Front Cover
 Incidence of citrus closterovirus...
 Evaluation of cultrue media for...
 Evaluation of cultrue media for...
 Survey, isolation, and characterization...
 Temporal dynamics of major banana...
 Back Matter
 Back Cover

Group Title: Journal of Tropical Plant Pathology
Title: Journal of tropical plant pathology
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00090520/00042
 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: June-December 1999
Frequency: semiannual
Subject: Plant diseases -- Periodicals -- Philippines   ( lcsh )
Plants, Protection of -- Periodicals -- Philippines   ( lcsh )
Genre: periodical   ( marcgt )
Dates or Sequential Designation: v. 1, no. 1 (January 1965)-
General Note: Title from cover.
General Note: "Official publication of the Tropical Plant Pathology."
 Record Information
Bibliographic ID: UF00090520
Volume ID: VID00042
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
    Incidence of citrus closterovirus (CTV) on different citrus species in the Philippines
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
    Evaluation of cultrue media for sporangial production of phytophthora clocasiae L. and control of taro blight using fungal antagonists
        Page 7
    Evaluation of cultrue media for sporangial production of phytophthora clocasiae L. and control
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
    Survey, isolation, and characterization of agrobacerium sp. in the Philippines
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
    Temporal dynamics of major banana diseases in monocropping and multicropping systems
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
    Back Matter
        Page 54
    Back Cover
        Page 55
        Page 56
Full Text

-4 7*


ce President
Tr aurer
Bss. Manager


A. M. Simo
L A.Pada
T U. Dalay
L R. Sorio
C A. Bn=*
E R.Ti gco
K M. ddl Cva
R. A. Zoil
M. G. M nay
A. B. Mona, Jr.

Philinppine hytopatholo
Editonal Board 1999-2000

L. Bayet
N. Bajet

A cite Editor
Associate itor



Subsriptions Communications should be addreaed to the TREASURER, PP.S. c o Iepqrtmat of Plat
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of claims made in advertisements is assumed by tbhe Journal or by the Philippne Phytopat ogical Society, Inc.

'~y~:; Y



'Senior Agriculturist, former Supervising Agriculturist, and 3Research Assistant, Bureau
of Plant Industry, Davao National Crops Research and Development Center, Bago-Oshiro,
Davao City

Biological indexing of citrus candidate parent trees from Luzon,
Visayas and Mindanao showed that all sample trees are infected with
CTV and that the virus is common in all citrus plantations. Detection of
the virus by ELISA on nursery mother trees maintained inside screen
houses can be done any time of the year under Davao conditions as long
as young flushes are available.


Citrus spp. is one of the most important
fruit crops worldwide, including the Philippines.
Among the various Citrus spp., pummelo
(C. granadis) is one of the more popular
species grown locally. The leading regions in
the production of pumelo in terms of area in
1997 are Southern Mindanao with 1,729 has;
Cagayan Valley, 870 has; ARMM, 290 has;
Western Visayas, 223 has; and Northern
Mindanao, 205 has. The leading regions in
terms of total production include Cagayan
Valley with 22,748 MT; Southern Mindanao,
13,075 MT; ARMM, 2,663 MT; Southern
Tagalog and CAR, 618 MT (BAS, 1998).

Tristeza was first reported in the country
in 1956. Etiological studies of a disease called
citrus decline resulted in the discovery of
pathogens including the tristeza virus (Wallace
et al., 1956). It significantly affects production
by lowering yield and quality of fruits. Tristeza
remains as one of the most serious problems
in many citrus growing countries. The stem
pitting strain (CTV-D) was the most common
among a number of strains ofthe virus detected

and identified in the Philippines (Herradura et
al., 1994).

A strategy adopted by a number of
countries for the control of tristeza is the
production of virus-free materials. These
materials would serve as mother trees for
secondary propagation by way of
comprehensive mandatory citrus certification
program in conjunction with an indexing
program, using among others, enzyme-linked
immunosorbent assay (ELISA). ELISA has
been the most popular technique for the
detection of CTV in nursery mother trees and
in assaying for the virus on shoot tip grafted
plants (STG) (Bar-Joseph et al., 1979;
Kyriakou and Polycarpou, 1989; Tsai et al.,
1991). To a limited extent, ELISA has been
used to detect CTV in the country (Herradura,
1993; Herradura et al., 1994).

