• TABLE OF CONTENTS
HIDE
 Front Cover
 On-farm trials of a fungus, paecilomyces...
 Species of gilocladium in the Philippines...
 Multilocation test for variations...
 Biological control of nematodes...
 Note: Leaf blight, ear rot, and...
 Abstracts of papers presented at...
 Information for contributors
 Back Cover














Group Title: Journal of Tropical Plant Pathology
Title: Journal of tropical plant pathology
ALL VOLUMES CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00090520/00029
 Material Information
Title: Journal of tropical plant pathology
Series Title: Journal of tropical plant pathology.
Alternate Title: Journal of Philippine phytopathology
Philippine phytopathology
Physical Description: v. : ill. (some col.) ; 26 cm.
Language: English
Creator: Philippine Phytopathological Society
Publisher: Philippine Phytopathological Society
Place of Publication: Philippines
College Laguna
Publication Date: January-June 1987
Frequency: semiannual
regular
 Subjects
Subject: Plant diseases -- Periodicals -- Philippines   ( lcsh )
Plants, Protection of -- Periodicals -- Philippines   ( lcsh )
Genre: periodical   ( marcgt )
 Notes
Dates or Sequential Designation: v. 1, no. 1 (January 1965)-
General Note: Title from cover.
General Note: "Official publication of the Tropical Plant Pathology."
 Record Information
Bibliographic ID: UF00090520
Volume ID: VID00029
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 54382605
issn - 0115-0804

Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    On-farm trials of a fungus, paecilomyces lilacinus agianst potato cyst nematode and other species in Benguet province
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
    Species of gilocladium in the Philippines and some cultural characteristics
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
    Multilocation test for variations in Philippines corn downy mildew caused by peronosclerospora philippinensis (Weston) Shaw
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
    Biological control of nematodes using paecilomyces lilacinus in the Philippines
        Page 18
        Page 19
        Page 20
        Page 21
    Note: Leaf blight, ear rot, and stalk rot of corn caused by diplodia macrospora Earle in the Philippines
        Page 22
        Page 23
    Abstracts of papers presented at the twenty-fourth annual meeting of the Philipine phytopathological society, Davao City, May 4-8, 1987
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
    Information for contributors
        Page 36
    Back Cover
        Page 37
        Page 38
Full Text

















Official C
THE PHILIPPINE PHYTOPATI

VOLUME 23 JANUARY and JI


rfhlTI


pine


thology


gan of
LOGICAL SOCIETY, INC.

NE 1987 NUMBERS1 and 2


MTQ


i--
On-Farm Trials of a Fungus, Paecilomyces lilacinus Against Potato
Cyst Nematode and Other Species in Benguet Province R. G.
Davideand R. A. Zorilla .............................. 1-7

Species of Gliocladium in the Philippines and Some Cultural Charac-
teristics Meity-S. Sinaga and Triticita H. Quimio .......... 8-12

Multilocation Test for Variations in Philippine Corn Downy Mildew
Caused by Peronoscierospora philippinensis (Weston) Shaw -
L.A. Ebron and A. D. ymundo...................... 13-17

Biological Control of Nematodes Using Paecilomyces lilacinus in the
Philippines- R.G.Davide............................. 18-21

Note: Leaf Blight, Ear Rot, and Stalk Rot of Corn Caused by Diplo-
dia macrospora Earle in the Philippines S. C. Dalmacio and
G.P. Lozano .................................... 22-23
'** **'i: 'GPX n& .' lg ^ .


- --






ie Philippine Phytops


HYTOPATHOLOGK


* President
* Vice-President
* Secretary
* Treasurer
* Auditor
* Business Manager
* Board Member
* BoardMember
* Board Member
* Board Member


OSCAR S. OPINA
ROSALINDA P. GARCIA
MARINA P. NATURAL
CASIANA M. VERA CRUZ
SILVINO D. MERCA
CEFERINO A. BANIQUED
LINA L. ILAG
REBECCA O. DE GUZMAN
ARCADIO J. QUIMIO
GIL G. DIVINAGRACIA
T W MEW









ON-FARM TRIALS OF A FUNGUS, PAECILOMYCES LILACINUS
AGAINST POTATO CYST NEMATODE AND OTHER SPECIES
IN BENGUET PROVINCE


R.G. Davide and R.A. Zorilla



Professor of Plant Pathology and Associate Dean and Researcher at the National Crop
Protection, College of Agriculture, U.P. at Los Banos, Laguna, Philippines, Respectively.
Received the Best Paper Award from the Philippine Phytopathological Society during its
Annual Meeting on May 4-8, 1987, Davao City. Also given the "Outstanding Development Award"
by PCARRD during its Los Banos Science Community Week Celebration on November 19, 1987.


ABSTIL

Based on several demonstration farm trials
rticipated in by 6 farmer-cooperators in Atok
Id Buguias, the new biological control technology
ing P. lilacinus against nematodes attacking po-
to proved effective and can be adopted by potato
rmers. As a result of the nematode control, pota-



INTRODUI

For the first time in 16 years of research


CT

to plants appeared more vigorous and gave much
higher yield (50-100%) than the non-treated check.
The effects of P. lilacinus application was compara-
ble with and in some cases better than the carbofu-
ran treatment. The tuber-dip application general
gave comparable results with the soil-mix method.



TION


Do- anwcinu


aera rTusocnlen55 Wvul), auIu UUiLI iiCInaLUUc
genera. The technology involves the use of the
soil fungus, Paecilomyces lilacinus (Thom).
Samson, which can be cultured easily on locally
available substrates such as ipil-ipil leaves,
chopped water lily, rice hull, rice bran, corn
cobs, coconut water and other farm waste
products. The fungus can be applied either as
soil drench, by soil incorporation or by dipping
seeds, seedlings, tubers and other planting
materials in the fungal suspension before plant-
ing. The fungus parasitizes mainly the nematode
eggs preventing them from hatching.
Greenhouse and field experiments have shown
that the application of this technology can ef-
fectively control nematodes resulting in more
than 50% increase in yield of potato, tomato,
okra. cotton and other crons (Davide and Zoril-


*w--o-. -r---------- --- -- --------- ------ ----
ing (Davide and Zorilla, 1983). The effective-
ness of the tuber-dip treatment was improved
when combined with the soil-mix treatment
which resulted in 60-80% nematode control and
38-58% increase in potato yield. The results
were comparable with the use of nematicides
carbofuran and isazofos at the rate of 4.5 and 3
cg a.i. per ha, respectively. Considering the high
sost of nematicides and the health hazards
these chemicals pose to the farmers, the use of
". llacinus as a biocontrol agent against nema-
todes is more advantageous.
These series of farm demonstration trials
were conducted in order to encourage and
convincee more potato farmers in Atok, Buguias
md other areas in the province of Benguet
to adopt the technology.











First Demo Trial. This was conducted fro
November 6, 1984 to February 20, 1985 in
farm severely infested with cyst nematode
Madaymen, Buguias, owned by Mr. Edwai
Depayso. The pilot farm was divided into 3
1 m x 8 m plots. Two methods of fungal app
cation were used; tuber dip method and chi
ken manure-soil mix method. In the tuber-di
the fungus was cultured in sterilized coconi
water medium for 2 weeks and macerated in
waring blender to prepare the spore and myc
lial suspension. Potato tubers were then dipped
into the fungal suspension containing appr
ximately 2 x 106 spores per ml, for 10 mi
before planting. In the chicken manure-soil m
method, the fungus was cultured in 1:1 (v/
rice hull-rice bran substrate. After two wee]
these cultures were mixed thoroughly wil
chicken manure in a 1:10 (v/v) ratio. Tl
resulting mixture was incorporated into the sc
at the rate of 20 g per hill. All the other trea
ments received the same amount of chicken
manure.
The P. lilacinus treatments were compare
with carbofuran (Furadan 3G) (2,3, dihydro-:
2 dimethyl-7-benzofuranyl methyl carbamati
which was applied at the rate of 4.5 kg a.i. pi
ha before planting. Control or untreated plo
were provided as basis for comparison. Eigh
plots were used per treatment and each ph
was planted with two rows of potato cv. Isol
40 cm between rows and 20 cm between hill
The farmer-cooperator followed his usu
practice of growing potato particularly in tl
application of fertilizer, weeding, and in pe
and disease control operations.
The efficacy of the treatment was evaluate
based on the nematode population in the sc
before and after treatment and on tuber yiel,
Cyst nematode populations were determine(
before the treatments and at 45 and 90 da.
after treatment, by taking 400 cc comp
site samples at a depth of 8 to 15 cm from
sampling sites per plot. From the composi
samples, subsamples of 100 cc per plot we
taken. These were air-dried for 2 days in pel
dishes and then transferred to 500 ml beake
filled with water and mixed thoroughly with
stirring rod to allow the cyst to float. The cys
were then picked up and counted under a di
secting microscope. At harvest, tuber yield
in each treatment was weighed and compared.


pilot farms. Pilot farm 1 was the same area usei
in the first demo trial in Madaymen. Pilot farn
2 was located in Sayangan, Atok, Benguet ano
it was infested with non-cyst-forming specie
l"Ia DwM^*"f^-vl r" "" lif SM^4n1^^"n^ma .v 0


.. . . .... -- . . . . . .
used in pilot farm 1, while cv. Grai
in pilot farm 2. The same pilot si


a was u!


t treaunent was repncaiea tour nimes. ine cys
I nematode population in each treatment wa
determined using the same procedure as in th


ciate the benefits derived from the biocontro
technology.

RESULTS

SFirst Demo Trial

S Effects on cyst nematode population and
tuber yield. The application of P. lilacinus either
S as tuber-dip or as chicken manure-soil
mix reduced the e.v.t nnnilatinn in the anil









while the carb,
cvst noDulation


)n in


lots increased by 18.6%. Th
cyst nematode population
nne-diasnt 4nnfea. in 4hk*


UIlU Was 5lUl Lury Iu ruu LU .v VVA, AlS uw.
during the growing season, the effect of P.
llacinus and carbofuran treatments was still
apparent as shown by yield increases of 48.9%,
52.6% and 63.2% in the tuber-dip, chicken
pnanure-soil mix, and carbofuran treatment,
'respectively (Table 1).

Second Demo Trials


population was 70.2% in plots with the tuber-
lip treatment. This is relatively higher than
he 64.9% reduction observed in the chicken-
nanure-soil mix treatment and the 58.4%
education in the carbofuran treatment (Table
). The cyst nematode population increased
y 31.9% in the untreated plots.
Likewise, tuber yield increased consider-
bly in the P. ilacinus treatment as observed
a the first and second demo trials. The tuber-
lip treatment increased the yield by 88.2%
while the chicken manure-soil mix treatment
increased yield by 66.7%. Both P. lilacinus
-i- .1-- -- '


farms. In fact, during the first demo trial,
fiber yield in the P. A acinus-treated plots one cooperator, Mr. Edward Depayso, accel


treatment increased yield by 75.3%. These yield
increases were comparable to or even better
than the yield increase in the carbofuran
treatment (Table 3).

Third Demo Trial I
Effects on cyst nematode population and
tuher vied. The results in this trial confirmed


ontroi .ecnnoiogy m ms rarm. uue to ue
promising results obtained in the P. lilacinus
treatments during the first trial, more and more
armers became interested in the new tech-
nology and consented to serve as farmer-
ooperators in the subsequent trials.
These series of farm trials confirmed our
initial greenhouse and field observations re-











obefunm treatments on cyst population
lid of potato cv. Isola in the first demo
ugulas


C Soil Mean3
Days Yield3
er Trt % Control2 (kg) % Increase

F.4 48.0 2.83 48.9

i.9 48.5 2.90 52.6
0.9 53.2 3.10 63.2
).6 18.6 1.90 -
increase





due to severe drought during the cropping season.





treatments on cyst population in the soil and on tubt
emo trial in Madaymen, Buguias.


:C Soill
-- Mean
I Days % Control2 Yield3 % Increase4
rTrt (kg)

.5 64.9 20.8 56.4
.0 58.1 20.4 53.4
.7 55.5 25.4 90.9
2 (20.5) 13.3 -
(Increase)


Table 1. Effects of P. Ulacius and
in the soil and on tuber y
farm trial in Madaymen,


Cyst Count/100
9(
Treatment Before Trt af

Tuber-dip 168.2 1
Chicken manure-
soil mix 147.3 7
Carbofuran 170.7 1
Control 169.1 2(



1Means of 8 plot replicates.
2Data were obtained using the formula
Before Trt Count After Trt Count
Before Trt Count
3 Means of 8 plot replicates. Low yields were obtain
4Data were obtained using the formula:
Trt Mean Yield Control Mean Yield
Control Mean Yield


Table 2. Effects of P. lilacinus and carbofuran
yield of potato cv. Isola in the second i


Cyst Count/100

Treatment Before Trt S
aft

Tuber-dip 175.2 6
Chicken-manure-soil mix 126.5 5:
Carbofuran 167.7 7,
Control 147.0 17'



1Data are means of 4 plot replicates
2Data were obtained using the formula:
Before Trt Cc
Befh

3Data are mean total yield from 4 plot replicates
4Data were obtained using the formula:
Trt Mean Yielh


0 ALL J.wutL



- Control Mean Yield









Table 3. Effects of P. ilacinus and carbofuran treatments on non-cyst nematode population in the
soil and on tuber yield of potato cv. Granol in the second demo trial in Sayangs, Atok,
Benguet

Nematode Count/400 CC Soill
Mean
Treatment Before Trt 90 Days % Control2 Yield3 % Increase4
after Trt (kg)

Tuber-dip 323.1 100.0 69.0 13.6 86.3
Chicken manure-soilmix 316.4 94.4 70.2 12.8 75.3
Carbofuran 360.4 159.5 55.7 12.5 71.2
Control 364.0 514.6 (41.4) 7.3 (-)
(Increase)

1Data are means of 8 plot replicates. The nematodes found were predominantly Pratylenchus, Rotylenchulug, Helico.
tylenchus, Trchodorus and Tylenchorhynchus.
2Data were obtained using the formula:
Before Trt Count After Trt Count
x 100
Before Trt Count
3Data are mean total yields from 8 plot replicates
4Data were obtained using the formula:
Trt Mean Yield Control Mean Yield
x 100
Control Mean Yield

Table 4. Effects of P. Ilacinus and carbofuran treatments on cyst population in the soll and on tuber
yield of potato cv. Isola in the third demo trial in Madaymen, Buguias

Cyst Count/100 CC Soil1
Mean
Treatment Before Trt 90 Days % Control2 Yild3 % Increase4
after Trt (kg)

