• TABLE OF CONTENTS
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 Front Cover
 Abstracts of papers presented at...
 Comparative effects of several...
 Evaluation of crude apint extracts...
 Pathogenicity, damage assesment,...
 Postharvest control of erwinia...
 Influence on tungro virus-infected...
 Phytopathological note: Occurence...
 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/UF00090520/00026
 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 1984
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: VID00026
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 54382605
issn - 0115-0804

Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Abstracts of papers presented at the twenty-first annual meeting of the Philipines phytopathological society, PCARRD, Los Baños, Laguna 21-23 May 1984
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
    Comparative effects of several fungicides on coffe leaf rust incidence and yield
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
    Evaluation of crude apint extracts as fungicides for the control of cercospora leafspot of mungbean [Vigna radiata (L.) Wilzeck]
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
    Pathogenicity, damage assesment, and field population pattern of hirschmanniella oryzae in rice
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
        Page 44
    Postharvest control of erwinia carotovora var. carotovora in cabbage with alum and lime
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
    Influence on tungro virus-infected rice plants on the behavior and biology of the green leafhopper nephotettix virescens and its role in tungro epidemics
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
        Page 60
        Page 61
        Page 62
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
    Phytopathological note: Occurence of citrus trizteza in Benguet and Mt. province, Philippines
        Page 68
        Page 69
        Page 70
        Page 71
    Information for contributors
        Page 72
    Back Cover
        Page 73
        Page 74
Full Text




uEn....


'hytopathology



LUME 20 JANUARY and JUNE 1984 NUMBERS 1 and 2








CONTENTS



*acts of Papers Presented at the Twenty-First Annual Meeting of the
Dkilinnin4 Dktnntknlnniral CnIai s DP ( AI D0D I n RaRfln I aniln


nparative Effects of Several Fungicides on
and Yield R.G. Atabug and M.O. San Ji

luation of Crude Plant Extracts as Fun
Cercospora Leafspot of Mungbean [ Vig
Clarissa Josefa M. Maroon, O.S. Opina an(

logenicity, Damage Assessment, and Field f
manniella oryzae in Rice J.J. Walawala

tharvest Control of Erwinia carotovora var.
Alum and Lime E.S. Borromeo and Lin

uence of Tungro Virus-Infected Rice Plants
of the Green Leafhopper Nephotettix vire
Epidemics Z.R. Khan and R.C. Saxena

topathological Note: Occurrence of Citri
Mt. Province, Philippines D.J. Roettge
franca and J.S. Mariano ............


fee Leaf Rust Incidence
. ............... 20-26

es For the Control of
adiata (L.) Wilzeck] -
.. Molina, Jr. ........ .27-38

nation Pattern of Hirsch-
R.G. Davide ........ 39-44

tovora in Cabbage with
Ilag ............. 45-52

ie Behavior and Biology
s and Its Role in Tungro
. .. .. . . . 53-67

rizteza in Benguet and
A. Versola, A.M. Cima-
.. . .. .. .. . .. .. 68-7 1













PHILIPPINE PHYTOPATHOLOGY
Official Organ of the Philippine Phytopathological Society, Inc.

BOARD OF DIRECTORS 1983-84


MR. VALENTINO G. BALAOING President


DR. AVELINO D. RAYMUNDO
MISS LINA C. LAPITAN
MR. FRANCISCO A. ELAZEGUI
MR. JOSE M. BANDONG
MR. FAUSTO L. NUQUE
DR. ROMULO G. DAVIDE
DR. GIL G. DIVINAGRACIA
DR. JOHN BONMAN
DR. DELFIN B. LAPIS
DR. AGUSTIN B. MOLINA JR.


Vice President
Secretary
Treasurer
Auditor
Ex-Officio
Board Member
Board Member
Board Member
Board Member
Board Member


EDITORIAL BOARD


DR. ARCADIO J. QUIMIO
DR. LINA L. ILAG
DR. FAUSTINO T. ORILLO


Editor-in-Chief
Associate Editor
Associate Editor


BUSINESS MANAGER
MR. CEFERINO A. BANIQUED





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Subscriptions: Communications should be addressed to the TREASURER, P.P.S. c/o Depart-
ment of Plant Pathology, UPLB, College, Laguna 3720. Philippine Phytopathology, published annually,
is the official organ of the Philippine Phytopathological Society, Inc. It is sent free to members in
good standing and Sustaining Associates. For others, it is P25.00 per copy (domestic) and $12.50 per
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Page Charge: The editorial board reserves the right to charge some authors a present amount for each
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any statement of claims made in advertisements is assumed by this Journal or by the Philippine
Phytopathological Society, Inc.












ABSTRACTS OF PAPERS PRESENTED AT THE
TWENTY-FIRST ANNUAL MEETING OF THE PHILIPPINE
PHYTOPATHOLOGICAL SOCIETY, PCARRD, LOS BAIOS,
LAGUNA, MAY 21-23, 1984

Experiments in the laboratory on the in- An undescribed plant parasitic nema-
sect parasitic nematode, Neoaplectana tode belonging to the family Aphelen-
carpocapsae Weiser (Leningrad strain) chidae was extracted in abundant num-
(Nematoda, steinernematidae). Tita Gal- bers from stem tissues of wilt-affected
bizo, Teresita Reyes and H. Nagraja, In- coconut palms and none from healthy
international Rice Research Institute ones in Socorro, Oriental Mindoro,
(IRRI), Los Baflos, Laguna. Philippines.
The nematode is very long (9 = 4.1
mm; 9 = 2.6 mm) and has a, slender
The insect parasite nematode Neoap- body (9 greatest body width = 0.075 mm;
lectana carpocapsae Weiser (Nematoda, + greatest width = 0.043 mm) with a set-
Steinernematidae) (Leningrad strain) ob- off head region which is narrower than
trained by the Biological Department of the body and not annulated. The stylet
the Cocoa Investors, Inc., Hagonoy. is short and the median bulb is ovate to
Davao del Sur from the Indian Station slightly elongate, while the esophagus
of Commonwealth Institute of Biological overlaps ventrally. The vulva of the adult
Control, Bangalore, India. In the labora- female which has an overlapping flap is
tory, the nematode was tested on the located about 95% of the body whose
following insect pests: Agrius convol- short tail has a pointed terminus. The
vuli (L.) (Lepidoptera, Sphingidae),Ama- adult male has a ventrally curved tail
thusia phidippus (L.) (Lep., Nympha- with caudal alae.
lidae), Chalococelis sp. (Lep., Limacodi- The nematode bears some similarities
dae), Oryctes rhinoceros (Coleoptera, to Rhadinaphelenchus cocophilus
Scarabaeidae), Ostrinia furnacalis (Gue- especially in so far as the males are con-
nee) (Lep., Pyralidae), Heliothis armiger cerned although the Philippine specimen
(Hb) and Spodoptera litura (F.) (Leo., is much longer (about 2 times in males
Noctuidae), Thosea spp. (Lep., Limaco- and 4 times in females). In addition,
didae), an unidentified coconut leaf the location of the vulva relative to the
roller (Lep.), and nymphs and adults of body length and the conical pointed tail
unidentified grasshoppers (Orthoptera). in females are distinct morphological
The use of this nematode for biological features.
control of noxious pests is dis-
cussed. The mechanism with which the Influence of tungro virus-infected rice
nematode kills the host is also discussed. plants on the behavior and biology of
the green leafhopper Nephotettix vires-
Aphelenchoid nematodes found asso- cens and its role in tungro epidemics.
cited with coconut palms affected by Z.R. Khan and R.C. Saxena, IRRI, Los
wilt disease in Socorro, Oriental Min- Baflos, Laguna.
doro, Philippines. Erlene C. Concibido,
Reynaldo G. Abad, Angelito P. dela Cruz The effects of tungro virus-infected
and Romulo G. Davide. University of rice plants on the behavior and biology
the Philippines at Los Banos. (UPLB), of the vector Nephotettix virescens
College, Laguna. (Distant ) were investigated. In a choice








Philippine Phytopathology


test, tungro-intectea plants attracteu sig-
nificantly more N. virescens individuals
than did the healthy plants, but after 24
hours and later, more individuals were
found to be settled on healthy plants.
Insect feeding on diseased plants was
disrupted and the quantity of food inges-
ted and assimilated was significantly less
than on healthy plants. There was no
significant difference in the number of
nymphs becoming adults on infected and
healthy plants, but the growth period
was prolonged on diseased plants. A
significant reduction in adult longevity,
fecundity, egg hatchability, and popu-
lation growth was observed on tungro-
infected plants, but ovipositional res-
ponse was not adversely affected. Bio-
chemical analysis of tungro-infected
plants showed an increase in the content
of free sugars but a decrease in soluble
proteins as compared to that in healthy
plants. The deleterious effects of tungro-
infected plants on N. virescens biology
could be attributed to changes in plant
food quality.

Postharvest control of Erwinia carotovora
var. carotovora in cabbage. Emerlito S.
Borromeo and Lina L. Ilag, UPLB,
r _.. 11 I T .


Ul DJL JUL. lt-, a W-- -- -* '
washed out by surface water in wrapper
leaves and so was ineffective in transit
particularly during the wet season.

Host range, development and survival
of potato cyst nematode Globodera
rostochiensis on potato in the Philippines.
Rustico A. Zorilla and R.G. Davide,
UPLB, College, Laguna.

The potato cyst nematode, Globodera
rostochiensis Woll., infected, developed
and reproduced only on potato and
tomato where they developed into cysts
60 days after inoculation. On the other
plants such as eggplant, onion, okra, mus-
tard, pechay, sweet peas, lettuce and
carrots, the nematodes invaded the roots
but none developed beyond the second
larval stage except that in eggplant where
three individuals reached the 4th stage.
The nematode did not invade pepper,
tobacco, cabbage, cauliflower, Baguio
beans and winged beans. The weeds
Spergulla arvensi and Lolium multiflorum
were not infected by the nematode.
G. rostochiensis developed much faster


/ol. 20








an. & June 1984 Abstracts of Papers 3



md assessed for their effect on yield of generally gave comparable effects with
xrabica coffee trees. All the fungicides the isolate from Peru. These two isolates
ested significantly reduced disease in- of P. lilacinus were generally more
idence levels as compared to unsprayed effective that G. roseum and A cladodes.
rees. Bayleton, a systemic fungicide, was The cyst reduction in P. lilacinus treat-
observed to be superior over all other ment of both isolates ranged from 31.9 to
ungicides in controlling the disease. 50.8% whereas those of G. roseum ranged
Coffee berry yield from the different from 22.5 to 41.9%. A. cladodes treat-
reatments did not significantly vary ment which was applied only as tuber
luring the 1982 season, but the effect dip showed only 20.5% reduction of the
if some fungicides on yield was apparent cyst nematode at the third month count.
he following year. Among the treatments Comparing the fungal treatment effects
hat increased in yields were those with the nematicides phenamiphos (Ne-
prayed with Cupravit, Bayleton, Saprol macur 106) and Isazofos (MIral 10G),
* Plantineb, Difolatan 4 Flowable, and only the combined tuber dip and soil
he control. The highest yields obtained mix treatment of P. lilacinus from Peru
rom Cupravit and Bayleton did not showed no significant difference with
significantly differ from that of Difolatan isazofos treatment based on the 1st, 2nd,
. Flowable, but were significantly higher and 3rd month cyst count. All other
han those treated with Saprol + Plan- fungal treatments effects were signifi-
ineb, Delan, Galben, Saprol and the cantly lower than the effects of the two
treated check. nematicides.
A notable decrease in yield was how- Based on the yield data all fungal
ver obtained from trees treated with De- treatment showed significant increase in
in, Galben and Saprol. yield as compared with the check. The


parea witn some nematciaes. Komulo
G. Davide and Rustico A. Zorilla, UPLB,
College, Laguna

Three nematophagous fungi Paecilo-
myces lilacinus (Thom.) Samson, Glio-
cladium roseum Thorn. (Link), and Ar-
throbotrys cladodes Dreschs.) were
shown to effectively control the potato
cyst nematode Globodera rostochiensis
Woll. on potato grown in Madaymen,
Bufguias in Benguet province resulting
in significant increase in yield of potato
cv. Isola. However, their effectiveness
varied with the methods of application
such as tuber dip, soil mix, and com-
bination of both. Chopped water lily
leaves were used as substrate for the
fungus used in soil mix treatment. P.


,ave 22.9 to 32.4% yield increase as
compared to 20.3% in A. cladodes treat-
nent. All treatments resulted in higher
percentage yield increase of marketable
irst and second class potato tubers.
Water lily applied as soil mix without
he fungus also controlled the nematode
ly reducing 16.8% the cyst counts in the
third month resulting in a yield increase
if 12.1% which is significantly better
han the check. This supports our pre-
ious finding that water lily extracts
ave some nematicidal value.


ome studies on bacterial brown spot of
orchids caused by Pseudomonas cattleyae
Pavarino) Savulescu. G.G. Divinagracia,
.L. Candole and E.T. Cadapan, UPLB,








rnnappine Ynytopamoogy


spot of orchids caused by Pseudomonai
cattleyae (Pavarino) Savulescu on Pha.
laenopsis orchids and Vanda lamellata
was studied, and described.
The disease developed in leaves ol
Phalaenopsis equestris and V. lamellata
infitrated with bacterial suspension of
1.4 x 106 to 1.4 xl09 cells per ml. No
disease developed at inoculum level,
lower than 1.4 x 101 cells per m.
Host range studies showed that the
bacterium was also pathogenic to 13
other orchids namely: Aranda 'Deborah',
Cymbidium finlaysonianum, Renanthera
philippinensis, R. storiei Trichoglottis
brachiata, T. ionosma. T. wenzelli, Van.
da lamellata, V Miss Joaquin, Vanda
T.M.A., Vandopsis lissochiloides and
Dendrobium hybrids D x 43 and D x 37
(from UPLB Floriculture Nursery).
The hypersensitive reactions of Phalae.
nopsis equestris to other phytopathogenic
Pseudomonas (3 strains of P. solana-
cearum isolated from abaca, eggplant
and tomato; P. aliicola isolated from
onion and P. putida, a saprophytic spe
cies) ranged from weak or partial to total
necrosis of the leaf areas infiltered with
bacterial suspensions.
Inoculation studies showed that the
bacterium infected host tissues only in
the presence of wounds.
Acremonium wilt of guava in the Philip.
pines. A.J. Quimio, E.A. de Villa and
R.S. Sumabat, UPLB, College, Laguna.
A very destructive wilt disease of gua
va (Psidium guajava), hitherto unreported
in the Philippines or elsewhere was dis
covered in November 1982 in College
Laguna. The disease is characterized bi
wilting of leaves and young shoots o
topmost branches followed by yellowing
and falling off of leaves and finally deati
of the plant. Wilting may first appear on
ly in certain branches or side of the treo
but sooner or later the whole tree wilt:
and dies. Primary symptoms include


location of the xylem tissues of the roots
and stem.
A new species of Acremonium ten-
tatively identified as Acremonium psidii
sp. nov. was proven to be the causal
agent of the disease. Histological studies
showed that it is a vascular wilt pathogen
invading the xylem vessels of its host. The
disease was named Acremonium wilt of
guava.
Screening of cotton varieties for resistance
to root knot and reniform nematodes and
determination of efficient assessment para-
meters. C.M. Barron, UPLB, College,
Laguna.
Twenty cotton varieties were tested ii
the greenhouse for resistance to Roty
lenchulus reniformis and Meloidogyne
incognita. Criteria for resistance or sus
ceptibility were root necrosis (for R. re
niformis) root galling (for M. incognita)
percentage growth reductions, nematode
recovery from roots and soil, and egj
production. None of the varieties
screened showed resistance to botl
R. reniformis and M. incognita. Tw(
varieties (Deltapine 55 and T-120-76
and one variety (Hoisevilly) appeared
moderately resistant, respectively, t(
R. reniformis and M. incognita. The res
of the varieties showed moderately sus
ceptible and susceptible reactions to boti
nematodes. Except percentage reduction
in top weight and number of nematode;
recovered from 250 cc soil, linear corre
lations between resistance ratings anc
each of the assessment parameters usec
in both experiments were significantly
positive. The most efficient parameter:
for determining resistance to R. rent
formis and M. incognita were the follow
ing: necrosis rating (for R. reniformis)
root gall rating (for M. incognita), per
centage reduction in root weight, num
ber of nematodes recovered from 1
of roots, number of egg masses/g ol
roots, and number of eggs/egg mass.


VUl. 41








aosuaus um rapria


rWcAcUs u runar spray wnn sieecceI
protectant fungicides on peanut Cer
cospora leafspots and rusts under na
tural field condition. L.B. Martinez anc
A.N. Pordesimo, UPLB, College, Laguna

Two fungicide efficacy trials were
conducted to determine the feasibility
of programmed foliar spray application
with protectant fungicides against peanul
leaf spots and rust. Chemicals tested were
Manzineb, Dithane M-45, Zincofol, Difo.
latan, Delsene MX, Duter, Bravo 500F
and Plantvax 75W. Among the eight
Bravo 500F was found be very promising
both for leaf spots and rust, leaves rela
tively green with little or no defoliatior
even at 100 DAE compared to the un
sprayed plots with almost all leaves de
foliated. Ocular inspection of the test cul
tivars along with the data on lesion coun
and rust rating indicate that Delsene M)
was effective on Cercospora but not witt
rust; Manzineb and Dithane M-45 were
less effective although leaves are still
greenish with slight yellowing and mode
rate defoliation; Zincofol and Difolatar
treatments were not quite different front
the control where defoliation was heav3
even as early as 70 DAE. With Plantvaw
75W and Duter treatments, further stud3
using lower dosages will have to be under
taken as spray injuries occurred as show
by the regular (Plantvax) and irregula
(Duter) patterns of necrotic spots on al
of the test cultivars used. It should b<
noted that all treatments were made
based on the manufacturer's recom
mended rate with 4 sprayings done start
ing at first appearance of diagnostic
symptoms.

Effect of solar exposure on the severity
of bacterial wilt in tomato. M.T. Lope;
and L.T. Empig. San Miguel Corp. Res
Stn., Calauan, Laguna
An experiment was conducted to de
termine the effect of solar exposure or


Two tomato lines which are very highl3
susceptible to bacterial wilt were planted
in previously mulched and nonmulchec
plots in a bacterial wilt infested area. Al
tomato plants grown in mulched plot:
died on the fifth week after transplanting
while those in exposed plot were able tc
survive up to the 12th week of the experi
ment and bear fruits. There was a clear in
dication that sunlight reduced the severity
of Pseudomonas solanacearum infection
The results suggest that growing of mode
rately resistant tomato varieties may be
profitable even in soil heavily infested
with bacterial wilt as long as the area was
previously exposed to sunlight during the
dry months.

Use of cut leaves for rapid screening foi
brown spot disease resistance in rice. E.S
Borromeo, P. Vidhyasekaran and T.W
Mew, IRRI, Los Bafios, Laguna.

A rapid and easy method is essential
for plant pathologists to screen thousand!
of germplasm types for disease resistance
To screen rice varieties against-browr
spot (Helminthosporium oryzae Breds
de Haan), rice plants are spray-inoculated
with conidia and incubated in dew cham
bers for 24-48 h. Then the plants are
transferred to greenhouse benches anc
disease intensity is scored after 3-10 days
Experiments were conducted to asses!
whether cut leaves can be used for this
purpose.
Leaf bits of 4 cm length were fixed or
glass slides by using gum tapes. The slide
were kept inside sterile Petri dishes line
with wet blotting paper. Filter paper disc
of 4 mm size were soaked in spore sus
pension (106 spores ml) ofH. oryzae anc
placed on the cut leaves. The petri dishe!
were incubated at laboratory temperature
After 48 h the leaves were scored foi
disease intensity. The reaction of five
varieties IR8, IR36, TNI, Co2o anc
CH45 to six strains of the fungus wa!


