insects fed on Pank-
hari 203 did not differ significantly from those fed on Taichung (Na-
tive) 1 on the second and third day after treatment by serial trans-
Pankhari 203 (B), and leaf sheath of Pankhari 203 (C) show
Fig.~~~~~~~~~~~~~~i: 7.Cosscinso efbae o acug(atv)1() n
Pankhari~~~~~~::: 20 (B, ndlef hetho Pnkar 23 C)shw
-1 LL- 29 Individual Experiments
Fig. 8. Infectivity of tungro-virus-laden Nephotettix impicticeps after
feeding on Taichung (Native) 1 and Pankhari 203.
LING: TUNGRO-RESISTANCE IN RICE 35
mission mainly because both treatments gave very low percentages of
infective insects. The percentage of infective insects fed on Pankhari
203 for 5 days immediately prior to 1-day acquisition feeding on dis-
eased plants was slightly lower than that of the control insects. No sig-
nificant difference in transmissive ability was obtained between insects
fed on Pankhari 203 for 1 day then on Taichung (Native) 1 for 4 days
and insects fed only on Taichung (Native) 1 for 5 consecutive days.
The inactivation of a virus by any. substance in vitro can be deter-
mined by the bioassay technique for virus infectivity. The inhibition
of viral multiplication by a substance can be determined by the quanti-
tative method of measuring virus concentration. These techniques are
not yet available for the tungro virus. But if a substance existing in
Pankhari 203 inactivates the tungro virus in the seedling, it should alsc
primarily a phloem feeder on the rice plant.
virus. However, a variety with either mechanism or resistance should
be resistant in the field. Pankhari 203 has shown its resistance to tungi
-4- 4-1- TDDT .9n- --, 4- -11-,- ------ 1-0d -4.. .-U- --1L- TO
preference of the insect, if any, for either of these two varieties.
Exposure of a susceptible variety to the virus generally results in
ie establishment of viral infection, multiplication of the virus, and
development of the disease symptoms. The mechanism of resistance of
variety to a viral disease may involve suppression of viral infection.
ince the viruliferous insects can be inactivated by formalin (Ling,
968b), it is conceivable that the reduction in the percentage of infective
sects after feeding on Pankhari 203 might have been the result of in-
ctivation of the viruliferous insects during feeding by a certain sub-
tance existing in Pankhari 203. The experimental results indicated,
however, that the effectiveness of the substance in inactivating the viru-
ferous insects was poor as evidenced by about 13% reduction in per-
entage of infective insects. Nevertheless, an inactivator is often a good
ihibitor. Therefore, it is possible that if an inhibitory substance dimin-
shed the infectivity of the insects, it might have inhibited the multipli-
ation of the virus introduced by the insects into the plant. According-
y, it is postulated that the tungro-resistance in Pankhari 203 may
e caused by the inactivation of the virus or the inhibition of virus mul-
iplication by a substance or substances present in the plant.
IARON, S. 1963. Mechanism of recovery from viral infection. Adv. Virus Res.
)AVIDSON, J. 1923. Biological studies of Aphis rumicis Linn. The penetration
of plant tissues and the source of the food supply of aphids. Ann. Appl.
Biol. 10: 35-54.
)AY, M. F., H. IRZYKIEWICZ, and A. McKINNON. 1952. Observation on
the feeding of the virus vector Orosius argentatus (Evans), and comparisons
with certain other Jassids. Aust. J. Sci. Res. (Ser. B) 5: 128-142.
[OLMES, F. O. 1954. Inheritance of resistance to viral diseases in plants. Adv.
Virus Res. 2: 1-30.
,IDDING, N. J. 1937. A greenhouse method for testing resistance to curly top
in sugar beets. Phytopathology 27: 773-779.
,AMEY, H. A. 1969. Varietal resistance to hoja blanca. p. 293-311. In Virus
diseases of the rice plant. Proc. Symp. at IRRI, 1967. Johns Hopkins Press,
Baltimore, Maryland, U.S.A.
,AMEY, H. A., P. SURIN, and J. LEEUWANGH. 1967. Transmission experi-
ments on the tungro virus in Thailand. Intern. Rice Comm. Newsletter
ease of rice. Plant Dis. Reptr. 49: 127-131.
SAKURAI, Y. 1969. Varietal resistance to stripe, dwarf, yellow dwarf, a
black.streaked dwarf. p. 257-275. In Virus diseases of the rice plant. Pro
Symp. at IRRI, 1967. Johns Hopkins Press,'Baltimore, Maryland, U.S.A
CULTURAL CHARACTERISTICS AND PATHOGENICITY
OF USTILAGO MAYDIS
O. R. EXCONDE, G. M. LOPEZ, AND S. A. RAYMUNDO
Assistant Professor, former undergraduate thesis student, and In-
structor, respectively, Department of Plant Pathology, U.P. College of
of Agriculture, College, Laguna.
This work was supported in part by Corn Project 3.3.
Potato sucrose malt extract agar, pH 8, and a temperature of 28 C
as favorable for growth of Ustilago maydis (DC.) Cda. Hypodermic
jection with sporidia from either agar cultures or smut balls was the
ost efficient method of inoculation.
Corn smut caused by Ustilago maydis (DC.) Cda. is one of the most
mmon diseases of corn. Practical measures of its control based on
und biological approach are still wanting. Basic knowledge about the
iltural character and pathogenicity of the causal fungus is essential
etiological and epiphytological studies.
The ability of the causal fungus to grow on agar media has not
it been investigated in the Philippines. It is also not well understood
whether the sporidia formed on agar media can cause infection similar
those of spores formed in smut balls in the plant.
For growing U. zeae in vitro, Ranker (1930) studied various agar
edia. He found that a synthetic medium composed of 3 g K2S04, 0.1
NH4NOs, 0.1 g CaCl, 0.1 g Mg3(P04)2.4H20, and 10 g dextrose in 1
;er distilled water was superior to the other media tested. On the other
ferent places differed in their virulence, size of colonies, color, and ra
and type of growth. Similar observations on varying degrees of vir
lence of isolates obtained from different places were found by Melch
(1921). But Christensen and Stakman (1926) believed that the d
ferent degrees of necrosis caused by U. zeae depend upon the lines a:
varieties of corn used in inoculation.
Tisdale and Johnston (1926) studied smut resistance in corn see
lings grown in the greenhouse. They found that plant showing resistan
in the field also showed resistance in the greenhouse when inoculat
during or after the 3-leaf stage. They also found that resistant plan
if ever infected, suppressed the invasion of the fungus in contrast
susceptible plants which were killed outright. But Griffiths (192
found that corn plants which were resistant to natural infection in t
field became susceptible inside the greenhouse.
Stakman and Christensen (1927) noted that when corn was i
oculated with certain physiologic forms of U. zeae alone, no smut ga
were formed but when inoculated in combination with another for
presumably of opposite sex, smut galls were formed on a large percex
MATERIALS AND METHODS
Isolation.--Two methods of isolation were employed: 1) Smut
.pores from broken galls on corn ear were suspended in 1% copper
sulfate solution for 1, 6, 12, 18, 24, and 48 hr in 1:1000 HgCl2 solution
for 1 min. With a flamed wireloop, 2 loopfuls of the resulting suspen-
sion were streaked on plated agar media. 2) From unbroken smut balls
surface disinfested with 1:1000 HgCI2 for 1 min, spores were obtained
with a sterile flat-end needle and streaked on agar slants. In either
method, different agar media were tested to find out which among them
will facilitate rapid isolation of the fungus. The isolated fungus was
maintained in pure culture in the most suitable medium for use in sub-
Effect of various agar media. The growth and cultural charac-
teristics of U. maydis were studied on 10 agar media, viz., PDA, carrot
sucrose agar, raddish dextrose agar, Ranker's medium, (Ranker, 1930)
Haskins' MB-50 agar (Haskins, 1950), malt extract agar, potato-sucrose-
malt extract agar, modified PDA (40 g dextrose added instead of the
usual 20 g), Czapek's agar (composed of 30 g sucrose; 2 g sodium
nitrate; 1 g dipotassium phosphate; 0.5 g magnesium sulfate; 0.5 g
potassium chloride; 0.01 g ferrous sulfate; 15 g agar and distilled
water to make 1000.00 ml) and Kernkamp's medium (Kernkamp, 1939).