Tuber-dip 145.2 43.3 70.2 17.5 88.2

Chicken manure-soil mix 133.0 46.6 64.9 15.5 66.7

Carbofuran 151.0 62.8 58.4 14.3 53.4

Control 141.2 186.3 (319) 9.3 (-)
(Increase)

1Data are means of 4 plot replicates
2Data were obtained using the formula:


Before Trt Count After Trt Count
Before Trt Count
3Data are mean total yield from 4 plot replicates
4Data were obtained using the formula:
Trt Mean Yield Control Mean Yield


x 100


Control Mean Yield


Jan. & June 1987


On-Farm Trials of a Fungus Paecilomyces lilacinus









Table 5. Effects of P. lhcham and carbofuran treatments on noncyst nematode population in the
soil and on tuber yield of potato cv. Granola in third demo trial in Bonglo, Atok, Benguet

Nematode Count/400 CC Soil
Mean
Treatment Before Trt 90 Days % Control2 Yield3 % Increase4
after Trt (kg)

Tuber-dip 308.0 64.6 79.0 4.9 81.5
Chicken manure-soil mix 3249 76.8 76.4 4.8 77.7

Carbofuran 367.5 114.1 68.9 4.3 59.2
Control 352.0 461.3 (31.05) 2.7 (-)
(Increase)

1Data are means of 4 plot replicates. The nematodes found were predominantly Pratylenchus, Rotylenchulus, Helico-
tylenchus, Trichodorus, and Tylenchorhynchus
2Data were obtained using the formula:
Before Trt Count After Trt Count
x 100
Before Trt Count
3Data are mean total yields from 4 plot replicates. Low yields were obtained due to Class 4 (inferior) potato tuber
planted.
4Data were obtained using the formula:
Trt Mean Yield Control Mean Yield
x 100
Control Mean Yield
Table 6. Effects of P. lIacinus and carbofuran treatments on non-cyst nematode population in the
soil and on tuber yield of potato of mixed var. Isola, Conchita and Cosima in third demo
trial in Natublenm, Buguis, Benguet

Nematode Count/400 CC Soil
Mean
Treatment Before Trt 90 Days % Control2 Yield3 % Increase4
after Trt (kg)

Tuber-dup 350.3 75.9 78.3 9.7 29.3

Chicken manure-soil mix 342.6 93.9 72.6 8.9 18.7

Carbofuran 335.0 126.5 62.6 8.7 16.0

Control 305.3 408.6 (33.8) 7.5 -
(Increase)

1Data are means of 4 plot replicates. The nematodes found are predominantly Pratylenchus, Rotylenchulus, Hell-
cotylenchus, richodorus and Tylenchorhynchus.
2Data were obtained using the formula:
Before Trt Count After Trt Count
Before Trt Count
Data are mean total yield from 4 plot replicates
4Data were obtained using the formula:
Trt Mean Yield Control Mean Yield
Control Mean Yield
Control Mean Yield


Vol. 23


Philippine Phytopathology









UiUIU~iu I UHIIUUJi g5.LI a4~rlal ULi .ULaLU
cyst nematode and other nematode genera
affecting potato (Davide and Zorilla, 1983b and
1986). In all cyst-infested demo farms, close to
or higher than 50% reduction in cyst popula-
tion was observed in the P. lilacinus treated
plots. likewise, yield was increased by as much
as 50-80% except for a farm in Natubleng,
Buguias which gave relatively lower yield due to
mixed planting of cultivars and to the poor
quality of tuber seedpieces planted. Generally,
the incidence of late blight was reduced in
plants with P. lilacinus treatments compared
with carbofuran and untreated plants. Further-
more, in the non-cyst nematode farm at Saya-
ngan where the potato seedpieces were cut into
halves (hence predisposing them to soil patho-
gens) before planting due to the shortage of

LITERATURE

DAVIDE, R.G. and R.A. ZORILLA. L983a. Evalua-
tion of a fungus Paecilomyces lilacinus for the
biological control of potato cyst nematode Glo-
bodera rostochiensis as compared with some nema-
ticides. Phil. Agric. 66:397-404.
DAVIDE, R.G. and R.A. ZORILLA. 1983b. Evalua-
tion of three nematophagous fungi for the biolo-
gical control of potato cyst nematode Globodera
rostochiensis as compared with some nematicides.
Phil. Phytopathol. 19: 28-35.
DAVIDE, R.G. and E. BATINO. 1985. Biological
control of root-knot nematodes on the cotton


rl.0lab faeva uAo, LnAruv, wo a a, viiiajL.auLIa uI -
crease in stand and yield of plants with P. lila-
cinus treatments particularly in the tuber-dip
treatments indicating that the fungus may have
also affected the growth of tuber rotting patho-
gens. Recent, studies confirmed the observation
that growth of Sclerotium rolfsii and Rhizocto-
nia solani, tuber and root rotting fungi, could
be affected by P. lilacinus (Molina and Davide,
1985, unpublished) but additional experiments
must be conducted along this line.
Although both methods ofP. lilacinus appli-
cation are equally effective in reducing the
nematode population and increasing the tuber
yield, the tuber-dip method is recommended
because it is easier and more practical to use
under farm conditions.


E CITED
through the use of fungi, Paecilomyces lilacinus
(Thor.) Samson and Gliocladium roseum Bainier
as seed treatment. Phil. Agric. 68: 159-167.
DAVIDE, R.G. and R.A. ZORILLA. 1986. Evaluation
of fungus Paecilomyces lilacinus for the biological
control of root-knot nematodes Meloidogyne
incognita on okra compared with a nematicide
isazofos. Phil. Agric. 69(1): In Press.
VILLANUEVA, L.M. and R.G. DAVIDE. 1984.
Evaluation of several isolates of soil fungi for
biological control of root-knot nematodes. Phil.
Agric. 67: 361-371.










AND SOME CULTURE

Meity S. Sinaga a

Former Graduate Student and Associate Prc
University of the Philippines at Los Banos, Col
Portion of the PhD dissertation of the senior
College, Laguna, Philippines.
AB

This study was done to isolate species of Glio-
cladium a fungus with biological control potential
against soil borne plant pathogens.
The organisms were isolated from soil mixed
with decomposing materials, cogon grass litter or
rice straw. Taxonomical studies identified 2 spe-

INTRODUCTION
TI...L -..- .r ... Z_ ... ._... A


kL CHARACTERISTICS

td Tricita H. Quimio

essor,Respectively, Department of Plant Pathology,
ege, Laguna, Philippines
author, University of the Philippines at Los Banos,

TRACT

cies of Gliocladium, G. deliquescens and G. fim-
briatum, reported for the first time in the Philip-
pines. They differed in color and morphology
especially the phialides. They grew and sporulated
on potato dextrose agar at a temperature range of
25-30 C, and pH 5 and 6.

pines and study their cultural requirements to
obtain maximum growth and sporulation.


Deuteromycetes and Kingdom Mycota. It was
established by Corda in Icones Fungorum IV of Sol
(1849). According to Gilman (1957) and Cook Colection of Soil Samples
and Baker (1983), the genus Glocladium is
often characterized as a counterpart of Penicil- Soil samples which included plant debris
lum with slimy conidia. The differences bet- were collected with a soil auger at a depth of
ween these two genera are, however, more fun- 15 cm from Maquiling Forest and soybean
damental. The characteristic features of GUo- fields of the Institute of Plant Breeding experi-
cladium are: densely penicillate conidiophores mental farm, Universty of the Philippines at
which bear slimy, one-celled hyaline or brightly Los Banos. The samples were placed in clean
pigmented, smooth-walled conidia in heads or plastic bags. Five samples from each location
columns. Besides the penicillate conidiophores, were mixed thoroughly into one composite
primary simple verticillate conidiophores may sample and divided into five sub-samples. Some
be present, which is the characteristic feature of soil samples were also kindly provided by V.G.
the clonostachys in addition to the conidial co- Cuevas of the Institute of Biological Sciences,
lumn. If the conidia cohere in chains, they are UPLB. In cases where solutions could not be
more or less imbricate and devoid of connec- done on time, soil samples were kept in a refri-
tives, in contrast to Penicillium. The conidia are gerator for not more than 2 weeks.
often slightly curved with a somewhat truncate Isolation of Glocldium from Soil
base. In isolates with predominantly verticil-
lium-like primary conidiophores, this feature Gliocladium species were isolated following
may be useful for their separation from Verti- the soil dilution-plating technique of Johnson
cillium itself, in which the conidia are usually et al. (1960). Ten grams soil sample was placed
symmetrical, in a graduated cylinder. Sterilized distilled
The genus GUocladium is still not satisfac- water was added to the soil to make a total of
torily delimited and a satisfactory species con- 100 ml. The suspension was stirred, poured into
cept has not yet been determined, Some well- sterile 250-ml Erlenmeyer flask and shaken
known species are G. penicillioides, G. catenu- thoroughly. Ten ml of this suspension was
latum, G. roseum, G. virens, G. virlde, G. nigro- pipetted aseptically and dispensed in a dilution
virens, G. solani, G. vermoeseni, G. fimbriatum, bottle with 90 ml of sterilized distilled water,
G. deliquescens, and G. atrum. Soil dilutions of 1:10, 1:100, and 1:1000 were
This study was conducted to isolate and prepared. One ml of the desired dilution was
lAt fi f Ai.- f 7jlJ, .j .,... M I, 1. -f -- 16






Jan. & June 1987 Species of Gliocladium in the Philippines


dishes, and 10 to 12 ml of melted potato dex-
trose agar with Rose Bengal medium was added
to each dish. The dishes where then rotated by
hand in a broad, swirling motion to disperse the
soil suspension.
Plates were incubated at room temperature.
After 2 to 5 days, the microbial growth was
noted. Bits of mycelium from suspected Glio.
cladium spp. colonies were transferred indivi-
dually to potato dextrose agar (PDA) slants.
These were further purified until pure cultures
were obtained. The pure cultures were then
incubated for 7 days at room temperature and
stored in the refrigerator. For each treatment,
there were 3 replications.

Identification of Giocladium spp.

Pure cultures of Gliocladium were tentatively
identified into species with the aid of the keys
to the species proposed by Gilman (1957) and
Domsch et. al. (1980). The isolates were cul-
tured on PDA, Czapek agar and malt extract
agar (MEA) media for observation of colony
growth and other characteristics. Conidia,
metulae, phialides, primary and secondary
branching of conidiophores were measured
using a filar micrometer.
The characteristic sporulation of Gliocla-
dium isolates was examined using the slide
culture technique and the characteristic
features were photomicrographed.

Cultural Studies of Gliocladium spp.

Effect of Temperature. Cultures of PDA in
Petri plates were incubated at 15, 20, 25, 30,
35 C and room temperature (27-30 C). Growth
of colony was measured 3 and 5 days after
inoculation and dates of sporulation were
noted.
Effect of pH. Cultures on malt extract agar
in Petri plates were subjected to pH 4, 5, 6, 7
and 8. The different pH levels were obtained
by adding sterilized 0.1 N HCI or 0.1 N NaOH
on the medium before plating. All cultures
were incubated at room temperature. All
treatments had 3 replicates. Growth of colony
was measured 3 and 5 days after inoculation
and dates of sporulation were noted.
Effect of Soil Moisture Content. Air-dried
soils were passed through a 5-mm sieve, mixed
thoroughly with dry coir dust and Leucaena
(ipil-ipil) leaves at a ratio of 6:1:1 by'volume.
Fifty grams of this mixture were placed in
Petri plates and sterilized in an autoclave at 15


psi for 2 hours.
After sterilization, 0, 5, 10, 15 and 20 ml
sterilized water were added to the petri plates
depending on the treatment. Each moisture
level had 3 replicates. Transfer was done by
placing a mycelial agar disk at the center of the
petri plate with soil food base medium and
incubated at room temperature. Growth was
observed daily and dates of sporulation were
noted.
RESULTS

Identification of the Organism

From several soil samples collected, 5 iso-
lates of Gliocladium were identified as two dif-
ferent species. Isolates 1, 2, 4 and 5 were iden-
tified as G. deliquescens and isolate 3 as G.
fimbriatum.
All isolates of Gliocladium produced hyaline
chlamydospores which were either terminal or
intercallary, but the G isolate produced more
chlamydospores than te other isolates. Figures
1A and B show the sporulation of the isolates.
Morphologically, all isolates were almost the
same, but G3 had shorter, depressed phialides.
On Czapek's, PDA, and MEA agar, colonies of
G. fimbriatum were at first white, becoming green
after 5-6 days due to green fruiting structures.
G. deliquescens turned green as it spreads on
the agar surface. It grew faster on PDA than
on Czapek's and produced abundant spores and
slime than G. fimbriatum.

G. deliquescens Sopp (Figure 1A)

Colonies on agar not fast growing and
abundant, greenish from start, conidiophores
arise from submerged and aerial hyphae,
65.1-187.4 x 39-6.5 u; conidial head sur-
rounded with too much slime; long primary
and secondary branches below metulae,
8.11-11.77 x 1.8-3.5 u; phialides, 5.4-193 x
1.6-3.5 u; conidia elliptical to ovate, green
smooth, 3.2-5 x 2.1-3.2 u.
Four isolates identified to this specs were
isolate 1 and isolate 4 from Batanes and Car-
ranglan, Nueva Ecija soils, both by V.G. Cuevas;
and Isolate 2 and 5 by the senior author from
Maquiling Forest and the experimental fields
planted to soyoean at the IPB-UPLB 1985.

G. fimbriatum Gilman and Abbot (Figure 1B)

Colonies on agar, pure white, broadly spread-
ing with green fruiting areas, erect, appearing


Jan. & June 1987


Species of Gliodladium in the Phffippines





VoL 23


Philippine Phytopathology


on the 5th to 6th day; conidiophores arise as
side branches from aerial hyphae, smooth,
septate, 65.2-170.1 x 4.7-6.5 u; conidial heads
round, enveloped in slime, chains not distin-
guishable, primary branches 31.5-81.5 x 5.04-
4.41 u; metulae 9.2-10.6 x 2.9-3.2 u; conidia in
chains, elongate elliptical to round, smooth,
hyaline, 5.5-6.5 x 2.9-3.6 u; chlamydospores
hyaline, terminal or intercalary.


while no growth was observed when water was
not added. This indicates that the optimum
soil moisture content for growth and sporula-
tion of the Gliocladium isolates is close to field
capacity.
Effect of Substrate on Growth and Sporula-
tion. All Giocladium isolates were tested for
mass production on eight different substrates.