Despite the popularity of citrus and
the relatively wide acceptance of farmers all
over the Philippines to grow it, the pace of
planting material production for distribution
has been slow. In addition, vascular and
bud transmissible diseases, which include

2 tristeza closterovlrus on different ci

tristeza, have been cited as major reasons
not planting the crop.

It has not been fully established when
source out materials for establishment
mother trees. This paper reports the incide
of CTV in the major citrus growing areas
Luzon, Visayas, and Mindanao and its detect
as affected by plant growth under Dai

Incidence of CTV

Important commercial species of cit
of good horticultural characteristics growr
Luzon, Visayas and Mindanao were surve,
and characterized by the Plant Materi
Certification Program (PMCP) team of
Bureau of Plant Industry (BPI). Thi
materials were further inspected for th
health status to select and collect poteni
mother trees. The presence of CTV and ot]
bud transmissible diseases were note
Budsticks of the selected Citrus spp. we
collected, brought to the BPI-Davao Natioa
Crops Research and Development Cen
(DNCRDC) and grafted to indicator pla
(Key lime) and maintained inside the scr

Detection of CTV on
Nursery Mother Trees

Young leaves of the different citi
cultivars that were identified as nursery motl
trees inside the screen houses were collect
monthly for ELISA test. These plants we
those indexed biologically as abovementior
and found free of greening and exocortis I
not indexed for CTV. In the absence of you
leaves, midrib and petiole from mature leai
were used. Collection started in March 19
with subsequent monthly samplings ur
January 1995.

a Using monoclonal (MacAb 3E
antibody obtained from Dr. Hong-Ji
National Taiwan University, I-DAS-ELI
o (Tsu and Su, 1991) was done to test
f presence of the virus in the different samp
e MacAb 3E10 recognizes all CTV strains te.
f (Tsai et al., 1994). Briefly, monoclonal antib
I (MacAb) diluted to 500 times with coal
o buffer was added to the ELISA plate at 10(
per well. The plate was incubated i
moistened box at 37 oC for 2 hr.

The unbound antibody was then remo
by washing 3-5 times with PBS-T. Anti
was prepared by grinding 0.5 g citrus tis
s with 4.5 ml of CTV extraction buffer (0.05
I Tris-HC1, pH=6.8 + 0.1% Na-DIECA), t
1 100 ul of sample extract was added per N
s then incubated and washed as above.

S Anti-CTV MacAb 3E10 conjugated v
r alkaline phosphates was diluted 500 times v
1 PBS-T containing 0.2% Carnationnon-fatn
r was added at 100 pl per well, incubated
above and followed by washing the plate
s above.
r The alkaline phosphate substrate
s nitrophenylphosphate at 1 mg/ml substi
i buffer was added at 100 Wl per well and
plate incubated as above. The reaction i
assessed visually and stopped after 30 mint
using 3N NaOH (50 ll/well). Absorbance
405 nm of the different wells was determii
using the ELISA reader. Monthly temperat
5 and rainfall in the station were also record


t Incidence of CTV by Biological
g Indexing
I Tissue-graft indexing revealed that n<
I single tree was totally free of CTV from
samples of Citrus spp. consisting ofpumma


tristeza closterovinus on different C!

Herradura, L.V. Magnaye, M.A. Alforque Volume 35 June-December 1999 3

nges and mandarn trom Luzon, seven trom
ayas and thirty from Mindanao. The disease
commonn in all citrus plantations as shown i
results of the biological assay using indicator
its on the collected Citrus spp. from Luzon,
ayas and Mindanao (Fig. 1). Most of the
nmelo trees showed severe symptoms.

Test of samples collected from Luzon also i
wed that the disease is prevalent in the sites E
ireas in the island especially in calamansi, I
nmelo, mandarins and oranges. The plants s
-e exhibiting different symptom patterns. I
suits of indexing on key lime showed mild I
i clearing on the indicator plant indicating I
sence of the mild strain. r
This apparent prevalence of tristeza in e
rent places of Luzon is not unexpected. r
steza has been reported as one of the causes i
citrus decline in Batangas before 1957 s
allace et al., 1956). When the disease s
stated mandarin plantings in Batangas,
us growing moved to Oriental Mindoro.
ever, since the plant materials came from I
:angas, the disease problem was carried t
ig and was responsible for the decline of c
us production in Oriental Mindoro. Citrus r
rkers from DA-Lipa surveyed Oriental c
idoro in 1997 and found tristeza as one of c
bud-transmissible diseases observed c
ether with greening. For calamansi, tristeza f
actionn ranges from mild to severe with t
lost all trees sampled showing different N
rees of stem pitting in Socorro, Oriental I
idoro. In Victoria, Oriental Mindoro, tristeza a
; also observed on older trees (B.G. I
rcado, pers. comm.). Likewise, Bigornia r
Calica (1961) reported tristeza incidence a
ie Bicol Region as early as 1958, and noted d
wise that the disease was prevalent. In r
highlands of Northern Luzon, Ochasan et 1
(1996) also reported that the disease is r
valent, particularly the stem pitting strain y
sweet oranges, calamondin, and a local ti