Jan. & June 1984


3









TVU. A&U


-0--.. ,Avv al- -.. flaOO4UL, Lu iaulatc
34, IR36 and TN1 to isolate 47 and Co20
to isolate 36. All the five varieties were


LuAllis lLuwcu unmerenual reaction simi-
lar to the fungal isolates. This type of


Liat -ru. 11 I~caLuL1U u1 i cut iMaves was me amount or electrolyte leaKage in-
almost similar to the whole plant reaction duced by the toxin in rice leaves. This
which was tested under greenhouse condi- suggests that the toxin produced by
tions. H. oryzae is host specific and the different
This suggests that the cut-leaf method violates produce qualitatively different
can be used to test the reaction of the toxins. This is the first report that races
whole plant. This method will be useful of the pathogen may produce different
for testing tissue culture-regenerated types of toxins and that the toxin may
plants without actually transferring the be responsible for the race pattern.
plants from the test tubes to the green- Ferric chloride induced resistance in a
house. Reaction of a single plant to dif- susceptible variety and there was less
ferent races of the pathogen can also be leakage of electrolytes in induced-resistant
tested by this method, leaves treated with toxin. Virulence of
the fungal isolates was correlated with the
Host-specific toxin production by Hel- amount of toxin production by them.
minthosporium oryzae. P. Vidhyasekaran, These studies suggest the importance of
E.S. Borromeo and T.W. Mew, IRRI, Los toxins in brown spot incidence in rice.
nt_-- T -_ -


Six isolates of Helminthosporium ory-
zae Breda de Haan differed in their patho-
genicity to five rice cultivars. These iso-
'lates were grown in modified Fires
medium for 21 days. The culture filtrates
were obtained, concentrated to 10 per-
cent of the original volume, equal quan-
tity of methanol added and incubated at
5C for 12 hr. The precipitates were re-
moved by filtration and evaporated in
vacuo to remove methanol. The water
fraction was partitioned with 3 volumes
of chloroform, and the chloroform frac-
tion was evaporated in vacuo. The crys-
tals formed were dissolved in known
quantity of water. This preparation
(toxin) reproduced symptoms of the
disease caused by the fungus. The toxin
induced quick electrolyte leakage when it
was infiltrated into rice leaves. At higher
concentration, toxins from different iso-
lates produced symptoms on the five cul-
tivars which showed differential reaction
to the fungal isolates. But when dilution
end point of the toxins to produce symp-
toms was considered as the criterion, the


Ingress, internal spread and some factors
affecting pathogenicity of Diplodia tu-
bericola (E. & E.) Taub. in sweet potato.
Vicha Sardsud and G.G. Divinagracia,
UPLB, College, Laguna.

Inoculation by placing the fungus in a
5-mm diameter and 8-mm deep hole in
sweet potato roots was successfully em-
ployed in these studies. Mycelial discs in-
duced disease development faster than
spores suspension. The mycelia could not
penetrate through the well-formed peri-
derm of sweet potato storage roots inocu-
lated 12 days after harvest. On newly har-
vested storage roots with loosely formed
periderm, the mycelia invaded intercellu-
larly and were restricted in the cork layer.
A periderm was formed in response to
penetration which separated the healthy
tissues from the penetrated cells. Inter-
and intracellular penetration through
wounds made on the storage roots were
observed 6 hours after inoculation and
pycnidial formation was noted at the
cork cambium layer 4 days after.
Incubation for 48 hours in moist


-`~~r-------r ~--r-l'~~~y








UbULffl% U1 raptrs


tion was'recommended for disease initia- corn, be it by E. carotovora var chrysan
tion. Disease development was favored at them, P. debaryanum, F. moniliforme o:
30 C. Six day-old storage roots were their combination.
more susceptible than the newly har-
vested or 3-day old roots when inoculated Control of pineapple Thielaviopsis frui
with the fungus. Injured surfaces of new- rot with postharvest dip in guazatine anc
ly harvested roots inoculated with the benomyl. A.J. Quimio, E. Jordow, anm
fungus was observed to form a wound R.S. Sumabat, UPLB, College, Lagum
periderm which protected the healthy
tissues from mycelial penetration. Comparative postharvest control o
pineapple fruit rot caused by Thielaviop
Effect of cultivation on the severity of sis paradoxa with Guazatine (panoctini
stalk rot of corn. Teresita C. Bayacag and 40) and benomyl was studied. The ex
Juan A. Soria, University of Southern perimental fruits were first artificially ino
Mindanao, Kabacan, North Cotabato. culated with the pathogen then dipped
into fungicide suspensions prior to pack
The study aimed to determine the aging and storing in a cold room operate
effect of cultivation on the severity of to simulate pineapple fresh fruit shipmen
stalk rot on corn under greenhouse condi- from the Philippines to Japan.
tions. Corn plants were inoculated with rn -1: .. ..


crtrysu nritrru, ryinmum ueoaryanum anu
Fusarium moniliforme ten days after
germination. The treatments were: no
cultivation, cultivation 15 cm away from


and disease severity index, with 3000
ppm a.i. Guazatine was comparable or
better than that of the standard commer-


seven days after inoculation, condition plus 5 days storage at 28-30 C
The plants cultivated 15 cm away
from the base produced significantly Pathogenic variability of Pyricularia
longer lesions than those cultivated 30 cm oryzae single spore isolates in the Philip.
away. Plants with no cultivation were also pines. T.I. Vergel de Dios and J.M. Bon.
infected, however, the lesions produced man, IRRI, Los Baioos, Laguna.
were significantly lower than the culti-
vated plots. Furthermore, the study Pathogenic variability Pyricularia ory-
showed that E. carotovora var chrysan- zae single spore isolates from single
them produced significantly longer lesions was studied. From each of 3
lesions both on plots cultivated at 15 and lesions from IR442-2-58 and 2 lesions
30 cm from the base of the plants. This from cv. Milyang 23, 25 single spore iso-
was followed by the combination of lates (SSI) were obtained and tested
E. carotovora var chrysanthemi, P. debar- against the Philippine differential variety
yanum + F. moniforme, then P. debarya- set. All sister SSI from 3 of the lesions
num and F. moniforme. Similar observa- had identical virulence patterns. From
tions were noted on plots where no cul- the other lesions, a few variants were ob-
tivation was applied; however, the lesions served, but these differed little from the
were significantly shorter. pattern of their sister SSI. In general,
The findings imply that cultivating the each lesion produced a homogenuous set


ail I. ,JUicA 1:70"1









Philippine Phytopathology


IkeacrlUll U 1 vI VUIaUC IU 1it v UUVllcA
under greenhouse and field conditions as
detected by latex test. R.D. Daquioag,
P.Q. Cabauatan, and H. Hibino, IRRI,
Los Bafos, Laguna.

Reactions of 26 IR varieties to tungrc
were serologically analyzed using antisern
against rice tungro bacilliform viru!
(RTBV) and rice tungro spherical viru,
(RTSV). A seedling was inoculated in a
test tube for one day by means of an
adult Nephotettix virescens which have
been exposed to latex test for the pres-
ence of RTBV and RTSV 30 days aftei
inoculation. When plants were inoculated
with RTSV alone, percentage infection
on IR varieties ranged from 0-82%. IR20,
IR26, IR30 and 1R40 showed less than
5% infection. When plants were inocu.
lated with both RTBV and RTSV, the
varieties which were resistant to RTSV in.
fection were mostly susceptible to RTBV
alone indicating resistance of these varie.
ties to RTSV infection. Percentage infec.
.: ,..;A. m y Tl7l _1___ .-. Ill o1 fno ---


liter-capacity Hudson sprayer with a dis-
placement of 14 kg/cm The first spray
application consisted of a fungicide-
insecticide combination + flower inducer,
while the three succeeding sprays did not
include flower inducer. Of the four pesti-
cidal spray mixtures, only benomyl at
25 g + 150 ml cypermethrin in 100 liter
water gave 100% control of anthracnose
and stem-end rot of mango stored in per-
forated plastic bags for 12 days under
ambient room conditions at UPLB. Fruits
from untreated trees were 70% rotted
after 12 days of storage.

Effect of fungicide 63444-01 on the con-
trol of culmiculous smut and on growth
and yield of sugarcane. Florante R. Hus-
millo and Rolando D. Dosayla, Philippine
Sugar Commission. La Granja, La Carlota
City.

Percent germination and growth com-
ponents of treated plants were not in-
fluenced by the different rates of fungi-


RTBV + RTSV were IR20, IR26, IR28, the control. Similarly, yield parameters
IR29, IR30, IR34, IR50, IR52, IR54, such as tonnage, sugar content and sugar
IR58, and IR60. IR varieties exposed to yield were not significantly affected al-
high tungro pressure in a field were also though maximum yield of 108.83 tons/
tested by latex. Low RTBV + RTSV in- Ha and 175.21 piculs/Ha were obtained
fection was noted in these varieties in- at higher dosage (1000 ppm) with dip-
cluding IR24 and IR56 but not in IR28 ping time of 30 minutes. Control plot
and IR34. However, IR20, IR24, and produced low tonnage and sugar yield
IR40 showed 53-60% infection with compared with other treatments. High
RTBV alone, yield was somewhat related to low smut
incidence.
Control of two mango postharvest diseases Fungicide 63444-01 significantly re-
by bloom spray mixtures. Juanito M. duced the smut incidence in the plant
Danean and Aaustin N. Pordesimo. UPLB. when setts were treated in 750 ppm solu-
Danizan and Aeustin N. Pordesimo. UPLB. ---- -


ege, Laguna. and tiller
and tiller
'our pre- and post-bloom pesticidal tively wer
ys were applied on 10-yr-old grafted
abao' mango trees in Cabatang, Chemical


Vol. 20









ADStraCTS 01 papers


a1A IlIUrUMUlIu WVT%, aLVViIVu iliU va-
luated against stem and foliage scab.
These fungicides were Difolatan, Captafol,
Manzate, Zincofol, Topsin and Delsene.
Difolatan which was tried three times was
found to be effective in controlling the
disease. Among the fungicides tested
only once, Topsin and Delsene were also
found to be effective. In one of the tests,
Topsin-treated plants had a lower disease
rating and higher tuber yield than Difo-
latan. However, Difolatan-treated plants
had the highest vine yield. Delsene, on
the other hand was found to adequately
protect new shoots and subsequent
growth of vines even surpassing Difolatan.
These tests also showed that stem and


In rice, Drechslera oryzae, D. Rostrata,
F. semitectum Verticillium sp., Rhyncos-
porium oryzae and Trichoconiella pad-
wickii were found associated with the
seeds while in sorghum several pathogens
were recorded.
Drechslera rostrata, Phoma sp., Verti-
cillium sp., F. moniliforme, Cephala-
porium sp. and Nigrospora oryzae were
observed on cucumber seeds while Phoma
sp. and Drechslera sp. were the only
fungal pathogens found associated with
eggplant seeds.

Rice grassy stunt virus 2: a new strain
of rice grassy stunt in the Philippines.
P C0 nhmnitnn H Hihinn r1 R T anic


erauicatea or greasy suppressed uy i. umura anu i. isucnlzaKi, IK.I, LOS
spraying effective fungicides. Bafios, Laguna.

Seed-borne fungi associated with diffe- A virus disease of rice which causes
rent economic seed crops in four seed stunting and yellowing symptoms was
farm stations. A.L. Piamonte and F.C. observed in IRRI and Koronadal, South
Quebral, UPLB, College, Laguna. Cotabato, Philippines. The disease is
transmitted by the brown planthopper,
Seeds of different crops collected from Nilaparvata lugens (Stal). Based on symp-
four locations were studied for seed- tomatology, virus-vector interactions,
borne fungal pathogens, serological reaction and particle mor-
F. moniliforme, F. oxysporum, F. phology, the virus was identified as a
semitectum, F. solani, F. camptoceras, strain of rice grassy stunt virus. The
Phoma sp., andAscochyta sp. were found new strain was designated as rice grassy
associated with mungbean and soybean stunt virus 2 (RGSV 2) while the type
seeds while Cephalosporium sp., Colle- strain (ordinary grassy stunt) was
totrichum graminicola, C. dematium, F. designated as rice grassy stunt virus 1
equiseti, Phomopsis sojae and Macro- (RGSV 1). Aside from causing tungro-
phomina phaseoli were recorded only in like symptoms, RSGV 2 differs from
soybean. Alternaria raphani was recorded RGSV 1 in pathogenicity to some rice
in mustard and pechay while Fusarium varieties. Oryza nivara which is highly
moniliforme was recorded on mustard, resistant to RGSV 1 is susceptible to
pechay and radish. Fusarium equiseti was RSGV 2. Consequently, IR varieties
found associated with pechay and cab- which possess 0. nivara genes for re-
bage seeds while F. solani, Phoma sp., and distance to RGSV 1 are susceptible to
Verticillium sp. were found associated RSGV in greenhouse tests.
with pechay seeds. Fusarium semitectum
was present on cabbage seeds while Alter- A new possible source of resistance to
naria brassicicola and Drechslera sp were rice grassy stunt virus 1 and rice grassy
present only on mustard seeds with stunt virus 2. V.M. Aguire, P.Q. Cabaua-
5.75% infection and/or contamination tan, and H. Hibino, IRRI, Los Bafios,


Jan. & June iwv54














The resistance of a perennial rice plant,
Guang-keng A/Oryza rufipogon'/ Oryza
longistaminata (IRRI Acc. No. 104315)
from China was tested against rice grassy
stunt virus 1 (RGSV 1 and rice erassv


I . . .. . . . .. .
Evaluation System" (RES) was developed
to assess quantitatively the disease deve-
lopment under field conditions. RES is
based on a common observation that
human evpeniht ic rplativplit onn t t


h~n~P r EiklPt, ~


for 2 to 4 days per tiller and/or seedling.
None of the 22 tillers inoculated with
RGSV 1 at 20 or 50 insects per tiller was
infected. However, one out of four was
infected when the number of insects per
plant was increase to 130 while one
out of 21 tillers inoculated with RGSV
2 at 50 insects per plant was infected.
The plants grown from seeds segregated
into dwarf and tall types. All dwarf plants
inoculated either with RGSV 1 or
RGSV 2 were infected and developed the
disease symptoms. However, in the case
of tall plants, one out of 4 and 4 out of 11


data can be subjected to statistical an
lysis. RES is particularly suitable f
breeders since their main interest is n,
the absolute amount of. damage but tl
relative performance of plant or lines
compared to reference materials or loc
check.

Reaction of some selected rice varietid
to rice tungro sperical virus (RTSV) I
Nephotettix virescens distant. Gane,
Dahal and H. Hibino, IRRI, Los Baio
Laguna.


S .. .. -, _-f-.- l. i U IIIIal UilladJta d1ll, I.JU
10-15 insects per seedling in one day and IR60 to TRSV was determined by
noculation access time to obtain 75- test tube method of inoculation using
100% infection on susceptible varieties. 1, 3, and 5 insects per seedling and serial
Therefore. the results indicate that the t, ,e; o;,,n TI, QTW : :e .....


- ~~CI r---- ~~~ -1-'---~0r









n. & June 1984 Abstracts of Papers 11



rieties. Regardless of the cultivars with pre-plant dip in guazatine and
ccessful virus recovery was obtained benomyl. A.J. Quimio, E. Jordow, and
3m plants infected by RTSV. These R.S. Sumabat, UPLB, College, Laguna.
suits indicate that cultivars Utrimerah,
trirajapan, Gam Pai 30-12-15, ASD 7, Comparative control of pineapple dis-
d ASD 8 could be the sources of the ease of sugarcane caused by Thielaviopsis
distance to RTSV infection, paradoxa with Guazatine (Panoctine 40)
and Benomyl was studied. The sugarcane
irvey on viral diseases of orchids by setts planting materials were artificially
mptomatology, EM and bioassay using inoculated with the pathogen prior to the
cal lesion hosts. G.G. Divinagracia and fungicide pre-plant dip treatments.
B. Exconde, UPLB, College, Laguna. Disease control based on percent ger-
mination of sugarcane setts, disease inci-
Periodic survey of viral diseases of dence after germination, number of
chids were conducted in several orchids shoots per hill, and plant height, in 250
irseries in Los Bafios, Baguio City, pri- or 1000 ppm Guazatine treatments were
te nurseries in Cavite and in Bifian, not significantly different from that of
iguna. Diseased specimens were also the 100 ppm benomyl standard control
ought to the laboratory from Bacolod treatment. Data indicated that Guazatine
ty and foreign countries like Thailand might be used for controlling pineapple
r determination of viral infection. disease of sugarcane.
Majority of the orchids observed were
inda, Cattleya and Dendrobium. The Screening sweet potato cultivars and
ost common symptoms expressed by crosses to Java black rot. R.F. Dalisay
rus-infected orchids were mosaic, ring and G.G. Divinagracia, UPLB, College,
ots, yellow streaks, wrinkling of Laguna.
hungerr leaves, chlorosis, flower breaking,
in clearing and diamond mottling. Twelve isolates of Diplodia tubericola
ittleyas appeared rugged, dehydrated (E. & E.) Taub. were collected from dif-
Id sunken. ferent sweet potato-growing regions in
Electron microscopy for determining the Philippines. These isolates which were


ILU I Cs Ilul1ilg LypC Ai IVi v allu yivlv,
!spectively.
Inoculation to indicator host plants,
namely, Cassia occidentalis, Chenopo-
uum amaranticolor, Datura stramonium,
omphrena globosa and Tetragonia ex-
insa showed symptoms consisting main-
Sof local lesions and ring spots. Type
MV-0 produced local lesions and ring
>ots on G. globosa and T. expansa 3 to 5
ays after inoculation. Type CyMV pro-
iced local lesions on D. stramonium 15
S22 days after inoculation.


ained for screening harvested storage
oots.
Storage roots of 89 cultivars and
crosses were evaluated for their resistance
o Java black rot (1982 Dry Season). Five
vere rated very resistant, 32 crosses and
)ne cultivar were resistant while 18
rosses were rated moderately resistant.
duringg the 1982 Wet Season, 45 cultivars
nd crosses were evaluated. Only RTaipei
led was rated resistant. Nine were rated
esistant and 18 were moderately resistant.









Phlippine Phytopathology


grain discoloration. S.C. Lee, M.E. Alven-
da, J.M. Bonman and E.A. Henrichs,
IRRI, Los Bafios, Laguna.

Discolored grains have been attributed
to fungal pathogens and rice bug asso-
ciated with the rice panicles. To deter-
mine the interaction between the patho-
gen and rice bug on grain discoloration,
IR36 at the early milk stage was infested
with 20, 14 & 8 5th instar rice bugs per
10 panicles before inoculation of the
pathogens Curvularia lunata and Drechsle-
ra oryzae. Results indicated that the inci-
dence of grain discoloration was signifi-
cantly higher in treatments where both
rice bug and pathogen were present than
when they occurred singly. Although
there were more discolored grains on
panicles treated with C lunata, there
were less unfilled grains as compared with
rice bug alone. With D. oryzae, similar
results on grain discoloration were ob-
tained, however, there was not significant
difference on the percentage of unfilled
grains between the fungus and rice bug
alone.

Pathological and bacteriological variation
of Xanthomas campestris pv. oryzae.
C.M. Vera Cruz and T.W. Mew, IRRI, Los
Bafios, Laguna.

Pathological and bacteriological studies
were conducted to determine the variabi-
lity of X.c. pv. oryzae, the rice bacterial
blight pathogen. Two hundred and nine
isolates, representing the field population
of the bacterium in the Philippines from
1980-1982, showed' that majority of
them were race 2, virulent to rice with
Xa-4 gene for bacterial blight resistance,
e.g. IR36. The variability of the same
field population of the bacterium from
1980-1982 was analyzed based on their
virulence to IR8, IR20, IR1545 and
DV85 expressed as variance of lesions
induced on these varieties. In each year,
there was a wide range of variation of the


isolates on IKm and 1K2U Dasea on var-
iance analysis of individual leaves infected
with the isolate, however the range of
mean lesions induced by them were less.
This may indicate the inherent variability
of the isolates as affected by the variety
to which they were evaluated. Strains of
these races were evaluated for their pheno-
typic similarity by numerical analysis of
132 phenotypic features to correlate bac-
teriological characteristics with virulence
on bacterial blight differential varieties.
No phenotypic features were found to
correlate with virulence of the strains. It
appears that X.c. pv. oryzae constituted a
phenotypically homogeneous group of
bacteria regardless of place and date of
isolation, variety where isolated and race
grouping. However, despite their homo-
geneity in bacteriological characteristics,
they varied with respect to their virulence
on a variety.

Variation in virulence of Xanthomas cam-
pestris pv. oryzicola on rice cultivars.
T. Adhikari and T.W. Mew, IRRI, Los
Bafios, Laguna.

Forty-four isolates ofXanthomas cam-
pestris pv. oryzicola were evaluated for
their pathogenicity to susceptible cultivar
IR50. The virulence pattern on IR50 was
ranked from high to low. To further eval-
uate the variation, six isolates were
selected and tested to 30 IR cultivars and
lines by spray inoculation. The result in-
dicated that the six isolates differed great-
ly in virulence. Some isolates were more
virulent than others and percentage leaf
area infection on the test cultivars ranging
from 9.4 37 but the interaction be-
tween the isolates and cultivars was not
significant. The incubation period (IP),
latent period (LP), bacterial exudate pro-
duction (BEP), lesion length and disease
severity of three isolates on IR58
(resistant) and IR14753-120-3 (suscep-
tible) showed that BLS93 was the most
virulent one. It produced longer lesion,


Vol. 20








Abstracts of Papers


shorter IP and LP, and higher BEP thar
the weakly virulent isolate BLS37. BEF
was determined by dilution method. 11
was found that colony forming units
(C.F.U/ml) was directly proportional tc
BEP and lesion length 15 days after ino-
culation in this system. The procedure
appears to provide a reliable estimation of
the virulence of the different isolates.