Fig. 1A Gliocladium deliquescens: conidiopho-
res, metulae, phialides and highly slimy
and agglutinated masses of conidia (800x)
Cultural Characteristics of the Isolates
Effect of Temperature. Table 1 shows that
all the isolates grew best at 25 C and 30 C but
were inhibited at 15, 20 and 35 C. These results
were significantly different only on the third
day of observation. These indicated that tempe-
rature effects were significant only during the
initial growth of the organisms. There was no
sporulation at 15 C.
Effect of pH. pH 5 and 6 were optimum for
both growth and sporulation of the different
isolates. The pH of the medium also affected
the days of sporulation but the differences
among the isolates were not significant. Late
sporulation was noted at pH 4 and 8 (Table 2).
After sporulation, the media were tinted yellow
green. This medium coloration was more in-
tense on media with pH 5, 6,and 7 where the
isolates sporulated well.
Effect of Soil Moisture Content. Moisture
content at field capacity and wilting point of
the soil used in this study was 23.62% and
18.24%, respectively. Thus, to maintain 50 g of
oven dried soil at field capacity, 11.81 ml of
water was added.
The best growth and sporulation occurred
when 10 ml of water was added. With 5 and 20
ml water, growth and sporulation were poor,


Fig. IB. Gliocladium fimbriatum: note paler
and bigger conidia. (800x)

Substrates 1 (Leucaena leaflets + Coir
dust), 2 (rice bran + coir dust, 3 (Leucaena
leaflets + sawdust), 4 (rice bran + sawdust) and
6 (rice bran alone) proved to be favorable for
growth and sporulation of G. deliquescens and
G. fimbriatum (table 3).The isolates did not
grow on substrates 7 (coir dust alone) and 8
(sawdust alone) but fair growth was obtained
on substrate 5 (Leucaena leaflet alone). Sub-
strates 2, 4 and 6 were more compact and the
two Gliocladium species appeared to have dif-
ficulty in growing deeper into them. As a con-
sequence, growth and sporulation were con-
fined only at the surface of the substrates.
Sporulation of the Gliocladium isolates start-
ed 3 to 4 days of growth on substrates 1,2,3,
4, and 6. The mycelium of the organism grew
faster and abundantly on substrates 2, 4,and 6
and did not reach deep into substrates 1 and 3.
At the 7th to 9th day of culturing, the whole
petri plate with either substrates 1, 2, 3, 4 or 6
was covered with mycelia and spores, but on
substrates 2, 4, and 6, sporulation was at the
substrate surface only.

DISCUSSION

Gliocladium and Trichoderma are widely









Table 1. Effect of temperature on hyphal growth diameter of Gliocladium isolates on PDA at the 3rd
day of incubation

TEMPERATURE

Hyphal Growth Diameter (mm) at
ISOLATES AVERAGE
15 C 20 C 25 C 30C 35 C RT (27-
30 C)

G1 7.67 2633 90.00 90.00 31.17 90.00 55.86b

G2 7.00 26.33 90.00 80.33 38.33 90.00 55.33b

G3 7.50 29.50 90.00 90.00 29.17 90.00 56.03b

G4 10.17 22.67 90.00 90.00 42.00 90.00 57.47a
G5 7.33 29.17 90.00 83.00 32.00 90.00 55.53b


Average 7.93d 26.80c 90.00a 86.67a 34.63b 90.00a

1Means of 3 replications. Means in same column and row with the same letters are not significantly different
(P = 0.05).


Table 2. Effect of pH on days of sporulation of Gliocladium isolates on malt extract agar.

pH
ISOLATE AVERAGE
4 5 6 7 8

G1 7.67 3.67 4.00 6.00 8.67 6.00a
G2 7.33 4.00 4.00 6.33 9.00 6.13a
G3 8.00 4.00 4.00 6.67 9.00 6.33a
G4 7.67 3.67 4.00 6.67 9.00 6.20a
G5 7.67 3.87 4.00 6.67 9.00 6.27a

Average 7.67b 3.87d 4.00d 6.47c 8.93a


Means in same column and row with the same letters are not significantly different


distributed over the world and occur in nearly
all soils and other natural habitats, especially in
those containing organic matter.
From several collected soil samples with
plant debris, there were less Gliocladium spp.
isolates and more of Trichoderma and Penicil-
lium due perhaps to more rapid growth of the
genera. This could be due also to the lack of pre-
cise techniques and the appropriate culture
media for isolation and enumeration of the
organisms.


In this study and in informal discussion with
Dr. V.G. Cuevas who had collected many spe-
cies of Trichoderma from different parts of the
Philippines, it was learned that Gliocladium
can be isolated from soil mixed with decompo-
sing material. Thus, the five isolates were col-
lected and isolated from soil mixed with cogon
grass liter, plant debris and also from rice straw
and mushroom spawn without soil. This infor-
mation can be appreciated since Gliocladium,
being a saprophytic fungus, has the ability to


1Means of 3 replications.
(P 0.05).


Jan. & June 1987


Spcies of Gliocladium in the Philippines






Philippine Phyto~athology Vol. 23


degrade various organic substrates in soil for
their growth and sporulation (Papavizas, 1985).
From the results of the temperature studies,
it is apparent that the optimum temperature
for growth and sporulation of the different
isolates is 25 to 30 C, indicating the tropical
nature of the genus. These results were also sup-
ported by that of Domsch et. al. (1980), who
reported 25-35 C as the optimum, 6 C the mi-
nimum and 36-37.5 C the maximum tempe-
rature for growth of G. deliquescens.
The above information indicates that the
Gliocladium deliquescens isolate was not a good
antagonist agent when applied on soil with low
temperature since this organism will not grow
and sporulate well at temperature 15 C and
below.


Good growth and sporulation of Glfocla-
dium occurred at 20 to 30% soil moisture
content, which is about the field capacity
where the soil has available moisture to be
released. At 10% soil moisture, this is already
below or near the wilting point, so that very
little or no moisture can be released. This ex-
plains the absence of growth of Gliocladium
at 0% or very slow growth at 10% soil mois-
ture content.


Table 3. Growth and sporulation of G. deliquescens and G. fimbriatum on different substrates.

SUBSTRATE G.d. Gf.

LL+CD /// ///

LL + SD I/I I/I

LLonly / /

RB + CD // I/

RB + SD I/ //

RB only // //

CD only -
SD only -


LL = Leucaena leaflets
RB = rice bran
CD = coir dust
SD = sawdust


/// = better growth and sporulation
// = good growth and sporulation
/ = fair growth and sporulation
- = no growth and sporulation


LITERATURE CITED


COOK, L.R. and K.F. BAKER. 1983. The nature and
practice of biological control of plant pathogens.
The American Phytopathological Society, St.
Paul, Minnesota. 539 p.
DOMSCH, K.H., W. GAMS and T.H. ANDERSON.
1980. Compendium of soil fungi. Vol. 1. London:
Academic Press. 859 pp.
GILMAN, J.C. 1957. A manual of soil fungi. 2nd ed.
Iowa State College, Press, Ames.


PAPAVIZAS, B.C. 1985. 7)ichoderma and Gliocla-
dium: Biology, ecology, and potential for bio-
control. Ann. Rev. Phytopathol. 23: 23-54.
JOHNSON, L.F., E.A. CURL, J.H. BOND and H.A.
FRIBOURG. 1960. Methods for studying soil mi-
croflora. Plant disease relationships. Burgess Pub-
lishing Co. 179 pp.


Philippine Phytopathology


Vol. 23




Philippine Phytopathological Society, Inc.
1987 Phil. Phytopath. 23: 13-17



MULTILOCATION TEST FOR VARIATIONS IN PHILIPPINE
CORN DOWNY MILDEW CAUSED BY PERONOSCLEROSPORA
PHILIPPINENSIS (WESTON) SHAW


L.A. Ebron and A.D. Raymundo

Science Research Associate, Institute of Plant Breeding and Assistant Professor, Department
of Plant Pathology, Respectively, University of the Philippines at Los Banos, College, Laguna,
Philippines.
A portion of the M.S. thesis of the senior author, University of the Philippines at Los Banos,
College, Laguna, Philippines


ABSTRACT


Considerable regional variations were observed
in corn downy mildew caused by Peronoscleros-
pora philippinensis (Weston) Shaw. Significant host



INTRODUCTION

Knowledge of pathogenic specialization is
essential in the development of cultivars resis-
tant to diseases. Pathogen races or biotypes can
occur by mutation and subsequent adaptation
with possible changes in virulence which may
alter the reaction of many resistant varieties
or hybrids.
Pathogenic variability of Peronosclerospora
philippinensis (Weston) Shaw, the pathogen of
Philippine corn downy mildew, has not been
adequately ascertained. Previous controlled
studies (Josue, 1976; Jover, 1977; Singh, 1977)
have indicated the existence of heterogenous
populations of the pathogen, but racial compo-
sition under field condition remains unclear:
Hence, this study was undertaken specifically
to determine regional variations that may be
found in P. philippinensis populations. Know-
ledge of this aspect will help explain the ob-
served seasonal and regional variation in resist-
ance among the Philippine downy mildew
resistant (DMR) corn varieties (Aday, 1975).
Likewise, it will provide an important tool in
breeding programs for corn downy mildew
resistance.

MATERIALS AND METHODS
Tests were conducted during the 1982 dry
and 1983 wet seasons. The inbreds used were
those that have shown differential reactions to


x location interactions were shown by combined
analysis of variance and Spearman's rank correla-
tion test.



Philippine corn downy mildew in previous
nursery tests in College, Laguna (Table 1).

During the 1982 dry season the locations
selected were College, Laguna; Sarangani,
South Cotabato; and Musuan, Bukidnon. Tests
in the 1983 wet season were conducted in the
following locations: College, Laguna; Cabagan,
Isabela; Pili, Camarines Sur; Musuan, Bukidnon;
and Davao.
The spreader row technique utilizing the
susceptible corn variety, UPCA VAR 1,was used
for inducing infection in nurseries. Seedlings
at 3- to 4-leaf stage were inoculated with spore
suspension of P. philippinensis. As soon as
systemic symptoms appeared, test entries
were planted in 5-meter row plots in a random-
ized complete block design with 2 replications.
Disease ratings based on percentage of sys-
temically- infected plants were taken at 30
days after seedling emergence.


RESULTS AND DISCUSSION

The corn inbreds used in both seasons
demonstrated regional variations in resistance
to corn downy mildew caused by P. philip-
pinenses. The apparent optimum conditions for
disease development were imposed throughout
the duration of the tests as shown by the gene-
rally high incidence of downy mildew in all
locations. For instance, during the 1982 dry









season, disease incidence of 80.3, 95.7 anc
100.0% were obtained in College, Laguna
Musuan, Bukidnon and Sarangani, Souti
Cotabato, respectively (Table 2). In the 1982
wet season, high infections ranging from 90.J
to 100% were obtained (Table 3). Analysis:
of variance showed significant differences ii
percentage systemic infection among th<
inbreds and among the locations on boti
seasons as well as significant inbred x location
interaction (Tables 4 and 5). The inbred:
probably have diverse genotypic background
eliciting in many cases, variable responses t(
P. philippinensis infection.
During the 1982 dry season, percent infec
tion on IPB inbreds and Ph 9 DMR (Table 2
were highest at College, Laguna and Soutl
Cotabato while CP lines had higher infection
Table 1. Differential corn inbreds used in deten
mildew caused by P. philippinensis

SEASON

1982 Dry




1983 Wet







Table 2. Percentage systemic infection of 8 cor
infected plants 30 days after seedling ei



College,
INBRED Laguna

IPB inbred 1 63.1 cd
IPB inbred 11 65.0 c
IPB inbred 19 57.6 d
IPB inbred 23 48.6 e


in Bukidnon than in the other locations. At
College, Laguna, IPB inbred 23 showed mode-
rate resistance with an infection of 48.6%
and was not infected in Musuan, Bukidnon
but was heavily infected in South Cotabato
with a 100.0% infection. In the 1983 wet
season test, CM 109 and KU 345-12 were
heavily infected in all locations. Ph lines and
KU 302-2 were highly infected in Davao but
were considerably resistant in 4 other locations
(Table 3). At Pili, Camarines Sur, and College,
Laguna, KU 205-6 had no infection but was
infected in Davao. It is also interesting to note
that SW 1 was resistant at Pili, Camarines Sur
and Musuan, Bukidnon, but was moderately re-
sistant to the pathogen populations of Davao
and Cabagan, Isabela.

ining regional variations in Philippine corn downy


ENTRY-DIFFERENTIAL INBRED

1 Ph 9 DMR; 2 IPB inbred 1
3 IPB inbred 11; 4 IPB inbred
23; 5 CP, 16; 6 IPB inbred
19; 7 CP 172; 8 CP 173

1 Ph 9 DMR; 2 KU 205-6;
3 KU 303-2; 4 KU 306-5;
5 Ph 101-25; 6 IPB inbred 23;
7 SW 1; 8 Genjah Kretek;
9 KU 326-5; 10 Ph 109-1;
11 CM 109; 12 KU 345-12

inbreds based on the total number of systemically
ergence at 3 locations (Dry Season, 1982)

LOCATIONS

Musuan, Sarangani,
Bukidnon South Cotabato

20.7 g 46.9 de
47.2 d 65.8 bc
34.6 e 100.0 a
0.0 h 100.0 a





Multilocation Test for Variations in Philippine Corn Downy Mildew


Table 3. Percentage systemic infection of.12 corn inbreds based on the total number of systemically
infected plants 30 days after seedling emergence at 5 locations (Wet Season, 1983)

LOCATIONS1/

Pili, College, Musuan, Cabagan, Davao
INBRED Cam. Sur. Laguna Bukidnon Isabela

IPB inbred 23 31.4 de 25.7 bcd 34.6 b 25.9 def 39.9 f
SW1 9.4 g 29.2 bc 8.9 ghi 24.2 def 38.2 fg
Genjah Kretek 62.9 b 20.8 d 26.6 c 44.4 c 22.9 ij
CM 109 92.7 a 90.4 a 100.0 a 75.0 b 92.1 a
Ph 9 DMR 38.3 cd 12.7 e 9.7 fgh 30.5 d 60.0 d
KU 326-5 42.8 c 10.1 ef 12.4 efg 43.9 c 28.4 hi
KU 205-6 0.0 i 0.0 i 2.5 j 7.5 ij 25.9 hij
KU 303-2 3.3 hi 4.1 hi 3.5 jk 5.6 j 55.0 de
KU 345-12 92.5 a 90.8 a 100.0 a 95.0 a 87.8 b
KU 306-5 33.1 de 7.2 fg 13.4 ef 29.0 de 32.2 g
Ph 109-1 36.1 d. 32.2 b 23.8 cd 12.8 h 83.2 c
Ph 101-25 23.8 f 10.3 ef 14.9 e 20.0 fg 57.6 d

1/ Means with the same letters) are not significantly different at 5% level using Duncan's Multiple Range Test.