icaya, which is known tor its Ferente
nges, the area is now shifting to other
ieties of citrus due to the presence of the
n pitting strain of tristeza and of greening.

Detection of CTV by ELISA

Pummelo, madarin and calamansi showed
ying symptom expression at the time of
ipling (Table 1). These symptoms ranged
mn slight vein clearing on sweet oranges to
ere stem pitting on pummelo. In general,
ISA detected CTV during all months except
rch and April especially on samples having
d symptoms (pummelo 3) (Table 2). The
noclonal antibody used recognized all CTV
Lins as this antibody recognizes a common
tope of CTV (Tsai et al., 1994). These
ilts also confirm the usefulness of ELISA
identifying/detecting the virus even in
nples with no apparent or with mild

The months when CTV was detected by
ISA can be considered the dry months in
country although there was no significant
Ferences in the recorded minimum and
ximum temperatures under Davao
editions as there was extremely low
relation between temperature and CTV
actionn (r=.014). This does not support the
lings of Dodds et al. (1987) which reported
t CTV antigen and dsRNA were detected
h difficulty when daytime temperature in
'erside, California was highest which
rages from 29-36 oC on June to September.
ler Davao conditions, the temperature
ge of 29-31 oC appeared not to have any
:ct on the detection of the virus. CTV was
:cted in all samples except during the
iths of March, April, June, and January.
: inability of ELISA to detect CTV in certain
iths can be attributed to the absence of
ng leaves of flushes. The samples used,
before were mature petioles and midrib.

4 Incidence of citrus tristeza closterovrus on different citrus

of rain from a previously mature twig/shoot,
which has remained dormant after a dry period.
Thus, for the routine indexing of citrus mother
trees maintained at BPI-DNCRDC to be used
in the national certification program in the
Philippines, validation and testing can be done
anytime of the year as long as young flushes
are available.ONCLUSION

CTV incidence in the country from the
highlands of Northern Luzon to the lowland
citrus growing areas like Cagayan Valley,
Batangas, Bicol, and Oriental Mindoro and
farther down to the southern part of the
country is reported. Results of biological
indexing of CTV in Region XI show that all
i samples indexed were positive for tristeza.

CTV is not only widespread all over the
country but is also affecting the production
volume and quantity of citrus fruits. This
problem has been left unchecked for several
years and has been going around in cycle
especially since the planting materials mainly
come from Batangas. To address this problem,
there should be a budwood certification
program for the production of virus-free plant
materials and concerted efforts on the early
detection of the bud-transmissible diseases
through sensitive indexing techniques should
be exerted:


LOBENSTEING. 1979. TheuseofELISAfor
detection of citrus tristeza virus.
Phytopathology. 69: 190-194.

BIGORNIAAE, CALICACA. 1961. Tristezain
thePhblippines,pp.101-106. W. C. Price(Ed).

Proc. 2"d Conf. Int Org. Citrus Virologists,
Univ. Florida Press, Gainesville, FL

CN. 1987. Efectaofstrain, host, timeofarvest
and virus concentration on double-stranded
RNA analysis of citrus tristeza virus.

HERRADURA LE. 1993. Isolation and partial
characterization ofcitrus tristezaclosterovirus
in the Philippines. Unpublished MS Thesis,
University of the Philippines Los Baftos,
College, Laguna. 87pp.

1994. Identification of citrus tristeza
closterovirus strains in pummelo. Philipp.
Phytopathol 30: 44-53.

Detection of citrus tristzavirus in Cyprusby
indexing. FAO Pt.ProtBull 37:11-132.