Multiplication of Xanthomonas campestris
pv. oryzae in different leaf positions of
rice cultivar zenith. Zhang Qi and T.W.
Mew, IRRI. Los Bafios, Laguna.

Zenith has Xa-6 gene for adult plant
resistance to bacterial blight of rice. The
disease reaction of the lower leaf posi-
tions is susceptible to bacterial blight,
while from the 11th flag leaf is resistant.
The bacterial multiplication in these
leaves were estimated by the bacterio-
phage method.
The population trends of Xanthomo-
nas campestris pv. oryzae on the 6th, 9th,
10th and 12th leaves was estimated at


it was quite reliable to establish popular
tion trend of the bacteria in infected
leaves after inoculation.

Influence of bacterial blight on yield loss
of rice. R.C. Reyes and T.W. Mew, IRRI
Los Bafios, Laguna.
To assess the yield loss of IR36 due t(
bacterial blight, three levels of disease
pressures were induced by infecting the
plants at early tillering, maximum tiller
ing and booting stages under 0, 60 & 12(
kg N/ha. The disease progression wa!
faster when infection was initiated al
early tillering than the other two stages
The severity index of infection at booting
stage was considerably less at 28 day!
after inoculation. The influence of N-leve
was not significant perhaps due to the
background fertility level of the fields
Reduction in yield was highest at 120 KE
N/ha than other levels. Under such level
of N application, infection at early stage
showed 17% yield loss as compared tc
infection at booting stage but more at


phage method, our results indicated that were isolated from Rhizoctonia solani


Jan. & June 198













sclerotia, ricefield paddy water, healthy
and infected plants. Many colonies ex-
hibited antagonistic activity to the rice
sheath blight pathogen by inhibiting my-
celial growth and also affected the viabi-
lity of the sclerotia. Isolate In-b-17 killed
the sclerotia while In-b-24 reduced germi-
nation to 27% after 2 weeks. The effect
of bacterization of rice plants with these
bacteria on the sheath blight fungus,
R. solani was evaluated in the greenhouse.
Spraying the basal portion of cv IR36
with a bacterial suspension of In-b-17 one
day before inoculation with the pathogen
reduced disease severity and incidence.
Two groups of bacteria, fluorescent
Pseudomonas and non-fluorescent bac-
teria were used for seed treatment. Seeds
of IR36 were soaked in bacterial suspen-
sion (109 cells/ml)for 10 min before
sowing in plastic trays filled with soil in-
fested with rice-hulls and grains colonized
with R. solani. The bacteria affected
greatly the infectivity and sclerotia pro-
duction of R. solani. Both bacterial iso-
lates promoted the growth of rice cultivar
IR36. Subsequent planting after the 1st
crop without seed treatment in the same
soil reduced the disease occurrence.

Characteristics of Xanthomonas cam-
pestris pv. vesicatoria infecting tomato
and pepper in the Philippines. Revelieta
B. Alovera and Arcadio J. Quimio, UPLB,
College, Laguna.

Twenty eight isolates of X. campestris
pv. vesicatoria (15 from tomato and 13
from pepper) representing 14 provinces
of the Philippines were characterized
using colony morphology, physiological
and biochemical traits, cardinal tempera-
tures for growth, nutritional traits and
host specificity.
Similar reactions were obtained from
nearly all the physiological and biochemi-
cal traits, however, 2 groups based on
their ability to hydrolyze starch, sensi-


romycetin (30 ug) and salt tolerance were
recognized. Each group consisted of
isolates originating from both host plants.
Cardinal temperatures for growth did not
clearly differentiate tomato isolates from
pepper isolates. However, most of the
pepper isolates had an optimum tempera-
ture of 280C while the tomato isolates
had an optimum temperature ranging
from 29-380C. All isolates were patho-
genic to both tomato and pepper plants.
They differed only in the time of appear-
ance of the first symptom on the leaves.
Three biovar groups within the pepper
isolates were recognized based on utiliza-
tion of mannose, xylose and trehalose.
Biovar 1 grew in all 3 carbon sources.
Biovar 2 did not utilize mannose and tre-
halose while biovar 3 did not utilize any
of the three sugars. All the tomato iso-
lates belong to Biovar 1.

Prevalence of Trichoderma spp. in the
rice rhizosphere from the IRRI upland
area. S.M. Haroon Usmani and T.W. Mew,
IRRI, Los Bafos, Laguna.

Five Trichoderma spp. viz. T. aureo-
viride, T hamatum, T harzianum, T.
koningii and Trichoderma sp. were found
prevalent in the rhizosphere of the rice
variety IR36 from the IRRI upland rice
area. Seeds of the rice var. were treated&
with PCNB (1.4 g ai/kg seeds) or non-
treated check and sown in completely
randomized plots. Population of Tricho-
derma spp. was determined by dilution
plate method on semiselective modified
Gallic acid medium at 0, 2 was found
more prevalent followed by Trichoderma
sp., T aureoviride, T koningii and T. ha-
matum. In the rhizosphere of untreated
control seeds, the population of T. aureo-
viride was higher at 0 days with a fall
after 1 week. No. T. hamatum was ob-
served in the rhizosphere soil of untreated
check. Trichoderma aureoviride is re-
ported here for the first time from soil of


- I- -- - 1-___ LI


.1-I l*








Aosunacs o rapens


oacienopnage senCUSnVy oI Aanmomo-
nas campestris pv. vesicatoria isolates
from tomato and pepper. Revelieta B.
Alovera and Arcadio J. Quimio, UPLB,
College, Laguna.

Four bacteriophage isolates isolated
from bacterial leaf spot infected tomato
and pepper plants and from soil col-
lected around the roots were used in de-
termining the phage sensitivity of 28 iso-
lates of Xanthomonas campestris pv.
vesicatoria.
Four phage types designated A, B, C,
and D were determined. Each type com-
prised the isolates originating from both
tomato and pepper plants. No phages spe-
cific for tomato and pepper isolates were
noted.
64.28% of the total number of isolates
constituted type D which showed resist-
ance to all phages. This group apparently
is the most common and widely dis-
tributed in the country. Type A com-
prised the isolates susceptible to all
phages. These results indicated that
tomato and pepper strains of Xanthomo-
nas campestris pv. vesicatoria could not
be differentiated using bacteriophages as


were 42.8I, 4.0, 52.50 and 32.50 percent
for CMV, PMV, MMV and SMV respec-
tively. Lower seed transmission was ob-
tained when plants were infected during
the pre-flowering and flowering stages.
The study also indicated varying transmis-
sion rates relative to seed position within
the pod. Higher seed transmission rates
were observed from seeds closer to the
peduncle. Both CMV and MMV were pre-
sent in all the seed parts while PMV and
SMV were present in the endosperm and
were not detected on the testa.

Vein enation or leaf gall of corn. A.N.
Pordesimo and B.A. Aday, San Miguel
Corp. Res. Stn., Calauan, Laguna.

The first epiphytotic outbreak of this
malady was noted on 7 June 1982 in
Area I, Barangay Lamba, Banga, South
Cotabato where roughly 20% or more of
a corn field exhibited hypoplastic symp-
tom characteristic of viral infection. The
most pronounced symptokn expression of
infected plants is invariably stunting with
reduced leaf size in breadth and length.
Vein enation or gallings is a consistently
diagnostic character that makes the leaves


instances, the young leaves enveloping the
Identification and seed transmission stu- tassels fail to unfurl. In January 1984, re-
lies of viruses commonly attacking field currency of this disease was noted in the
legumes. Cecilia V. Bautista. BPI, Davao same area. But prompt detection of in-
City. fected plants and roguing them comple-
mented by insecticide spray application
Legume viruses commonly attacking saved the crop from serious damage. The
cowpea, peanut, mungbean and soybean distribution pattern of infected plants
were identified and studied for seed trans- and the diagnostic character of symptoms
mission. Based on symptomatology, host strongly suggests that the malady is
range, electron microscopy and serology, caused by a virus transmitted by ambu-
these viruses were identified as cowpea lant insect vectors. The consistent pres-
mosaic virus (CMV), peanut mottle virus ence of the leafhopper Cicadulina bipunc-
(PMV), mungbean mottle virus (MMV) tella (Matsumara) Cicadellidae, Homop-
and soybean mosaic virus (SMV). Seed tera on volunteer plants and weed hosts
transmission rates varied with the dif- in this corn area supports this contention.
ferent viruses with higher seed transmis-
sion obtained from plants infected during Reaction of selected rice varieties to rice
the seedling stage. Seed transmission rates ragged stunt virus and its vector Nila-


Jan. o June ivoy









Philiopine Phytopatholo


parvata lugens. Amara Parejarearn, I
Lapis and H. Hibino, IRRI, Los Bai
Laguna.

Based on percentage infection to
.....- -..I. . ..;-.. fD OIAT' ; l,


were also evaluated in the replic
upland yield trials carried out by
departments of Agronomy and P


J111 1 IIU il U Ild d iL 5 Up1 liu i I'/ L .uJJVal Vg lEr, waa n a iS. wan in.
Sto. Tomas, Batangas to evaluate 3 mix- the leafhopper from plants infected i
ture sets, each composed of three culti- RTBV alone, while RTVS was efficie
'ro,-c nr hrorlina line Thp thrie Rp tc trannmittpd from nlants infected 1


16








Abstracts of Papers


SV alone. RTSV transmission occur-
only when the leafhoppers were pre-
isly fed on RTSV-infected plant. This
ilt showed that RTBV is dependent
RTSV for transmission by the leaf-
pers. Similar results were obtained
n nymphs were used for transmission.
V was retained hv adult laafhnnnprc


:gonia. The fungus on tissues remained
ive for 2 months under dry conditions
Ad about 5 months when placed in dry
moist sterile soil.

detection by ELISA of the rice tungro-
sociated viruses in rice seedlings. Nar-
o B. Baiet. IRRI. Los Bailos. Laguna.


!n the leafhoppers were given access (ELISA) has been developed and applied
RTBV-infected plant, RTBV trans- to detect the rice tungro bacilliform
ation of AAT, This result indicates (RTBV) and rice tungro spherical (RTSV)
:RTSV itself may not be the "helper viruses in rice seedlings. Seven-to 9-day
or" for RTBV transmission. However, old Oryza sativa cv. TN1 seedlings in test
"helper factor" for RTBV trans- tubes were exposed to viruliferous green
ion was lost after molting. leafhopper (GLH), Nephotettix virescens
(5 insects/seedling) for 24 hours inocula-
f blotch of giant pandan. G.G. Divina- tion access. After inoculation, the insects
:ia, I. Telan and E.T. Cadapan. UPLB. were removed and the seedlings were
lege, Laguna. transplanted in pots and kept in screen-
cages in the greenhouse. Controls were
The disease was first observed several seedlings exposed to non-viruliferous
rs ago during the rainy season. Since GLH or seedlings not exposed to the
a it has occurred regularly on this insects. Samples were obtained at 2, 4, 6,
it. The leaf spots or blotches were and 8 days after inoculation (DAI) and
ally large and circular with various each seedling was processed separately
Jes of brown at the center and with for ELISA. At all sampling dates the
er-soaked boundaries. They started as viruses were detected in the inoculated
11l water-soaked lesions on any part of seedlings but not the controls. The
leaf with neighboring leaf spots extracts of about 15-45, 67-95, 85-95.
lescing to form circular to irregular and 95-100% of the seedlings sampled at
tches. During wet weather, the spots respectively 2, 4, 6, and 8 DAI reacted to
irged. They stopped expanding during both anti-RTBV and anti-RTSV IgGs,
dry spells but continued enlarging and to either IgG. These results indicate
mn conditions became wet again, that, by ELISA, tungro can be successful-
ing leaves were most susceptible. ly detected during the early vegetative
-n conditions were favorable for a stage (pre-and post-transplant) of the rice
g period the spots spread down to the plant. The role of ELISA in rice tungro
Nn causing a heart rot. Some plants monitoring and early identification of
1, others developed side shoots. virus reservoir within the crop is discussed.
rhe causal fungus was readily isolated.
fungus did not form fruiting bodies Recent outbreak of two destructive
produced sclerotia in culture but diseases of ornamental plants in the
idia were observed on masses of hy- Philippines. G.G. Divinagracia and L.M.
e. Enrique, UPLB, College, Laguna.
[he fungus was pathogenic to 5 other
:ies of pandan and other plants like
), rhoeo, peperomia, calla lily and rose 1. Bacterial Blight of Anthurium


17









Philippine Phytopath


The disease occurred in epiphyte
proportion in the farm of the bigi
anthurium grower in Los Banos, Lagi
around August, 1982. It also occurred
a destructive manner in a small growe:
Calauang, Laguna. Other unconfirn
reports of its occurrence were given
authors in other backyard growers
Los Banos.
The disease started as small, yellow
ilfgaor.-nL-ari entE mpacllrino a fpw r


nish to reddish-brown to red and
margins appeared lightly chlorotic
yellowish. On the lower leaf surf
the affected areas appeared dull in cc
compared with the corresponding area
the upper surface. Generally, the affec
leaves or a large portion of them bec,
yellow before defoliation occurred.
On young stems irregular red(
areas developed and later some of
affPctPd nrpma CrarrkAd formino panl


came circular to irregular, yellow brown is Feronospora sI
with necrotic center and water-soaked reported in the U.


i. possible '. spa


aliu yYuUwiii 5 auvalu.JI aL uuVluEi. mI
necrotic center became rough, dry and Pathogenic variability of Pyricularia
sometimes curled. zae single spore isolates in Korea.
Infected leaves when viewed in trans- Bandong, E.J. Lee and J.M. Bon
mitted light showed yellowing of veins IRRI, Los Bafios, Laguna.
and areas further from the spots. The
stalks and petioles when split showed A study on the pathogenic varial
light discoloration of the vascular bundles. of the balst fungus, Pyricularia or
The leaves turned generally yellow before was conducted in Suweon, Korea. S
defoliation, spore isolates (SSI) from two s
Internally, the stem and roots were lesions on cultivar Milyang 23 wern
discolored and eventually rotted. The tained and tested against the Philit
infected plants were killed and the disease differential variety set. Based on
spread rapidly. virulency patterns, all 19 SSI from Li
The causal bacterium was isolated. Milyang 23-3 were identical and or
Initial inoculation test was successful of the 18 SSI from lesion Milyang
by leaf injection using a hypodermic differed slightly from its sister SSI.
needle. SSI variant from lesion Milyang 23-:
identical to its sister isolates excep
2. Downy Mildew of Rose a slightly more virulent reaction
S cultivar CI 5309. The degree of vari
The disease occurred in epiphytotic observed among the SSI was less than
proportion in a newly established farm viously reported by other researchers
in Silang, Cavite starting around January,
1983. The disease outbreak was so fast Reaction of IR varieties to rice yc
it defoliated a lot of plants in 2 months. dwarf. R.D. Daquioag and H. Hil
All the varieties in the farm were affected. IRRI, Los Baios, Laguna.
The disease started as small irregular
discoloration on any part of the leaf. Reactions of 26 IR varieties to
This area appeared slightly curled. On the yellow dwarf (RYD) infection was t(
upper leaf the affected areas became in a greenhouse. Newly emerged nyr
chlorotic to yellow. Later these areas of Nephotettix virescens were giv
though remaining irregular in shape, 25 days acquisition access time on F
enlarged, the central areas became brow- infPetPd TNIi nlantc Riv.rain-rid co


18









Abstracts of Papers


-re confined with the viruliferous in-
;ts in test tube at two insects per seed-
ig for one day. Inoculated seedlings
ere transplanted in clay pots and grown
screened trays. Svmvtoms anneared


,ased infection of RTBV only as the
mber of viruliferous insects per plant
s increased. However, ASD 7 had
'ere svmptoms as compared to the


section lower than 30% and were con- (BPH) infestation and sheath blight
ered resistant to RYD. pathogen infection in rice plants. S.C.
Lee, D.M. Matias, T.W. Mew and E.A.
action to RTV complex as influenced Heinrichs, IRRI, Los Bafios, Laguna.
insect pressure. R.C. Cabunagan, E.R.
ngco and H. Hibino, IRRI, Los The interaction between BPH in-
ios. Laguna. festation and sheath blight pathogen in-
fection on rice plants was studied. Two
Five IR and 9 non-IR varieties were varieties (IR22 and TNI) both susceptible
ted for their reaction to RTV com- to BPH were used in the study. Both
x when inoculated by 1, 5, 10, 20 and varieties, grown in clay pots, were inocula-
tungro viruliferous green leafhoppers ted with the sheath blight pathogen (Rhi-
plant, zoctonia solani) at maximum tillering
In the moderately resistant varieties stage with a hill of 10 tillers at 7 days
36 and IR42, an increase in infection after infestation with 100 4th instar
both RTBV and RTSV was obtained BPH/pot. Disease severity and degree
en the number of insects per plant was of hopperburn were evaluated simulta-
reased from 1 to 30. However, in the neously 14 days later. Disease severity
hly resistant IR50 and IR54 an in- was significantly higher in the treatment
ase in infection of RTBV only was where BPH and the sheath blight patho-
:ained. Variety IR56 had almost equal gen were present in combination than
action of both RTBV and RTSV, and when the sheath blight pathogen was
BV only. alone. Likewise, the egree of hopperburn
Among the non-IR varieties tested, less was significantly higher in the BPH +
section of either both RTBV and RTSV sheath blight combination as compared
RTBV alone were observed in varieties with that of BPH alone. There seems
) 18, Habiganj DW8 and ARC 11554 to be a synergistic relationship between
;ardless of number of insects per plant BPH infestation and sheath blight patho-
licating stability of resistance to RTV gen infection. Further studies on the me-
nplex. Varieties Palasithari, Gam Pai chanism of interaction between the two
, Gam Pai 30, and ASD 7 had an in- pests are in progress.


19














ON COFFEE LEAF RI

R.G. ATABUC

Plant Pathologist and Senior PI;
search Center, Madaum, Tagum, Davao

ABSTR

Several systemic and contact
rust and consequently assessed for th<
All the fungicides tested significantly
pared to unsprayed trees. Bayleton, a
other fungicides in reducing rust incide
Coffee berry yield from the c
vary during the 1982 season, but thi
apparent the following year. Among
those sprayed with Cupravit, Baylet
Flowable. The highest yields obtain
significantly differ from that of Difo
higher than those treated with Sapro
the untreated check.
A notable decrease in yield w
with Delan, Galben and Saprol.


INTRODUCTION

Coffee rust caused by Hemileia vasta
trix Berk. et Br. induces premature falling
of leaves which adversely affects the yieli
of susceptible arabica coffee trees. Fung:
cide spraying is currently one of th
practical measures to control the disease
At Eden Fruits and Vegetables Co., Inc
in Davao City (altitude 853 m.) coffe
trees (S-288) are sprayed with coppe
oxychloride for protection against th
disease with the frequency of application:
and dosage depending upon the survey,
level of rust incidence.
No fungicide controlled coffee rus
more effectively than the copper-base,
fungicides until pyracarbolid, a system
fungicide, was found by Mulinge et. al
(1974) to have cured coffee rust lesion:
Since, then, other systemic fungicide
such as oxycarboxin, carboxin, (Muthai
pa and Kumari, 1976) and triadimefo
(cKsners and Patel. 19801 have been rT


r INCIDENCE AND YIELD

d M.O. SAN JUAN

Pathologist, respectively, Twin Rivers Re.
Norte.

T

eicides were tested to control coffee
effectt on yield of arabica coffee trees.
aced leaf rust incidence levels as com-
temic fungicide, was superior over all

rent treatments did not significantly
fect of some fungicides on yield was
treatments that increased yield were
Saprol + Plantineb, and Difolatan 4
rom Cupravit and Bayleton did not
n 4 Flowable, but were significantly
Plantineb, Delan, Galben, Saprol and

however, obtained from trees treated



ported to provide highly effective p
tective, curative and eradicative cont
of leaf rust. The availability of some n
systemic and protectant fungicides
testing prompted us to compare th
efficacy in controlling coffee leaf rust
supposedly rust-resistant S-288 arab
coffee trees and to assess their effect
yield in Eden, Toril, Davao City.