Table 4. Combined analysis of variance across locations (Dry season, 1982)
Source of Degree of Mean of
Variation Freedom Squares F Value

Replication with
location 3 5.75

Inbred 7 7.77 12.51**
Location 2 17.28 27.87**

Inbred & Location 14 8.74 14.03**
Error 21 0.62

**Significant at 1% level of probability.

Table 5. Combined analysis of variance across locations (Wet season, 1983)

Source of Degree of Mean of
Variation Freedom Squares F Value
Replication witn
location 5 2.58
Inbred 11 55.60 56.73**
Location 4 23.96 24.45**
Inbred x Location 44 1.85 1.89*
Error 55 0.98


**Significant at 1 level of probability -


Jan. & June 1987





16 Philippine Phytopathology



Table 6. Ranking of entry corn inbreds at different locations based on percentage systemic infection
30 days after seedling emergence

1982 DRY SEASON 1983 WET SEASON

College Musuan, Sarangani Pili, College Musuan, Cabagan
RANK Laguna Bukidnon So. Cotobato RANK Cam. Sur Laguna Bukidnon Isabela Davao

ENTRY ENTRY

1 5 4 2 1 2 2 2 3 8
2 1 2 8 2 3 3 3 2 2
3 4 1 1 3 7 4 7 10 9
4 6 6 7 4 6 9 1 6 4
5 2 3 3 5 10 5 9 5 7
6 5 6 6 1 1 4 7 6
7 8 8 4,5,6 7 5 10 5 4 3
8 7 7 .8 9 6 10 1 5
9 4 7 8 9 1
10 8 10 6 8 10
11 11 11 11 11 12
12 12 12 12 12 11


Table 7. Spearman rank correlation coefficients
in 1982 dry and 1983 wet seasons


1982 Dry


1983 Wet


Location


College,
Laguna

Sarangani,
So. Cotobato
Location


College,
Laguna,
Pili, Cam.
Sur


Musuan,
Bukidnon
0.5200*


- 0.0500ns

Pili,
Cam. Sur

0.5034ns


in percentage systemic infection between locations


Sarangani,
So. Cotabato
- 0,4300ns


Cabagan,
Isabela

0.5454ns
0.9020**


Cabagan,
Isabela
Musuan,
Bukidnon


Musuan,
Bukidnon

0.7692**

0.7622**


0.6153*


Davao


0.2027ns


0 4755ns


**Highly significant
* Significant
"Not significant











Further examination of the inbred x loca-
tion interaction was made through the applica-
tion of Spearman rank correlation test to the
*data. Results indicated large differential rank-
ings in percentage systemic infections of test
inbreds as influenced by locations (Table 6).
Mnrro en indonifirant ,nrrelatinn fnr Inaetinn


tions. Previous reports (Barredo and Exconde,
1973) claimed that P. philippinensis can infect
the host over a wide range of temperature and
relative humidity combinations. However, the
levels of temperature and relative humidity
in some locations may not be adequate to
cause higher inbreds to become heavily infected


comomatons were recognized m me ouowing: uy ume pauluglu.
for the 1982 dry season Sarangani x Musuan It should also be emphasized,in addition to
(-0.0500) and Colllege x Sarangani (-0.4300); this possibility, that different types of the
for the 1983 wet season College x Pili pathogen may exist. Due to the ability of the
(0.5043), College x Cabagan (0.5454), Pili x pathogen to produce other forms such as races
Davao (0.2973), Davao x Cabagan (0.2027) or biotypes and each having distinct pathoge-
and Musuan x Davao (0.4755) (Table 7). These nicity type, undoubtedly, more virulent and
are clear indications that each location has its possibly more aggressive types maybe present
own distinct components and effects on disease in locations where they are responsible for
development. Therefore, Sarangani and Musuan the alteration of resistance of some inbreds. In
are, in nature, 2 different location types con- other locations, it is believed that the prevailing
ferring different effects on the hosts' respon- types of the causal pathogen may not be as
ses to downy mildew as indicated by their virulent and aggressive to initiate higher amount
negative coefficient values. Insignificant of infection on the same inbreds. Their exist-
positive correlations are likewise indications fence may provide plausible explanation as to
of differences in location types but the dis- why some Philippine DMR varieties differ in
parity between them with respect to influ- resistance when grown in other locations.
encing host performance is not so wide. In
this view, some inbreds may perform similar- Although pathogens are impossible to man-
-n- +-- nn-* +t1ni;l --l+.-+;. Ilifte


situations. Breeamg ror corn aow
It appears that inbred x location inter- resistance should be done in the
action asresistance should be done in the
action, as shown auantitativelv through com- e... -. -0 ,-


ny muaew


bined ANOVA across locations and Spearman that are inherently resistant to the prevailing
rank correlation test, is largely influenced by types of P. philippinensis at specific localities
the combined effects of host genotypes, envi- should be improved and utilized. This specific
ronmental differences and differential patho- resistance breeding approach eliminates enor-
gen virulence. These effects are evident in some developing a new
mous losses and saves time in developing a new
considerably resistant inbreds which become resistant corn cultivar.
highly infected when planted in other loca-


LITERATURE CITED



ADAY, B. A. 1975. The Philippine program in breed- JOVER, E.M. 1977. Virulence pattern, comparative
ing for resistance to downy mildew of maize. Trop. aggressiveness and gross morphology of isolates of
Agr. Ser. 8: 207-219. Sclerospora philippinensis on corn from Isabela
.msl P-nl1la T mlno M Thheic IT P at I nt


ed by inoculum, suscept and environment, Phil.
Agr. 57: 232-244.
JOSUE, A.R. 1976. Virulence pattern and gross mor-
phology of isolates of Sclerospora philippinensis
Weston on maize in Bukidnon. M.S. thesis U.P.
at Los Banos. College, Laguna. Philippines.


SINGH, J. 1977. Effect of temperature-relative hu-
midity and corn cultivars on morphology, viru-
lence and aggressiveness of Sclerospora philippi-
nensis PhD. Thesis, U.P. at Los Banos, College,
Laguna, Philippines. 119 pp.










LILACINUS IN
R. (
Professor of Plant Pathology and Assoc
Philippines at Los Banos, College, Laguna, Phil
Paper presented at the International Col
of Integrated Pest Management for Root an,
Institute of Tropical Agriculture, Ibadan, Nigei

The discovery of a nematophagous fungus
Paecilomyces lilacinus (Thom) Samson, in 1975
by Jatala et. al. at the International Potato


THE PHILIPPINES
. Davide
ste Dean, College of Agriculture, University of the
)pines
Ference and Workshop on the Status and Prospects
Tuber Crops in the Tropics at the International
i, October 25-30, 1987.


particularly isazofos, phenamiphos and carbo-
furan (Davide and Zorilla, 1983). Both P.
liin7in-., i4 nl f t.m f-rn ar.n th Ph innae


atAii -l ..a, & ,u', HaO 5va u U WCIC IIGUIdII VUpaIallVly iCCLIVC H1I I;U11LIUlUlll UIV
our 16 years of study on the biological control cyst nematode and their use resulted in a signi-
of plant parasitic nematodes in the Philippines. ficant increase in potato yield. In subsequent
Since 1967, when we first isolated two genera experiments, the effectiveness of P. lilacinus
of nematode-trapping fungi Arthrobotrys sp. was greatly improved by mainly increasing the
and Dactyllela sp. from rice straw compost, we spore density of the fungus suspension. P.
have been continuously searching for micro- lilacinus proved more effective as a tuber-dip
organisms that can be used for biocontrol of treatment, that is, dipping the seed pieces for
plant parasitic nematodes (Cortado and Davide, 5-10 minutes in the spore suspension before
1968; Reyes and Davide, 1975). However, our planting (Davide and Zorilla, 1986b).
results have not been generally convincing until
we shifted to the use of P. lilacinus. Our work To encourage potato farmers to adopt the
with P. lilacinus, which started in 1981 has P. lilacinus biocontrol technology, a series
been quite successful. We now have three local of on-farm trials with six farmer-cooperators
isolates, which are comparatively as effective were conducted in cyst nematode-infested
as the Peru isolate. One of them is now being areas, as well as in areas where there were no
mass produced and marketed as BIOACT cyst nematodes but where the Pratylenchus sp.
(formerly BIOCON) by Asiatic Technologies, population was high. Results showed a great
Inc. in Manila, Philippines. improvement on the effectiveness of P. lila-
cinus, with the farmers getting better nematode
This paper reviews the findings of various control and higher increase in potato yield.
experiments using P. lilacinus as a biological control and higher increase in potato yield-
control agent of the potato, The cyst nematode control ranged from 48-73%,
control agent of the potato cyst nematode, with An.a-IQO/ inrrp.ep in viplrl Tho trila. al.f


ing economic crops in the Philippines. The
potato cyst nematode biocontrol studies were
mainly supported by the International Potatc
Center (CIP).

Nematodes Controlled by P. lilacinus

Potato cyst nematode. The discovery ol
the potato cyst nematode, Globodera rosto-
chiensis Woll., by Sikora (1981) in potato.
growing areas in the highlands of Benguel
Province, has prompted us to immediately try
P. lilacinus against the cyst nematode before it
could become a serious problem of our potato
industry. A series of experiments conducted
in the cyst nematode-infested farms showed
that the fungus can effectively and consistently
control the cyst nematode with results being


showed that P. lilacinus was effective against
other nematode species especially Pratylenchus
sp., as indicated by the significant reduction in
the nematode population with corresponding
increase in potato yield (Davide and Zorilla,
1986b).
To share the remarkable experience of the
farmer-cooperators with other farmers in the
area, a workshop and field day was conducted
on May 20, 1986, where 25 farmers attended.
They were taught how to use P. lilacinus as
a tuber dip and were given a tour of the demon-
stration farms to observe the growth of potato
plants in P. lilacinus-treated and non-treated
areas. Convinced by the effectiveness of the
fungus as biocontrol agent against the cyst
nematode and other species, many of these
farmers are now using P. lilacinus (Smith,
- 1\r ^\










ratory and field tests using P. lilacinus against less effective but was significantly better than
Meloidogyne incognita on tomato, okra, the check. On potato, P. lilacinus gave better
mungbean, and cotton revealed that the fungus control of the nematode. Through tuber dip
is generally more effective against root-knot application, the fungus reduced the nematode
nematodes than against the cyst nematode. population in the soil by 80.9%, compared to
Greenhouse test on tomato using the drenching 71.3% reduction by the carbofuran treatment.
method of application showed that the fungus This resulted in yield increases of 76.2 and
grown in different substrates had considerably 81.6% of the first and second class tubers,
controlled the root-knot nematodes, showing respectively, while in the carbofuran treatment
trace to slight gall index rating as compared to the corresponding yield increases were 55.4
severe gall index on the check. This resulted and 74.5%.
in 20-33% increase in yield (Davide and Zorilla,
unpublished). In okra, it was shown that P. Tylenchulus semipenetrans on citrus.
lilacinus could remain effective against M. Findings in one greenhouse experiment showed
incognita up to the fourth cropping season, that P. lilacinus controlled about 64% of T.
whereas the effects of the nematicide isazofos semipenetrans in the roots of citrus seedlings.
(Miral 10G) could no longer be detected after Some adult females parasitized by the P. lila-
the second cropping (Davide and Zorilla, cinus were seen under a microscope. However,
1986a). Root galling in plants treated with the effect was less than phenamiphos (Nemacur
P. lilacinus remained at trace to slight levels 10G) at 1000 ppm rate. P. lilacinus-treated
whereas in the nematicide treatment, root plants showed 27% increase in height, 56%
galling was at a severe level, similar to that in increase in top weight and 57% increase in root
the check. The yield increased by 60-78% in weight (Tandingan and Davide, 1986).
P. lilacinus treatments using different sub- Radophulus similis on banana. Two expe-
strates as compared to 5.9% yield increase in riments had been conducted under greenhouse
the isazofos 10G treatment. conditions using Cavendish banana as test
P. lilacinus, applied as seed treatment or plant. Larvae and adults of R. similis were
seed dressing on undelinted and delinted cotton observed being parasitized by P. lilacinus. The
seeds, effectively protected the plants from nematode was effectively controlled by P.
root-knot nematode attack resulting in a sig- lilacinus, applied either as a root dip or soil
nificant increase in yield (Davide and Batino, drench treatment with effects comparable, and
1985). in some cases better, than the 100 ppm phena-
miphos treatment (Generalao and Davide,
Rotylenchus reniformis. Results of expe- 1986; Tandingan and Davide, 1986). As a
riments conducted against R. reniformis in follow up to these experiments, field trials
mungbean and pineapple showed that P. are currently being conducted in one of the
lilacinus can effectively control the nematode, commercial Cavendish banana plantations in
resulting in considerable yield increase. On Davao del Norte, a province in the island of
mungbean the nematode control due to Mindanao. Partial results obtained recently
P. lilacinus treatment ranged from 52-54% on nematode counts made three months after
as compared to 44% in the carbofuran (Furadan P. lilacinus application indicate that the fungus
3G) treatment. In the case of pineapple, P. has already reduced the nematode population
lilacinus provided 73% nematode control, by more than 50% in some treatments. This
based on 7th month nematode counts, while indicates that the fungus is a highly promising
in the nematicide treatment, the nematode biocontrol agent against R. similis on banana.












were antagonistic effects when P. lilacinus was This result is also reflected on the yield o
combined with Penicillium anatolicum and sweet potato from the solarized soil where
Penicillium oxalicum. With P. anatolicum, P. it was much lower than the check. The 20-da:
lilacinus control was reduced from 69.2% to solarization of the soil with temperature rang
47.7% while with Penicillium oxalicum, its ing from 61-81 C prior to the application o
effectiveness was reduced to 51.6%. When com- P. lilacinus must have affected the soil enviror
bined with both fungi, P. lilacinus control was ment making it detrimental to fungus growth
further reduced to 50.8%. This indicates that as well as to sweet potato root growth. It i
the presence of P. anatolicum and P. oxalicum therefore, suggested that more experiment
in the soil could inhibit the growth of P. be conducted on integrated control wit
lilacinus, thereby reducing its effectiveness to P. lilacinus to gain more knowledge on factor
onntrnl npm.tnalp that favor or limit its effectiveness as biocontrc


iematoes C l.iG~onno to nnnh~lo fn -rr


JuaVlU, 1*I) UAlfl~t~MflJV.O fl-- --- uu v *
that the nematode population of mostly R.
reniformis, M. incognita, and Hemicycliophora
sp. in the solarized soil was not considerably
reduced by the subsequent addition of P.
lilacinus. Nematode counts at harvest revealed
that P. lilacinus treatment alone gave 35-49%
nematode reduction but when combined with
solarization the nematode control was only
12.9%, indicating some adverse effects of the
solarized soil on the growth of the fungus.