Three 250-ml flasks were filled with 30 ml each of each medium. These
were then seeded with 5-mm disc of agar culture of the fungus. The
seeded flasks were then incubated at room temperature of 28-32 C for
9 days. On the ninth day measurements and growth characteristics of
the fungus were determined.
Effect of pH. The effect of pH on the growth of U. maydis was
studied on potato-sucrose-malt-extract agar. The fungus was grown at
pH 3 to 14 at 1-unit interval. The pH of the medium was adjusted by
thi anditinn of aithpr 0 1 N THCI or 0.1 N NaOH. The Beckman Zero-
at room temperature (28-32 C) for 13 days, then the diameter of th
colonies was measured.
Effect of temperature. Potato-sucrose-malt extract agar adjusted
to pH 8 was used in this study. Fifty ml of the medium contained i
250-ml flask were aseptically seeded with 5-mm disc of agar culture c
the fungus. The seeded flasks were incubated for 12 days at constar
temperatures ranging from 4 to 44 C at intervals of 4 degrees. Colon
diameter was the criterion used in growth measurement.
Test of Patkogenicity
Philippine Corn Hybrid No. 3 was used as test plant. Seeds wer
planted in, baked soil contained either in pots or in seed flats depend
ing upon the methods of inoculation.
Two kinds of inoculum were used in this study. These were spore
obtained from smut balls and sporidia from 2- to 3-wk-old agar culture
Before inoculation, the spore suspension was passed through 2 to 3 layer
of sterile gauze to remove bits of agar.
Inoculation was done by inserting the needle of a hypodermic syring
into the tissues below the base of the lower-most leaf and injecting th
suspension until it rose to the whorl and drip from the axils. The ii
oculum was also injected by inserting the needle into the side of th
plant about 1 inch above the ground. Limited inoculations were als
done by injecting young corn ears. Several other methods of inoculatio
were tried, viz., immersing disinfected corn seeds in smut spore susper
sion for 1 hr; planting corn seeds in smut spore-infested soil; sprayin
smut spore suspension on 1-month-old corn seedlings; injecting emerging
corn ears with smut spores suspended in 2% sucrose solution; injection
3-week-old seedlings with sporidial suspension, and spraying 2-week-ol
corn seedlings with sporidial suspension.
RESULTS AND DISCUSSION
Isolation. Spores of U. maydis soaked in 1% copper sulfate sol
tion for 1 ,6, 12, 18, and 24 hr grew on PDA, potato-sucrose-malt e.
tract agar, Czapek's agar, modified PDA, Ranker's medium, and Ken
kamp's medium. Fungal colonies were discernible 2 to 3 days aftA
-harapndin annroa on nlat d aoar media. They were minute dull whii
pores disinfest6d:with HgCl2 solution or 1 min before streaking them
a plated agar media. Spores obtained from unbroken smut galls and
directly streaked on agar slants of these inediaigave, rise to colonies that
litable for obtai
Effect of va
waydis on the di:
1 Fig. 1. Base
ialt extract agar
lalt extract agE
Effect 6f pH
y colony size ar
im colonies) we
3 and 14. The
onforiis, with t
found that:this p
nes of U. zeae I
Effect of t&
radient cn~ colo
ungus did not
rown and no co]
hanging from 16
o 37.8 mm, and
thesee results co
nan, et al. (1921
us agar media. The grow
ent agar media are present(
n colony size, the best med
Ilowed by modified PDA, Ke
Czapek's agar, Ranker's m
ctrose agar, and carrot suc:
rhe effects of pH on the fur
bown in Fig. 2. Moderate :
t pH 3 to 6, and 10 to 12.
ttained at pH 7 to 9. No
ility of U. maydi~,,to grow
findings;of HirschIrn and
ogen: gfew rapidly ,t pH $.
found that the pH did not"i
erature.- Fig. 3 shows th
size of U..:maydis in vitro.
r at 4, 36, 40, and 44 C.
lose exposed to 36, 40, and
es developed. The fungus g
24 C at which colony dial
32 C at which colony diam
as at 28 C at which colony
)orate the findings of Pier
various methods of inoculal
the fungus are presented i
i characteristics of U.
in Table 1 and: shown
im' was potato-sucrose-
nkamp's medium, PDA,
lium, Haskins' kMB-50
us growth as evidenced
growth (11.2 to 20 mm
Tood growth (23,to 33
rowth' appeared at pH
>) an alkaline medium
iirschbrn (1939) who
*arid poorly at pHI 3.1.
feet the growth.sof the
:effect of temperature
Results show that this
ulttre$ exposed to 4 C
4. becaine dried, turned
w well at temperatures
ster ranged from 35.9
terjwas 6.8.3 mm But
liaftieter lvi 42 mm.
4isel (1917) and Stak-
)i employed in testing
A ---- 4-1.- 1- -A Z-Z* _44 1---~l~r~r
TABLE 1. Effect of various agar media on the growth of Ustilago maydis after 9 days.
Diameter of Growth Characteristics
Medium Colony in
mm.a Shape Elevation Edge Consistency Colorb
16.3 irregular to
15.7 irregular to
PDA 14.0 turoloid to convex
Malt extract agar
viscid to buty-
viscid to buty-
viscid to buty-
viscid to buty-
viscid to buty-
allied purplish to gray
when young; cream
buff to tilluel buff
light drab to vinaceous
buff when young; be-
coming pallid purplish
gray to tilluel buff
light vinaceous fawn
when young; turning
to sheel pink with age
pallid purplish to light
drab when young; be-
coming cream buff to
tilluel buff with age
vinaceous buff to pallid
purplish gray when
young; then acru olive
to tilluel buff with age
TABLE 1. (Continued)
12.6 irregular to convex
12.4 irregular to
11.8 irregular to
11.0 irregular curl
7.3 irregular to convex
slimy to buty-
cream buff to pallid
purplish when young;
tilluel buff with age
pale orange to yellow
olive ochre when
young becoming buffy
olive to white with age
viscid to vinaceous buff to pal-
butyraceous lid purplish when
young; turning to
cream buff to tilluel
buff with age
acru olive to pallid
purplish gray when
young; tilluel buff with
pallid pinkish buff to
a Average of 3 flasks.
b Color determination after
Ridgeway color standards and color nomenclature, 1912.
Fig. 1. Growth of Ustilago mnydis after 9 days.on various agar media.
Left to right, potato shcrose malt extradt agar; modified potato
dextrose agar; Kernkamp's medium; potato dextrose agar; malt
extract agar; Czapek's agar; Ranker's medium; Haskin's MB-50
agar; Raddish dextrose agar and carrot sucrose agar.
Fig. 2. Effect ;of varying pH, levels on the growth of Ustilago maydis.
Photographed 13 days after transfer.
'r.ii~fti Wr AT, -` c '' 9A*urk
'ig. 3. Effect of different temperatures on the growth of Ustilago
maydis. Note the abundant growth of the. fungus at 28 C.
Photographed 12 days after transfer.
'ig. 4. Far left, galls caused by U. maydis on the whorl of 3 weeks old
corn seedling, inoculum used was sporidia from pure culture of
T7 Wan.ml)id mirdla hhalhf l rn nI lanf-* wnrl -Fnr r;h+ n"lla
48 PHILIPPINE PHYTOPATHOLOGY
TABLE 2. The effect of inoculation with suspension of smut spore and eporidia <
Ustilago maydis on Philippine Corn Hybrid No. 3.