MATERIALS AND METHODS

The treatments were applied to ru
susceptible 2-1/2 years-old Coffee arab
line (S-288) trees capped at a height
6 feet. The trees were planted 2 x
meters apart in blocks that contair
four rows of trees. A randomized cc
plete block design was used in the
perimental area consisting of th
blocks replicationss) each of which w4
divided into eight plots (treatments)
20 trees. Ammonium sulfate and muri;
of notash were annlied at 80 and 70









! Effects of Several Funxicid


ee, respectively once every three
months.
The fungicides tested and their dosages
er liter of water were: Bayleton (25%
iadimefon) 1 g; Cupravit Ob 21 (50%
opper oxychloride) 5 g; Delan (75%
ithianon) 3 g; Difolatan 4 flowable
t8% captafol) 4 ml; Galben (25% galben)
g; Saprol (18% triforine) 1 ml; Saprol +
lantineb (18% triforine + 80% maneb)
ml + 2 g; and the unsprayed control.
11 the fungicides were mixed in water
ith 0.5 ml Triton B1956 per liter of
,lution and sprayed unto the leaves
nce a month from July 1982 to Decem-
er 1983 using an Arimitsu motorized
napsack mistblower. Each tree received
approximately 330 ml of the fungicide
)lution.
Coffee rust incidence data were taken
om 15 primary branches apportioned
t 5 branches each for the top, middle
rd lower portions of six sample trees
tuated at the center of the plot. The
)tal number of leaves and the number
f rust infected leaves in the marked
ranches were counted monthly and
Pressed as percent rust incidence. The
lean rust incidence of the treatments
or the 18 month period were subjected
) analysis of variance and tested for
significance by Duncan's Multiple range
est (DMRT).
Coffee berries from the six sample
*ees per plot were harvested at green-
pe stage and weighed. The yield ob-
tined during the harvest seasons which
nded in November during 1982 and in
december, 1983 were analyzed separately
nd tested for significance by DMRT.

RESULTS
Effect on Coffee Leaf Rust Incidence
Under prevailing Davao climatic con-
itions favorable for rust infection, the
litial percentage of rusted leaves ranged
rom 40.15 to 50.92% at the start of the
-v-rs;-ir+ ;in l11 10Q') Ri ct inirl onro


ntinued increasing until September,
982 in the systemic fungicides Bayleton,
ilben, Saprol and Saprol + Plantineb
Id until October, 1982 in the protect-
its Cupravit, Delan and Difolatan (Fig.
. Thereafter, rust incidence slowly
creased, remaining below the 10%
tion threshold level from April to
ly, 1983 in the Galben, Saprol, Saprol
Plantined and Difolatan treatments
Id from April to August, 1983 in Bay-
ton, Cupravit and Delan. The onset
Sthe rainy season in June, 1983
iggered the sharp increases, one to two
months later, of disease incidence in all
e treatments except in Bayleton. Bay-
ton consistently had the lowest rust
cidence and it stayed longest below the
i% damage threshold for a period of
ne consecutive months.
Comparison of the average rust inci-
nnces of the treatments for the 18
onth period revealed that Bayleton
gnificantly controlled the disease better
an the other fungicides tested. Delan,
ipravit, Galben, Saprol, Difolatan and
iprol Difolatan and Saprol + Plantine
d not significantly differ in their
ficacy against coffee rust. Nevertheless,
ey had significantly lower rust in-
dence means than the unsprayed
introl (Table 1).
Among the fungicides tested, only
ayleton exhibited curative action. The
irative effect was manifested by the
esence of small, pale brown, non-
orulating lesions with a distinct watery-
een margin. Some of the "cured"
sions had brown centers while those of
hers remained pale green. On the other
and, the unsprayed leaves had yellow
lots with a diffuse margin. The yellow
lots later on turned orange when uredo-
iores were produced and coalesced into
gger pustules.

Effect on Yield
The coffee berry yields of the different


21










Philippine Phytopatholoi


90
LEGEND:
S-- BAY LI
85 +- + GAL?
A--A SAPF
S----- SAPF
80- ----D CUPF
o----0 DELA
x----x DIFO
75- -- CONT
*----. RAIN

70 -



60- I $'
o55- I
460-





z
t 5


I-
U.



S25- \

20- I


*5- i

10-

5-

0 I I I I I I
MONTH 7 1 9 10 II 12 I
1982

Figure 1. Comparative effects of sever


ii
LANTINFe /
/,\


II
i ?







I I'
r I
I













,/ 600


-l 500 :

1*300


S200 3




5 6 7 8 9 10 II 12
1983

7gicides on the incidence of coffee leaf rust.
19830

2gicides ~ ~ ~ ~ ,o onteicdneo ofela ut


22









ve Effects of Several Fungici


'able 1. Effects of fungicides on coffee leaf I


Leaf Rust
treatmentt Incidence (%.


layleton 25.82 a
:upravit 35.22 b
)elan 34.60 b
)ifolatan 36.24 b
;alben 35.64 b
eprol 36.15 b
aprol + Plantineb 37.64 b
controll 46.53 c

C.V.(%) 7.49


All figures are averages of 3 replications c
!ach column followed by the same letter
according to Duncan's Multiple Range Test.

Figures presented are the mean rust incid
beginningg July, 1982 until December, 1983.


Itments during the 1982 harvest
son did not significantly vary at 5%
el. The effect of some fungicides on
Id was however evident during the
83 harvest as yield increased over that
1982 by 57.90%, 48.55%, 24.60%,
61% and 7.70% in the Cupravit, Bay-
)n, Saprol + Plantineb, Difolatan and
ntrol treatments, respectively. In con-
st the 1983 yield decreased in Delan,
ben and Saprol by 7.57%, 14.17% and
51%, respectively.
The 1983 yields (g/tree) of both
pravit (5686) and Bayleton (5672)
e not significantly different from that
Difolatan (4724) but they were signi-
antly higher than the rest of the other
atments (Table 1). Yields form Galben
106) Delan (2989) and Saprol (2849)


icidence and yield.'


Yield (g/tree)
1982 1983


3818 a 5672 a
3601 a 5686 a
3234 a 2989 c
4086 a 4724 ab
3852 a 3306 c
4042 a 2849 c
3190 a 3975 bc
3477 a 3752 bc

19.51 17.28


simple trees/replicates. Means within
At significantly different at 5% level


and yield for the 18 month period


e lower than the control (3752)
/ever, their differences were statis-
Ily not significant from each other.
Saprol + Plantineb mixture obtained
substantiallyy higher yield of 3975
ee than Saprol (2849) but the differ-
e was likewise insignificant.

DISCUSSION
1ll the fungicides tested effectively
uced coffee rust incidence as shown
their significantly lower rust incidence
n the unsprayed control. The systemic
gicide Bayleton was however clearly
erior over all the other fungicides.
ike the normal pustules on leaves
m the other treatments, spots found
Bayleton-treated leaves were small,


23









Philippine Phytopatl


I- tU. V t aLI-.. 11.l ..-LI-UI5V1. sUlaLl
eating that Bayleton killed H. vasi
after spore germination but b
symptom appearance. In addition 1
curative action, Bayleton was rep,
by Paul and Patel (1980) to have
dicative properties. They showed
when Bayleton was sprayed unto all
sporulating pustules, the uredos
were killed and further uredoi
formation was inhibited. The redu
of inoculum due to the curative
.A: ^^4.: nF^*-^* ,C n -iA -


51r;5IEi U ,uuay1, 171 U) allU I llpiU
leaf retention thereby increasing croppi
capacity (Miguel et. al., 1978). It v
noted that the control treatment p:
duced a slight increase in yield wh
Delan, Galben and Saprol, which h
significantly lower rust incidence, g
negative yield response. This indical
that there were factors other than ru
induced defoliation that influenced yi(
adversely. There was abnormally low ra
I .. I I .-- ..^.


pravit, Delan and Difolatan did not ments.
ibit curative and eradicative action When a highly effective
inst H. vastatrix. fungicide such as Bayleton is t
The insignificant differences in yield as the sole agent of coffee leaf
'IL- 3. .r- ..- .-_I.I-. 1- - 1 -i.:I..1_ Ir-n +,1 , -- -r L..:I-


L't









rative Effects of Several I


lates of Phytophthora infestans in
potato fields in Israel. Phytopathology
73: 925-927.

COHEN, Y., M. REUVENI, and Y.
SAMOUCHA. 1983. Competition bet-
ween metalaxyl-resistant and sen-
sitive strains of Pseudoperonospora
cubensis on cucumber plants. Phy-
topathology 73: 1516-1520.

HASHIZUME, H., I.P.R. ANDRADE,
Z. MANSK, and J.B. MATIELLO.
1973. Efeito de differences volumes
de calda e tecnicas de aplicacao de
fungicidads no control da ferrugem
do cafeeiro e a sua influencia na pro-
ducao. Resumos Congresso, 89-90.

JONES, A.L., and R.J. WALKER. 1976.
Tolerance of Venturia inaequalis to
dodine and benzimidazole fungicides
in Michigan. Plant. Dis. Reptr. 60:
40-44.

KABLE, P.F. and H. JEFFERY. 1980.
Selection for tolerance in organisms
exposed to sprays of biocide mix-
tures: A theoretical model. Phyto-
pathology 70: 8-12.

KASPERS, H. and N.K. PATEL. 1980.


do cafeeiro. Resumos Congresso, 247-
248.

MIGUEL, A.E., J.B. MATIELLO, G.N.
DOS REIS, Z. MANAK, and S.R.
ALMEIDA. 1978. Efeitos da apli-
cacao de fungicidas cupricos em
cafeeiros com diferentes graus de
intensidade de ataque de ferrugem
.(Hemileia vastatrix Berk. et Br.).
1 -M .... . . "7 ' o


'AUL, V. and N.K. PATEL, 1981
Studies on the curative and eradicatii


Bayer 33: 152-164.
PAULINI, A.E., A.E. MIGUEL, aj
EVY, Y., R. LEVI, and Y. COHEN. C.M. FRANCO. 1977. Niveis X'epoc
1983. Buildup of a pathogen sub- de desfolha e efeito na protutividai


tegies: A
Phytopatho


ible simulation mod
S73: 1475-1480.

J.B. MATIELLO, a
I n7A Acf+ ', ,ia


RUPPEL,
L.M. B
benomi
S pora bt
mvl. Ph


Ian_ A lima 1 QA


rud IRpmilpin vintntriy Rerk t-t Rr) ~ n~nE Fr


nlnor, 7'n. 9K.9









Philippine Phytopatholo;


KYLAKAKIS, (
nating and n


ixine pesticides on I


pathology 7


ol. 20









Philippine Phytopa


c.


EVALUATION OF CRUDE PL)
FOR THE CONTROL OF C
MUNGBEAN [ VIGNA 1


CLARISSA JOSEFA
and A.B. I

Respectively, Instructor, Assistant F
Agriculture, University of the Philippines
Protection Center, College, Laguna.
Undergraduate thesis at U.P. at Los 1



ABS


EXTRACTS AS FUNGICIDES
:OSPORA LEAFSPOT OF
IA TA (L.) WILZECK]


LROON, O.S. OPINA
NA JR.

sor, Dept. of Plant Pathology, College of
)s Bafios, and Researcher, National Crop

; of the senior author.



CT








Philippine Phytopathology.


& Rigler, 1941;Bergman; 1966;Angell et
al., 1930;Elnaghy & Shaw, 1966).
Among the various potentially fungici-
dal plants grown locally, kamantigue
[Impatiens balsamina L.], garlic vine
[Pseudocalymna alliaceum (Lam.) Sand-
witz], .garlic [Allium sativum L.] and
tagetes.[Tagetes erecta L.] were proven
highly effective againstHelminthosporium
oryzae Cav. (Lapis and Dumancas, 1978;
Lapis and Dumancas, 1979). Ipil-ipil
[Leucaena leucocephala (Lam.) de Wit.]
and makahiya [Mimosa pudica L.] in-
hibited mycelial growth and conidial ger-
mination of a number of fungi (Quebral,
1981;Ebuenga et al., 1979).
This study was conducted to evaluate
the efficacy of extracts from local plants
as fungicides through laboratory, green-
house and field tests to evolve an indi-
genous method of controlling Cercospora
leafspot of mungbean.

MATERIALS AND METHOD

Collection and Maintenance of
the Test Organism

Table 1. List of plants and the respective
property'


The organism was isolated through the
tissue planting technique. Pure cultures
were maintained in onion agar slants at
room temperature (28-300C).


In Vitro Bioassay

Preparation of crude extracts The
methods described by Lapis and Duman-
cas (1978, 1979) and MacDonald and
Bishop (1953) were adopted. Twenty
grams of the plant materials (i.e., leaves,
cloves, corms, stems and fruits) from the
different plants to be screened were col-
lected. These were disinfected with 1:10
NaOCL (5.25% commercial grade) and
rinsed with sterile distilled water three
times. The plant materials were macerated
in 40 ml of sterile distilled water using a
sterilized waring blendor. The resulting
slurry was filtered using a sterilized two-
layer gauze cloth and kept in sterilized
250-ml Erlenmeyer flasks. The extracts
were used immediately after preparation.
Forty-three plant extracts were tested
(Table 1).

plant part screened for their fungicidal


Scientific Name Common Name2 Plant Part


Aerva lanata (L.) Juss
Allamanda cathartica L.
Allium cepa L.
A. sativum L.3
Amaranthus spinosus L.4
Anacardium occidentale L.
Artemisia vulgaris L.
Averrhoa bilimbi L.
Blumea balsamifera D.C. Prodr.
Bixa orellana Linn.
Bougainvillea glabra Choisy
Cadiaeum variegatum (L.) Bl.


apug-apugan (Tag.)
yellow bell (Eng.)
onion (Eng.)
garlic (Eng.)
spiny amaranth (Eng.)
cashew (Eng.)
kamaria (Tag.)
kamias (Tag.)
sambong (Tag.)
achuete (Tag.)
bougainvillea (Eng.)
San Francisco (Eng.)


leaves
leaves
bulbs
cloves
leaves
leaves
leaves
leaves
leaves
leaves
leaves
leaves


Vol. 20















cassia alata L. aKapuiKo (i ag.) leaves
Catharanthus roseus (L.) Don pink periwinkle (Eng.) leaves
Coleus amboinicus Lowe. oregano (Span.) leaves
C scutellarioides (L.)3 mayana (Tag.) leaves
Euphorbia pulcherrima Willd.3 poinsettia (Eng.) leaves
Gehdarussa vulgaris Ness. bunlao (Bis.) leaves
Glicirida sepium (Dacq.) Stwd. kakawati (Tag.) leaves
Hibiscus rosa-sinensis L. gumamela (Tag.) leaves
Impatiens balsamina L. kamantigue (Span.) leaves
Leucaena leucocephala (Lam.) de Wits ipil-ipil (Tag.) leaves
Mangifera indica L. mango (Eng.) leaves
Manihot esculenta Crantz3 cassava (Eng.) leaves
Mimosa pudica L.6 makahiya (Tag.) leaves
Mirabilis jalapa L.3 alas cuatro (Span.) leaves
Moringa oleifera Lam. malunggay (Tag.) leaves
Pandamus odoratissimus L. F. pandan (Tag.) leaves
Piper nigrum black pepper (Eng.) leaves
Phylanthus nirure L. sampasampalukan (Tag.) leaves
Plumeira acuminata Ait. kalachuchi (Tag.) leaves
Portulaca oleracea Linn. olasiman (Tag.) leaves
Psidium guajava L. guava (Eng.) leaves
Sandoricum koetjape (Burm. f.) Merr. santol (Tag.) leaves
Symphytum officinale L.3 comfrey (Eng.) leaves
Tabernaemontana pandacaqui Poir. pandacaqui (Tag.) leaves
Tagetes erecta L.3 tagetes (Tag.) leaves
Tamarindus indica Linn. sampalok (Tag.) leaves
Terminalia catappa L. talisay (Tag.) leaves
Vitex negundo L. lagundi (Tag.) leaves
Zingiber officinale Roxb.3 ginger (Eng.) corms

11 g : 2 ml extract dilution used in the in vitro test.
2Tag. Taglog; Eng. English; Span. = Spanish; Bis. = Visayan.













Test of effectivity Agar plates were sample. The relative rate
prepared by pouring to each plate 2 ml of crease was computed using
the conidial suspension standardized at r' = (X2 X1)/(t2 t ) =
35,000 conidia/ml. To each plate, 10 ml r' is the relative rate of le
of mungbean seed decoction agar pre- X, the number of lesions a
cooled to 400C was poured. The plates -assessment date, t; AX, cl
were carefully rotated to insure even dis- number of lesions; and, Z
tribution of the conidia and were incu- assessment date.
bated for 24 hr at room temperature
(28-30C) after which majority of the Field Evaluatioi
conidia had already germinated. *
Four' sterile chromatographic discs Preparation of the field
previously dipped in one of the aseptical- field with a size of 1l4 m


For the control, the discs were dipped in
sterile distilled water. For comparison,
three fungicides viz., Benomyl (200 ppm),
Benomyl + Mancozeb (1800 ppm), and
Mancozeb (320 ppm) were included in
the test.
The plates were incubated at room
+n___-+--.ra 0 n t2o -1 + >nn- - >f


apart. The treatments were a
randomized complete bloc
three times.

Planting and maintenance
ran granules (0.5 kg a.i./ha)
(20-20-0 kg NPK/ha) wen


planting. Three trials were done with four 1c a Lti icav"'m 1J
replicates per trial. meter. Whenever necessary


Pot Tests


water
Weedin
tiral r


ginger, tagetes, spiny amaranth and garlic, tory ana greenhouse tests were eva
were further evaluated in the greenhouse in the field, viz., spiny amaranth ar
for protective and eradicative actions. ipil, together with Benomyl (200
They were compared with Benomyl (200 and an untreated check. The spray
ppm), Benomyl + Mancozeb (1800 ppm) ments were applied 21, 29, 35 a
and Mancozeb (320 ppm). Untreated DAP at the rate of 2 li/16 m2.
plants served as control. Sampling and data collection -
To assess the efficacy of the extracts ty-five plants were randomly se
as protectants, each treatment was from the three middle rows ofeac
sprayed with 30 ml of the crude extract a as sampling units. Disease assessme
day prior to inoculation with the conidial done by counting the number of C
suspension standardized at 50,000 coni- pora leafspots of each plant s&
dia/ml. Extracts as eradicants were Assessments were carried out 20, 2
sprayed upon the appearance of the first 43 and 50 DAP.
symptom. Yields were also obtained by rec,
Assessments were done by obtaining the weight of seeds from dried poc
the actual lesion count of each plant vested from the five rows of each pl








Jan. & June 1984 Evaluation of Crude Plant Extracts as Fungicides 31



RESULTS the zones of inhibition they produced
(Table 2). Crude extracts of ipil-ipil pro-
In Vitro Bioassay duced the largest inhibition zone fol-
Only 12 out of the 43 crude plant ex- lowed by garlic and makahiya. Inhibition
tracts tested manifested fungicidal activi- zones of garlic and makahiya increased
ty against C. cruenta in vitro. They were with time unlike those of pepper, poin-
extracts of garlic, spiny amaranth, pepper, settia, comfrey and ginger which de-
mayana, cassava, poinsettia, ipil-ipil, ma- creased with time.
kahiya, alas cuatro, comfrey, tagetes and The three commercial fungicides were
ginger, ineffective in vitro as mahifestecdby no
The twelve extracts, however, varied in inhibition zone at all.


Table 2. Diameter of zones of inhibition of crude plant extracts and selected fungicides
tested against C cruenta of mungbean.

Diameter of Inhibition Zone (mm)1
Treatment 2 DAD 4 DAD 6 DAD


Ipil-ipil 24 24 24
Garlic 18 18 18
Makahiya 10 11 11
Spiny amaranth 10 10 10
Cassava 10 10 10
Alas cuatro 10 10 10
Tagetes 10 10 10
Pepper 10 10 0
Poinsettia 10 10 0
Comfrey 10 0' 0
Ginger 10 0 0
Benomyl 0 0 0
Benomyl + Mancozeb 0 0 0
Mancozeb 0 0 0
Distilled Water 0 0 0


1Average of three trials; three replicates/trial; four discs/replicate; DAD days
after disc-planting.