LITERAT
CORTADO, R.V. and R.G. DAVIDE. 1968. Nema-
tode-trapping fungi in the Philippines. Phil. Phyto-
pathol. 4:4.
DAVIDE, R.G. and R.A. ZORILLA. 1986a. Evaluation
of a fungus Paecilomyces lilacinuus for the biolo-
gical control of root-knot nematode Meloidogyne
incognita on okra as compared with a nematicide
Isazofos. Phil. Agric. 68: 493-500.
DAVIDE, R.G. and R.A. ZORILLA. 1986b. On farm
trials of Paecilomyces lilacinus for the biocontrol
of potato cyst nematode Globodera rostochiensis
Woll. and other species in Atok, Benguet. Paper
presented at the 2nd International Workshop on
the Biological Control of Nematodes, PCARRD,
Los Banos, Philippines, February 9-16, 1986.

DAVIDE, R.G. and R.A. ZORILLA. 1983. Biological
and chemical control studies of the potato cyst
nematodes found in Madaymen, Buguias, Benguet.
Phil. Phytopathol. 19: 28-35.
DAVIDE, R.G. and E. BATINO. 1985. Biological
control of root-knot nematodes on cotton through
the use of fungi Paecilomyces lilacinus and Gliocla-
dium roseum as seed treatment. Phil. Agric. 68:


through in nematode biocontrol, we are conti-
nuing our research to improve the effectiveness
of P. lilacinus through strain selection and
other means, as well as to screen and establish
the effectiveness of other potential nemato-
phagous fungi. We are optimistic that other
more effective biocontrol agents can be dis-
covered in the near future.


IRE CITED
GAPASIN, R.M. 1986. Evaluation of Paecilomyces
lilacinus (Thom) Samson for the control of Praty-
lenchus sp. in corn. Presented at the 2nd Inter-
national Workshop on the Biological Control of
Nematodes, PCARRD, Los Banos, Philippines,
February 9-16, 1986.
GENERALAO, LOURDES C. and R.G. DAVIDE.
1986. Biological control of Radopholus similis
on banana with three nematophagous fungi PhiL
Phytopathol. 22: 36-41.
JATALA, P., P.R. KALTENBACK and M. BOCAN-
GEL. 1979. Biological control of Meloidogyne
incognita and Globodera pallida on potatoes. Jour.
Nematol.11: 303.
REYES, T.T. and R.G. DAVIDE. 1975. Fungi for
biological control of plant parasitic nematodes.
NSDB Tech. Bull. No. 3, p. 53.
SIKORA, R.A. 1981. The potato golden cyst nema-
tode Globodera rostochiensis, found in the Philip-
pines. Plant Disease Focus Early Riser News 4(3):
1.
SMITH, O.P. 1986. A farmer's experience on the use


tematoaes c





JIUJUU 4(L[ i* I&rm^-


1986.
TANDINGAN, IRMA C. and R.G. DAVIDE. 1986.
Biological control of Tylenchulus semipenetrans
on citrus and Radopholus similis on banana with
Paebilomyces lilacinus and Penicillium anatolicum.


phagous fungus Paecilomyces lilacinus (Thom)
Samson. Phil.-Agric. 67: 223-231.
VILLANUEVA, LUCIANA M. and R. G. DAVIDE.
Tnflnpnpp nf nH tpmnpratilrp liaht and anar media




Philippine Phytopathological Society, Inc.
1987 Phil. Phytopath. 23: 22-23

NOTE: LEAF BLIGHT, EAR ROT AND STALK ROT OF CORN
CAUSED BY DIPLODIA MACROSPORA EARLE
IN THE PHILIPPINES

S.C. Dalmacio and G.P. Lozano


Plant Pathologist and Research Assistant,
Isidro, Cabuyao, Laguna, Philippines
In January, 1985, we observed a high inci-
dence of corn ear rot reaching as high as 20%
in some farmers' fields in South Cotabato.
Leaf blight with symptoms resembling that of
Northern leaf blight caused by Helminthos-
porium turcicum Pass. was also commonly
observed. Microscopic examinations of the
diseased ear and leaf samples showed frequent
association of Diplodia macrospora Earle, a
fungus reported in the Philippines in 1931,
causing leaf spot of corn. The incidence of
these two diseases in a major corn growing area
in Mindanao was alarming enough to warrant
further study.
Experiments were conducted to determine
the development of ear rot, leaf blight and stalk
rot diseases of corn caused by D. macrospora.
Three methods of inoculation were done,
namely: whorl, ear, and stalk inoculations.
Whorl and ear inoculations were done by
introducing either sections of infected leaves
containing pycnidia of the fungus or pure cul-
ture of the fungus grown on sorghum grains.
Stalk inoculation was done either by injecting
conidial suspension of the fungus, prepared by
scraping the pycnidia containing conidia from
infected leaves and suspending them in a small
amount of water, using a hypodermic syringe,
or by inserting toothpicks, previously sterilized
and infested with pure culture of the fungus,
into the internodes. To compare symptom
development on artificially-inoculated plants
with symptom development under natural
conditions, plants showing initial infection in
the field were tagged and observed regularly.
All inoculation tests yielded positive results.
Leaf blight symptoms started as small, yellow
specks 3 to 5 cm above the whorl as early as
5 days after inoculation. These specks gradually
enlarged into oval spots with gray centers, dark
brown margins, and pale yellow halos. Later,
these spots became elliptical, measuring over
10 x 1.5 cm. Two to four spots may coalesce
resulting in extensive drying of the leaves. Tiny,
black, globose to flask-shaped pycnidia ap-
peared 20 days after inoculation and were
mostly found at the center of the lesions. Thus,
the presence of pycnidia is a diagnostic sign of
the leaf blight caused by D. macrospora which
distinguishes it from blights caused by H.


Respectively, Pioneer Overseas Corporation, San

turcicum and Erwinia stewartii (Smith) Dye.
Mature pycnidia contain numerous elongated,
two-celled (rarely three-celled) conidia about
67 um in length. The leaf blight symptoms
described in this paper fit the description by
Stevens and Celino in 1931. Foliar symptoms
of naturally-infected plants developed in the
same manner as those on artificially-inoculated
plants. Spots generally originated at a given
point on the expanded leaf, suggesting that
infection occurred at the whorl where free
moisture was available to support spore germi-
nation and subsequent infection.
Ear rot symptoms appeared about 5 days
after inoculation as small, circular, bleached
to dark brown spots at the point of inoculation.
Spots gradually expanded and spread to the
inner husks up to the cob, causing premature
death of the husks. Husks became pasted
together by the whitish mycelia which even-
tually ramified over the corn cob. Pycnidia
then developed on the husks, cob tissues, and
sides of kernels. Under natural conditions, ear
rot usually started on the outer husk near
the base of the ear, adjacent to the stalk.
This often led to ear rot starting from the base
spreading upward. It was common to find ears
showing profuse mycelia only at the base. Cobs
of infected ears became soft and kernels became
discolored and light.
Plants inoculated two to three weeks after

flowering showed positive stalk infection which
was shown by the brown discoloration starting
from the point of inoculation. Pith discolora-
tion gradually spread both upward and down-
ward and was later observed on the outer sur-
face of the rind. Symptoms of natural infection
of the stalk usually started at the nodal portion
and spread in both directions. Stalk surface
showed circular to elongated discoloration
which was also observed in the pith when stalk
was split. Infected plants showed wilting above
the affected node. Whitish mycelium of the
fungus sometimes appeared on the surface of
the stalk near the node but rarely developed
pycnidia. Thus, stalk rot symptoms caused by
D. macrospora differ in some respect from
symptoms caused by D. maydis (Berk.) Sacc.
Pith disintegration with only the vascular
bundles remaining, which characterizes stalk





Jan& Jne 987Not: Laf ligt, ar ot nd tal Rn ofCor


infection by D. maydis, was not observed on
stalks infected by D.. macrospora. The presence
of subepidermal, minute, dark brown to black
pycnidia clustered near the nodes, which is
also a characteristic sign of D. maydis infection
(Shurtleff, 1980), was rarely observed on stalks
infected by D. macrospora.
Based on the above experiments and field
observations, we have arrived at the following
hypothesis on the mode of infection by D.
macrospora. Conidia that are left in the field
during the previous season initiate infection in
the whorl during the vegetable stage, causing
leaf blight. After a few weeks, pycnidia contain-
ing conidia develop on the lesions. The conidia
later find their way down the stalk by means of
rain or dew and settle on the nodes or husks
adjacent to the stalk. Conidia then germinate
and penetrate through the node, initiating
stalk infection leading to stalk rot. On the other
hand, conidia on the outer husks, near the base
of the earshoot germinate and penetrate the
outer husks, initiating ear infection leading to
ear rot. The above hypothesis is consistent with
field observations that the leaf blight phase
usually precedes both the ear and stalk rot
phases, while the stalk rot phase usually comes
after the ear rot phase.
Among the control measures recommended
for diseases caused by Diplodia spp., the use of
resistant cultivars has proven to be the most
effective, hence, the need to screen all presently
grown cultivars against D. macrospora and ini-
tiate disease resistance breeding if necessary.
Since stalk and ear infection by D. macrospora
appear to be highly dependent upon leaf infec-


tion, adequate leaf blight phase resistance should
greatly minimize damage by the disease. How-
ever, there is also a need to establish correlations
of resistance for the different phases. While the
stalk inoculation method for various stalk rot
pathogens has been widely used abroad and
may be applicable in the Philippines, develop-
ment of a screening technique for the. leaf
blight phase resistance deserves attention. The
whorl inoculation technique using pure culture
of the fungus on sorghum grains showed
promise and should prove highly effective if
production of abundant pycnidia on the grain
medium could be induced. Another possibility
is whorl inoculation using ground infected
leaves but this will require a large amount of
naturally infected leaf materials containing
mature pycnidia. So far, we have not been
successful in inducing pycnidia production
on infected leaves incubated in petri dishes
lined with moistened filter paper, unlike H.
maydis or H. turcicum which can be induced
to produce conidia in 24 to 48 h.
This paper is the first report on the occur-
rence of stalk and ear of rot of corn caused by
D. macrospora in the Philippines. The ear rot
of corn in the Philippines studied by Lopez
(1950) was caused by D. maydis, which is a
distinct species. The only report on the occur-
rence of D. macrospora in the country was by
Stevens and Celino in 1931 where they demon-
strated that the fungus can cause leaf spot in
corn.


LITERATURE CITED


LOPEZ, M.E. 1950. A study of the Diplodia ear rot
of corn. B.S. Thesis, University of the Philippines
at Los Banos, College, Laguna.
SHURTLEFF, M.C. 1980. Compendium of Corn


Diseases. The American Phytopathological Society,
USA.
STEVENS, F.L. and M.S. CELINO. 1931. Two diseases
caused by Diplodia., Phil. Phil. Agric 20: 370-374.


Jan.& June 1987


Note: Leaf Blight, Ear Rot and Stalk Rot of Corn






















Institute for Food Crops (MORIF), South cacy Against the Black Leat Streak and biga-
Sulawesi, Indonesia from August-October 1986 toka Diseases in Giant Cavendish Banana.
to determine the transmission of rice tungro- M.O. San Juan and R.G. Atabug, Twin Rivers
associated viruses by green leafhopper (GLH) Research Center, Davao del Norte.
colonies maintained in IR20, IR42, IR54 and
TN1. The test varieties used were IR26, IR30, Three rates of triadimenol (Bayfidan 250
IR36, IR42, IR50, IR54, IR60, and TN1. Other EC) were drenched unto the bases of the mother
IR varieties like IR28, IR29, IR34 and IR58 in plant pseudostem at three application frequen-
addition to IR50, IR54, IR60 and TN1 were cies and evaluated for efficacy in controlling
used in the test on Gam Pai 30-12-15 progenies the black leaf streak and sigatoka diseases in
using GLH colonies from IR54 and TN1 for Giant Cavendish banana. All the triadimenol
transmission. Transmission was studied by test treatments provided significantly longer disease
tube inoculation method using one insect per incubation and transition periods, and more
seedling. Aside from visual scoring of infection functional leaves per plant than the untreated
based on symptoms taken 4 days after inocu- control. Application of triadimenol at 1.0 g ai
lation, test plants were also sampled and and 0.75 g per mat once every 2 and 3 months
indexed serologically for the presence of was most effective against the disease with resi-
rice tungro-associated viruses by latex test 30 dual efficacy extending several months after the
days after inoculation. last application of the fungicide. The most
Regardless of virus source, distinct differen- effective triadimenol treatments were two to
tial reaction was only observed using GLH three times costlier than the standard aerial
colony maintained on IR54, wherein virus spray scheme used in the plantations due to the


Davide and R.A. Zorilla, National Crop Protec-
tion Center (NCPC),, College, Laguna

Based on several demonstration farm trials
participated in by 6 farmer-cooperators in Atok
and Buguias, the new biological control tech-
nology using P. lilacinus against nematodes at-
tacking potato proved effective and can be
adopted by potato farmers. As a result of the
Tenaatbde control, potato plants appeared more
vigorous and gave much higher yield (50-100%)
than the non-treated check. The effects of P.
liacinus application was comparable with and
in some cases better than the carbofuran treat-
ment. The tuber-dio application generally gave


,TT,:


ses by Different Colonies of Nephotettix vires-
cens Distant R.C. Cabunagan and H. Hibino,
International Research Institute (IRRI), College,
Laguna.
This study, part of "IRRI and ARRD Colla-
borative Research on Rice Tungro Virus Di-


ed to the variety as a result of continuous
rearing, and all other varieties with the same
gene for resistance became susceptible to
tungro when inoculated by this GLH colony.


C~ml*:A* ~^f r%-1n6-n T1mnr. l fA- FFM.


ce lungro lilacin


Wile colomIes maiiamUu Uiln oumI vail4.IC
transmitted only RTBV in most cases. On th
susceptible TN1, low tungro and high RTBI
infection were obtained by using GLH colon
from IR54.
Transmission by GLH colonies from IR21
and IR42 on their respective differential varie
ties was not significantly different compared
with other GLH colonies.
When the transmission of GLH colony fror
IR54 was tested on other Gam Pai 30-12-1:
progenies, significantly high tungro infection:
was obtained on these varieties which reacted
generally to the presence of both RTBV an,
RTSV, compared with GLH colony from TNI






Jan. & June 1987 Abstracts of Papers


The Status of Citrus Nurseries in Batangas and
Laguna and Their Importance in the Develop-
ment of the Philippine Citrus Industry. D. M.
Nora, V.M. Dimailig and A. F. Austria, Bureau
of Plant Industry (BPI), Lipa City.