No. of Plants Per Cent
Method of Inoculation Inoculated Infection
Immersing corn seeds for 1 hr in suspension of
spores from smut galls 8 0
Planting corn seeds in soil contaminated with
spores from smut galls 8 0
Spraying 1-month-old corn seedlings with suspen-
sion of spores from smut galls 14 0
Injecting 1-month-old corn seedlings with suspen-
sion of spores from smut galls 14 7.1
Injecting emerging corn ears with spores (from
smut galls) suspended in 2% sucrose solution 17 5.8
Injecting 3-week-old corn seedlings with suspension
of sporidia from agar culture 58 69.0
Spraying 2-week-old corn seedlings with sporidia
from agar culture 44 0
EXCONDE ET AL.: USTILAGO MAYDIS
Fig. 5. Galls formed by Ustilago maydis on the leaf blade and midrib
of corn plants (right). Note the size of the galls on the leaf
blade and midrib. Inoculum used was sporidia. Two leaves at
far left are healthy.
EXCONDE ET AL.: USTILAGO MAYDIS 51
KERNKAMP, M. F. 1939. Genetic and environmental factors affecting growth
types Ustilago zeae. Phytopathology 29: 475-484.
MELCHER, L. F. 1921. Ecologic and physiologic notes on corn smut, Ustilago
zeae. (Abstr.) Phytopathology 11:32.
PIEMEISEL, F. J. 1917. Factors affecting the parasitism of Ustilago zeae.
Phytopathology 7: 294-307.
RANKER, E. R. 1930. Synthetic nutrient solution for culturing Ustilago zeae.
J. Agr. Res. 41: 435-443.
ROWEL, J. B. and J. E. DE VAY. 1953. Factors affecting the partial vacuum
inoculation of corn seedlings with Ustilago zeae. Phytopathology 43: 654-658.
SCHMITT, C. G. 1940. Cultural and genetic studies on Ustilago zeae. Phyto-
pathology 30: 381-390.
STAKMAN, E. C. and J. J. CHRISTENSEN. 1927. Heterothallism in Ustilago
zeae. Phytopathology 17: 827-834.
STAKMAN, E. C., J. J. CHRISTENSEN, C. J. EIDE, and E. PETURSON.
1929. Mutation and hybridization in Ustilago zeae. Minn. Agr. Expt. Sta.
Tech. Bull. 65.
TISDALE, W. H. and C. O. JOHNSTON. 1926. A study of smut resistance in
corn seedlings in the greenhouse. J. Agr. Res. 32: 649-668.
WILKINSON, R. F. and G. C. KENT. 1944. Some factors determining the in-
fection of corn by Ustilago zeae. Iowa State Coll. J. Sci. 19: 401-413.
PATHOLOGIC REACTIONS OF FIELD AND FIBER CROPS TO
THREE ISOLATES OF MELOIDOGYNE INCOGNITA
D. T. BEGONIA AND R. G. DAVIDE
Former undergraduate thesis student and Assistant Professor,
respectively, Department of Plant Pathology, UPCA, College, Laguna.
Based on root gall index and nematode development in the host tis-
sues, the crop varieties considered resistant to the 3 isolates of Meloido-
gyne incognita Chitwood were peanut (CES 101), soybean (CES 486),
Centrosema, tropical kudzu, rice var. Palawan, corn (UPCA Var 1, Phil
Hybrid No. 4), sorghum var. Darso, wheat var. Cagayan, cotton (Lankart
57, D & PL Fox, Batangas White), sugarcane (CAC-57), and gabi.
Considered susceptible were cowpea (New Era, Alabama Crowder, Native
White-Seeded), mungo (ACC No. 2, CES 14, MG 50-10A), tapilan, kenaf
(6-1G1, Cuban 108, Everglade 4), jute (H.G.B. No. 7, Jute Green, native
jute (Native Green), and abaca (Libotanay, Tinawagang Pula, Mini-
nunga). Some of the crop varieties that showed an intermediate re-
action, i.e., between trace and slight galling index were soybean (CES
276, Wayne), kadios, and pineapple var. Smooth Cayenne.
In the resistant crops where no galls formed, no nematodes were
recovered 2 months after inoculation. But in the resistant soybean var.
CES 486, corn, and Centrosema on which there was little galling, few
nematodes were found in the root tissues; they were apparently poorly
developed and only a few reached the reproductive stage 2 months after
Evidence has been obtained indicating the existence of pathogenic
variability among the 3 isolates of M. incognita. Isolates from ramie
and tomato severely damaged all the varieties of cowpea and mungo
whereas isolate from banana caused less damage on these crops. The
banana isolate gave lower galling index and few nematodes developed
in the root tissues than the more pathogenic isolates from ramie and
BEGONIA AND DAVIDE: MELOIDOGYNE INCOGNITA
FAO (1966) reports that the Philippines has about 5.2 million
hectares of cereal crops with an annual production of about 5.45 million
metric tons. There are about 0.34 million hectares planted to pineapple,
soybean, and cassava with aggregate yearly production of about 117.78
million metric tons. The fiber crops such as abaca, Agave, and cotton
have a total area of about 0.2 million hectares. It is evident from this
report that this country has vast area planted to field and fiber crops.
Despite this, production among these crops is still low to meet the local
and foreign market demands. The low production of these crops is
usually attributed to attack by pests and diseases. It has been noted
that root-knot nematode (Meloidogyne incognita Chitwood) is a threat
to various Philippine vegetables, fiber and field crops (Ocfemia and
Calinisan, 1928; Claudio and Davide, 1968; Valdez, 1968).
Reports from other countries indicate that the root-knot nematode
poses a serious problem to crop production (Martin, 1958; Crittenden,
1958; Summers and Ceale, 1958; Wilson and Summers, 1966; Dropkin,
1959; Toler et al., 1963).
In the Philippines, there has been no thorough investigation on the
relative susceptibility or resistance of cultivated crops. In the develop-
ment of effective control measures through crop rotation or planting
resistant varieties, it is important to know which varieties of these crops
readily succumb to or resist nematode attack.
This study was primarily aimed to 1) evaluate the pathologic re-
actions of various varieties of field and fiber crops, and 2) determine the
pathogenic capabilities of three isolates of M. incognita. The experi-
ments were conducted in the Department of Plant Pathology, UPCA,
College, Laguna from December 1967 to Nevember 1968.
MATERIALS AND METHODS
Identification and designation of the S nematode isolates. The root-
knot nematode, Meloidogyne incognita, was identified based on the mor-
phology of perineal patterns of several adult females at egg-laying stage.
The 3 isolates were obtained by picking separately single egg mass
from infected roots of ramie, tomato, and banana and were designated
as isolate A, B, and C, respectively. Each was colonized and multiplied
separately on susceptible tomato (var. rainy season) grown in disinfested
sandy-loam soil in clay pots. Each pot was properly labelled and placed
atop an inverted pot spaced far apart to avoid cross contamination
TABLE 1. Grouping of crops, their scientific names, and varieties.
Crop Scientific Name Variety
Vigna sinensis (Torner) Savi
Glycine max (L.) Merr.
Centrosema pubescens Benth.
Arachis hypogaea L.
Phaseolus calcaratus Roxb.
Cajanus cajan (L.) Millsp.
Pueraria javanica L.
Phaseolus aureus Roxb.
Hibiscus cannabinus L.
Corchorus capsularis L.
C. olitorius L.
Gossypium hirsutum L.
Musa textilis Nee
Zea mays L.
Sorghum vulgare Pers
Triticum aestivum (L.)
Oryza sativa (L.)
Colocasia esculenta (L.) Schott
Saccharum officinarum L.
Ananas comosus (L.) Merr.