32 Philippine Phytopathology Vol. 20



Pot Tests Consistently as effective as Benomyl,
Preliminary trial The application of Benomyl + Mancozeb and Mancozeb
crude extracts, except that of ginger, which were apparently effective as pro-


comparable t


track


nt extracts as eradicants Iti
tested, except those of tal
L _- -- . r' *,.


getes, ipl-ipu ana alas cuatro (laple 4). --



Table 3. Lesion development of Cercospora leafspot of mungbean as a
*application of selected crude plant extracts and Benomyl'


Rel. I
Treatment Average No. of Lesions/Plant Incre
lesio
1DBS 7 DAS 14 DAS 7 DAS
(r'0)

Benomyl 20 a 41 a 91 a 3 a
Ipil-ipil 24 a 53 a 259 a 4 ab
Spiny amaranth 38 a 72 b 210 a 5 b
Tagetes '47 a 75 b 216 a 4 ab
Garlic 50 a 86 bc 207 a 5 b
Ginger 70 a 109 d 191 a 6b
Control 46 a 99 cd 146 a 9 c


'Average of three replicates, three samples per replicate; Means fc
same letter are not significantly different as determined by Duncan's N
Test at 5% level of significance; DBS days before spraying; DAS
spraying.


esion



DAS




2a
2a
7a
la
8a
9a

y the
Lange
after


'r'l~'0 \I"LI' "'"' ~"~~UIJ) ~'V"













sion development of Cercospora leafspot of mungbean plants treated wil
elected plant extracts and fungicides as protectants'


--


2vVS. i'iu. ul Litiulis/rluiaii


27 DAP 35 DAP


2 a 17 a
2a 5a
3a 6a


lesions/&d
16 DAP-27
DAP (r'j)

0.1 a
0.2 ab
0.3 ab


.1 1


4 ab 44 ab
4 ab 95 bc


0.4 abc
0.4 abc


1-1puZ 3 aoc / a v.W adu v.7 a
anger 5 abc 112 ecd 0.5 bc 5.9 c
is cuatro 7 bcd 22 a 0.7 cd 1.2 a
Ikahiya 8 cd 46 ab 0.9 d 2.1 ab
mfrey 9 d 20 a 0.8 d 1.6 a
tyana 10 d 156 de 0.9 d 8.2 cd
pper 14 e 187 e 1.3 e 10.0 d
rlic 18 f 125 cde 1.6 e 6.6 c
mtrol 10d 129 cde 0.8 d 6.8 c


'Average of three replicates, three samples per replicate; Means followed by the
ne letter are not significantly different as determined by Duncan's Multiple Range
st at 5% level of significance; DAP days after planting.








Philippine Phytopathology


Table 5. Lesion development of Cercospora leafspot of mungbean plants treated with'
selected plant extracts and fungicides as eradicants1


Rel. Rate of Lesion
Avg. No. of Lesions/Plant Increase (r' =
Treatment lesions/day)
25 DAP 32 DAP 42 DAP 25 DAP-32 25 DAP-42
DAP (r') DAP (r')

Garlic 5a 15 a 26 a la la
Benomyl 7 a 20 a 35 ab 2 a 2 ab
Poinsettia 7 a 20 a 38 ab 2 a 2 ab
Mayana 4 a 25 ab 56 abc 3 a 3 abc
Alas cuatro 2 a 25 ab 53 abc 3 a 3 abc
Mancozeb 7 a 27 ab 69 bc 3 a 4 bcd
Comfrey 10 a 28 abc 54 abc 3 a 3 abc
Benomyl + Mancozeb 9 a 32 abc 54 abc 3 a 3 abc
Spiny amaranth 10 a 36 abcd 61 abc 4 a 3 abc
Ipil-ipil 6 a 36 abcd 84 c 4 a 5 cd
Ginger 6 a 45 bc 67 abc 6 a 4 bcd
Cassava 5 a 46 bcd 56 abc 6 a 3 abc
Tagetes 17 a 51 cd 135 e 5 a 7 e
Makahiya 10a 56 e 141 e 6 a 8e
Pepper 13 a 81 e 89 cd 10a 4 cd
Control 19 a 53 d 123 de 8 a 6 de

'Average of three replicates, three samples per replicate; Means followed by the
same letter are not significantly different as determined by Duncan's Multiple Range
Test at 5% level of significance; DAP days after planting.


Field Evaluation
Extracts ofipil-ipil and spiny amaranth
significantly reduced the number of
lesions (Fig. 1). Spiny amaranth extract,
although not as effective as Benomyl, was
more effective than ipil-ipil. Untreated
plants had the highest count during each


assessment.
Yields obtained from plots treated
with Benomyl and spiny amaranth were
not statistically different and were signifi-
cantly higher than those obtained from
untreated plots and that of ipil-ipil
(Table 6).


Vol. 20









Evaluation of Crude Plant Extracts as Fungicides


Table 6. The effect of application of crude extracts of spiny amaranth and ipil-ipil and
of Benomyl on lesion counts of mungbean plants and plot yield1


Treatment Average No. of Lesions/ Plot Yield
Plant 50 DAP2 (kg/16 m2)3


Benomyl 157 a 1243.33 a
Spiny amaranth 388 b 1217.33 a
Ipil-ipil 545 c 1089.33 b
Control 686 d 1064.00 b


1Means followed by the same letter are not significantly different as determined
by Duncan's Multiple Range Test at 5% level of significance.
2Average of three replicates, 25 samples per replicate.
3Average of three replicates (blocks), five rows per block.


20 40
DAYS AFTER PLANTING (DAP)

Fig. 1. Lesion development of Cercospora leafspot of mungbean as influenced by the
application of the extracts of spiny amaranth and ipil-ipil and ofBenomyl.


Control



600
/ ipil-ipil

z /
- /
C)
0
O Is
S400 '

oL I
d ,
z
S* .,-' spiny amaranth


Jan. & June 1984












DISCUSSION actions between the active i
fungicides and specific nutri
Df the twelve plant extracts with bio- ticular medium.
ical activity against C cruenta in vitro, As the screenhouse tests
lic (Lanis and Dumaneanr 197R- Ark :- -1 ... _- .


Url u A IllV/lll^OVll, 1./-// A llJt oy allu -
ton, 1975; Quebral, 1981; Lapis and
mancas, 1978), mayana (Quebral, 1!
Lapis and Dumancas, 1979), poinsi
and comfrey (Lapis and Dumancas, 1!
Lapis and Dumancas, 1979), ipil-ipil
makahiya (Quebral, 1981; Ebuenga el
1979), alas cuatro (Lapis and Dumar
1978). spiny amaranth (Quebral, 19
and tagetes (Walker et al., 1937; P:
et al., 1940) were previously repo
possessing fungicidal properties. Exi
tion and identification of the active I
ciple, although not conducted in
study, are very important in explain
the action manifested by potent:
fungicidal extracts. For instance,
presence of mimosine [beta (N) [3-hy
xy-4-pyrimidine] alpha-amino propii
acid] in ipil-ipil and makahiya le
(Ebuenga et al., 1979) and allicin, wl
is 40% sulfur, in garlic (Cavallito
Bailey, 1944) explains their effi(
against certain fungi.
Changes in the size of inhibition z(
in certain cases could be attributed to
diffusion rate, volatility, photostabi
thermostability and compatibility of
active component with the med
(Lapis and Dumancas, 1978). Fungic
sensitivity test in vitro cannot be, th
fore, regarded as a good indicator
fungicide performance in vivo as exen
fled by Benomyl, Benomyl + Mancc
and Mancozeb, since it does not take
consideration the suscept-pathogen-ch
ical interaction (Sharvelle, 1961). H
and co-workers (1965), likewise,
plained that certain fungicides hydrc
much faster in vitro than when applie
plants. Thus, Saeed and Hussain (1S
and, Wicks and Volle (1978) rec
mended the use of several media to
sibly negate probable occurrence of


found effective as protectants an(
eradicants.
Spiny amaranth and ipil-ipil extr
were chosen to be tested in the field
the bases of the results of the laboral
and greenhouse tests and their availabi
(i.e., they were easier to procure in g
amounts than poinsettia, alas cuatro, e
The difference in efficacy of the
extracts may be attributed to the probi
differences in their respective active c,
ponent and/or to the dilution of the
tracts used in each case. The difference
the extract dilution was due to the d
culty in extracting ipil-ipil which yiel
a very vicious slurry. Thus, the ext:
of ipil-ipil applied in the field was nr
dilute than that of spiny amaranth.
This, therefore, underscores the n
for instituting more efficient, convene
and cheaper methods of extraction
*order to facilitate more extensive util
tion of fungicidal extracts. This n
should be real if one is to prepare 1l
amounts of extracts that will be nee,
in much larger field experiments
eventually for commercial product
Furthermore, dilution and purificat
tests, and studies on the frequency
timing of application are, likewise, ne
sary in establishing an effective indigen
control method.

CONCLUSIONS

Certain plants possess antifungal c
ponents and can, therefore, be utilize
control certain plant diseases (e.g.,
cospora leafspot of mungbean). The
stitution of fungicides with plant extr
will provide a tremendous impact on
present socio-economic situation by
of significant reduction in cheir









Evaluation of Crude Plant Extracts as Fungicides


importation. However, further studies are
necessary before they can be recom-
mended for wider applications.

LITERATURE CITED

ANGELL, H.R., J.C. WALKER and K.P.
LINK. 1930. The relation of proto-
catechuic acid to disease resistance in
the onion. Phytopathology 20: 431-
438.

ARK, P.A. and J.P. THOMPSON. 1959.
Control of certain diseases of plants
with antibiotics from garlic (Allium
sativum L.). Plant Dis. Reptr. 43: 276-
282.

BERGMAN, B.H.H. 1966. Presence of a
substance in the white skin of young
tulip bulbs which inhibits the growth
of Fusarium oxysporum. Netherlands
J. Plant Pathol. 72: 222-230.

BURKHARDT, J.J.,V. MAIZEL and H.K.
MITCHELL. 1964. Avenacin, an anti-
microbial substance isolated from
Avena sativa. II. Structure. Biochemis-
try 3: 426-431.

CAVALLITO, C.J. and J.H. BAILEY.
1944. Allicin, the antibacterial prin-
ciple of Allium sativum. I. Isolation,
physical properties and antibacterial
action. J.Am. Chem. Soc. 66: 1950-
1951.

EBUENGA, M.D., LINA L. ILAG and
EVELYN MAE T. MENDOZA. 1979.
Inhibition of pathogens of field
legumes by mimosine. Philipp. Phyto-
pathol. 15: 58-62.

ELNAGHY, M.A. and M. SHAW. 1966.
Corelation between resistance to stem
rust and concentration of a glucoside
in wheat. Nature 210: 417-418.

FAWCETT, C.H., D.M. SPENCER and
R.L. WAIN. 1969. The isolation and
properties of a fungicidal compound


present in the seedlings of Vicia faba.
Netherlands J. Plant Pathol. 75: 72-81.

GERRETSEN, F.C. and NETTY HAAGS-
MA. 1951. Occurrence of antifungal
substances to Brassica rapa, Brassica
olercea and Beta vulgaris. Nature
169: 659.

GREATHOUSE, G.A. and N.E. RIGLER.
1941. Alkaloids from Zephyranthes
texana, Cooperia pedunculata and
other Amaryllidaceae and their toxici-
ty to Phymatotrichum omnivorum.
Am. J. Bot. 28: 702-704.

HEYN, A.J., GA. CARTER, K. ROTH-
WELL and R.L. WAIN. 1965. Investi-
gations on fungicides. XII. The fungi-
cidal activity of certain N-carboxyme-
thyl-dithiocarbamic acid derivatives.
Ann. Appl. Biol. 56: 399-409.

LAPIS, D.B. and EDNA E. DUMANCAS.
1978. Fungicidal activity of crude
plant extracts against Helminthospo-
rium oryzae. Philipp. Phytopathol. 14:
23-37.

and
1979. Survey of higher plants for fun-
gicidal properties against Pyricularia
oryzae Cav. Philipp. Phytopathol. 15:
23-34.

MACDONALD, R.E. and C.J. BISHOP.
1953. A further survey of plants for
antibacterial substances. Canadian J.
Bot. 31: 123-131.

PRYOR, D.E., J.C. WALKER and M.A.
STAKMAN. 1940. Toxicity of allyl
isothiocyanate vapor to certain fungi.
Am. J. Bot. 27: 30-38.

QUEBRAL, F.C. 1981. Assay on the fun-
gicidal properties of some medicinal
plants. National Crop Protection Cen-
ter Annual Report 1981. p. 20-25.


Jan. & June 1984









Philinnine Phvtonatholoc


SAEED, M. and S. SHAHID HUSAIN.
1970. Influence of some nutrient
media on the toxicity of zerlate to
Helminthosporium hawaiiaense. Pakis-
tan J. Sci. Ind. Res. 12: 387-388.

SHARVELLE, E.C. 1961. The nature and
uses of modern fungicides. Burgess
Publishing Co., Minnesota. 308 p.

TANSEY, M.R. and J.A. APPLETON.
1975. Inhibition of fungal growth by
garlic extract. Mucologia 67: 409-413.

VALENTA, J.R. and H.D. SISLER. 1962.
Evidence for a chemical basis of resist-
ance of lima bean plants to downy


mildew. Phytopathology 52; 1030-
1037.

WALKER, J.C., S. MORREL and H.H.
FOSTER. 1937. Toxicity of mustard
oils and related sulfur compounds to
certain fungi. Am. J. Bot. 24: 536-541.

WHITNEY, N.J. and C.G. MORTIMORE.
1959. An antifungal substance in the
corn plant and its effect on growth of
two stalk-rotting fungi. Nature 3: 341.

WICKS, T. and D. VOLLE. 1978. Effects
of agar media on sensitivity of isolates
ofBotrytis cinerea to fungicide. APPS
Newsletter 7: 8-9.


_~ __









C.


PATHOGENICITY, DA
FIELD POPULATION PAT
OR YZ

J.J. WALAWAI

Respectively, Training Specialist I,
tion and Professor of Plant Pathology, C
pines at Los Baflos. The senior author w
section Center when the study was condt
The study was supported by a r(
Center.

ABST
Rice plants inoculated with Hirse
levels used (1,000-30,000 individuals)sh
degree of necrosis or discoloration of rc
ficant reduction in plant height, number
H. oryzae entered the roots in 2
many nematodes were already found i
brown color when examined on the 1:
of the infected roots was observed. Sec
noted 52 days later.
Field population of H. oryzae in
seedling stage to maturity of the plants
the roots started to increase 1 week a:
peak 60 days later, whereas those in the
first month and thereafter increased col
vation period when the plants had alrea
tode population peak in the soil planted
planted with IR-62 and IR-18348-36-3
nematode population peak in roots than


INTRODUCTION


Nematodes are known to attack rice
plants but the degree of damage to the
crop has not been thoroughly investigated.
The rice root nematode, Hirschmanniella
oryzae, rice stem nematode, Ditylenchus
angustus, rice white tip nematode, Aphe-
lenchoides besseyi, and. rice root-knot
nematode, Meloidogyne graminicola, have
been reported abroad to infect rice plants
(Taylor et al., 1966; Sher, 1968; Rao and
Israel, 1973). H. oryzae and A. besseyi
are more common on rice in the Philip-
pines (Sukit, 1973; Madamba et al..
1981).


LUE ASSESSMENT, AND
N OF HIRSCHMANNIELLA
N RICE

id R.G. DAVIDE

BCA La Granja Research and Training Sta-
;e of Agriculture, University of the Philip-
n Special Detail at the National Crop Pro-

:h fund of the National Crop Protection


T
iniella oryzae regardless of the population
severe infection as manifested by high
The nematode infection resulted in signi-
lers, panicles, top growth and yield.
36 hours after inoculation-Within 9 days
the root tissues. Infected roots showed
ay and on the 25th day severe browning
generationn infection by the nematode was

oots and soil varied considerably from the
erally, the population of the nematode in
transplanting of seedlings and reached the
showed a decline in population during the
ously until the end of the 90th day obser-
ached maturity. There was a higher nema-
. vars. C1136-3 and UPL Ri-4 than in soils
however, IR-18348-36-3-3 had the highest
theirr three varieties.


Seven species of Hirschmanniella are
known to infect rice (Sher, 1968). Severe
infection of these nematodes on the
plants could reduce and delay tillering,
flowering and suppress root and shoot
growths as well as the grain yield (Baba-
tola and Bridge, 1979). In Thailand, it
was claimed that control of the nema-
tode may be the key to improve rice
production (Taylor, et al., 1966). In
the Philippines, surveys have indicated
that the nematode is commonly asso-
ciated with lowland rice (Palo and Calinga,
1965; Davide et al., 1966). Results of
greenhouse experiments showed that
Hirschmanniella mucronata reduced grain
yield significantly of C4-63G and IR-8


LI ~m








Philippine Phytopathology


varieties m greenhouse experiment (Sukit,
1973).
Hirschmanniella spp. are well adapted
to conditions in marshes and flooded
rice paddies. They can infect and repro-
duce on some sedges and grasses (Taylor
et al., 1966). When the paddies become
dry, the nematodes would remain dor-
mant until the next season (Thorne,
1961). The nematode usually move out
from rice roots into the soil soon after
seed formation or when rice growth
ceased and survives in paddy soil up to
7 months (Park et al., 1970). Yokoo
and Su (1966) observed a 33% decrease
in H. oryzae within 50 days after removal
of flood water. They also found that the
nematodes occurred most abundantly in
10 to 20 cm deep flooded field soils.
This paper presents the findings of our
study on the pathogenicity of H. oryzae
on rice var. C4-63G and the effects of
varying inoculum levels of the nematode
on plant growth and yield of rice var.
UPL Ri-4. Results of field observations
of the population pattern of the nema-
tode under lowland rice conditions are
also discussed.

MATERIALS AND METHODS
Pathogenicity of H. oryzae on rice
C4-63G var. To determine the disease
reaction of C4-63G var. to H. oryzae
infection, an inoculation study was con-
ducted in the greenhouse. Two-week
old rice seedlings were transplanted into
360 mm diam. clay pots (70 pcs.) filled
with baked soil. Twenty four hrs. later,
each potted seedling was inoculated with
50-100 H. oryzae individuals. The ino-
culum was prepared by extracting the ne-
matodes from rice roots using the incu-
bation method (Young, 1964). To ob-
serve nematode infection on the roots,
one potted plant was examined everyday.
It was carefully removed from the pot
and washed thoroughly with tap water to
clean the root system. The appearance of


disease symptoms on the roots due to
the nematode infection was observed up
to 60 days after inoculation. The move-
ment of the nematode into the root
tissues was determined by fixing the root
in FAA for 24 hrs. and then stained in
boiling acid-fuchsin lactophenol for at
least 48 hours before examining the roots
for nematode penetration under a stereo-
scopic microscope.
Assessment of H. oryzae damage on
rice plants. This study was conducted
under a greenhouse condition to evaluate
the effects of H. oryzae infection on
growth and yield of rice plants. Two-
week old rice seedlings var. UPL Ri-4
were transplanted in 30.5 cm diam clay
pots (30 pcs.) filled with baked soil. Five
days later, the seedlings were inoculated
with the nematode suspension by intro-
ducing it into the soil near the base of the
plants through three poke holes about
3 cm deep and then covered with soil.
Five inoculum levels of H. oryzae, name-
ly; 1,000, 3,000, 9,000, 20,000 and
30,000 per potted plant were evaluated.
An uninoculated control treatment was
provided. There were 5 replicates per
treatment. All pots were then randomly
arranged inside the greenhouse. They
were fertilized with complete fertilizer
(14-14-14) and watered regularly. The
plants were allowed to grow to maturity.
To assess the nematode damage on the
inoculated plants, the following data
were gathered; number of tillers and
plants panicles in each pot, plant height,
and top growth and yield.
Observation of the field population
patterns of H. oryzae.- The study was
conducted at the lowland rice production
area of the Institute of Plant Breeding,
UPLB, College of Agriculture, where four
rice varieties were grown, namely; UPL
Ri-4, C1136-3-31, IR-62 and IR-18348-
36-3-3. The population density of the
nematode in the soil and roots of these
four rice varieties was monitored at 7,
30, 60 and 90 days after transplanting


VI1 1n









r nfamoPi A~.sucrm n


of the seedlings in the field. This was
done by randomly collecting 5-10 soil
and root samples from each variety.
Each soil sample was thoroughly mixed
and 400 cc was taken out for nematode
analysis using the sieving-Baermann fun-
nel method (Christie & Perry, 1951).
The root samples from each variety
were washed in tap water and cut into
small pieces about 3 cm long and mixed
together and 10-gr composite sample
was taken out for nematode extraction
using the incubation method in the
Baermann funnel as described by Young
(1964). After 24 hrs. in the funnel about
10 cc of the nematode suspension was
drown out into the vial and allowed
to settle for 5-10 minutes. The top 5 cc
was carefully poured out and remaining
5 cc containing the nematodes that
settled at the bottom of the vial was
shaken and placed in the counting dish
where the nematodes were counted under
a stereoscopic microscope.