VERZOLA. 1996. Occurrence of graft-
transmissible disease ofcitrus in the highlands
ofNorthernLuzon, Philippines, pp. 291-296.
In Proc. 13t Conf. Intern. Org. Citrus
Virologists. J.da. Gracia,P. Moreneo and RK.

TSAI MC, SU HJ. 1991. Development and
characterization of monoclonal antibodies to
citrus tristeza CTV) strains in Taiwan). In
Proc. 11 Int. Org. Citrus. ViroL RH. Bransky,
RF. Lee, and L.W. Timmer, (Ed.) IOCV,
Riverside, CA.

HOFMEYER JDJ. 1956. Distribution of
viruses of tristezaand other diseases of citrus
inpropagativematerial Pit Dis. Reprt. 40:3-


Table 2: Mean Monthly maximum temperature

Months Temp Rainfall (mm)

3/1/1994 30.8 102.4
4/1/1994 31.6 241
5/1/1994 30.4 470.7
6/1/1994 29.7 384.2
7/1/1994 30.4 94.2
8/1/1994 30.5 166.6
9/1/1994 29.4 44
10/1/1994 31.3 230.5
11/1/1994 32.5 152.9
12/1/1994 29.2 74
1/1/1995 29.9 143.4

melo 1 severe stem pitting
melo 2 moderate stem pitting
darin no symptoms
et Orange slight vein clearing
mansi stem pitting
melo 3 slight vein clearing on key li

nd rainfall at the time of sampling for ELISA agair

ELISA result

Pum 1 Pum 2 Pum 3 Mandarin

Pos Pos Neg Pos
Pos Pos Neg Pos
Pos Pos Pos Pos
Pos Pos Pos Neg
Pos Pos Pos Pos
Pos Pos Pos Pos
Pos Pos Pos Pos
Pos Pos Pos Pos
Pos Pos Pos Pos
Pos Pos Pos Pos
Pos Pos Pos Pos

r. r

Incidence of citrus tristeza closterovrus on different citrus








ig. on: ro (


uIL mum



Aig. 1. Incidence of citrus tristeza closterovirus (CTV) in the Philippines.


and G. M. EDURISE4

Portion of a ViSCA-funded project conducted at the Department of Plant Protection,
Visayas State College of Agriculture (ViSCA), Baybay, and Leyte.

'Professor, 2Associate Professor and 3,4Science Research Assistants, Department of Plat
Protection, ViSCA, Baybay, Leyte.

Four artificial media were used to determine where Phytophthora
colocasiae R. would best grow and reproduce. Mycelial growths of
83.47, 79.90, 76.90 and 51.46 mm of R colocasiae were obtained in V-8
juice agar I, V-8 juice agar II, onion agar (OA) and potato dextrose agar
(PDA), respectively. P colocasiae grown for 4-7 days in onion agar gave
abundant production of sporangia after an agar disc of mycelia was
transferred to replacement liquids (sterile water) for 2-3 days under
laboratory conditions. Among the fungal isolates, 10 Trichoderma species
were found to be effective in vitro. However, based on the ability to lyse
pathogen mycelia, T viride and Trichoderma spp. from yam and coconut
trunk (FI50) showed consistent reactions, although their efficacy differed
significantly. Significant reductions of percentage infected leaves and
disease rating were observed in plants sprayed with T viride and
Trichoderma sp. from yam one day prior to artificial inoculation of the
pathogen, indicating effectiveness as biological agents when applied as

Key words: Phytophthora colocasiae, biological control, microbial antagonist, Trichoderm
sp.,taro blight.

INTRODUCTION Epidemics of this disease may occu
throughout the year, but especially during th
Among the root crops grown in the rainy season when night temperature is lo,
Philippines, taro (Colocasia esculenta and temperature during the daytime i
(Schott) Lam) ranks third in volume and area moderate. An entire field of taro may b
I> 1 - - 1 1A I I I I J .1 I

8 Evaluation of culture media for sporanglal production of Phytophthora colocaslae

taro, the fungus seems to have a poor
competitive saprophytic ability (Narula and
Meherotera, 1984). This contributes to the
lack of success in isolating and growing
P colocasiae in an artificial medium. This
problem makes it difficult to have an accurate
diagnosis and to conduct experiments
which involve artificial inoculation using
its reproductive structures. Sporangia and
mycelia play very important roles in inoculation
and are essential in the initiation and
development of infection.