New Era, Alabama Crowder
Wayne, CES 276, CES 486
Acc. No. 2, CES 14,
6-1G1, Cuban 108
H.G.B. No. 7, Jute Green
Lankart 57, D & PL Fox
Aroman, UPCA Var 1,
Phil. Hybrid No. 4
BEGONIA AND DAVIDE: MELOIDOGYNE INCOGNITA 55
rates. Two months after, the plants with the corresponding
re removed from the pots and their root systems were washed
in running tap water to get rid of soil particles and plant
gg masses of each isolate from the galled roots were then
used as inoculum to test the pathologic reactions of the dif-
varieties to each of the 3 isolates.
.tion of pathologic reactions to M. incognita. A total of 35
f field and fiber crops were tested for their pathologic re-
he 3 isolates of M. incognita. These were conveniently grouped
ominous, fiber, cereal, and oher crops (Table 1). Planting
ere obtained from the Division of Plant Breeding, Department
ny, UPCA, B.P.I. Economic Garden, IRRI, and some were
n public markets. Abaca suckers and gabi corms were dis-
dipping in 1: 1000 HgCL, for 10 min. Slips were used
ple while the legume, cereal, and fiber crops were propa-
I seeds. Each crop variety was grown in decontaminated
soil in 3 clay pots (6-8 inch diam) and placed atop inverted
I far apart to avoid contamination. When the plants were
hes tall, they were thinned to 4 plants per pot. But for abaca,
sugarcane, and gabi, no thinning was done because only one
>ot was used per isolate, and inoculation was made 60 days
ing to ensure good root development. After thinning, 30 egg
M. incognita were placed in 4 holes about 5 cm deep around
E the 4 plants per pot. An equal number of uninoculated
But kadios, soybean var. Wayne and CES 276 were rated intermediate
Tapilan and all the cowpea and mungo varieties showed a susceptible
-nao+n,- +n +1- 9 -l+n- TR! + 4-1 n rr rt,. C 41- ,,,-- -- --V ,
gical races of M. incognita (Davide and Struble, 1966; Riggs and Win-
stead, 1959). In the Philippines, it is not yet known whether M. incog-
nita is composed of several races although Valdez (1968) noted that
an-nc nVf hic iQnInfanc diff-r in ntfhncrani r itv +fr diffiraint khnat nITnn+
DIIr r~~rrun 1Chrrm~nrmrrrr- ~~--
Crop and Variety A-
A B C
New Era 5.0 4.8 3.2
Alabama Crowder 4.7 3.9 3.0
Native White-Seeded 4.5 3.7 2.4
Acc. No. 2 4.9 4.7 4.4
CES 14 4.9 4.1 3.7
MG 50-10A 4.8 4.0 3.1
Wayne 2.5 2.1 2.0
CES 276 2.6 2.4 2.5
CES 486 2.1 2.0 2.0
Centrosema 2.1 2.0 2.0
CES 101 1.0 1.0 1.0
Native 5.0 5.0 5.0
Native 2.2 2.1 2.2
; 91 90 20
TABLE 3. Mean gall index of fiber crops infected by the 3 isolates of M. incognita.
Crop and Variety
A B C
H.G.B. No. 7
D & PL Fox
a Gall index 1 for no galling, 2 for trace, 3 for slight, 4 for moderate, and 5 for
severe galling. Data for abaca represent the mean of 3 plant replicates and the rest
represent the mean of 6 replicates.
b Isolate A from ramie, B from tomato, and C from banana.
*I U.'tlV 11J. IV.LA~IJ'JIYE I 1 I N
reacLton. ine roots oI inocularea plants snowea some aegree or necrosis.
All the varieties of kenaf, jute, and abaca were relatively susceptible to
he 3 isolates. Their degree of galling in response to isolate A are shown
n Fig. 1. The expression of pathogenic variability by the 3 isolates was
lot manifested among these fiber crops. There was only slight pathol-
ogic variation among the 3 isolates in kenaf and jute varieties while no
such variation could be detected among the abaca varieties.
Reaction of cereals and other crops. In contrast to the leguminous
and fiber crops, none of the cereals, pineapple, sugarcane, and gabi
showed a high degree of susceptibility to the nematode (Table 4). All
theirr crops except pineapple var. Smooth Cayenne have a resistant re-
action to the 3 nematode isolates. All the corn varieties showed only
;race galling. The same type of reaction was shown by sorghum where-
is wheat var. Cagayan, and rice var. Palawan were rated a gall index
of 1 which indicated total absence of nematode gall.
Similarly, sugarcane and gabi showed a galling index of 1. But pine-
Ipple showed trace to slight galling (Fig. 1) which corresponded to in-
termediate reaction to the 3 isolates of M. incognita.
Our results showed that there were resistant and susceptible varie-
ties among our field crops. Majority of the legumes were susceptible to
root-knot whereas all the cereals were resistant. Our fiber crops abaca,
kenaf, and jute were susceptible but cotton was not. Sugarcane and gabi
were highly resistant while pineapple var. Smooth Cayenne was only
slightly affected by any of the 3 isolates.
The resistance of these crops was generally manifested by trace or
no galling, root necrosis that occurred in cotton, low rate of nematode
penetration, and slow or retarded development of individuals that were
able to invade the roots. These types of resistant reaction to the root-
knot nematode have been commonly observed by various investigators
abroad (Barrons, 1939; Christie, 1946; Dean and Struble, 1953; Crit-
tenden, 1958; Dropkin and Nelson, 1960; Madamba et al., 1965).
Development and Reproduction ,of Nematodes
Fig. 1. Degree of calling produced by isolate A of Meloidoayne inco
ANn AVTfTR- Mi"r.nT T'nrvW 1W
TABLE 4. Mean gall index of cereals and other crops infected by the 3 isolates
of M. incognita.
Crop and Variety Nematode Isolateb
Crop and Variety
A B C
Aroman 2.0 2.0 2.0
UPCA Var 1 2.0 2.0 2.0
Phil. Hybrid No. 4 2.0 2.0 2.0
Darso 2.0 2.0 2.0
Cagayan 1.0 1.0 1.0
Palawan 1.0 1.0 1.0
Smooth Cayenne 3.0 2.7 2.7
CAC-57 1.0 1.0 1.0
Native 1.0 1.0 1.0
a Gall index 1 for no galling, 2 for trace, 3 for slight, 4 for moderate, and 5
for severe galling. Data represent mean of 6 replicate plants.
b Isolate A from ramie, B from tomato, and C from banana.
Leguminous crops. The development and reproduction of eac
isolate on various legumes are summarized in Tables 5 to 7. There
evidence that the nematode population varied with the different legume
Generally, greater number of nematodes were recovered from the sur
ceptible varieties of cowpea on which majority of the nematodes wei
already in the reproductive stage. On the other hand, the resistai
legumes with trace or no galls showed much lower nematode count
In the case of peanut (CES 101), no galls formed and no nematod(
were retrieved from the root tissues. In the soybean varieties which
had trace galling, there were some nematodes that penetrated, developed
and reproduced. But nematode count was 3 to 5 times lower than th.
in susceptible crops. In most cases, few nematodes reached the repre
ductive stage; many were still in the larval stages of development. TI
same trend of nematode development was found in kadios and tropic,
kudzu whose response to the 3 isolates was trace galling.
The 3 isolates demonstrated some degree of variability in popul:
tion density in the different crops. There was higher nematode court
in the more pathogenic isolates A and B than in the less pathogen:
isolate C. But no wide variation in nematode count among isolates wei
noted in crops with trace to slight galling.