RESULTS AND DISCUSSION

Pathogenicity of H. oryzae on rice var.
UPL Ri-4.-H. oryzae started to penetrate
the roots within 24 hrs. after inoculation..
The same observation was made by
Buangsuwon et al. (1971). During this
period only the head region had pene-
trated the root tissues. Within 48 to 72
hours, about 2/3 of the anterior portion
of the body was already inside the root
tissues. On the average, it took about
9 days for the nematode to completely
penetrate the roots and become endo-
parasites. Some nematodes were observed
to enter through the root tips, other
some distance from it. This observation
was contrary to previous report that the
nematode can penetrate rice roots at any
point except near the root tips (Buang-
suwon et'al., 1971) and the nematodes
never fed on the root tips or thin lateral
roots (Mathur and Prasad, 1972).
Ir" '- f- -4 + - t, -A +r


have changed color from whitish to
brown on the 13th day after inoculation.
New sedentary root systems had deve-
loped. On the 16th, almost all root sys-
tems turned brown. Severe browning
of the roots were observed on the 25th
day after inoculation. The primary root
systems started to develop necrosis
and rotting. Infected secondary as well as
the tertiary roots also become brownish.
Severe browning of the infected root
systems was very pronounced on the
40th day after inoculation. Thp nema-
todes deposited their eggs in the root
tissue (Fig. 1) and hatched larvae were
observed on the 52nd day after inocu-
lation. This indicates that secondary
infection by these larvae may have taken
place making more damage to the roots.
























Fig. 1. A portion of rice root showing
H. oryzae inside (1) and the eggs
(arrows A & B) deposited in the
tissues (2).
Assessment of nematode damage on
rice var. UPL Ri-4 The data summarized
:._ I I_ .. J I 1 1 r __


..n A Inna 1QOR








Philippine Phytopatholo


Table 1. Mean number of tillers, pani
potted plants of UPL Ri-4 vi
population levels based on foru


Nematode Tillers Panicles H(
Pop./Pot (No.) (No.) (c

0 28.3 a 33.3 a 59
1000 19.0 bc 24.0 bc 52
3000 24.8 abc 29.8 abc 52
6Q00 23.5 abc 28.5 abc 51
9000 19.3 bc 24.3 bc 50
20,000 22.5 abc 27.5 abc 50
30,000 21.3 bc 26.3 abc 48

1Means followed by the same letters i
DMRT.

significantly affect the growth and yielc
of rice plants regardless of the inoculun
levels used. Severe root necrosis was gene
rally observed in plants with high ino
culum levels which was usually accom
panied by considerable root growth
reduction (Fig. 2). There was also a sig
nificant reduction in the number o
tillers produced by the plant as well a
in the number of panicles developed an(
a significant reduction in plant high
and top growths compared with th
control. Apparently, this detrimenta
effect on plant growth has significantly
affected the yield of the infected plants
The yield reduction ranges from 36.6% t(
61.6% (Table 1).
Velcitesan et al. (1980) reported tha
even at population density level of 29 t(
68 nematodes per 500 ml soil sample the
nematode could reduce tiller production
by 15%,and yield reduction by 13.8 t(
19.2%. Other investigators also showed
that population levels of 100 to 1,00(
nematodes per plant could already causi
significant reduction in growth and yielc


plant neign, top grown ana yiela per
oculated with H. oryzae at different initial
ications


Top Growth Yield % Yield
(Dr wt. gr) (gr.) Reduction

1 52.4 a 28.2 a
S 32.1 b 13.4 cdef 52.5
b 34.5 b 18.7 b 33.9
b 37.1 b 17.9 bc 366
b 30.9 b 11.4 cdef 59.7
b 30.1 b 16.7 bcd 41.0
S 32.0 b 10.9 cdef 61.6


column are not significantly different at 5% level


of rice plants (Babatola & Bridge, 1979).
Observation on the field population
patterns of H. oryzae. The population
pattern of the nematode inside the root
was evidently different from those in th
soil. The root nematode population ir
creased continuously starting from seve:
days after transplanting and reached th
peak at 60 days and then declined sharply
thereafter as the rice plants reached matu
rity or when the plants had evident:
ceased growing (Fig. 3). However, th
population density of the nematode
varies with the varieties observed. Mud
higher population peak was observed ii
var. IR-18348-36-3-3, than in other varied
ties which may indicate the variety wa
more susceptible to the nematode.
On the other hand, the nematod
population pattern in the soil showed
decline in population one month or 3(
days after transplanting of seedlings. Thi
may indicate that during this period mos
nematodes were entering the roots fron
the soil. After this period, however, the
soil population of the nematode con


Vol. LI















tinuously increased until 90 days (Fig. 4)
which may indicate that many of the
nematodes may have moved out of the
roots and stayed in the soil. Higher soil
nematode population was obtained in
soils planted to rice vars. C1136-3 and
UPL Ri-4 as compared with those in
soils planted to rice vars. IR-62 and IR-
18348-36-3-3.
Evidently, the data showed that H.
oryzae easily infected the rice roots and
reproduced rapidly within the growing
period of the'plants and when the plants
reach maturity the nematodes would
move out of the roots and stay in the soil
waiting for new host roots to feed. Parker
et al. (1970) observed that the nematode
ceased feeding when rice plants ceased
growing and our results seemed to con-
firm the finding.







2000






















Fig. 3. Fie/ population pattern of Hirsch-
200 anniella oryzae in roots
1100,









60 10 20 30 60 O 9 100




Days Mer Planting




Fig. 3. Field population pattern of Hirsch-
manniella oryzae in roots of four


OD0

500 -

600 -





400 -
36-3-3


100


0 10 20 30 40 50 60 50 50 g 00
%aps After Plastln


Fig. 4. Field population pattern of' HirIch-
manniella oryzae in soils planted
with four rice varieties.


LITERATURE CITED

BABATOLA, J.O. and J. BRIDGE. 1979.
Pathogenicity of Hirschmanniella
oryzae, H. spinicaudata and H. ima-
k muri on rice. Jour. Nematol. 11:128-
132.

BUANGSUWON, D., P. TONBOON-EK,
G. RUJIRACHOON, A.J. BRAUN and
A.L. TAYLOR. 1971. Nematodes. In
rice diseases and pests of Thailand.
(Abstract) Helminthol. Abstract 44:
116-117.

CHRISTIE, J.R. and V.G. PERRY. 1951.
Removing ftematodes from soil. Proc.
Helminthol. Soc. Wash. 18:106-108.

DAVIDE, R.G., O.R. EXCONDE and
F.D. FUENTES. 1966. Plant parasitic
-1 -:1 _+-A- --+.A -.4,prl ~ r:,


. ...


____ A _- --Ann








Philippine Phytopathology


lowland rice fields. Jour. Phil. Phyto-
path. 2:6-7.

MADAMBA, C.P., V. SUKIT, E.T. ONG
and N.C. SEVILLA. 1981. Incidence
of plant parasitic nematodes associated
with rice grown in the Philippines.
Phil. Agric. 64: 231-246.

MATHUR, V.K.and S.K. PRASAD. 1974.
Control of Hirschmanniella oryzae as-
sociated with paddy. (Abstract) Hel-
minthol. Abstract 44: 199.

PALO, A.V. and R.H. CALINGA. 1965.
Plant parasitic nematodes associated
with some agricultural crops of the
Philippines. (Abstract) Jour. Phil.
Phytopathol. 1:17.

PARK, J.S., S.C. HAN and Y.B. LEE.
1970. Studies on the ecology and feed
preference of rice root nematode,
Hirschmanniella oryzae. Res. Rep. Off.
Rural Dev. Suon S. Korea. 13:96-98.

SHER, S. 1968. Revision of the genus
Hirschmanniella Luc and Goodey
1963. (Nematoda: Tylenchoidea).
Nematologica 14: 243-275.


SUKIT, V. 1973. Studies of plant parasi-
tic nematodes associated with rice
with emphasis on the rice root nema-
tode Hirschmanniella mucronata (Das
1960) Luc and Goodey 1963. M.S.
Thesis, Univ. Phil. Los Bafios.

TAYLOR, A.L., T. KAOSIRI, T.
SITTAICHI and D. BUANGSUWON.
1966. Experiments on the effect of
nematodes on the growth and yield
of rice in Thailand, P1. Prot. Bull.
FAO 14(1): 17-23.

THORNE, G. 1961. Principles of nema-
tology. New York; McGraw Hill Co.,
Inc. p. 233.

VENKITESAN, T.S., T. NALINAKU-
MARY and J. SATYKUMAR. 1980.
Distribution of rice root nematodes in
Kerala. (Abstract) Helminthol. Abstract
1980 No. 1025.

YOUNG, T.W. 1964. An incubation
method of collecting migratory endo-
parasitic nematodes. Plant Dis. Reptr.
38: 798-795.


Vol. 21









IL;,.


I nC ]A[ U IJ UlU
1aO 1.* I....--


POSTHARVEST CONTROL
VAR. CAROTOVORA IN CA

E.S. BORROME(

Research Assistant, International Ri
University of the Philippines at Los Bafios
Portion of the Masters thesis of thi
supported by the ASEAN Postharvest Hot

ABS

Calcium hypochlorite, boric acid
slaked lime were evaluated for the contrc
artificially inoculated cabbage stem slices.
alum [KAl (S04)2. 12H20], 15% solutil
suspension.
Transport experiments with alum
soft rot incidence was high showed that
butt end of the cabbage head before pa
rot by 70% compared with the control. I
by surface water in wrapper leaves and so
during the wet season.
The incidence of soft rot during t-
alum nor lime provided significant control.
Alum or lime application also redi
bage heads stored in perforated plastic 1:
heads exhibited some black specks but c
moval of the outer leaves would take care





INTRODUCTION


Cabbage production in the Philippines
has increased within the last decade or so,
but unfortunately, this has also been
accompanied by a concomittant increase
in the amount lost after harvest. It was
estimated that as much as 40-50% of the
harvested cabbage is lost before it reaches
the consumer (Pantastico and Bautista,
1976). About half of this lost is due to
decay from bacterial soft rot.
The disease is the most ubiquitous and
the most destructive postharvest disease
of cabbage. It is manifested by the trans-
formation of the affected part into a soft,
pulpy and watery mass, often giving off
an offensive odor.


ERWINIA CAROTOVORA
,GE WITH ALUM AND LIME

I LINA L. ILAG

research Institute and Associate Professor,
.B), College, Laguna, respectively.
ior author, submitted to UPLB Research
ture Training and Research Center, UPLB.

CT
ax, sodium chloride, alum and
bacterial soft rot in cabbage using
most effective among these were
id slaked lime (CP(OH)2], 75%

ime during the wet season when
alum when sprayed toward the
ng reduced the incidence of soft
ne coating was easily washed out
ineffective in transit, particularly
season trial was low and neither

the incidence of soft rot in cab-
Fhe outer leaves of alum-treated
1 application of the alum or re-
problem.




Soft rot bacteria are generally oppor-
tunistic pathogens, i.e. they usually
attack plant organs when there is injury
and/or reduction of plant vigor. Crops
normally decline in vigor after harvest,
and injury cannot be completely avoided
during harvesting and handling operations.
Hence, harvested crops are generally more
susceptible to soft rot than standing crops
in the field. Soft rot in the field becomes
very destructive only when frequent pre-
cipitation and warm weather prevail at
heading stage. Losses due to soft rot are
likely greater after harvest than during
the growing period.
There is an acute need to find an
adequate and practical control for bac-
terial soft rot of cabbage during transport
and storage in wet weather.













MATERIALS AND METHODS

The isolate of Erwinia carotov
var. carotovora used in the experim
was isolated by plate dilution metal
using yeast glucose violet agar (y(
extract, 10 g; glucose, 10 g; crystal '
let, 0.1% aqueous solution; agar, 15
distilled water, 1 L). The isolate ,
maintained on yeast dextrose ch
agar (yeast extract, 10 g; glucose, 2(
calcium carbamate, 20 g; agar, 15
distilled water, 1 L) and tested
macerating ability on *carrot sli,
Identification was based on morph(
gical and biochemical characters
according to Bergey's Manual of De
minative Bacteriology (Buchanan
Gibbons, 1974).
Evaluation of chemicals for soft
control
The chemicals tested were calci
hypochlorite [Ca (OC1)2], 1000 pI
boric acid (H3BO3), 7.5%, borax, (I
B404), 7.5%; sodium chloride (NaC
25%; slaked lime [Ca (OH)2], 75%
alum [KAl (SO4)2. 12H20], 15%.
Five-millimeter thick cabbage st
sections were separately dipped in
above solutions (except for lime), plain
in moist chamber and inoculated w
0.05 ml bacterial suspension contain
106 viable cells of the most virul
isolate which came from Bugias, Bengt
The 75% lime suspension was pain
on the section, allowed to dry after wh
the sections were placed in a moist chE
ber, inoculated as previously descrit
and incubated at ambient conditi,
(21-320C).
Each replicate consisted of
sections. There were four replications
each treatment. Sections were consider:
rotted if the lesions occupied at le
15% of the surface area. The percent;
of rotting was recorded 24, 48, 72 a
96 h after inoculation.


Effect of alum and lime applied afl
infection
Cabbage core sections were inoculat
with 0.05 ml bacterial suspension cc
training 106 cells, incubated for 12
in a moist chamber after which the rott
portions were scraped off in runni
water. The sections were then separate
treated with 75% lime paint and 1;
alum, and water as control. Each replic;
consisted of 10 sections. There were fc
replications. Soft rot incidence w
recorded after 24, 48, 72 and 96 h.

Effect of alum and lime applied bef(
infection.
Cabbage core sections which had be
treated with 15% alum or with lii
paint 0, 6, 12, 24, 48 and 72 h in advar
were simultaneously inoculated w:
0.05 ml bacterial suspension contain
106 cells, in a moist chamber th
observed for soft rot incidence after :
48, 72 and 96 h incubation. Delay
application of chemical by 6 h m
included.

Transport trials
Wet season trial

Cabbage heads were harvested fre
a field in Bugias, Benguet during co
editions of intermittent light, rain show<
in June, 1982. These were transport
in bulk to Baguio City where treatme
was done 24 h after harvest. A factor
experiment involving two factors (trii
ming and alum spraying) was conduct
One group of cabbage heads was spray,
with 15% alum solution towards the bi
end without prior trimming, anoth
group was first trimmed of a portion
the butt end plus two to three wrapp
leaves before alum treatment, and st
another group was trimmed but with
any further treatment. The heads we
then packed in bamboo crates wi
30-40 kg per crate. Heads which receive


.v


---. I r-- -.-- ----









est Control of Cabbage


neither trimming nor alum application
served as control. No artificial inoculation
was done as some heads exhibited in-
fections so it was presumed that the
heads were naturally infected. One day
after the treatment, the crates were
transported to the Postharvest Horti-
culture Training and Research Center
(PHTRC), University of the Philippines
at Los Bafios, College, Laguna through
the usual commercial conditions. The
crates were opened two days after arrival.
Disease incidence was recorded as the
proportion of heads with infections at
the butt end per crate.
Dry Season Trial
The dry season trial was conducted in
February, 1983. Cabbage heads were
harvested in Bugias and transported to
Baguio City in bulk. The heads were
trimmed of a small portion of the butt
end to remove the contaminated surface.
A bacterial suspension containing 106
cells/ml was sprayed towards the butt
end. After inoculation, separate heads
were immediately given the following
treatments: (a) butt end sprayed with
15% alum, (b) butt end pressed on lime
powder spread on a shallow container,
(c) butt end exposed under the sun until
the surface dried off, and (d) sprayed
with water as control.
In this experiment and the succeeding
one on storage, the lime used was CaO
instead of Ca (OH)2. Both are generally
referred to as lime; the latter is sometimes
called slaked lime. Since CaO can also
form a coating on the butt end, it was
presumed that CaO and Ca (OH)2 could
be used interchangeably, whichever is
available.
After treatment the heads were packed
in open bamboo crates and transported to
PHTRC simulating normal commercial
conditions. The truck suffered a mecha-
nical breakdown along Pangasinan, thus
delaying transport by one day. The crates
were open three days after treatment and


ease incidence was recorded

rage experiment
Three replicates were provided for
h treatment. Cabbage heads were
nmed of wrapper leaves. Each trimmed
.d was inoculated with 0.05 ml bac-
ial suspension with 106 cells, treated
h 15% alum and lime powder as pre-
usly described, placed inside per-
ated plastic bags and stored at ambient
editions (20-32oC). Disease incidence
i determined after four days.


RESULTS

iluation of chemicals for soft rot control
Cabbage sections treated with borax,
-ic acid, sodium chloride, and calcium
)ochlorite all had from 72'5% to 100%
action 24 h after inoculation (Table 1).
ase treated with 15% alum.and painted
h 75% lime suspension were devoid of
ting even up to the third day. Growth
a saprophytic fungus (Aspergillus sp.)
i observed on the third day in alum-
ited,sections. Soft rot symptoms ap-
red on the fourth day.
Alum and lime were quiteetffective in
control of soft rot as shown by initial
:s thus various concentrations of these
pounds were tested in the manner
viously described. Alum solutions of
7.5, 10, 12.5 and 15% and lime sus-
sions at 25, 50 and 75% (w/v) were
:ed.
Among the various alum concentration
ed the 15% aqueous solution gave the
most effective control. The effectivity
:he chemical decreased with decreasing
centration.
Lime was best applied at 50 or 75%
,ension. There was practically no in-
ion when these concentrations were
ited with a brush into cabbage stem"
ions prior to inoculation with the soft
pathogen.


47









A n


Table 1. Mean percentage rotting in c
chemicals and then inoculate
carotovora. 1


Chemicals Concentrat


Lime 75.0
Calcium hypochlorite 0.1
Sodium chloride 25.1
Borax 7.5
Boric acid 7.5
Alum 15.0
Control (water)

'Data are averages of 3 replicati<
are significantly different at 1% level.

Effect of alum and lime applied after
fection had been established
It was noted in previous experimel
that rotting continued to progress in
fected core sections even when the ma
rated portion had been thoroughly
moved. This indicated that deeply seal
bacteria were present in the apparent
healthy tissue beneath the infected p
tion that was removed. Lime applicati
did not prevent the resumption of r
ting; all lime-treated sections rott
within 24 h. However, alum delay
the recurrence of rotting as soft j
symptoms were completely absent 24
after incubation and began to appi
only on the second day and continue
'to increase until 60/ of the alum-treat
sections were rotten on the fourth d,
These results suggest that alum (
delay infection even if the pathogen 1
already penetrated the host. The effect
lime, however, is superficial and would
useful only if applied before the pathol
is entrenched in the host.

Time interval for effective control w


ge stem sections pre-treated with differer
th a suspension of Erwinia carotovora vai



Time After Inoculation
24 h 48 h 72h 96

Oc Oc Ob 01
100a -
100a
72.5b 90b 100a
82.5b 95b 100a -
Oc Oc 0b 101
100a

eatment. Means followed by different lette


alum or lime
The incidence of rotting increased
the time interval between treatment wi
alum and inoculation with the pathog
increased (Table 2). Thus, as the inter
between alum treatment and introducti
of the bacterium widened, the effective
of alum decreased. While infection w
only 15% (after 96 h incubation) wh
the bacteria were introduced 6 h afl
alum treatment, infection reached 10(
when the interval between chemical tre
ment and inoculation was 24 h (Table :
This suggests that the effectivity
alum in inhibiting the pathogen declir
in about 24 h after treatment and cc
tinues to decline with time (Table 2). A
other treatment may therefore be nec'
sary if prolonged storage under hi
inoculum density is perceived.
The inoculation of lime-treated s<
tions at any time after the lime coati
had dried off failed to cause any signi
cant rotting. When the inoculum was i
produced while the lime coating was st
wet, a percentage infection of 10 al
11 mprP nhorr ,rld oftor on- 1- -1


lg 6ira ...