On the other hand, cultural and chemical
control can reduce infection, although these
methods may be less attractive to small-scale
farmers because of the current low market
value of root crops and the rising price of
chemicals. The use of biological agents can
be an alternative measure since they are
economical, sustainable and ecologically
friendly (Cook and Baker, 1983). While many
naturally-occurring biological agents have
been reported in other countries, no
detailed inventory of beneficial micro-
organisms and their action on P. colocasiae
has been conducted in the Philippines, hence
this study.

This paper reports on the isolation of
P colocasiae from infected leaves and the
evaluation of four culture media based on the
growth and sporangial formation of the
fungus, the screening of different Trichoderma
species/isolates against P colocasiae, and the
determination ofthe most promising antagonists
against P colocasiae.


Isolation and Purification of the

Several attempts were initially made to
isolate P colocasiae from infected leaf tissue

using the standard procedure of isolating a
fungal pathogen. Prepared potato dextrose
agar (PDA) and water agar were used as
isolation culture media, but the attempts
remained unsuccessful until an adapted
technique was used.

The collected diseased leaves were cut
into pieces approximately 1 cm2. Leaf sections
were disinfected with 70% ethyl alcohol for
30 sec. They were rinsed well with two
changes of sterile water and blotted dry on
sterilized filter paper. Leaf sections were
planted on plated water agar containing 1 ml
of20-ppm benomyl and 60 ppm penicillin plant
grade. Following plating, the plates were
incubated at room temperature for 3-5 days
and examined for mycelial growth. Mycelial
discs from the growth of the fungus were cut
and transferred aseptically to another plated
water agar.

Composition of Different Media

Four different media were tested and
evaluated as to which best supported the
cultural growth and sporangial formation of P

The composition and preparation ofthe four
different media were as follows:
1. Potato Dextrose Agar (Difco)
1 liter distilled water

2. V-8 Juice Agar I
100 nil V-8 Juice
2 g Ca CO,
15 g agar
900 ml distilled water

3. V-8 Juice Agar II
300 ml V-8 Juice
4.5 g CaCO,
15 gagar
Water to make a liter

M. K. Palomar, Y.C. Mangaoang, V.G. Palermo and G.M. Edurise Volume 35 June-December 1999 9

Clear V-8 juice with CaCO, and centrifuge
at 300 rpm.
200 ml of this made up to 1 liter

4. Onion agar
200 g red bulb onion

Boil the red bulb onion with 1 liter distilled
water for 15 min., strain the resulting juice or
liquid and pour into a beaker. Add distilled
water to make a liter. Add 15-g agar

Each prepared medium was initially cooked
using a double boiler and thoroughly mixed.
The medium was transferred to flat bottles/
flasks, plugged with cotton and sterilized using
a pressure cooker at 15 psi for 15 min.

Evaluation of Four Different Media

Cultural Growth. Mycelial discs from
water agar culture were transferred to different
culture media (PDA, V-8 Juice Agar I, V-8
Juice Agar II and Onion Agar) and incubated
for one week. Data on mycelial growth
diameter, cultural characteristics and sporangial
formation were recorded.

Induction of Asexual Reproduction.
The mycelial growth on the different media
was cut into discs approximately 1 cm2 in
diameter and transferred to sterilized plates.
Replacement liquid (sterilized water), enough
to submerge the mycelial discs, was added to
the plates, which were incubated at room
temperature for three days. The plates were
then examined for sporangial formation.

Sporangial Counts. The mycelial discs
were crushed using nylon tulle, and the
suspension mixed thoroughly using a magnetic
stirrer. The sporangia were examined and
counted using a hemacytometer.

Collection and Isolation of Possible
Microbial Antagonists

Associated microorganisms from newly-
harvested taro tubers and healthy leaves were
isolated and purified using standard procedures.
Other microbial isolates existing in the
Department of Plant Protection (DPP), ViSCA
were also screened for their antagonistic
activity against P colocasiae.

Screening of Different Microbial
Isolates against Phytophthora colocasiae

The dual culture technique used involved
a culture plate wherein each antagonist and
the pathogen were aseptically seeded on
opposite sides of the petri plates containing
approximately 10 ml of solidified onion agar.
The seeded plates were incubated in the
laboratory under ambient conditions. The
growth of the pathogen and the screened
antagonists was noted seven days after
incubation. The degree of antagonism was
scored using a standard scale (Bell et al., 1982).