Fiber Crops. Among the fiber crops, cotton varieties were rate
highly resistant to the 3 isolates. No nematode was found in their ro<
tissues. But in the susceptible varieties of kenaf, jute, and abaca (Tabl(
8 to 10), population was high and almost all stages of nematode deve
opment was found. Majority of which were adult females in the repre
ductive stage. Variation among the 3 isolates was clearly demonstrate
by the number of individuals recovered from the root tissues. The lei
pathogenic isolate C usually have lower nematode count than the mol
pathogenic isolate A and B in any of the susceptible varieties of kena
jute, and abaca. But no appreciable differences were noted on the ral
of development and reproduction of the 3 isolates in these susceptib:
Cereals and other Crops. The cereals demonstrated resistant rn
action to the 3 isolates (Tables 11 to 13). In wheat and rice on which
no root galling occurred, there were no nematodes recovered. In sorl
hum and corn varieties on which trace galling occurred, a few nematod(
were retrieved from the root tissues; most of them were still in t,
larval stages of development, 2 months after inoculation (Fig. 2).
Trrh ianil,+F flal.d tn infpt mnarn.anp and gabi: no nematode
TABLE 5. Number and developmental stages of M. incognita isolate A in one gram root sample from each variety
of legume 2 months after inoculation.
Crop and Variety
Ace. No. 2
Tropical Kudzu 52
Sex Female Male
Total Undiffer- Larval Stage Adults Larval Stage Adults
entiated 2nd 3-4th No Eggs W/eggs 2nd 3-4th
7 2 2 51 18
3 2 29 17
TABLE 6. Number and developmental stages of M. incognita isolate B in one gram root sample from each variety
of legume 2 months after inoculation.
Sex Female Male
Crop and Variety Total Undiffer- Larval Stage Adults Larval Stage
entiated 2nd 3-4th No Eggs W/eggs 2nd 3-4th Adults
Ace. No. 2
CES 276 152
CES 486 112
21 12 100
18 6 73
1 133 179
56 22 11
15 6 1 23
- ---~-- -------------------
7 1 -
TABLE 7. Number and developmental stages of M. incognita isolate C in one gram root sample from each variety
of legume 2 months after inoculation.
Sex Female Male
Crop and Variety Total Undiffer- Larval Stage Adults Larval Stage
entiated 2nd 3-4th No Eggs W/eggs 2nd 3-4th Adults
Acc. No. 2
38 16 9 61 148
71 47 18 102 187
389 80 34 6 170
Tropical Kudzu 30 2
52 5 1 1
195 2 1 .
26 3 -
61 1 2
22 11 1 3
32 3 5
17 4 3
7 1 2
3 -- 34 27
4 17 6
- -- 5
TABLE 8. Number and developmental stages of M. incognita isolate A in one gram root sample from each variety
of fiber crops 2 months after inoculation.
Crop and Variety Total Undiffer-
No Eggs W/eggs
2nd 3-4th Adults
H.G.B. No. 7
D & PL Fox
37 2 121
TABLE 9. Number and developmental stages of M. incognita isolate B in one gram root sample from each variety
Sof fiber crops 2 months after inoculation.
Sex o Female .
Crop and Variety Total Undiffer- Larval Stage Adults Larval S
entiated 2nd 3-4th No Eggs W/eggs 3-4th
H.G.B. No. 7
D & PL Fox
TABLE 10. Number and developmental stages of M. incognita isolate C in one gram root sample from each variety
of fiber crops S months after inoculation.
Sex Female Male
Crop and Variety Total Undiffer- Larval Stage Adults Larval Stage
entiated 2nd 3-4th No Eggs W/eggs 2nd 3-4th Adults
H.G.B. No. 7
D & PL Fox
254 52 16 78 104
TABLE 11. Number and developmental stages of M. incognita isolate A in one gram root sample from each variety
of cereals and other crops 2 months after inoculation.
Crop and Variety Total
UPCA Var 1 109
Phil. Hybrid No. 4 136
Smooth Cayenne 180
Sex Female _Male
Undiffer- Adults Larval Stage Larval Stage Adults
entiated 2nd 3-4th No Eggs W/eggs 2nd 3-4th
of cereals and -other crovs 2 months afft
Crop and Variety Total Undiffer- Adults
entiated 2nd 3-4th I
Aroman 79 16 2 -
UPCA Var 1 106 3 13 -
Phil. Hybrid No. 4 64 12 -
Darso 75 16 21 1
Smooth Cayenne 206 58 2 1
_:- : -_ -.. T . ..
entiated 2nd 3-4th No Egg
Aroman 82 3 20 27
UPCA Var 1 127 13 52
Phil. Hybrid No. 4 94 26 3 38
Darso 76 27 11 15
Smooth Cayenne 172 22 3 1 65
Res. 58: 263-271.
CHRISTIE, J. R. 1946. Host-parasite relationships of the root-knot nematode,
Heterodera marioni. II. Some effects of the host on the parasite. Phytopa-
thology 36: 340-352.
3LAUDIO, M. Z. and R. G. DAVIDE. 1968. Pathogenicity and identity of root-
knot nematodes on five varieties of banana. Philippine Agriculturist 51: 241-251.
JORTADO, R. V. and R. G. DAVIDE. 1968. Survey, identification and patho-
genicity tests of nematodes associated with tobacco grown in Cagayan Valley
and Ilocos region. Philippine Agriculturist 51: 779-801.
3RITTENDEN, H. W. 1958. Histology and cytology of susceptible and resistant
soybeans infected with Meloidogyne incognita acrita. (Abstr.) Phytopathology
)AVIDE, R. G. and F. B. STRUBLE. 1966. Selection from a field population
for variability in Meloidogyne incognita on sweet potato. Philippine Agricul-
turist 50: 15-29.
)EAN, J. L. and F. B. STRUBLE. 1953. Resistance and susceptibility to root-
knot nematodes in tomato and sweet potato. (Abstr.) Phytopathology 43: 290.
)ROPKIN, V. H. 1959. Varietal response of soybeans to Meloidogyne-A bioassay
system for separating races of root-knot nematodes. Phytopathology 49: 18-23.
)ROPKIN, V. H. and P. E. NELSON. 1960. The histopathology of root-knot
nematode infections in soybeans. Phytopathology 50: 442-447.
'AO. 1966. Production Yearbook 20, 763 p.
&iADAMBA, C. P., J. N. SASSER, and L. A. NELSON. 1965. Some character-
istics of the effects of Meloidogyne spp. on unsuitable host crops. North Caro-
lina Agr. Expt. Sta. Bull. 169, 34 p.
&ADAMBA, C. P., R. G. DAVIDE, and R. K. PALIS. 1967. Plant parasitic
nematodes on ramie and their control by soil fumigation. (Abstr.) Philippine
&ARTIN, G. C. 1958. Plant species attacked by root-knot nematodes (Meloidogyne
spp.) in the Federation of Rhodesia and Nyasaland. Nematologica 3: 332-349.
)CFEMIA, G. 0. and M. R. CALINISAN. 1928. The root-knot of abaca or Ma-
nila hemp. Phytopathology 18: 361-367.
ZIGGS, R. G. and N. N. WINSTEAD. 1959. Studies on resistance in tomato
to root-knot nematodes and on the occurrence of pathogenic biotypes. Phyto-
pathology 49: 716-724.
SUMMERS, T. E. and C. C. CEALE. 1958. Root-knot nematodes, a series of
problems of kenaf in Florida. Plant Dis. Reptr. 42: 792-795.
rOLER, R. W., S. S. THOMPSON, and J. H. BARBER. 1963. Cowpea (South-
ern pea) diseases in Georgia, 1961-1962. Plant Dis. Reptr. 47: 746-747.
rRIANTAPHYLLOU, A. C. and H. HIRSCHMANN. 1960. Post-infection devel-
opment of Meloidogyne incognita Chitwood 1949 (Nematoda: Heteroderidae).
Ann. Inst. Phytopathol. Benaki n.s. 3: 1-11.