Pbstharvest Control of Labb


ole 2. Mean percentage rotting in cabbage
with E. carotovora var. carotovora aft


ime of _
culation 24h


before treatment 0d
ultaneous with treatment 0d
after treatment Od
h after treatment 0d
h after treatment 12.5c
h after treatment 20b
h after treatment 77.5a

'Data are averages of 3 replications/tre;
significantly different at 1% level.

r days, respectively (Table 3). Lime
dlication after inoculation failed to
itrol rotting. Cabbage sections that
-e treated with lime 6 h after inocula-


ble 3. Mean percentage rotting in cabbage i
var. carotovora at various times after


ime of
culation 24h .

before lime treatment 70a
lultaneous with lime treatment 10
after treatment 2.5c
h after treatment 0
h after treatment 0
h after treatment 0d
h after treatment Od

'Data are averages of 3 replications/tre
different letters are significantly different a


sections inoculated at various times
atment with 15% alum.'


ation Time After Inoculation
48h 72h 96h

2.5c 22.5d 37.5b
5c 10.0C 30P
2.5c 2.5f 15d
2.5c 10.0e 12.5d
45b 60c 100a
45b 90b 100a
100a

it. Means followed by different letters


n had 70% rotting on the first day,
ich increased to 100% on the third




sections inoculated with E. carotovora
ing with 75%lime suspension.'


Time After Inoculation
48h 72h 96h

90a .100a -
12.5 12.5b 12.5b
2.5c 2.5c. 2.5c
gd 0d dd
0d 0d 0d

Od. 2.5c 2.5C
d d d

nt. Means in vertical column followed
level.


ty








CA


Transport trials

Wet Season Trial
Alum application in trimmed cabba
cores effected a 70% reduction of soft i
infection during the transport trial c(
ducted in the wet season when soft rot
cidence was particularly high. Alum tre
ment alone (without prior trimming
the heads) caused a 53% reduction in r,
ting, and trimming alone (without alui
effected the least control (Table 4).

Dry Season Trial
The incidence of soft rot was low di
ing the dry season transport trial. Inocu
tion of cabbage heads with E. carotovc
var. carotovora prior to transport result
in only 3.0-8.2% infection. Different
between the treatment means were r
statistically significant at the 5% level
significance, hence chemical control
not deemed necessary as long as the c,
bage heads are kept dry.


Table 4. The effect of trimming and al
in cabbage heads during transp



Treatment


Trimming + alum (15%)
Trimming only
Alum (15%) only
Control (no trimming, no alum)

'Data are averages of 3 replicatio
% rotti
l .i ^in con1
2% reduction in rotting = in con
%r


Storage experiment
Alum or lime application reduced t
incidence of soft rot in cabbage hes
stored in perforated plastic bags. Lin
treated heads had only 13% rotting, alu
treated cabbage had 23% rotting wh
non-treated heads exhibited 100% rotti
after a storage period of four days at a
bient conditions. The outer leaves
alum-treated heads showed some bla
spots which reduced the aesthetic qual
of the commodity. However, this v
confined to the outer leaves and can
minimized or eliminated by the care
application of alum on the butt end
the cabbage head. The unsightly ou
leaves may also be simply removed
show the healthy leaves underneath.

DISCUSSION

Among the six chemicals tested, ah
and lime showed promise for the effect:
control of bacterial soft rot in cabbage.


eatment on the incidence of bacterial soft r
wet season, June 1982).'


lean Difference Percenta
.entage' With Reductic
Voting Control In Rotti

5.2a 33.8 70
3.g 15.2 31
3.0b 16.0 53
9.0d

satment.
% rotting in
treatment
X 100
g in control









harvest Control of Cabbage


Alum was effective when applied prior
or even after the bacteria had pene-
ited the host tissue. This is an indica-
mn of its bactericidal property and abi-
y to penetrate into the tissue several
Us deep. The inhibitory effect of alum
i soft rot development may be due to
e presence of Al+++ ion and/or low pH.
ie pH of the alum solutions were quite
w, ranging from 4.30 to 4.20 (Table 5).
nce bacteria are sensitive in low pH, the
Fectivity of alum treatment may be due
this. In addition, the Al+++ ion is
town to form complexes with organic
pounds found in the cell (Henderson
d Easton, 1980) which may be fatal to
e pathogen. The bactericidal effect of

able 5. Colony count of E. carotovora var. ct
of alum for different lengths of time.


Alum
concentration (%) ph

0 7.0


5 4.30


7.5 4.30


10 4.25


12.5 4.25


15 4.20



10.05 ml bacterial suspension added to
2Average of 3 replicates yeast glucose
numerous to count; more than 200 colonies p


am was enhanced by increasing its con-
ntration or the time of contact with the
Ithogen. With 5% alum, bactericidal
tivity was observed only if the bacteria
ere suspended in the solution for 20
minutes; no bactericidal effect was
cited with shorter period of contact
able 5). There was total eradication of
e bacteria in vitro when the pathogen
is suspended in 12.5 and 15% alum for
re minutes.
Lime was effective protectant when it
roughly covered the butt end of the
bbage stem. However, it was no longer
fective when applied after the pathogen
d penetrated the host tissue (even if
ft rot symptoms are apparent yet). This

)vora exposed to various concentrations



Time of Colony
Contact (Min) Count2

5 x
10 x
20 x
5 x
10 x
20 5
5 123
10 113
20 0
5 41
10 0
20 0
5 0
10 0
20 0
5 0
10 0
20 0

filter-sterilized alum.
plates after 48 h incubation; x = too
ate.


31








Philippine Phytopa


implies that the lime merely provide
protectivebarrier and has no bacterici
property. Lime may also play a phys
role in; that it absorbs the water wh
bacteria require to initiate infection. F
surface water is required for the mc


LITE

BUCHANAN, R.E. and N.E. GIBBOI
(Eds.). 1974. Bergey's Manual
Determinative Bacteriology. 8th <
The Williams and Wilkins Co., BE
more. pp. 332-340.

HENDERSON, D., and R.G. EAST
1980. Stingose: a new and effect
treatment for, bites and, stings. Med
Aust. 67: 146-150. (Abstract in B
Abstr. 71: 63262).

PANTASTICO, ER.B., and O.K. BAUI
TA. 1976. Postharvest handling


ACK]

The authors appreciate the sugge
of the experiment.


ment of bacteria. Once the water poten
of the tissue decreases to a critical le'
.soft rot development is inhibited (Tan;
and Kikumoto, 1977). Thus, the dry
effect of lime deters infection.



URE CITED

tropical vegetable crops. Hort. Sci. 11:
122-124.

SOCIETY OF AMERICAN BACTERIO-
LOGISTS. 1957. Manual of Micro-
biological Methods. McGraw Hill,
New York.

TANAKA, T., and T. KIKUMOTO. 1977.
Inhibition of soft rot development by
lowering the water potential of a
detached leaf of Chinese cabbage.
Rep. Inst. Agr. Res. Tohuku Univ.
28: 1-8.


LEDGMENT

s made by Dr. O.K. Bautista during the coui


3L









1c.


INFLUENCE OF TUNGRO VIRUS-I]
BEHAVIOR AND BIOLOGY OF
NEPHOTETTIX VIRESCE,
TUNGRO EPI




Z.R.KHAN and
Respectively, Post Doctoral Fellow ii
International Rice Research Institute (IRI
search Scientist, International Centre of
Kenya, based at IRRI.





ABSTRA(
The effects of tungro virus-infected r
the vector Nephotettix virescens (Distant) v
infected plants attracted significantly more
thy plants, but after 24 hours and later, mc
healthy plants. Insect feeding on diseased
food ingested and assimilated was signficar
there was no significant difference in the n
fected and healthy plants, the growth perio
ficant reduction in adult longevity, fecundit
was observed on tungro-infected plants, bu
affected. Biochemical analysis of tungro-infi
tent of free sugars but a decrease in solubl
plants. Thus, observed deleterious effects
biology could be attributed to changes in pla




.ey Words: Epidemiology, Green leaf-
opper, Nephotettix virescens, Rice,
ungro, Vector behavior and biology.

ungro is a dreaded disease of the rice
lant in tropical Asian countries. It
trikes suddenly and destroys large tracts
f the rice crop, leaving little scope for
alliative or remedial measures. Severe
utbreaks of the disease have been re-
orded in the recent past in Bangladesh
Mian and Ahmed, 1974), India (John,
970; Anjaneyulu, 1974), Indonesia
Oka, 1971; Sama, 1972); van Halteren


CTED RICE PLANTS ON THE
GREEN LEAFHOPPER
LND ITS ROLE IN
IICS




SAXENA
omology Department of Entomology,
.os Bafios, Laguna and Principal Re-
:t Physiology and Ecology, Nairobi,








ants on the behavior and biology of
ivestigated. In a choice test, tungro-
escens individuals than did the heal-
lividuals were found to be settled on
was disrupted and the quantity of
ss than on healthy plants. Although
r of nymphs becoming adults on in-
prolonged on diseased plants. A sig-
hatchability, and population growth
ositional response was not adversely
plants showed an increase in the con-
:eins as compared to that in healthy
Igro-infected plants on N. virescens
id quality.




Id Sama, 1973), and Thailand (Lamey
al., 1967). In many locations in the
tilippines, major disease outbreaks oc-
irred in 1957, 1962, 1970, 1971, 1974,
ad 1977 (Bergonia, 1978; IRRI, 1983).
recently, tungro destroyed nearly 50%
* the total crop area in South Cotabato
the height of the infestation in 1981
anonymous, 1984).
The disease is caused by polyhedral
rus particles consisting of isometric
icilliform and spherical types of vi-
ises (Hibino et al-, 1979; Hibino, 1983).









Philippine Phytopa


The virus particles are most efficie
transmitted by the green leafho
Nephotettix virescens (Distant) (R:
and Ou, 1965) in a semipersistent ma
(Ling, 1966; Hibino et al., 1979).
virus-infected plants show severed ,
ting and leaf yellowing because
phloem-specific virus (Galvez, 1
interferes with phloem transport (Sri
et al., 1978). The diseased plants
show some aberrations in physio]
such as starch accumulation in h
(Ling, 1972; Sridhar et al., 1S
increased cytokinin activity (Sridhl
al., 1978), and abscisic acid-like
tances (Mohanty et al., 1979). The
also induces accumulation of prolir
the leaves of the diseased plants w
attract N. virescens and may contri
to subsequent spread of the di!
(Mohanty and Sridhar, 1982; Moh
et al., 1983). However, various int
tions between tungro-infected rice p
and the vector are not well studied.
information could enhance our ui
standing of the tungro epidemiol
The present study was, therefore, ui
taken to compare the behavior and
logy of N. virescens on tungro-infe
and healthy rice plants. The healthy
tungro-infected plants were also anal
for soluble proteins and free si
because the plant food quality is kr
to have profound effects on the physic
of phytophagous insects (McNeill
Southwood, 1978).
MATERIALS AND METHODS

A tungro-infected plant conta
both bacilliform and spherical
particles was obtained from Dr
ST-' --I r- I- -1 -^ Tr'r>J --A1 l-


30 days old, potted, healthy and tui
virus-infected TN1 rice plants were u
Each pot containing three plants was 1
in an insect-free screenhouse under
tural conditions.
For virus inoculation, 15 days
TNI plants were exposed to 1 to 2 <
old viruliferous N. virescens females
rate of five females per pot for 12 he
Control plants were similarly expose,
newly-emerged non-viruliferous fem
Both inoculated and healthy plants \
maintained in an insect-free screenhi
for 15 days for the appearance of tui
symptoms in inoculated plants.
For experiments on the veci
settling response and ovipositional
ponse, 200 seedlings were grown f
seeds in two separate 75 cm by 40
wooden trays. When 15 days old,
seedlings in one tray were expose<
400 viruliferous N. virescens females
12 hours while seedlings in the o
tray were exposed similarly to
viruliferous females. Ten infected and
healthy plants were then randc
transplanted in a circle near the circ
ference of a 60-cm diameter iron tray
kept in an insect-proof screenhouse
15 days when infected plants sho
tungro symptoms.
The following studies were ur
taken to compare the biology and
havior of N. virescens on healthy an(
tungro-infected rice plants in greenhc
insectary, and laboratory conditi


Settling behavior. For settling resp(
N. virescens females were allowed
choice of 10 healthy and 10 tur
. I . I I I- I Il ---A


54













idred 1 to 2 days old non-viruliferous nected to the negative input terminal of
iales. The number of females settled a transistorized,automatic,null-balancing,
healthy and tungro-infected plants D.C. chart recorder having a 250 mm
i recorded at 1-, 8-, 24-, and 48-hours recording width and input resistance of
:r release. The experiment was repli- IMS2 (Unicorder Pantos, Nippon Denshi,
ed 8 times and the percentages of Kagaku. Japan) The voltage source con-
ects settled at different time inter- sisted of two 1.5 V DC batteries con-
5 on healthy and diseased plants were nected in a series. The positive battery
:ulated. terminal was connected with the plant
root through a moistened filter paper
ctronic recording of feeding be- and an aluminum foil (Fig. 1). The nega-
ior. The feeding activity of non- tive battery terminal was directly con-
jliferous N. virescens females was nected with the positive input terminal
initored on healthy and tungro-in- of the chart recorder. The recorder pen
ted rice plants using an electronic was adjusted to the baseline of the chart
ording device (Khan and Saxena, and the insect's feeding activity, com-
B4). A 5-cm-long, fine (18 mpA) gold prising the number of probes, salivation
e (Tanaka Denshi Kogyo, K-K., period: and the duration of xylem and
kyo, Japan) was attached to the dor- phloem feeding, was monitored for
n of a 1 to 2 days old female by a 180 minutes. The chart speed of 1.5 cm/
all quantity of silver paint (Litsilber min at 500 mV ampere power was ade-
), Demetron, Hanau, W. Germany). quate for distinguishing various wave-
e insect was starved but water-satiated forms and associated reversals obtained


ni. ine golu wire was unrecy con-









GI




rice leaf


aluminum foil (+

moist filter paper
Speaker


1. Schematic diagram of circuit and equij
,,--_f-- rDDr IfnA


)ned room. A total of 15 replications









f STRIP CHART

RECORDER



(+)







t for recording N. virescens feeding on








3ruppine nytopamology


were maae eacn for neaitny and aisea,
plants, each replicate using a fresh fem
and a fresh plant.

Ingestion and assimilation of food. -
determine the quantity of food ingesi
and assimilated, newly-emerged, n(
viruliferous N. virescens females wi
weighed individually on a microbalar
and enclosed singly in 5 cm by 5 ,
parafilm sachets through each of whi
passed the leaf of a healthy or a tung
infected plant. After 24 hours, t
weights of the insects and their excri
were recorded separately. A cont:
check was similarly set in which t
insect was given access to a moist cott
swab to assess the loss in body weight d
to tear and wear. The amount of fo
ingested and assimilated by the inst
was calculated as follows (Saxena a
Pathak, 1977):
Food assimilated = Wl x ( C-C
Cl
+ W2 Wl
where Wl = initial weight of insect, \
= final weight of insect, Cl = initial wei4
of control insect, C2 = final weight of cc
trol insect; and food ingested = foi
assimilated + weight of excreta. The
were 15 replications each for health
and diseased plants, each replicate coi
prising 5 females caged individually
parafilm sachets on five different plan
Growth. To determine the growth
N. virescens, potted, healthy and tungi
infected plants covered with mylar ca
(90 cm high, 10 cm diameter) and arrang
in a randomized complete block desi,
(RCBD) in a water-filled tray were i
fested with first-instar nymphs in batch
of 10 each. There were 15 replicatio
for each treatment. Growth was al
measured in terms of the number
nymphs becoming adults and the tin
taken to reach the adult stage. TI
growth index of N. virescens on health


and diseased plants was calculated as I
ratio of percentages of nymphs become
adults to the mean growth period in d,
(Saxena et al. 1974).

Adult longevity and fecundity and i
hatchability. The longevity of new
emerged, non-viruliferous N. virescE
males and females, fecundity of female
and hatchability of eggs were determine
on healthy and tungro-infected plan
The potted plants, arranged in RCBD i
water-filled, galvanized iron tray, wi
covered with mylar cages (90 cm hil
10 cm diameter) and infested at a rate
10 pairs of males and females per p
There were 15 replications for each tre
ment, each pot representing a replica
Survival of males and females was
corded daily up to 20 days after
festation. The total number of nymr
emerging on the plants was recorded a
represented the number of viable el
produced by the females during th
life. At the end of the emergence
nymphs, unhatched eggs in plants w(
counted by dissecting leafsheaths unc
a 20X dissecting binocular.

Ovipositional preference. One hundi
non-viruliferous, gravid females reared
healthy TN1 plants were released in 1
middle of a circular (60-cm diamet
tray which was covered with a mylar c,
and had at its periphery 10 each of n
domly arranged, healthy and diseai
rice plants. The insects iWere allowed
oviposit for; 24. hours after which 1
plants were removed and dissected unt
a binocular to record the number of el
laid. The experiment was replicate
8 times.

Population increase. Potted, healthy a
tungro-infected plants were covered wi
mylar cages (90 cm high, 10 cm diameter
and arranged in RCBD in a water-fill
galvanized iron tray. There were 15
plications per treatment; each pot


jU








i. & June 1984 Influence of Tungro Virus 57



ted with three gravid, non-viruliferous healthy ones (Table 1, Fig. 2). However,
nales represented a replication. The after 8 hours almost equal numbers of
:al number of nymphs and adults was females were recorded on infected and
;orded at 30 and 60 days after in- healthy plants. After 24 hours or more,
station. Insects were transferred to the insect's settling response was com-
sh plants of identical age if infested pletely reversed and significantly higher
[nts started showing symptoms of number of females were recorded on
pperburn. Insects which fell off the healthy than on infected plants.
ints on soil and died were counted
-ry week and also pooled with the rest
the progeny. Insarsettled(
timation of soluble proteins and free
gars in plants. Thirty days old healthy
d tungro-infected TN1 rice plants were
alyzed for soluble proteins and free
gars following the estimation methods 20 *healthy plans
Lowry et al. (1951) and Yoshida et al. Otungroinfested
976), respectively. The analyses were
sed on 12 samples of each of healthy o 8 24 48
d diseased plants; each sample consist- Hours after infestation
Sof 3 plants. Soluble proteins and free
gars were estimated on both dry and
t weight basis. Fig. 2. Settling response vf N. virescens
RESULTS females on healthy and tungro-
infectted TN1 rice plants 1, 8,
ttling response.. In the choice test, 24, and 48 hours after infestation
nificantly more insects settled initially in a free choice test. IRRI, 1983-
i the tungro-infected rice plants than on 84.

'able 1. Settling response of N. virescens on healthy and tungro virus-infected rice
plants 1-, 8-, 24-, and 48-hours after infestation (HAI). IRRI, 1983-84.


Females (%) settled on plants1
Plants
1 HAI 8 HAI 24 HAI 48 HAI


Healthy 35.5 46.7 57.5 58.9

'-- ,., -,;-,"_,. fatard O A AO ( IR 1 ?4 fl



















1. P


Fig. 3. Waveform sequences recorded during feeding by N. virescens females on healthy
TN1 rice plants showing (a) initial probings (P) and salivation (S); (b) xylem in-
gestion (Xi), and (c) short duration phloem feeding (Pi). Cessation of feeding or
rest is indicated by R.


P;_
I : C
.--:._Si_ sJ


.. ..... i .: .11
l :: I[



; : p :-
MA s!


i.. .. I .. : sL
" :- .. :


I t l I


i


'" J


" ~"


Philippine Phytopathology


Vol. 20


Electronic recording of feeding behavior.
The waveforms recorded for non-viruli-
ferous N. virescens females on healthy
(Fig. 3a-d) and tungro-infected (Fig. 3e-f)


TN1 plants showed more or less similar
patterns for probing, salivation, and xy-
lem ingestion. The phloem feeding was
sustained for long durations and its








Influence of Tungro Virus


associated waveform pattern was normal
on healthy TN1 plants (Fig. 3d). How-
ever, in most of the cases phloem feeding
on tungro-infected plants was inter-
17^-----' *-- ---


rupted and the associated waveform
showed repeated voltage reversals (Fig.
3f).


Fig. 3. (Cont.) (d) normal, sustained phloem ingestion (Pi) on healthy plants; (e) nor-
mal xylem ingestion (Xi) on tungro-infected plants; and (f) unidentified, phloem
feeding (U [Pi? 1) on tungro-infected plants. IRRI, 1983-84.


Jan. & June 1984








Philippine Phytopathology


Ingestion and assimilation of food. The
quantity of food ingested and assimilated
by N. virescens females was significantly
higher on healthy TNl rice plants than on
tungro-infected plants (Table 2).
Growth. There was no significant differ-
ence in the percentages of nymphs


becoming adults on healthy and tungro-
infected plants (Table 3). However, the
growth period was significantly prolonged
on tungro-infected plants, thus signifi-
cantly reducing.the growth index.
Adult longevity, fecundity, and egg
hatchability. Male and female survival


Table 2. Quantity of food ingested and assimilated by N. virescens female on healthy
and tungro virus-infected rice plants in 24 hours.1 IRRI, 1983.84.