The Philippine citrus industry declined be-
cause of a disease popularly known as leaf mot-
tling. The disease is known locally to our citrus
growers as "nag sasanfrancisco" because of the
close resemblance of leaf symptoms of in-
fected tree to an ornamental plant called San
Francisco, or Croton, Codiaeum variegatum
pictum, a tropical shrub with variegated foliage.
This disease is transmissible by grafting and by
insect vector. The only identified insect vector
of this disease is the citrus psyslla, Diaphorina
citri Kuway.
Aside from leaf mottling, other virus diseases
in the Philippines aie exocortis, xyloporosis and
psorosis. All these viruses are also transmissible
by grafting.
Recognizing the problems on diseases as the
principal constraint in the development of the
citrus industry, the creation of Plant Board for
fruit trees was proposed. Under the concept,
scheme of certification and/registration with
defined procedures and sets of standard would
be organized and implemented so that only
quality and disease-free planting materials are
distributed to farmers. Cognizant of its impor-
tance, the Director of Plant Industry in 1983,
created a project management staff that formu-
lated a program which is now known as Plant
Material Certification Program (PMCP) with res-
ponsibility to produce and develop scion-source
trees of superior varieties that are free from
bud-transmissible diseases.

Susceptibility of the Rice Cultivar Carreon to
Pyricularia oryzae. C.Q. Torres, T.I. Vergel de
Dios, B.A. Estrada, J.M. Bandong, and J.M.
Bonman, IRRI, Los Banos, Laguna

To identify the sources of resistance in rice
to blast disease, multi-location tests have been
conducted since the 1960s. Through these tests,
cultivars with resistance at many locations and
for many years were found, and these were
used as "resistance sources" in rice breeding
programs. The traditional Philippine cultivar
Carreon was one such resistance source. In
international tests from 1975 to 1984 it was
completely resistant (no sporulating lesions) in
74% of 298 trials conducted, and in only 1% of
the tests did it show more than 50% leaf area


affected by blast. In 1986 typical blast lesions
were found in Carreon at an upland test site in
Cavinti, Laguna. The fungus from Carreon was
isolated and tested. The isolate infects all ac-
cessions of Carreon, but has a narrow spectrum
of virulence compared to other common P. ory-
zae races from the Philippines. We hypothesize
that Carreon has one or a few genes giving high
resistance in the international tests. Such resist-
ance is unlikely to be agronomically useful,
especially in upland rice.
Components Analysis of Leaf Scorch of Sugar-
cane. R.C. Sampang and T.T. Reyes, Sugar
Regulatory Administration, Pampanga and Uni-
versity of the Philippines at Los Banos (UPLB),
College, Laguna
Components analysis was used to determine
the virulence of 3 isolates of Stagonospora sac-
chart Lo and Ling from Laguna, Pampanga and
La Carlota on cane varieties CP 3617, Nco 310,
H 37-1933, Phil 58260, Co 453 and Phil
6111.
Test with the three isolates of S. sacchari
showed that the resistant cane varieties Phil
58260 and Nco310 gave longer incubation and
latent periods and fewer pycnidia compared to
the susceptible varieties Phil 6111 and H
37-1933. Pampanga isolate was the most viru-
lent as shown by its shorter incubation and
latent periods in the host varieties. More and
bigger lesions and more pycnidia were produced
on the test varieties.
Developing Near-Isogenic Lines of Rice with
Single Blast Resistance Genes. T.I. Vergel de
Dios, P. Tenorio, DJ. Mackill, and J.M. Bon-
man, IRRI, Los Banos, Laguna

A set of near-isolines in rice is being deve-
loped for use in research with blast disease
caused by Pyricularia oryzae. Previous work
indicated that cultivars Tetep Lac 23, Pai-kan-
tao, and 5173 had several r-genes and that
resistance to different races was controlled by
different dominant genes. These cultivars were
used as r-gene sources. Cv C039 was used as
the recurrent parent because of its suscepti-
bility to most P. oryzae isolates in the tropics.
Five races of P. oryzae were used to screen re-
sistant seedlings from backcross progeny. Back-
cross six F3 progenies have now been screened
to select homozygous lines. Six to 16 resist-
ance genes have been isolated in the C039 back-
ground; the exact number will be determined
through tests with differential isolates and, if
necessary, by intercrossing. The nmar-iom Ms


Jan. & June 1987


Abstracts of Papers









--',rn .- -. u5 z, 1IIOt 1 u MUM


IRRI, Los Banos, Laguna
rparative Smut Reaction of Sugarcane
ieties in Field Test and Histopathological An experiment with two blast levels
mination of Buds. M.M. Guevarra, Sugar and high) and two water levels (fully irr:
ulatory Administration (SRA), Pampanga and stressed from 42 to 58 days after sei
was conducted using the upland cv C22. I
-istopathological examination of buds for climate and plant mineral nutrient coi
d detection of resistance to smut was tested were also determined.
comparing the disease reactions of test N i b w l
No interaction between water level and
arcane varieties with those obtained in the level was detected. Highest disease occur
, t. level was detected. Highest disease occur:
I resistance test. water-stressed inoculated plots with 4'
)f the 35 test varieties, 32 gave the same seased leaf area and 44% severe neck
it reactions in both tests. Three varieties had The highest grain yield was obtained ir
lerate reactions under field test but were tected, fully-watered plots (2.23 t/ha
:eptible in histopathological examination. (1 t/ha). Blast and water deficit caused ad
ieties with resistance and moderate reac- reductions in 1000-grain weight, perce
is had none to scarce fungal invasion on the filled grains, and total dry matter.
tissues while susceptible varieties had P t a s
lerate to abundant fungal invasion. Plant tissue analysis showed that pla
water stressed plots had higher % N and
listopathological examination of buds was % SiO2 content compared to plants in irri
parable to the field resistance test as indica- plois. Microclimate was more favorable f
by the rank correlation of 0.92. It can be sease development in the irrigated plots tl
I for shortening screening test to 20 days as the water-stressed plots because of a 1
pared to the 9-month period in field resist- period of leaf wetness. However, after fu
e test. gation was restored, disease increased fas
plants that had been stressed. Higher diseal
f and Neck Blast Resistance in Rice. B. A. served later in the stressed plots was not c
rada, J.M. Bandong, and J.M. Bonman, microclimate differences between plots bt
U, Los Banos, Laguna. probably due to increased susceptibility
stressed plants.

The relation between seedling and neck blast Evaluation of Different Inoculum Source
stance in rice was studied in 29 IR lines and Cultivation Methods in Screening Rice
eties during the dry season of 1986. Three Sheath Blight Resistance. R.C. de la Pena
Is were conducted in upland blast nursery to Ahn, and T.W. Mew, IRRI, Los Banos, La
ess leaf blast resistance at the seedling stage Different inoculum sources and culti,
ig the short row mini-plot technique, and methods were evaluated for their efficier
-e plantings in an irrigated lowland field sheath blight resistance screening. The t
e done to evaluate neck blast resistance. To potato + soil substrate produced signific
are blast development at the panicle stage, higher disease severities than using rice g:
plants were inoculated at heading stage with rice hull substrate. On the other hand, the
mixed population of Pyricularia oryzae. Leaf cultivation methods were not signifi(
;t resistance was expressed as the area under different from each other based on d
disease progress curve (AUDPC), and neck severity. However, the incidence of disea,
it resistance was expressed as percentage the uniformity of infection were signifi
:re neck blast (SNB). The mean AUDPC higher in upland and in lowland draine
ies at the seedling stage correlated with the days before inoculation than in strictly lo
centage SNB (r = 0.63, 0.75, and 0.70) in cultivation method. Furthermore, uplan(
It -Fif +1^ -, +-.*1- *+ 41- -nA -- 11





Jan. & June 1987 Abstracts of Papers 27



Effect of Water Deficit on Components of Rice Three genera of fungal pathogens causing
Blast Resistance. M. Arshad Gill and J.M. Bon- crown rot of banana at Hijo Plantation were
man, IRRI, Los Banos, Laguna identified as Colletotrichum musae (Berk and
Curt) Arx, Botryodiplodia theobromae Pat. and
In a greenhouse study, components of most Fusarium roseum.
resistance such as disease efficiency (DE), latent Among the fungicides tested, prochloraz at
period (LP), lesion size (LS) and sporulation the rate of 0.33 ml/liter of water effectively sup-
capacity (SC) were examined in C22, a mode- pressed the growth of C. musae, B. theobromae
rately susceptible upland rice cultivar, at diffe- and F. roseum. Benomyl at recommended rate
rent water stress levels. Two sets of irrigated of 1.0 g/liter of water was as effective as proch-
check plants were included in the test. One set loraz in suppressing the growth of B. theobro-
involved plants of the same chronological age mae. Bitertanol, tridemorph. nuarimol, and
and the other set of the same physiological age. triforine were less effective against the test
Water deficit increased susceptibility by increa- pathogens.
sing DE and SC compared to plants of the same
chronological age but had no significant effect Efficiency of Chemical Control of Cercospora
on DE compared to unstressed plants of the Leaf Spot of Mungbean Grown Before Rice as
same physiological age. Latent period was re- Affected by Crop Stand. F.A. Elazegui and
duced by one day in the water deficit treat- T.W. Mew, IRRI, Los Banos, Laguna
ment and LS was larger compared to both
checks. Daily spore production counts from the The effect of fungicide to control Cercos-
stressed plants were significantly higher than pora leaf spot was determined on mungbean
from both checks. crop with good and poor establishment. The
crop was grown in two fields, one where the
The Potential Use of Propiconazole for the growth and development of the bean was good
Control of Major Philippine Crop Diseases. A.V. and the other where the crop was stunted and
Barrenechea, F.V. Palis, and J.I. Calderon. with leaf chlorosis.

Propiconazole, a highly effective foliar fungi- Regardless of crop stand, the disease severity
cide has been successfully developed for the and incidence were significantly lower in plants
control of disease complex in cereals. The sprayed with the fungicide than those in check
active ingredient (propiconazole) 1-(2-(2,4- plot. In plots with poor plant establishment,
dichlorophenyl) 4-propyl-l, 3-dioxolan-2-yl- infection level was similar in sprayed and un-
methyl)-lH-l,2,4-trazole, inhibits fungi by in- sprayed plants, but at seed maturity stage fungi-
terfering with ergosterol biosynthesis. The act- cide-sprayed plants had more leaves left than
ive ingredient is absorbed by the assimilating the unsprayed plants. The yield in plots with
parts of the plant and transported acropetally. good crop stand was higher than yield in plots
The systemic movement assures protection of with poor crop stand. The yield difference
actively growing parts of the plant. Propicona- between sprayed and unsprayed plants was sig-
zole is protected from wash-off by rain or irri- nificant only in plots with good stand. It is
gation and provides control for 24 weeks de- therefore practical to apply fungicide for Cer-
pending on the pathogens, disease pressure, and cospora leaf spot control on mungbean planted
the carrier used. before rice, provided that the crop has a good
Under local conditions, propiconazole at stand.
0.33% a.i. concentration applied by fixed wing Funicidal Property of Fruit feelings Against
aircraft every 21 days gave satisfactory control F cal Po y o F P ain
*of Blk S At p t pe Colletotrichum coffeanum Noack Causing
of Black Sigatoka. At present propriconazole Anthracnose of Coffee. P.Q. Sumaoy and N.G.
is registered as Tilt 250EC for use in control- Tangonan, USM, Kabacan, North Cotabato
ling Black Sigatoka in Cavendish banana.
Crude sap extracted from the peelings of
Identification and Control of PathogensCausing mango, pineapple, mabolo, banana, calamansi,
Crown Rot of Banana at Hijo Plantation, avocado, guava, papaya, and santol were as-
Madaum, Tagum, Davao del Norte. L. R. Hilo- sayed for fungicide properties against Colleto-
men, N. G. Tangonan, and J. C. Silvestre, trichum coffeanum Noack causing anthracnose
University or Southern Mindanao (USM) Kaba- of coffee.
can, North Cotabato






Philippine Phytopathology Vol. 23


Crude sap of calamansi was the most potent
against the test fungus, with a mean inhibition
zone of 20.42 mm followed by the crude sap
of mango, santol, papaya, and banana peelings
with inhibition zones and means of 16.55,
15.23, 13.87, and 12.61 mm, respectively.
The inhibitory effect of the five crude saps
against the test organism was further con-
firmed in the screenhouse test. Seedlings treat-
ed with calamansi and mango crude sap had the
least infection means which was comparable to
the effect of captain.

Bioassay of Fungicides Against Fungal Patho-
gens Associated with Sugarcane Seed Pieces.
E.L. Espina and J.C. Silvestre, USM, Kabacan
North Cotabato.
The efficacy of some commercial fungicides
against Colletotrichum falcatum Went causing
red rot and Thielaviopsis paradoxa (de Seynes)
v. Hohnel causing pineapple disease of sugar-
cane was determined in a bioassay conducted at
at the Department of Plant Pathology Labora-
tory, University of Southern Mindanao.

Bioassay test showed that Benlate and Pol-
yoxin AL at 0.2% concentration inhibited the
growth of T. paradoxa. C. falcatum was inhibi-
ted by Benlate and Dithane M-45 at the same
concentration.
Differentiation of Conidia and Conidiophores
of Powdery Mildews Collected from Nine Plant
Species. R. Quitco and R. de Guzman, UPLB
College, Laguna
Conidia and conidiophores of the powdery
mildew fungi from nine plant species were
examined. Majority belongs to the formgenus
Oidium; the rest, to the form-genus, Oidiopsis.
The contradictions between the reported pow-
dery mildew general and general predicted by
the asexual stage observed are pointed out.


Diplodia macrospora: A Threat to Corn Pro-
duction in the Philippines. S.C. Dalmacio and
G.P. Lozano, Pioneer Overseas Corporation,
Cabuyao, Laguna.

In 1985, Diplodia macrospora was found
associated with ear rot and leaf blight on corn.
Ear rotting in one corn-growing area in South
Cotabato was about 20 percent. Since then,
both the ear rot and leaf blight have been
consistently observed in almost all corn-growing
areas in South Cotabato.


Field observations and inoculation experi-
ments indicated that the fungus causes three
phases of infection, namely: the leaf blight, ear
rot and stalk rot. The leaf blight phase appears
to be initiated first, followed by the ear rot and
stalk rot phases. Infection of the ear either pro-
ceeds or occurs simultaneously with the stalk
rot phase. Symptoms of the leaf blight, ear rot
and stalk rot are described.
Additions to Philippine Fungi. K. Soytong and
R. O. de Guzman, UPLB, College, Laguna

Ampelomyces sp. which was found to be
associated with powdery mildew on squash and
Darluca sp. which was found, in the uredinia of
a legume rust are reported in the Philippines for
the first time. Both fungi are reported in other
countries as mycoparasites. Other crops infect-
ed with powdery mildew and rust were exa-
mined but neither of the fungi were found on
any of them.
Spegazzinia sp. from rice seed, Phyllachora
sp. from banana, teliospores from pole sitao
rust, and a possible Guignardia sp. from Folia
are also reported.