TALDEZ, R. B. 1968. Surveys, identification and host-parasite relationships of
root-knot nematodes occurring in some parts of the Philippines. Philippine Agri-
culturist 51: 802-824.
VILSON, F. D. and T. E. SUMMERS. 1966. Reaction of kenaf, roselle, and
related species of Hibiscus to root-knot nematodes. Phytopathology 56: 687-690.
T*------~--- -r\---~-^- ---^-
EFFECT OF CHICKEN MANURE ON THE INCIDENCE
)F SCLEROTIUM DISEASE OF VEGETABLES
V. M. MERCADO AND A. N. PORDESIMO
former undergraduate thesis student and Instructor, respectively,
anent of Plant Pathology, U.P. College of Agriculture, College,
feet of increasing levels of chicken dung on the incidence of
disease on pechay, cabbage, cauliflower, tomato, cucumber,
was studied using Sclerotium rolfsii Sacc. as the pathogen.
nationn on the rate of emergence showed an appreciable delay
rgence of seedlings in treatments containing manure. Cru-
tomato seemed to be more sensitive to chicken dung; their
was completed on the 12th day after sowing. All vegetables
highest percentage emergence on baked soil. At 2- and 3-kg
,ola onknm ber l an rmnnaah harl mnva or laan Knolf A0 amr*ino
increase yieia per unit area at a minimum production cost.
inorganic fertilizers has shown promise in this regard but
e soil and improves its texture. On t
application of chicken dung tends to
,-off and Sclerotium disease. The
)f Sclerotium disease on vegetables
,nure has not yet been demonstrated
well as in other countries. Studie
.e effect of certain organic and inorj
s on the influence of mineral fertil
been conducted by a few investing,
(1955) observed that when treatment
LS 01 v, 1, 0, 4, or a LUIIS
rtilizer were used, the number of fungi generally increased
creasing rate of fertilization. However, Turk (1939) ob-
Sapplication of 0-8-24 fertilizers resulted in a decrease in
-. 0 ^ J?_ -..0.^ T_ i'_ 0 0 OA J---1* -- .1-^ *
was also found that one- and two-way interactions of NPK also sig-
ificantly decreased the incidence of several fungi in laboratory soils;
however in field soils, the addition of fertilizer increased the yield of
*fr\a li4- rl AM; -- -l - 4-U- 4 in, A
Isolation and artificial soil infestation. The test fungus (S. rolfsii)
as isolated from infected bean plants obtained from infested seedflats
i the Department of Agronomy. Sclerotial bodies were picked from
[fected parts of the bean plant. They were then dipped in 1:1000 HgCl1
>r 45-60 sec, rinsed in sterile water and blotted dry in sterile filter
iper. The sclerotial bodies thus treated were planted in each of the
prepared plates of PDA. The plates were incubated and from the fungal
growth, several transfers were made.
A desired amount of soil was decontaminated by baking at 70 to 80
for one hour. A portion of the baked soil was set aside to serve as
ae of the checks. The rest was artificially infested with one-week-old
are cultures of S. rolfsii. The artificially-infested soil was incubated
)r 1 month to allow the organism to get established. It was watered
daily to provide moisture for the growth and establishment of the
oun ureatemenv ana aeszgn or expermenrs. Elgnteen seeaiiats (tib
x 24" x 4") were prepared for 6 treatments which included 2 sets of
control (baked and infested soil). The baked soil served to indicate
the rate of emergence while the infested soil served as the gauge of the
inoculum potential. The 6 treatments were replicated 3 times and ar-
ranged in a randomized complete block design.
Of the eighteen seedflats, 15 were filled 2/3 full with infested soil,
while the remaining 3 were filled 2/3 full with decontaminated soil
and served as the control. The desired amount of the dried manure was
mixed thoroughly with infested soil, and the mixture passed thru a 60-
mesh sieve. The following composed the different treatments:
Control 1 .............. Baked soil
Control 2 .............. Infested soil
Treatment 1 ........... Infested soil + 0.5 kg chicken dung/ft2
Treatment 2 ........... Infested soil + 1 kg chicken dung/ft2
Treatment 3 ........... Infested soil + 2 kg chicken dung/ft2
Treatment 4 ........... Infested soil + 3 kg chicken dung/ft2
Test plants. Pechay, cabbage, cauliflower, tomato, cucumber, and
squash were used as test vegetables. Susceptible varieties were selected
and were used throughout the experiment. The 6 varieties representing
each test plant are given below:
Test vegetables Variety
Cauliflower India Early Parkner
Pechay Wong Bok
The 6 selected vegetables were tested for viability before they were
sown. Six petri plates were lined with 4 layers of moistened tissue paper
and each was planted with 100 representative seeds of each kind. Plates
were set aside for observation until germination was completed. Per-
centage viability was obtained from the total number of seeds that
Seedflats, each containing 4 rows, were placed side by side on an
outdoor bench. Each row represented one test plant. One hundred of
the viable smaller seeds were sown, but only 25 of the large ones were
- ----^ -I W -T W'WJL
MERCADO AND PORDESIMO: SCLEROTIUM DISEASE 79
sed. Necessary precautions on planting were observed to obtain uni-
orm germination. Seedflats were irrigated over-head with equal amounts
f tap water often enough to maintain a desirable moisture level for
ermination and seedling development. All seedflats were sprayed with
lalathion (2.25 ml emulsion/liter of water) to project the test plants
rom insect damage.
Mechanics of evaluation. Seeds that emerged were counted daily
o determine the rate and percentage of emergence. The incidence of
amping-off was. reckoned within 21 days after emergence. The number
f damped-off seedlings in the 21-day period was recorded. Percentage
mergence was computed from the total number of seeds planted. Like-
rise, the percentage damped-off was computed from the total number
0 - T-- 3 _ .1__ .- --- --- 3- -1 2- 4-1-- n-l .3-___ --
. . . . . . SMIS ,
. . . . . . . . .
. . . . ......
.VAlPLAUIU AN LIUKJUVIU) 0S;LLZJKU I IU L)JVi
and squash (1 to r). Note the failure of pechay and tomato
seeds to germinate at 2- and 3-kg levels. (Photographed by UPCA
manure. In the infested soil treated with 2 and 3 kg of chicken manure,
none emerged. In comparison, cucumber and squash in infested soil
treated with 2 and 3 kg of chicken dung had more or less 50% seedling
emergence. These results suggest that at 2- and 3-kg levels, the effect
of chicken dung is lethal to small-seeded vegetables but not to large-
seeded ones like cucumber and squash.
Differences in mean percentage emergence between treatments were
statistically significant (Table 1). This held true for all test vegetables.
The results indicated that the bigger the amount of chicken dung added
to infested soil, the more incidence of seed rot.
Between the 2 sets of control, baked soil gave a more significant in-
crease in seedling emergence than the infested control. This can be attri-
buted to the absence of the pathogen in the baked soil. Lower percentage
emergence was obtained in infested soil with chicken dung than in in-
fested soil without chicken manure. This condition seems to suggest
that the test fungus must have caused seed rot and the addition of
chicken dung must have favored its activity.
Percentage damping-off at increasing levels of chicken dung. The
data on percentage damping-off presented a consistent picture of in-
creased incidence of the disease with heavier application of chicken dung
(Table 2). Differences were not statistically significant on cabbage,
cauliflower, tomato, squash and cucumber but on pechay, the mean per-
centage damping-off was statistically significant between treatments.