In V4vo Experiments

Promising Trichoderma isolates were
further tested for their potential to control taro
blight in potted experiments. Cultures from in
vitro set-ups showing effective antagonism of
Trichoderma isolates were inoculated to taro
plants to verify their antagonistic action on the
Phytophthora pathogen in vivo by crushing
the medium containing the mycelial growth of
the pathogen and the antagonists, then adding
water to make an inoculum suspension. The
inoculum suspension was inoculated to healthy
taro leaves using a hand sprayer. The
inoculated plants were observed for the
occurrence of symptoms. In addition, the
potential isolates were used as foliar spray
applied at different times to determine their
protective or eradicative effect.

M. K. Palomar, Y.C. Mangaoang, V.G. Palermo and G.M. Edurlse

Volume 36 June-December 1999 9

RESULTS AND DISCUSSION but sporangial production was not always
Pathogen Isolation and Evaluation of
Four Different Media Based on the results mentioned earlier,
onion agar medium isrecommended instead
When grown on four different media, P of V8 juice agar and PDA for sporangial
-olocasiae showed variable characteristics in production of P. colocasiae. Another
he amount and visual appearance of mycelial advantage of using onion agar is the low cost
;owth (Table 1, Fig. 1). Phytophthora grown of preparation.
n onion agar and V-8 juice agar showed similar
cultural characteristics wherein the mycelia of Bioassay of Antagonists In VHtro
he fungus were visible 2-3 days after and In Hvo
introduction to the media; the surface was filled
vithcreepingwhitishmyceliawithslightgrowth Isolates consisting of 24 fungi were
ones or striations. On potato dextrose agar screened against P. colocasiae in vivo.
PDA), the fungus produced slower mycelial Among the fungal isolates, ten Trichoderma
growth, with moderate cottony whitish aerial species namely T. viride, T glaucum, T.
lycelia with a colony diameter of 51.46 mm harzianum, Trichoderma from yam,
observed after one week, a difference of 24.44 Trichoderma from corn, Trichoderma from
nm from that of onion agar. peanut, Trichoderma from coconut trunk
(FI) and Trichoderma isolates from cassava
Microscopic examination revealed that roots (FIr, FIZ and FI) were found to be
Doranaial production of P colocasiae arown effective based on the hicnanv dprerihlp hv,

higher than when it was grown in V-8 juice
Cigar and PDA after agar discs of mycelial
growthh were transferred to sterilized Petri
plates and added with sterile water.
furthermore counts revealed 1.2 x105, 1.8 x
04- 5.3 x 10land 1.0x 104sporangia/mlin onion
gar, V-8 juice agar (I and I preparation) and
IDA, respectively. The difference obtained
nay be due to the high nutrient content of PDA
nd V-8 juice agar According to Smith and
ierry (1976), media with high nutrient
concentrations are usually unfavorable for
production. It could also be that high
arbohydrate content is unfavorable for
population of the fungus. Garraway (1973)
reported that sporulationofHelminthosporium
iaydis was inhibited by a high glucose

Furthermore, Rajalakshay and Joseph
1 O2" ...,LA *I. DL-.QZ.#lZ.. -,1..L-1

ride, Trichoderma from yam, coconut trunk
FI50) and corn were most effective compared
o other isolates. However, based on the ability
o lyse mycelia of the pathogen, T viride,
rrichoderma from yam and coconut trunk
FI50) showed consistent antagonistic activity,
although their effectiveness differed
significantly (Table 2, Fig. 2).

The effectiveness of Trichoderma isolates
nay be attributed to the direct effect of
antagonists onthe pathogenthrough antibiosis,
arasitism, competition, and hypovirulence.
'richoderma from yam and coconut trunk
FI50), for example, produced substances that
hanged the medium's color from cream to
ellowish. Perhaps, this substance had
antibiotic properties that suppressed the growth
fthe pathogen. In addition, the colony growth
f P colocasiae was arrested and the mycelia
.,.llmaa ,, pn. kl;. ,.n n+-I, .,,, ;.+,,,<-. +. .. .

K. Palomar, Y.C. Mangacang, V.G. Pal ~lume 35 June-December 1999 11

e finding that antagonism by Trichoderma
)uld be either mycoparasitic or antibiotic
:het, 1987).