Food ingested/ Food assimilated/
Plants female / 24 h female / 24 h
(mg) (mg)


Healthy 8.27 0.68

Tungro virus-infected 5.69 0.46

Difference 2.58** 0.22**


IAverage of 15 replications, each replication had 5 newly-emerged females caged individually in
parafilm sachets.
** = significant at 0.01 level of probability by LSD.


Table 3. Growth of N. virescens nymphs on healthy and tungro virus-infected rice
plants.' IRRI, 1983-84.


Nymphs
Plants becoming Developmental Growth index2
adults (%) period (days)

Healthy 96.7 14.7 6.58
Tungro virus-infected 94.7 17.3 5.48
Difference 2.0ns -34** 1.10**


IAverage of 15 replications, each replication with 10 lst-instar nymphs.
2Growth index = percent nymphs becoming adult/mean developmental period (days).
ns = not significant, ** = significant at 0.01 level of probability by LSD.


Vol. 20









Influence of Tungro Virus


'as significantly higher on healthy than laid by gravid N. virescens females on
n tungro-infected plants (Table 4). healthy and tungro-infected rice plants
likewise, fecundity of N. virescens (Table 5) indicating that both healthy
males was significantly more on healthy and diseased plants are suited for ovi
ian on infected plants. The percentage position.
f eggs hatched on healthy plants was
[so significantly higher as compared to Population increase. A significantly lowei
iat on infected plants (Table 5). increase of N. virescens population, cor
prised of nymphs and adults, was record
positional preference. In the choice ed at 30 and 60 days after infestation or
est, almost equal number of eggs were tungro-infected plants than was observed



able 4. Longevity and fecundity of N. virescens adults on healthy and tungro virus-
infected rice plants.' IRRI, 1983-84.

Adult longevity (days) Fecundity
lants (no. of eggs laid
Male Female by 10 females)

healthy 13.5 15.2 857
rungro virus-infected 11.4 11.3 572
differencee 2.1** 3.9** 285**

Average of 15 replications, each replication having 10 newly-emerged males and females.
* = significant at 0.01 level of probability by LSD. 0


Table 5. Ovipositional preference and egg
tungro virus-infected rice plants. I

No. of
Plants 100 fen


Healthy

Tungro-infected

Difference

1Average of 8 replications, each replication had
females.

2Average of 15 replications, hatchability based i
ns = not significant, ** = significant at 0.01 level


ability of N. virescens on healthy and
1983-84.

aid by Egg hatchability2
in 24 h1 (%)


94.6

88.3

7ns 6.3**

!althy and 10 diseased plants, and 100 gravid

s laid by 10 gravid females in each replication.
liability by LSD.


Jan. & June 1984









Philippine Phytopathology


on healthy plants (Table 6).

Estimation of soluble proteins and free
sugars. The soluble protein content de-
creased significantly in tungro-infected
4




Table 6. Population increase of N. viresce?
plants after 30 and 60 days of infe,


Plants

Healthy

Tungro virus-infected

Difference

1Average of 15 replications, in each replication 3 j
** = significant at 0.01 level of probability by LSI






Table 7. Soluble proteins and free sugars in
on dry and wet weight basis.' IRR


Soluble prot,
Plants Dry wt.
basis


Healthy 9.05

Tungro virus-infected 7.16

Difference 1.89**

1Average of 12 replications, each replication had t
** = significant at 0.01 level of probability by LSI


plants as compared to that in healthy
plants (Table 7). However, a significant
increase in free sugars was recorded in
tungro-infected plants.







I healthy and tungro virus-infected rice
on.1 IRRI, 1983-84.

o. of insects recovered after
iys 60 days

1652

732

** 920**

females were released.







thy and tungro virus-infected rice plants
84.


(%) Free sugars (%)
et wt. Dry wt. Wet wt.
basis basis basis


79 5.17 1.01

45 14.61 3.04

34** 9.44** -2.03**

30 days old plants.


fol. 20








Influence of Tungro Virus


DISCUSSION

Natural attraction of N. virescens
to tungro-infected rice plants and the ease
with which the insect becomes infective
are important factors in the spread ol
tungro disease. Infected plants show cha
racteristics yellowing of leaves, slight
stunting and reduced tillering, but survive
until maturity (Ling, 1976), acting a!
sources of inoculum. However, it iv
observed that vector population generally
goes down in fields following tungrc
outbreaks (Dr. G.S. Khush, plant breeder
IRRI, personal communication). The
cyclic nature of tungro outbreaks ha&
thus been related to fluctuations in popu
lation of the vector, but definite inform
ation is lacking on the deleterious effect:
of tungro-infected rice plants on thi
vector biology. Maramorosch (1969) ex
eluded the possibility of any direct o
indirect effects of the virus on the vecto
because the virus is not circulative, yel
the effect of the altered physiology anc
nutritional status of tungro-infectec
plants on the vector and its impli
cation in tungro epidemiology cannot be
overlooked. The insect's greater alighting
on tungro infected plants than on health
plants is apparently due to the attractive
yellow color. However, N. virescens
individuals do not stay there for a lonj
period, but move over to healthy plants
Significantly less intake of food by the
insect on diseased plants than on healthy
plants indicates that either the infected
plants failed to meet the nutritional
requirement of the vector or that the
food quality was such that it did nol
evoke adequate phagostimulator)
response. The insect's restlessness or
diseased plants, as evidenced by uni.
identified voltage reversals in electro
nically recorded waveforms during
phloem feeding might also be related tc


in the insect's suboptimal growth, adult
longevity and fecundity, egg hatcha-
bility; and population increase on tungro-
infected plants.
Maramorosch and Jenson (1963) dis-
cussed a wide range of effects of plant
viruses in insects, from directly lethal
and seriously detrimental to beneficial.
Sometimes the plant virus plays a bene-
ficial role in the biology of the vector
by altering the morphology and che-
mistry of the plant so that it provides
better shelter (Carter, 1939) or better
food for the vector (Kennedy, 1951;
Hodgson, 1981; Gildow, 1983). On the
other hand, tangible deleterious effects
of the 'irus on vector biology are also
known (Yoshii and Kiso, 1957; Watson
and Sinha, 1959; Everett, 1965; Naka-
suji and Kiritani, 1970). In N. virescens,
it is more appropriate to relate the
observed deleterious effects on vector
biology to the nutritional quality of the
tungro-infected plants because the virus
itself is semipersistent or stylet-borne.
The observed significant increase in
sugar content, but a decrease in content
of soluble proteins, in diseased plants
as compared to that in healthy plants
may affect N. virescens biology. Accu-
mulation of carbohydrates in tungro-
infected rice plants has been reported
(Ling, 1972; Sridhar et al., 1976). Among
carbohydrates, sugars are the most
important phagostimulants for phytopha-
gous insects (Schoonhoven, 1968).
Saxena and Saxena (1974) determined
the gustatory excitation of feeding in
a cotton leafhopper, Empoasca devas-
tans (Distant), at different concentra-
tions of fructose, glucose, and sucrose
in comparison to water. They found
that fructose was not phagostimulatory
to the leafhopper, but ingestion of
0.01M and 0.1M glucose solution was
about twice that of water. On the other


Jan. a June lyi








64 Philippine Phytopathology Vol.



0.01M concentration was ingested three these unique events in the life of tl
times more than water, decreased at vector and the host.
0.1M concentration to the same level as
that of water. This indicated that higher








in. & June 1984 Inlnuence of Tungro Virus 65



ALVEZ, G.E. 1967. The purification WANGH. 1967. Transmission experi-
of virus like particles from rice tungro ments on the tungro virus in Thailand.
virus-infected plants. Virology 33:357- Int. Rice Comm. Newsl. 16(4):15-19.
359.
LING, K.C. 1966. Nonpersistence of
ILDOW, F.E. 1983. Influence of barley tungro virus of rice in its leafhopper
yellow dwarf virus-infected oats and vector, Nephotettix impicticeps. Phy-
barley on morphology of aphid topathology 56:1252-1256.
vectors. Phytopathology 73:1196-
1199. LING, K.C. 1972. Rice Virus Diseases.
International Rice Research Institute
IBINO, H. 1983. Transmission of two Los Bafios, Laguna, Philippines.
rice tungro-associated viruses and rice
waika virus from doubly or singly LING, K.C. 1976. Recent studies on rice
infected source plants by leafhopper tungro disease at IRRI, International
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IBINO. H., N. SALEH, and M. ROE- per Series No. 1 11 pp. Int. Rice Res.
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by .insect vectors. Phytopathology LOWRY, O.H., N.J. ROSEBROUGH,
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turnip as a host to Myzus persicae rc v s on tr ect
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)HN, V.T. 1970. Yellowing disease of
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ENNEDY, J.S. 1951. Benefits to aphids
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infected leaves. Nature 168:825-826.

HAN, Z.R. and R.C. SAXENA. 1984.
Electronic device to record feeding
behavior of whitebacked planthopper
on susceptible and resistant rice varie-
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\MEY, H.A., P. SURIN, and J. LEE-


IARAMOROSCH, K. and D.D. JENSON.
1963. Harmful and beneficial effects
of plant viruses in insects. Ann. Rev.
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.CNEILL, S. and T.R.E. SOUTHWOOD.
1978. The role of nitrogen in the
development of insect/plant relation-
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Coevolution (J.S. Harbone, ed.).
pp. 77-98. Academic Press, London
& New York.

ICZYNSKI. K.A. 1961. Studies on the
free amino acid composition of to-
bacco plants infected with potato









Philippine Phytopathology


00


virus X. Rev. Appl. Mycol. 40:127

MIAN, S.A. and S. AHMAD. 1
Sources of resistance and bree
for resistance to tungro and bact
blight in Bangladesh. Paper prese
at Int. Rice Res. Conf., April 2;
1974, IRRI, Ips Bafios, Philipp
15 pp.

MOHANTY, S.K. and R. SRIDE
1982. Physiology of rice tu
virus disease: proline accumulk
due to infection. Physiol. P
56:89-93.

MOHANTY, S.K., S.K. MOHANTY
ANJANEYULU, and R. SRIDE
1979. Physiology of rice tungro
disease: Involvement of abscisic
like substance in susceptible I
virus interactions. Physiol. Plant.
132-136.

MOHANTY, S.K., M.K. SATPAT
and R. SRIDHAR. 1983. Signific
of virus-induced proline accumula
in rice tungro epidemics. Current
52:311-314.

NAKASUJI, F. and KIRITANI, K. 1
Effects of rice dwarf virus upoi
vector. Nephotettix cincticeps I
(Hemiptera: Deltocephalidae) an(
significance for changes in rel
abundance of infected indivic
among vector populations. Appl.
Zool. 5:1-12.

OKA, J.N. 1971. An outbreak of a
disease showing tungro symptorr
Cnlth ,,-fmnrnoa on I mnlln


SAMA, S. 1972. Re;
rice infestation ii
Sidrap and Pinranl
Sulawesi, Indonesia.

SAXENA, K.N. and
1974. Patterns of
ween certain leafh
hoppers. Part II.
stimuli in oriental
Entomol. Exp. A

SAXENA, K.N., J.R
R.C. SAXENA. 1
relationship betw
hoppers and plants
to plants. Entomo
303-318.

SAXENA, R.C. and
1977. Factors affe
rice varieties to
hopper, Nilaparva,
presented at the
ference of the Pes
of the Philippine
18-20 May 1977. 34

SCHOONHOVEN, L.]
sensory basis of hi
Ann. Rev. Ent. 13:1

SRIDHAR, R., P.R. R
JANEYULU. 1976.
tungro virus disease
rophyll, carbohydr,
and phenol conte
Z. 86:136-143.

SRIDHAR, R., S.K.
A. ANJANEYULU.


on dist
lone, S
districts,
p.

.C. SA:
ationshil
ers and
le of a
and f
S17:4S

3ANDH
,. Patte
certain
rt I. Re!
Exp. Ap


.D. PA
g resist
brown
lugens.
Annua
control (
Bacolod


1968. (
plant se]
136.

)Y, and
ysiology
changes i
,amino
Phyto


)HANT'
78. Phy


.. .. .,b kV'- of rice tungro virus disease: In,
vinces. Min. Agric. Cent. Res. Inst. of rice tungro virus dsease: In
Agr., Bogor, Indonesia. 4 pp. cytokinin activity in tungro-i
rice cultivars. Physiol. Plar
363-366.
RIVERA, C.T. and S.H. Ou. 1965. Leaf-
hopper transmission of tungro disease VAN HALTEREN, P. and S.
of rice. Plant Dis. Reptr. 49:127-131. 1973. The tungro disease in









uence of Tungro Virus


ilawesi. Cent. Res. Inst. Agr. July
i-28, Bogor, Indonesia. 51 pp.

SON, M.A. and R.C. SINHA. 1959.
udies on the transmission of Euro-
an wheat striate mosaic by Delpha-
des pellucida Fabricious. Virology
139-163.

HII, H. and A. KISO. 1957. Studies
i the nature of insect-transmission
plant viruses (II) Some researches




Acknowle

We thank Dr. H. Hibino, Virologist, 11
rice plants and the Institute of Plant Breed
Baiios, for assisting us in analyzing sugars and


a the unhealthy metabolism in the
ruliferous planthopper, Geisha dis- .
nctissima Wal., which is the insect
:ctor of the dwarf disease of Satsuma
range. Virus (Osaka) 7:315-320.

HIDA, S., D.A. FORNO, J.H. COCK,
Id K.A. GOMEZ. 1976. Laboratory
manual for Physiological Studies of
ice 3rd edition. Int. Rice Res. Inst.
os Bafios, Laguna, Philippines. 83 pp.





ent

or providing us tungro virus-infected
University of the Philippines at Los
)le proteins of rice plants.


67









cal Society. Inc.


PHYTOPATHOLOGICAL NOTE
IN BENGUET AND M

D.J. ROETTGER, E.A.
and J
Senior author is GTZ Crop Prot
the Buguias Experiment, Bureau of Pla


A


CURRENCYE OF CITRUS TRIZTEZ,
PROVINCE, PHILIPPINES

;OLA, A.M. CIMAFRANCA
ARIANO
i consultant and the rest are researchers at
iustry, Baguio City.


LACT


and around Baguio City and La Trinidad, Benguet and in Sagada and Bauko Mt
Province. The survey was made on December 1983-February 1984.
Tristeza virus was found to be generally present in all the sampled locations.
Budded varieties were all infected except in one commercial farm where two newly
important varieties were still free of Tristeza but surrounded by older virus-infected
citrus trees. Rootstocks raised from imported seed by one commercial grower, the
Mountain State Agricultural College, and the Buguias Experiment Station in Benguet
were found to be free from the virus.



INTRODUCTION the industry as experienced in the Ic
land regions also took place here after 1
Tristeza and citrus Greening caused second world war. Most of the plant
the downfall of the citrus industry in the materials were then introduced from 1
Philippines in the 60's and early 70's Batangas region probably carrying Ti
(Martinez and Wallace, 1970). These dis- teza virus and citrus Greening disea
eases can be spread with grafted planting Aphids, in general, are usually not pres<
material. Tristeza can readily be trans- in high population density in this co
mitted by aphids, e.g. Toxoptera citri- mountain areas.
cidus, Aphis gossypii, A. spiraecolor and This survey was undertaken fr<
T. aurantii whereas citrus Greening is December 1983 to February 1984
vectored by the psyllids, Diaphorina citri Benguet and Mt. Province with t
and Trioza erytraea. Surveys on the following objectives:
actual distribution of the two diseases i. To determine the distribution
were undertaken in Batangas and some Tristeza virus in established plantatic
other regions of the lowland Philippines and nurseries; and
(Martinez and Wallace, 1967, Martinez 2. To identify isolated areas frc
and Wallace, 1970). The authors de- diseased citrus plants which wot
tected the diseases to be widespread in constitute suitable locations for ni
Batangas and Laguna and reported the healthy citrus nurseries where pla
possible presence of the same malady in materials for commercial production w
Bicol and Central Luzon as well as the be propagated.
Visayas and Mindanao.


Philippine Ph,









Phy topathological Note


per tree (165 trees) were gathered from
the surveyed nine (9) orchards. The
ultra-sensitive Enzyme-Linked Immuno-
sorbent-Assay, ELISA (Bar-Joseph, M. et.
al., 1979) was used to assess the presence
of Tristeza virus in the leaf samples.Tris-
teza-specific antiserum was obtained from
Germany/Florida and conjugated for this
purpose by Dr. Gasper/Germany.

RESULTS AND DISCUSSIONS

The survey was conducted in and
around Baguio City, La Trinidad, Benguet
and in Sagada and Banko, Mt. Province.
(Fig. 1).
Tristeza virus was present in all loca-
tions surveyed as shown in Table 1. How-
ever, imported scion and budwood root-
stock samples (grown from seeds) at the
greenhouses of the Buguias Experiment
Station as well as rootstocks of Troyer
Citrange, Taiwanita and Trifoliate Carrizo
in the Mt. State Agricultural College at
La Trinidad, Benguet and one commercial
farm near Baguio City were free from
Tristeza. The rootstocks at Mountain
State Agricultural College and the com-
mercial farm were less than one year old
at the time of testing.
In order to revive the citrus industry
in this region, this survey indicates the
need to:


1. prevent further entry of diseased
plant materials;
2. use resistant rootstocks; and
3. start with disease-free material
raised and multiplied in isolated areas
preferably where citrus was never intro-
duced before.
The low incidence of aphid popula-
tions, the adaptability of citrus and the
I / AREAS SURVEYED OR TRISTEZA IAE
SIN THE HIGUOHLANDS OF LUZON ( REGION I) r I


Fig. 1 Areas surveyed for citrus tris-
teza in the highland of north
Luzon (Region 1).


Table 1. Occurrence of Tristeza virus in Benguet and Mt. Province.


No. of No. of
Location Scion Varieties Rootstock Varieties plants plants
tested infected


Hamlin, Suenaga,
Satsum a Grape fruit,
Valencia late,
Meyerlemon,
Unshiu mandarin


Calamansi,
Calamandarin,
Troyer Citrange


Troyer Citrange


3 0


BAGUIO
commercial
orchards


Jan. & June 1984









Philippine Phytopathology


BAGUIO
backyard trees


calamansi, unknown


Meyer lemon
Eureka lemon
SValencia late


Calamandarin


Atwood navel, Hamlin
Trovita A, Meyer lemon
Citromelo,
Carrizo, Ctirange,
Cleopatra, Rough
lemon Milam;
Volkameriana;
Trifoliate


LA TRINIDAD
Mountain State Duncan grapefruit, Japa-
Agricultural nese summer grapefruit,
College Unshiu mandarin, Was- Calamandarin;
hington navel, Valen- Sour orange,
cia late, Cleopatra Pomelo; Trifo-
mandarin (seedling late
seeds)


Taiwanita, Trifoliate,
Carrizo and Troyer
Citrange


Valencia late, Szin-
com-Batangas
mandarin



Valencia late


SAGADA Unshiu mandarin
backyard trees Valencia Late


Calamansi and
Calamandarin




Calamandarin


Calamandarin


fact that there are many areas where
citrus was never introduced before are
leading to the prospect of expanded
citrus production and nursery establish-
ment in this highland region.


Some identified areas in this survey
which constitute suitable nurseries are:
1. selected, isolated sites in the muni-
cipalities of Sagada, Bauko and Besao,
Mt. Province.


BAGUIO
BPI, Baguio
Experiment
Station

BAGUIO
BPI, Buguias
Experiment
Station


BAUKO
commercial
orchard


SAGADA
commercial
orchards


Vol. 20





Phytopathological Note


71


Citrus Greening disease symptoms
are also noted but shall not be reported
this paper.

LITERATURE CITED
AR-JOSEPH, M. et. al. 1979. The use
of enzyme-linked-immuno sorbent-
assay for detection of citrus tristeza
virus. Phytopathology 69: 190-194.

RIESBACH, J. 1981. Evaluation report
on the feasibility of fruit growing in
the highlands of North Luzon/Philip-
pines. Technical cooperation between
.I 11-!---- -,-A IU ^- l >_ .U11


REZDOURN, A.H. 1977. Final report
of consultancy on citrus and tropical
fruits in Ethiopia. Technical coopera-
tion between socialist Ethiopia and
Federal Republic of Germany. 92 pp.

.ARTINEZ, A.L. and J.M. WALLACE,
1967. Citrus-Leaf-Mottle-Yellows
Disease in the Philippines and Trans-
mission of the Causal Virus by a
Psyllid, Diaphorina citri. Plant Disease
Reptr. 51: 692-695.

[ARTINEZ, A.L. and J.M. WALLACE,
1970. Citrus ,reenine disease in the
















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


NAME ADDRESS

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