Taxonomic Notes on a Hyperparasite Found
Associated with Citrus Black Mildew. E. C.
Concibido and R. O. de Guzman. UPLB,
College, Laguna
A hyperparasite found associated with the
citrus black mildew, Meliola sp. is described. It
is identified as Calonectria sp. (synonym:
Epinectria), belonging to the Family Hypocrea-
ceae, Order Sphaeriales and Class Ascomycetes.

Identification of Some Graminocolous "Hel-
minthosporium" Isolates. R. Ong Sotto and
R.O. de Guzman. UPLB, College, Laguna.

The genus Helminthosporium causing disea-
ses of Graminae has been segregated into four
genera Drechslera, Bipolaris, Exerohilum, and
Helminthosporium. This study was done to de-
termine the proper genera to which some of the
common graminocolous Helminthosporium

belong.
Isolates were obtained from Helminthospo-
rium infected rice, wheat, and corn. Their
morphological characteristics were compared
based on keys described by Luttrell (1977)
and Alcorn (1983). The isolates that were iden-
tified were Bipolaris maydis, B. oryzae, B. soro-
kiniana, Drechslera sp., Exorohilum rostratum,
E. holmii and Helminthosporrium torulosum.


Philippine Phytopathology


Vol. 23






Jan. & June 1987 Abstracts of Papers


Effects of a Fungus, Paecilomyces lilacinus on
Nodule Formation and Nematode Infection on
Mungbean. R.G. Davide and R. A. Zorilla,
UPLB, College, Laguna.

Results of greenhouse experiments showed
that Paecilomyces lilacinus applied alone and
in combination with Rhizobium sp. was effect-
ive against root-knot nematode infection as
shown by slight root galling and lower gall
counts. The control plants and those inocula-
ted with Rhizobium alone showed moderate
to severe gall index and higher gall counts.
Paecilomyces lilacinus applied to mungbean
without prior inoculation with M. incognita
eggs increased nodule formation by 78.61%
which was comparable with the results ob-
tained from the Rhizobium treatment. The
plant without P. lilacinus and Rhizobium
treatments and M. incognita inoculation had
the lowest number of nodules.
Mungbean plants inoculated with M. incog-
nita eggmasses prior to P. lilacinus application
had 100% increase in nodule formation. Same
results were obtained from the combined
Rhizobium and P. lilacinus treatment. Rhizo-
bium application after inoculation of the
root-knot nematodes did not induce nodule
formation. Mungbean plants inoculated with
eggmases of M. incognita alone without either
P. lilacinus and Rhizobium treatment did not
form nodules.
Field experiments showed that P. lilacinus
used as seed-dip and as rice hull-rice bran
soil mix treatments generally increased nodule
formation by 36.56% and 49.10%, respectively.
Better plant growth, yield and percentage
nematode control were obtained compared
with plants treated with Furadan 3G at 4.5 kg
a.i./ha. The untreated plants had the lowest
percentage germination, nodule formation and
yield. Nematode population in the soil also
increased.


Evaluation of Primicid 10G for the Control of
Tomato Root-Knot and Potato Cyst Nema-
todes. R.G. Davide and R. A. Zorilla, UPLB,
College, Laguna

Primicid 10G, which is basically an insecti-
cide, was tested in the greenhouse for its effi-
cacy against tomato root-knot nematodes,
Meloidogyne incognita, and potato cyst nema-
tode, Globodera rostochiensis. Results showed


that the chemical was less effective in redu-
cing nematode infection in roots of tomato as
shown by higher root galling indices (slight to
moderate) compared with Nemacur 10G and
P. lilacinus treatments. The same trend was ob-
served in the reduction of nematodes in the
soil. Although the galling indices and root-knot
nematode population in the soil were higher,
Primicid 10G treated plants showed higher
yield increases at 3 and 2 kg a.i./ha (116.0%
and 95.1%) as compared with that of Nemacur
10G (82.7%) and P. lilacinus (85.2%). How-
ever, at lower rates and using corn cobs as car-
rier the chemical treatment gave lower yield.
On the other hand, Primicid 10G is capable
of reducing the cyst nematode population in
the soil and roots of potato with control ran-
ging from 77.4% to 86.7%. The chemical was
not as effective as the nematicide Nemacur and
the biocontrol fungus P. lilacinus as shown by
the nematode counts, Primicid 10G treatment
resulted in higher percent increases in roots,
shoots and tuber weights compared with the
chemical in powdered corn cobs. On the other
hand, those of P. lilacinus and Nemacur treat-
ments exhibited more or less the same root and
shoot weights. The tuber weight increase in
P. lilacinus treated plants was higher. The un-
treated check plants had the lowest yield
among the treatments.


Transmission of Tungro-Associated Viruses by
Field Colonies of Nephotettix virescens and
their Mode of Feeding on Selected Rice Culti-
vars. G. Dahal, V.M. Aguiero and H. Hibino,
IRRI, College, Laguna
During May to August 1986, adult green
leafhoppers (GLH) Nephotettix virescens,were
collected in Koronadal, South Cotabato; Mali-
gaya, Nueva Ecija; Camarines Sur and Albay
(Bicol); and Los Banos, Laguna, and reared on
TNI seedlings. A colony selected on TN1 was
also included in the this study. The first genera-
tion adult GLHs which had fed on plants in-
fected with rice tungro bacilliform virus
(RTBV) and rice tungro spherical virus (RTSV)
were tested individually for their transmission
efficiency and feeding behavior (xylem and
phloem feeding) during the inoculation feed-
ing. Inoculated seedlings were indexed by
latex test. Most of GLH fed on both phloem
and xylem or xylem alone in all the cultivars
tested. Generally in GLH resistant cultivars
IR26, IR36 and IR54, GLH that transmitted


Jan. & June 1987


Abstracts of Papers





Philippine Phytopathology Vo



'BV and/or RSTV, fed more on both phloem infection, while ASD 7, Gam Pai 30-12-15,
i xylem, and those that failed to transmit the Palasithari 601 had relatively high infec-
us(es) fed predominantly on xylem. How- Habigani DW8 and Utri Rajapan had low I
Tr, some GLH fed on xylem and mostly of infection, whereas IR22 and TN1 had
nsmitted the viruses, levels. All cultivars, except IR22 and
After 4-5 overlapping generations on TN1, which were mostly infected with both R'
fl of Koronadal, Bicol and TN1 colonies and RTSV, were infected most frequently
re given an inoculation access in the plastic RTBV alone. Ultri Rajapan and Babiganj 1
ys with randomly planted seedlings of IR26, showed resistance to virus infection in spit
36, IR54 and TNI, GLH number that alight greater phloem feeding by the leafhoppel
on each cultivar was counted and seedlings them.
re indexed for virus infection. The three The amount of acidic and basic honey
onies preferred TN1 but IR26,.IR54. Bicol excreted differed on the cultivars tested. I
1 Koronadal colonies preferred IR36 more ever, there was no significant difference in
in TN1 colony. During the test, the two field amount of basic honeydew on each cultivar
lonies transmitted RTBV and/or RTSV in ween virus-transmitters and non-transmit
;her rate than TN1 colony. The field colo-
!s transmitted the viruses more efficiently on
26, IR36 and IR54, than TN1 colony. High Transmission of the Tungro Associated Vir
igro incidence on IR54 in Koronadal could by Nephotettix nigropictus. V. Aguiero, E.
explained by the presence of GLH popula- sina and H. Hibino, IRRI, College, Lag
n which transmits both RTBV and RTSV
>re efficiently on IR54.
re efficiently on R54. Adult Nephotettix virescens and N. ni
pictus were allowed to feed on the same pli
msmission of Tungro Associated Viruses and infected with both rice tungro bacillif
de of Nephotettix virescens (Distant) Feed- (RTBV) and rice tungro spherical (RTSV)
in Ten Rice Cultivars. G. Dahal, H. Hibino ses for 4 days, and then confined with 5.
R.C. Saxena, IRRI, College, Laguna old seedlings of 14 varieties in test tubes at
insect per seedling for 1 day. One month a
Relationship between feeding behavior of inoculation, seedlings were indexed by
Ahotettix virescens adults and transmission latex test.
the tungro virus agents was determined in N. nigropictus transmitted either RTBV,
dlings of ten rice cultivars showing resistant RTSV together, or RTBV or RTSV alone,
susceptible reaction to either the vector or its transmission efficiency was lower than t
igro disease or both. Phloem feeding and of N. virescens. N. nigropictus preferential
[em feeding of leafhoppers which had fed on transmitted RTBV alone to almost all varie
nts infected with both rice tungro bacilli- tested. IR26, IR56, IR62 and IR64 were
m virus (RTBV) and rice tungro spherical infected with either virus when N. nigropic
is (RTSV) were demonstrated by the pre- was used as vector while they were mo
ce of acidic or basic honeydew spots on bro- infected with RTBV alone when N. viresc
cresol treated filter paper discs, and by the was used.
hydrin-safranin test, respectively. Seedlings
:ed for the feeding site were indexed for the Isolation, Purification and Serology of f
sence of RTBV and RTSV. Tungro-Associated Viruses. P. Q. Cabaua
Dn all cultivars, the leafhoppers fed either qnd H. Hibino, IRRI, College, Laguna
xylem and/or phloem during inoculation
ess. Greater xylem feeding occurred on vec- Rice tungro is a composite disease cau
resistant cultivars ASD 7, Gam Pai 30-12- by rice tungro bacilliform virus (RTBV)
Ptb 1, and ARC 11554. In contrast, greater rice tungro spherical virus (RTSV). Susce
ding occurred on vector-susceptible cultivars ble rice cultivars, which are used for v
bIganj DW8, Utri Rajapan, IRII, and TN1.
ganj DW8, Utri Rajapan, IRI, and TN. propagation, are infected with both viruses
long the vector resistant cultivars, ARC hinh franiipn,-, PriPrftin nmf DTIlY





Jan. & June 1987 Abstracts of Papers 31



RTSV and RTBV were isolated from plants jected to off-barring and hilling-up operations.
inoculated by leafhopper, Nephotettix vires- Apparently, cultivation of the field and spread
cens, fed on tungro infected plants. RTSV- of the disease increased the severity of infec-
infected plants were identified serologically tion.
using antiserum to rice waika virus which is Highest corn yield was obtained from the
closely related if not identical to RTSV. RTSV population of 80,000 plants/ha with a mean
was multiplied in rice cv Taichung Native 1 yield of 5633.66 kg/ha aid 4721.65 kg/ha in
(TN1) by a series of transfers using leafhoppers. wet and dry season trial, respectively. Stalk rot
RTBV, on the other hand, is non-transmissi- was high at 90,000 plants/ha and reduced signi-
ble from plants infected with RTBV alone. To ficantly the yield of corn. Plots subjected to the
multiply RTBV, leafhoppers fed on tungro- off-barring, hilling-up, and hand weeding had
infected plants were allowed to feed on anti- 3ff-brkg/ha hiin wet season and 4155.33 kgha
RTSV serum for 16h and then on RTBV- 3371.64 kgha inwet season and4155.33 kgha
.inf d p ts for 8 h befre an inoc ion in dry season, respectively. Handweeded plots,
infected plants for 8 h before an inoculation on the otherhand yielded 5519.49 and 5863.2
on the other hand, yielded 5519.49 and 5863.2
access on TN1 seedlings. both in wet and dry season trials, respectively.
RTBV and RTSV were separately purified The lowest yield of 2323.16 kg/ha in wet and
using the same procedure. Plant extracts were 3040.86 kg/ha in dry season was obtained from
clarified by heat and the virus was precipitated unweeded plots. The reduction in yield due to
by PEG. After differential centrifugation, the stalk rot was higher in plots with high popula-
virus was further purified by sucrose density tion of 90,000 plants/ha. Plots that were culti-
gradient centrifugation. Purified RTBV and vated had higher losses compared to plots
RTSV had UV-light absorption spectra typical which were not cultivated. The different cul-
of nucleoproteins. Absorbance ratios,(A 260/ tural practices adopted in growing corn influ-
280) were 1.13-120 and 1.52-1.75, for RTBV enced stalk rot incidence and consequently the
and RTSV, respectively, yield of corn.
Rabbit antisera with titers of 1/2560 for
RTBV and 1/640 for RTSV in precipitin ring Effect of Plant Growth Stage on the Expres-
interface test were obtained. Latex test and sion of Moderate Resistance of Rice to Bacte-
ELISA specifically detected RTBV and RTSV real Leaf Blight. M. F. Koch, IRRI, College,
in leaf extracts. Healthy plant sap gave nega- Laguna
tive reactions to either antiserum in both tests.
The antisera did not cross-react with the viru- Six cultivars ranging from highly susceptible
ses. to moderately resistant reaction were planted in
pots at weekly intervals to produce 7 plant
Incidence of Stalk Rot on Corn as Influenced ages. When these were respectively 30, 42, 49,
by Different Cultural Practices. T. C. Bayacag- 56, 63, 70 and 77 days after sowing, all plants
Bayoran and 0. R Exconde, USM, Cotabato were clip-inoculated so that half of the plants
and UPLB, College, Laguna per pot were inoculated with Xanthomonas
and UPLB, College, gun campestris pv. oryzae isolate PX086 and half
with PX099 (both + 108 cells/ml). Measure-
This study was conducted at the Southern ments at 14 days after inoculation showed that
Mindanao Agricultural Research Center lesion length on plants between 50 days and
(SMARC), University of Southern Mindanao to booting were shorter than on younger plants of
determine the effect of different cultural prac- all cultivars.
tices such as population density, tillage, and A second experiment was done to test di-
weed control practices on the occurrence of sease reaction at the flowering/post-flowering
stalk rot, and to evaluate the effect of stalk rot stages of development. Via staggered planting,
on the yield of corn. the seedling, maximum tillering, late booting/
Increasing population density of corn from early flowering, and post-flowering stages of the
50,000 to 90,000 plants/ha did not significant- six cultivars were synchronized. All plants were
ly affect the percentage infection of stalk rot in simultaneously inoculated as described above.
the field. No difference between the. reaction of the flag
leaf at and after flowering could be found; flag
In tillage and weed control practices, the leaves always developed shorter lesions than top
highest infection was obtained from plots sub- leaves of plants at maximum tillering.