In pot experiments, significant reductions
the percentage of infected leaves and
sease rating were observed in plants sprayed
ith T viride and Trichoderma spp. from
un. The efficacy was best shown when
)plied as a protectant rather than as an
adicant, as indicated by the lower percentage
infected leaves and disease rating scores
.able 3, Fig. 3). No control was observed
hen Trichoderma viride and Trichoderma
om yam were applied one and two weeks
ior to the inoculation ofP colocasiae. Plants
rayedd with either Trichoderma from yam
* T viride one day prior to inoculation of P
dlocasiae were significantly protected from
fection compared to when Trichoderma was
prayed one week ahead of the inoculation of
colocasiae. The results indicate that both
olates are effective biological agents when
)plied as protectant.


vitro antagonism of Trichoderma species
against six fungal plant pathogens.
Phytopathology 72:372-382.

HET L (Ed.). 1987. Trichoderma- application,
mode of action and potential as biocontrol
agent of soil borne plant pathogenic fungi. In:

Innovative Approaches to Plant Disease
Control. John Wiley and Sons. New York

'OOK RJ, BAKER KE 1983. The Nature and
Practice of Biological Control of Plant
Pathogens. Amer. Phytopathol. Soc., St Paul,
Minnesota, USA

;ARRAWAY MO. 1973. Sporulation in
Helminthosporium maydis: Inhibition by
thiamine. Phytopathology 63: 900-902.

saprophytic survival of Phytophthora
colocasiae in soils. Indian Phytopathol. 37:

)OKAJJ. 1982. Taro diseases, pp. 236-257. In:
Taro, A Review of Colocasia esculenta and
Its Potential. Wang, J. K. (Ed.). University of
Hawaii Press. USA.

CARR. 1977. The Philippines Recommends for
Gabi. Philippine Council for Agriculture
Resources Research, Los Bafios, Laguna. 15pp.

of sporangia by Phytophthora meadii. Indian
Phytopathol. 34: 539.

MITH JE, BERRY DR. 1976. An introduction
and distribution of races C1 and C, of
Cercospora beticola from sugarbeet.
Phytopathology 66:1158-1160.

'RUJILLO E E. 1967. Diseases of the genus
Colocasiae in the Pacific area and their control.
Proc. Int. Symp. Trop. Root Crops. Trinidad.
February 13-28, 1967.

K. Palomar, Y.C. Mangaoang, V.G. Pal

Dlume 35 June-December 1999 11

Table 1. Growth characteristics and sporulai
media one week after incubation.'

Media Cultural

Potato Mycelia of the fungus
Dextrose visible 3-4 days aft
Agar introduction to the medium;
produced moderate
cottony whitish aerial

Onion Mycelia of the fungus
Agar visible 2-3 days after
Introduction to the medium:
Surface filled with creeping
whitish mycelia with slight
growth zones or striations

V-8 Mycelia of the fungus
Juice visible 2-3 days after
Agar I introduction to the medium;
Surface filled with creeping
whitish mycelia with slight
growth zones or striations.

V-8 Mycelia of the fungus
Juice visible 2-3 days after
Agar II introduction to the medium;
surface filled with creeping
whitish mycelia with slight
growth zones or striation

'Means with the same letter are not significantly different at
'Sporangial counts were taken from five plates grown with i
1 cm2) and added with replacement liquid
Av\',rage of two trials with 15 plates for each medium

in of Phytophthora colacasiae on four different cult

Sporangial Colony
Counts/ml' Diameter3

1.0 104 d 51.46 b

1.2 x 105 a 76.90 a

1.8 x 10 c 83.47 a

1.8 x 10 c 83.47 a

% level by LSD
celia cut into discs (about

_ _______

r""""" - I-~r--'

raullluII, i.. mallinauaCliy, V.ur. raICllhu allu u.m. ruurIse vulurne 0o June-uecemUner lw-w 14

Fe 2. Degree of antagonism exhibited by different
colasiae in vivo1


hoderma (yam) 1
hoderma vi ride 1
hoderma (coconut trunk FIso) 1
hoderma (corn) 1.
hoderma (cassava roots F44) 1.
hoderma (cassava roots FIc) 1.
hoderma glaucum 1
hoderma (peanut) 1
hoderma harzianum 2
hoderma (cassava root FI37) 22
as with the same letter are not significantly different at 5% level bi
ig based on the method described by Bell et al. with 1 as the most
least antagonistic.
age of two trials with 15 plates per trial taken after one week of in

'e 3. Effect offoliar application of Trichoderma is(
and eradicant.