The result suggests that only pechay responded differently at increasing
levels of manure application. For cucumber, the mean percentage damp-
ing-off was the same in treatments containing 1, 2, and 3 kg of chicken
Treatment Pechay Cabbage Cauliflow
Baked soil 96.6 90.3 87.3
Infested soil 68.6 64.6 54.3
Infested soil + 0.5 kg chicken dung 67.3 45.6 43.3
Infested soil + 1 kg chicken dung 67.0 27.3 19.6
Infested soil + 2 kg chicken dung 0 0 0
Infested soil + 3 kg chicken dung 0 0 0
LSD --0.05 7.7 3.5 12.3
0.01 5.3 18.6
a Baked and infested soils constitute double checks. Chicken dung w
TABLE 2. Mean percentage damping-off of 6 vegetables at indicated treatments
Cabbage Cauliflower Tomato
Baked soil 0
Infested soil 13.6
Infested soil + 0.5 kg chicken dung 16.6
Infested soil + 1 kg chicken dung 23.0
Infested soil + 2 kg chicken dung -
Infested soil + 3 kg chicken dung -
LSD -0.05 4.3
a Baked and infested soils constitute double checks. Chicken dung was
ns Not significant.
.. None emerged.
0 0 0
8.3 9.3 2.6
14.3 16.0 5.3
16.3 17.3 8.0
ns ns ns
used in kg per square foot.
MERCADO AND PORDESIMO: SCLEROTIUM DISEASE 85
In order to explore further what causal fungus was predominantly
associated with the damped-off seedlings, several isolations were made
in vitro cultures. Abundant growth of S. rolfsii was produced on PDA
within 3 days (Fig. 3).
Fig. 3. A 3-day pure culture of Sclerotium rolfsii Sacc., isolated from'
damped-off vegetables. Note the white young sclerotial bodies
at the periphery of each colony. (Photographed by UPCA Photo-
,_ - I_
and to a certain extent it kills the seed. But after emergence is con
summated, chicken manure is beneficial to young seedlings because i
provides the nutrients needed in their critical stages of growth. Thomp
son (1939) stated that organic nitrogen from manure is released faste
and is as effective as the inorganic fertilizer. His analysis showed tha
chicken manure contains the 3 essential elements N2 (1%), P,05 (0.8%)
and K20 (0.4%) which through decomposition are made readily avail
able to a growing plant. Besides these major plant nutrients, they als
contain essential trace elements.
This study demonstrated that the use or introduction of excessive
amount of chicken dung in soil mixture is detrimental to germinatin
seeds in general because it impairs emergence and to a certain exteni
it kills the seed. Furthermore, an increase in the incidence of damping
off was noted with heavier application of chicken dung in soil infeste
with S. rolfsii. Based on these results, the application of chicken manur
in soil mixture is not advisable in cases where soil is originally infeste
with this pathogen. A small amount of chicken dung added to infeste
soil may result in more incidence of Sclerotium damping-off than ir
fested soil without dung. But the use of chicken dung in soil mixture
in seedflats, seedbed, or potting soil in the absence of the pathogen, i
practical and beneficial. Under poor soil conditions, proper utilizatio
of chicken manure will improve soil texture and at the same time enric
it. The use of chicken manure in commercial production of field crop
is not essential in maximizing yield since it contains only small amount
of essential elements. But for green vegetables and ornamental plant
of aesthetic value, application of chicken manure is advisable when ?
rolfsii is not present.
BLUE, W. G., C. F. ENO and P. J. WESTAGATE. 1955. Influence of so
profile characteristics and nutrient concentration on fungi and bacteria i
Leon fine sand. Soil Sci. 80: 303-308.
FELLOWS, H. 1929. Studies of certain soil phases of the wheat take-all problem
(Abstr.) Phytopathology 19: 103.
KAUFMAN, D. D. and L. S. WILLIAMS. 1964. Effect of mineral fertilizatic
and soil reaction on soil fungi. Phytopathology 54: 134-139.
LEACH, L. D. and A. E. DAVEY. 1942. Reducing southern Sclerotium rot 1
I -1. .. I A -- Tt D-S. I 10
. MAYBER. 1963. The germinatic
N. Y. 236 p.
)BBINS, W. R. 1942. Resistance o:
The Macmillan Co.,
ICCLURE, T. T. and Ri
s. 5th ed., McGraw-Hill Bk. Co.,
ral elements on some microbiological
culturall practices affecting important
3. Thesis, Univ. of the Phil., College
962. Effect of mineral fertilizers on
logy 52: 1285.
u ln., 1I. aV. Jo.. ra .-JX U.l koallL linil
activities in much soil. Soil Sci. 47:
'ICTOR, L. B. 1966. Interactions of some
horticultural characters of tomato. M.
of Agriculture, College, Laguna.
'ALE, J. W. Jr. and E. K. VAUGHAN.
damping-off of table beets. Phytopath(
A BACTERIAL LEAF BLIGHT OF COCONUT
J. B. TUNAC AND MA. SALOME DEL ROSARIO
Former Research Assistant, and Associate Professor, respectively,
Department of Plant Pathology, UPCA, College, Laguna.
This study was partly supported by Cadang-cadang Research
A foliage disease of coconut, the symptoms of which were typic
of bacterial infection was observed on 2- to 4-yr old palms in the coc,
nut experimental projects of the UPCA Department of Plant Patholog
and PHILCOA at the Cadang-cadang Research Foundation, Inc. lo,
in Pili, Camarines Sur. The disease was first noticed in January, 19(
and became severe during the succeeding months of February, Marc]
The diagnostic symptom on various leaf stages are shown in Fil
1. It consists of water-soaked linear streaks which first appear c
Fig. 1. Diagnostic symptom on various leaf stages.
TUNAC AND DEL ROSARIO: COCONUT LEAF BLIGHT 89
res situated at the middle position of the plant. A translucent linear
pe originating from the portion of the leaflet constitutes the first
:ernible symptom. As the disease progresses, the stripe elongates
ning parallel to the tip of the leaflet and veins. Discoloration of in-
;ed tissues with reddish brown stripes follows the elongated areas.
the more advanced stage, adjacent linear stripes coalesce and event-
.y assume a blighted appearance. Coalesced stripes dry and turn
iw-colored. The entire leaflet may be blighted. Blighting moves up
;he succeeding leaflets until the entire frond is finally blighted. In
are cases, the whole leaves of the crown are blighted assuming a
nt appearance. In some instances, infection extends to the midrib
;he affected pinnae. The weakened midribs break off leaving droop-
pinnae attached only to the other half by the uninfected leaf blades.
similar disease of coconut was mentioned by Shaw (1963) and Menon
At first the disease was noted on a few coconut plants in the plan-
on. Four individuals in a group of 130 plants were originally af-
;ed in Lot B of the Plant Pathology Project experimental plantation
ing the first week of January. Increasing percentage of infection
s noted during the following month. In March, 76 plants were counted
infected, representing 58.5% of the plants in the same lot. In Lot A
-e 139 plants of which 71.2% was infected by the end of April. The
rage percentage of infection was 68.3 which was recorded during
month of March.
Thnrinno" hli rpnilra nf diQpnqp nnlthr.ak in thp Plann Pfathnlnow- Inft
TABLE 1. Incidence of bacterial leaf blight of coconut in the experimental lot of
the UPCA Department of Plant Pathology Project in Pili, Camarines
Sur, during the indicated months in 1965.
Lot A (Control lot) Lot B (Cadang-cadang lot)
Month No.a infected Per cent No.a infected Per cent
plants infection plants infection
January No record 4/130 3.1
February 49/139 32.3 64/130 48.1
March 95/139 68.3 76/130 58.5
April 99/139 71.2 55/130 42.3b
a Numerator represents infected plants; denominator represents population.
b Rigid pruning was made in late March.
So far, the disease has been observed only within the experimental
farm of the Cadang-cadang Research Foundation, Inc. in Pili, Cama-
rines Sur. Bacteria were consistently isolated from infected leaves.
SHAW, D. E. 1963. Plant pathogens and other microorganisms in Papua and
New Guinea. Dept. Agr. Stock and Fisheries (Port Moresby) Res. Bull. 1.