Vol. 23


storage time. The total


ean Xanthomonas campestris pv. oryzae races ity. The biochemical changes in the feed
a Suweon, South Korea. Varieties resistant to significantly correlated with fungal and I
ome or all X. c. pv. oryzae races in the Philip- rial population.
lines were also resistant to three races in Korea
.t seedling, maximum tillering and flagleaf
tages. Milyang 83, a Korean variety was resist- Survey, Pathogenicity and Chemical Cont
nt to 3 Korean races at 3 growth stages. Alto- Clubroot (Plasmodiophora brassicae Wos
ether, 11 varieties from both institutions con- Chinese Cabbage (Brassia pekinensis). S
istently showed adult plant resistance to the awan, BSU, Benguet
The study was conducted to determir
hree races; susceptible at seedling and resistant Te s c t to d ri
*,. ~ : .... s occurence of clubroot disease in crucifer-


,.a- ,smoatopnora orasswcae wc
Id may be useful to differentiate iso- rwsmowopnor orassicae wc
Cabbage; and to compare the
rea. Renlate Rracirnl Previciir N


r-r--~ - ,, TPTR o house ana elia conditions.
e Philippines. R. P. Garcia, UPLB, College, lu oot disease incidence as e
Clubroot disease incidence was ge


.s part or


clubbing ot the plants; the del
fumigatus, A. niger, A. oryzae, A. petrakii, genelly inches ith
generally increases with incre
id A. Tamarii. The probable identities of the inocula.
enicillium spp. identified were: P. citrinum, iocu a
uc sm Among the five chemicals t
cyclopium, P. frequentans, P. funiculosum, e e t e he
islandicum, P. oxalicum, P. patulum and when used to rai./wee effe
.iiiausicol at 70 kg aji./ha were effe
vidicatumling the disease both under
Of the 122 Aspergillus isolates analyzed for field conditions. Clubbing wa!
latoxin, 17 isolates were positive for aflatoxin burnt lime and Brassicol even u
i and 6 isolates produced both aflatoxin BI of 160,000 and 10,000 spore:
d G1. One htindred twenty six Penicillium ively.
plates were found negative for ochratoxin.
Physiological Characterization
deterioration of Mixed" Feed at Different distance to Sheath Blight of Ric
dlative Humidity Levels. A. Nagamani and V.P. Coronel, S.W. Ahn, S. A
. Nusrath Mew, IRRI, College, Laguna

The effect of varying levels of relative Varietal differences and dy:
timidity on the microbial growth and on the carbohydrates, sugars, starch,
ochemical constituents of mixed feed during phorus, potassium, calcium, w-
orage was studied. Different species of fungi rice sheaths and leaves at booti
)minated in the feed at different levels of rela- days after flowering (10 DAF)
re humidity and storage time. The microbial from 7 rice cultivars/lines in re]
)pulation, moisture content, the free fatty blight development. Starch and
idity and the total reducing content increased were significantly higher in re
whereas the total crude protein content and susceptible cultivars while silica
iluble carbohydrate content in the feed de- contents were significantly high
eased with a concomittant increase in rela.- than in resistant cultivars. Vari


ied, bur
:o 7.2 an
tive in c
reenhou
suppres
to popi
Ig soil, I


of Varie
. B.L. C
kita, ani


amics o
nitrogen,
(, and s
g stage
were an
-


tal diffh





e 1987 Abstracts of Papers 33



ier chemicals analyzed were not signi- Bacterial Wilt of Peanut. M. P. Natural, L.D.
Valencia and A.R. Pua, UPLB, College, Laguna
*gative correlation between the con-
egative correlation between the con- The presence of bacterial wilt of peanut
tarch, sugars and total carbohydrates caused by seudomonas solanacearum E. F.
ves and sheaths and cultivar differen- caused by omos solanacearum E. F.
Smith is hereby reported. Isolation and patho-
mage measured as the percentage of e ty tested
heath areas infected was statistically genicity tests were conducted.
. On the other hand, phosphorus con- Inoculation experiments on tomato, egg-
e leaves and sheaths was positively plant, peanut, pepper, tobacco and abaca indi-
with the damage levels of different cated that the peanut isolat belongs to race 1.
Biochemical tests showed that it belongs to
Sheath silicon contents was positively biovar 3.
with sheath blight. The results strong-
with sheath blight. The results strong- Of the twenty-one selected promising peanut
a close association between in- cultivars and advanced IPB lines/accessions
susceptibility and the carbohydrate
susceptibility and the carbohydrate evaluated for resistance by scalpel-leaf-clip
Inamics between vegetative parts and
dynamics between vegetative parts and method in the greenhouse, five peanut lines
ive parts at critical periods of the
Were highly resistant, six lines were moderately
gress resistant while the rest were susceptible to high-
ly susceptible.

POSTER PRESENTATIONS

f Undergraduate Research in the the students were detailed on practicum at
nt of Plant Pathology, College of various government and private agencies.
-e, University of Southern Minda-
scan, Cotabato. L. Sanchez, Jr. and Use of Endomycorrhizal Fungus to Challenge
gonan, USM, Kabacan, North Cota- Rhizoctonia Infection in Selected Field Crops.
Lina L. Ilag, Avelita M. Resales and T.W. Mew,
ly to document undergraduate re- IRRI, College, Laguna
diseases of plants or agricultural crops Mycorrhizal fungi which form symbiotic
icted in the Dept. of Plant Pathology, associations with higher plants may have
f Agriculture, University of Southern varying effects on plant disease. This study was
. The findings of the study would be conducted to determine the effect of a vesicu-
reference material to agriculture lar-arbuscular mycorrhizal (VAM) fungus on
researchers, policy makers, and other infection caused by Rhizoctonia solani.
individuals and institutions both at Glomus sp. which was isolated from a rice-
elsewhere. field in Pangasinan was used to challenge R.
1 of 333 undergraduate theses on di- solani in corn, rice, mungbean and peanut in
plants was conducted from school pot experiments. The VAM fungus reduced the
7-1978 to 1985-1986. Based on causal incidence of Rhizoctonia infection in corn
, fungi constitute 283; viruses, 60; from 66.6% to 8.3% in steamed soil and from
41; and nematodes, 28. On the other 16.6% to zero disease occurrence in natural
ied on the nature of study done, field soil. Less severe infection was observed
identification as objective totalled in mycorrhizal corn plants compared to non-
ase development, 121; plant disease mycorrhizal plants.
02; surveys on disease occurrences, Sheath blight incidence in rice was reduced
range, 21; screening for varietal re- by 45% when Glomus sp. and R. solani were
7; and techniques, 3. Furthermore, both added to the soil at the time of seeding
hosts/crops infected, cereals consti- and by 30% when Glomus sp. was added at
highest, 149; plantation crops, 62; root seedling, and sclerotia of the pathogen added
; fruit crops, 13; vegetables, 29; spi- a month after seeding.
Id weeds and ornamentals, 4. The VAM fungus had no effect on infection
ition, a total of 47 reports of infirm by R. solani in mungbean as the pathogen
ire also listed. The reports dealt on caused damping-off of seedlings a few days
t of plant pathology at a time when after seeding before mycorrhizae could be









established. R. solani did not cause any nota- famacalis Guenee. It has been established in
ble infection in peanut and no significant dif- corn growing areas in Mindanao and in Isa
ferences were observed between mycorrhizal where it was first released in 1983-84. Para
and non-mycorrhizal plants. zation on corn borer ranges from 30 to 1C
Our results indicate the potential of utilizing The predator coccinellid beetle Cur
mycorrhizae in the management of Rhizoctonia coerruleus Mulsant, was tested and has sh
solani infection in rice and corn. great promise as a biological control al
against the jumping plant lice (Heterops
Evaluation of Two Soil Fungi for the Biocon- cubana Crawford; Syn. H. incisa Sulz) of
trol of Citrus Nematodes Irma C. Tandingan ipil. The beetle has adapted in areas whel
and R. G. Davide, UPLB, College, Laguna was released.
The fungal agent, Metarrhizium anisol
This study compared the biological control Sorok, was found effective against the cocc
potential of Paecilomyces lilacinus (Thom) beetle (Oryctes rhinocerous L.). Another st
Samson and Penicullium anatolicum Stolk with of the fungus has shown to work well ag,
the effect of fenamiphos against Tylenchulus termite. Neoaplacetana carpocapsaea Wi
semipenetrans (Cobb) on citrus using two appli- (syn. Steinernema sp.), an entomogenous
cation methods. Control efficiency was based matode, infected larvae of corn borer, coc(
nn O npm.tnral rpPratinn hnth in th+ rmntr ant black beetle (Orvctes rhinocerous). hornw


r. iiacinus or r. anaroacum appnea a
drench using spore suspension or grown in
state (1:2 rice hull-rice bran) and appli(
soil mix significantly controlled T. semij
trans under greenhouse conditions. Effects
comparable with fenamiohos at 100 onm. 1


Onset and Spread of Tungro Infection in
Field. Z.M. Flores, E.R. Tiongco, and
Hibino, IRRI, College, Laguna


anu appueu
seei


individual effects of the fungi. Generally, bc
fungal treatments greatly affected nemato
population in the soil than those in the roo
Microscopic examination of nematodes pa
sitized by P. lilacinus showed mycelial grow
around and inside the body. P. anatolicum c
not parasitize the nematodes but produce
toxic substances that killed them.
Results indicate that P. lilacinus or P. ar
tolicum applied as soil drench or grown in ri
hull-rice bran substrate and applied as soil mi
has biocontrol potential comparable with
better than the nematicide fenamiphos at 11
ppm.
Biological Warfare Against Crop Pests. Biol
gical Control Laboratory, Bureau of Pla
Industry, Manila

Work at the Biological Control Laborato:
has been expanded to include four biologic
control agents.
The most common egg parasitoid Trich
gramma evanescens West. was found effect
ive against the Asian corn borer Ostrin


Lilll Ildpilll 111 LIuV 11lU. 1I4U LUIIU r IlUC;LJ
was observed 22 DAT in all plants from i
covered seedbed while infection rates of 0.:
in plants from the uncovered seedbed plant
in the screenhouse and 0.1% in the field we
recorded. At 37 DAT, the plants in the fi
from the covered seedbed had 13% infecti
and those from the uncovered seedbed I
12% which increased to 77 and 79% at
DAT.
The spatial spread of tungro in the fit
from the initial infected hills to three distar
classes of surrounding (direct neighbor, dial
nal, and distant) hills was determined using
varieties with different levels of resistance
the green leafhopper. Although higher level
infection was recorded on TNI plants at
DAT, no difference in the occurrence of
fection in the three distance classes was <
trained in all varieties. At 37 DAT, more dir,
neighbor hills of TNI plants were infect
compared with those of diagonal or dist,
hills while infection rates of the three distar
classes in IR36 and IR54 plants did not diff
However, infection rates between direct neij






ADSKUCIS 01 rap~r~ 35


cted than IR36 and IR54 plants. At 44
r, the same results were obtained.
results showed that the onset of tungro i
action occurred within a month after trans- 1
citing and the spatial spread of the disease is
e likely to occur on the immediate sur-
iding (direct neighbor and diagonal) hills of I
cted plants of a susceptible variety.
I
survey of Trichoderma Species in Rice Field s
i of the Philippines. A. Nagamani and T.M. I
v, IRRI, College, Laguna

i survey was carried out to understand
hoderma occurrence and distribution in
i of rice fields in the Philippines. During
aber 1985 to 1986, 200 soil samples were i
,cted from 23 provinces. Trichoderma was I
ited and detailed morphological study was
led out to identify the species by using light 1
electron microscopes. Thirteen species
e identified. T. hamatum, T. koningii, T.
,ibrachiatum, T. polysporum, T. pilulife-
., T. reesei, and T. viride are recorded for 1
first time in the Philippines. Two uniden-
:d species were recorded from some provin- 1
Other species encountered include Tricho-
na aureoviride, T. glaucum, T. harzianum,
T. pseudokonqii. All species were found
be antagonistic to sheath blight fungus of
in vitro.

ects of Storage on Antigenecity of Rice
ssy Stunt Virus in Infected Leaves. E.
iina and H. Hibino, IRRI, College, Laguna

ice grassy stunt virus (RGSV) infected rice
es were dried and cut into three equal


ces. inese pieces Irom eacn ieai were store
3 different temperature conditions namely,
im temperature, in a refrigerator, andin a
ezer. The latex test and ELISA were adopted
test antigenecity of RGSV in dried leaves.
e latex test detected RGSV antigen up to 10
inths of storage in the freezer, while ELISA
:ected it even after one year.

ect of Preinoculation Temperature on Re-
ance to Rice Blast. K.K. Baloch and J.M.
nman, IRRI, College, Laguna

Three temperature regimes; 30/20 C, 30/28
and greenhouse 36/26C (control) (day/night)
re evaluated for their effects on rice blast
ease in 18 rice cultivars. The test materials
luded 14 cold tolerant lines selected in the
ernational Rice Testing Program. Ten-day
Seedlings were exposed to the tempera-
e treatments in the IRRI phytotron for 10
Is and seedlings were thereafter inoculated in
reenhouse with a compatible isolate ofPyri-
aria oryzae at 50,000 spores/ml. Disease was
assured by counting the susceptible-type le-
ns on individual leaves 6 days after inocula-
n. Significant differences were observed bet-
en temperature treatments and between cul-
ars. Both the Japonica cultivars Giza 171,
,a 172, Reiho and Fuji411, and the Indica
Itivars China 1039, China 988, Bikong Ps-
1, IR 36 and IR50 had significantly more
ions/plant at low night temperature than at
;h night temperature. Two Indica cultivars
680B and IR9202 had fewer lesions/plant
der the low night temperature treatment.


35


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Republic of the Philippines
-tment of Public Works, Transportation and Communication
RIIRFAII OF PO.T.


SWORN STATEMENT
(Required by Act 2580)

The undersigned, AVELINO D. RAYMUNDO, Editor-in-Chief of PHILIPPINE
'HYTOPATHOLOGY, published semi-annually in English, in College, Laguna, after
having been duly sworn in accordance with law, hereby submits the following statement
>f ownership, management: circulation, etc., which is required by Act 2580, as amended
y Commonwealth Act No. 201.

Editor :AVELINO D. RAYMUNDO
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ated at the last issue date June 1985.

1. Sent to paid subscribers ...... 120
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SGD. AVELINO D. RAYMUNDO
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SUBSCRIBED AND SWORN to before me this ____ day of May 1987 at
college Laguna, the Affiant exhibiting his Residence Certificate No. 10087677 issued at
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Zv liv. Xv u11 LHYtU. 31, ILYO
)ok No. 3 PTR No. 1174223
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