MENON, K. P. V. and K. M. PANDALAI. 1958. Coconut diseases: Bud, leaf,
nuts, petioles, roots, etc. Central Coconut Res. Sta. Kayangulam, Kasara-
god. pp. 208-232.
A HELICOTYLENCHUS SPECIES PARASITIC ON
COCONUT AND AFRICAN OIL PALM
A. C. PIZARRO
Supervising Plant Pathologist, Bureau of Plant Industry, Manila.
The author wishes to thank Mr. Carlos A. Calica, Chief, Plant
Pathology Section, Bureau of Plant Industry, Manila, for the diagnoses
of cadang-cadang-affected palms.
The role of nematodes in the etiological complex of coconut cadang-
cadang in the Philippines has attracted the attention of earlier investi-
gators. In a survey of nematodes at locations where the incidence of
coconut cadang-cadang in the Bicol Region was high, Palo (1963) found
different genera of plant parasitic nematodes at various depths and
distances from the base of apparently healthy and diseased coconut palms.
Valdez and Ferino (1962) reported an unusually high population of the
plant parasitic Helicotylenchus sp. associated with coconut roots in cer-
tain sections of the Bicol Region.
Besides nematodes, several theories regarding the cause of coconut
cadang-cadang have been advanced. These are virus (Ocfemia, 1937;
Price, 1957), nutritional imbalance (Velasco et al., 1959), phytotoxemia
(Castillo, 1960), and a few others (Price, 1957). Investigations on the
cause and control of the disease for nearly two decades (1947-1966)
yielded inconsistent results. Recent observations on the disease incidence
in badly affected areas suggest that certain factors in the soil contribute
to its spread. This investigation was conducted to gather information
on the role of nematodes in the causal complex of the coconut cadang-
Samples of soil where a suspected cadang-cadang affected African
oil palm was growing were collected. These were processed by the Cobb
sifting and gravity technique to extract the nematodes for identifica-
tion. One to two-year old coconut seedlings planted in decontaminated
soil in 12-inch clay pots were inoculated. To each pot a suspension of
about a thousand individuals of Helicotylenchus and a few admixtures
-- .. i- - - 1- r -- L _1...L-- i--
Fig. 1. Portion of a root from a one-year old coconut (Cocos nutcifera
Linn.) seedling inoculated with nematodes. The spiral nema-
tode, Helicotylenchus sp. could be seen embedded and feeding on
the rootlets indicating that it is parasitic on coconut roots. (Il-
lustrated and photographed by D. Salandanan and H. R. Ve-
seedlings of coconut, African oil palm (Elaies guineensis Jacq.), anahao
(Livistona rotundifolia Mart.), and an undetermined species of orna-
mental palm were inoculated. The same number of plants were pro-
vided as control for each set of tests. Some of the plants were kept in
the greenhouse and others were placed outdoors.
In another set of experiment, about 250 handpicked Helicotylenchus
obtained from the soil near the base of a cadang-cadang-affected African
oil palm were introduced into a glass cylinder planted to seedlings of
African oil palm. Experimental and check plants were kept in the labo-
ratory for observation on site, manner and duration of feeding, and
movement of nematodes during feeding.
Diagnosis of affected plants was based on the symptom pattern
described by Calica and Bigornia (1960). On the African oil palm,
presence of water-soaked spots on leaves and the gradual decline of the
plants distinguished infected plants. Visual examination of roots of
affected palms showed extensive rotting. Microscopic examinations of
the nematodes extracted from soil around the base of cadang-cadang-
affected African oil palm yielded plant parasitic forms. The most pre-
dominant among which was the spiral nematode Helicotylenchus. A few
ring nematode, Criconemoides, and lance nematode, Hoplolaimus were
also present. Helicotylenchus have been reported to be consistently asso-
ciated with the roots of coconut but has not been observed to feed on
them (Palo, 1963; Timm, 1964; Velasco et al., 1959).
Roots of inoculated coconut seedlings when examined 50 days after
inoculation showed that among the different nematodes, Helicotylenchus
was the only one capable of feeding and parasitizing on coconut roots.
Several individuals were found feeding on the branch roots or rootlets
and usually at a distance from the root tip as shown in Fig. 1. They
have not been observed to bury themselves completely in the root tissue.
Roots taken from the same cadang-cadang-affected African oil palm
growing at the Bureau of Plant Industry compound in Manila yielded
a number of individuals of Helicotylenchus attached to the roots and
feeding with their head portions embedded.
Figure 2 shows a feeding nematode with its head portion embedded.
Various amounts of root exudates accumulating around the nematode's
body may be noted. This nematode has perhaps just started to feed as
evidenced by the absence of root exudates above the wound area and
Fig. 2. Rootlet of a cadang-cadang-infected African oil palm (Elaies
guineensis Jacq.) showing the spiral nematode, Helicotylenchus
sp. in its feeding position. (Illustrated and photographed by D.
Salandanan and H. R. Velasco, respectively).
PIZARRO: HELICOTYLENCHUS ON PALMS
around the nematode's body. It may also be noted that it is feeding
on a branch root and its point of attachment is away from the root tip.
Figure 3 shows two nematodes in a feeding position on another
Fig. 3. Rootlet of a cadang-cadang-infected African oil palm with two
nematodes, Helicotylenchus sp. feeding on it. These nematodes
must have been feeding on the root for sometime as shown by
the presence and amount of root exudates around the nematode's
body. (Illustrated and photographed by D. Salandanan and H.
R. Velasco, respectively).
rootlet. A larger portion of the nematode's body feeding on the upper
part of the root is embedded. Around the body of both individuals are
root exudates, a response of the plant to the wound inflicted by the
nematode's entry and its subsequent feeding. This suggests that these
nematodes have been feeding in the same spot for sometime as shown
by the presence and amount of root exudates surrounding the wound
It was observed during the examination of the roots that some
the nematodes got detached from their feeding position. These neir
todes were alive and their stylets extended indicating they were tryi:
to penetrate the roots by thrusting their stylets or they must have ;
ready been feeding. These nematodes are identified as Helicotylench
Early symptoms produced on leaves of the experimental cocon
were small irregular water-soaked spots on one of the leaflets situat
on the middle of the frond of the leaf next to the youngest, 60 da
after inoculation. The control plants did not show any of the symptom
expressed by the inoculated plants. This finding is another circumsta
tial evidence of the etiological complexity of the coconut cadang-cadar
CALICA, A. C., and A. E. BIGORNIA. 1960. The symptomatology of the yell
mottle decline. Bureau of Plant Industry Leaflet. Manila. 17 p.
CASTILLO, B. S. 1960. The coconut candang-cadang disease. Studies on phy
toxemia complex as a new approach to the disease. Plant Industry Digi
OCFEMIA, G. 0. 1937. The probable nature of the cadang-cadang disease
coconut. Philippine Agriculturist 26: 338-340.
PALO, A. V. 1963. A preliminary report on species of plant parasitic nematoc
found in cadang-cadang infected areas in the Bicol Region. Philippine
Agr. 28: 31-34.
PRICE, W. C. 1957. Report to the Government of the Philippines on the yelli
mottle decline (cadang-cadang) of coconut. Manila. 87 p.
TIMM, FR. R. 1964. A preliminary survey of the plant parasitic nematodes
Thailand and the Philippines. Thai Sambhand Printing Press. Bangkok. 71
VALDEZ, R. B., and M. P. FERINO. 1962. Studies on nematodes as possil
cause of cadang-cadang of coconuts. Third Progress Report, Univ. Phili
pines, Coll. Agr. p. 12-16. (Mimeographed)
VELASCO, J. R., A. HOLASO, R. S. DE LA PERA, E. PANTASTICO, a
V. F. GUEVARA. 1959. Aluminum and its possible relationship to cadan
cadang of coconut. Philippine Agriculturist 43: 177-199.
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