EAMENTS % Infected Lc

tophthora alone 97.50 a

hoderma + Phytophthora
week after T.) 32.50 b

hoderma + Phytophthora
week after T.) 85.00 a

hoderma + Phytophthora
weeks after T.) 95.00 a

'ophthora + Trichoderma
Jays after P.) 92.50 a

ns with the same letter are not significantly different at 5% level b3
ase Rating Scale:
1 less than 1% infection ofthe entire le
3 Ito 15% infection ofthe entire leaf
5 16 to 25% infection ofthe entire leaf
6 26 to 49% infection of the entire leaf
9 more than 50% infection of the entin

Trichoderma isolates against Phytophthora


) a 38.27 a
)a 35.13 b
) a 31.23 c
7a 22.23 e
ab 24.03 de
lab 22.17de
)ab 25.33 d
Sbc 12.17 g
Scd 14.90 f
dd 7.60h
agonistic and


ttes on taro blight asprotectant

rest Disease Ratinge
.viride T.(yam) T. viride

00.00 a 8.95 a 8.93 a

45.00 b 2.43 b 2.88 b

87.50 a 7.63 a 8.06 a

95.00 a 8.79 a 8.60 a

92.50 a 8.37 a 8.18 a



Fig.1. Phytophthora cole
A) Onion Aga, B) V-
D) V-8 Juice Agar Il(

wiae, grown on four artificial media
juice AgarI, C) Potato Dextrose Agar

Palomar, Y.C. Mangaoang, V.G. Palermo and G.M. Edurise Volume 35 June-December 1999 15

Fig 2. In vitro bioassay showing the most ]
viride (a) and Trichoderma from yam i

nmising Trichoderma isolates, T
against P colocasiae (X=0.05).

Fig. 3. Taro plants showing the effe
colocasiae alone (a) and Trica

f artificial inoculation ofPhytophthora
lerma viride + P colocasiae (b) (X=0.05).

-r-----~--- r---------- -- --~--r--------


I nrr -f CS..Dk~~kk~~ ~lr

C!TDT717V TQ T ATIn11r AmlnTI "T'ADAP"TIr7DIATT'ATrnlT fl\

IN. L. OINAill, J. E. VILLA 1

N. L. OPINA', J. E. VILLA2 :

n1ri rrIllrIrIlljEa


18 Survey, isolation and characterization of Agrobacterium species in the Philippines

in the country until Bayot (1993) reported the
presence of bacterial crown gall of roses
caused by Agrobacterium tumefaciens. This
is the first report of the presence of the
organism in the country. With the continued
importation of plants into the country, it is
assumed that Agrobacterium species might
have been inadvertently introduced, prompting
the ban on importation of this species.

This study aimed a) to survey the
geographical distribution and incidence of
Agrobacterium species in the Philippines;
b) to isolate Agrobacterium species into pure
culture and test their pathogenicity; c) to
characterize and classify each isolate into


Survey and Isolation

The presence ofAgrobacterium spp. was
surveyed in different provinces in the country
namely, Albay, Batangas, Benguet, Bohol,
Bukidnon, Bulacan, Camarines Sur, Cavite,
Davao del Sur, Davao Oriental, Ilocos Sur,
Iloilo City, Laguna, La Union, Mountain
Province and Nueva Ecija. In one to two towns
of these provinces, samples of different crop
plants in gardens and backyards were
collected. These crop plants were roses (Rosa
spp.), chrysanthemums (Chrysanthemum sp),
tobacco (Nicotiana tabacum L.), tomato
(Lycopersicon esculentum Miller), apples
(Malus sylvestris L.), pear (Pyrus communis),
plum (Prunus sp.) and grapes (Vitis vinefera).
Samples of plant parts, both with and without
gall or hairy root symptoms, plus soil samples,
were collected from the field and brought to
the laboratory for isolation of Agrobacterium

Plant samples, with or without disease
symptoms, were washed thoroughly with

running tap water, disinfected with 10% chlorox
for 5 minutes and then rinsed three times with
sterile distilled water (Bayot, 1993). Galled
roots and stem tissues were diced and
suspended in sterile distilled water for 30
minutes. Halfofthe resulting suspensions was
streaked on plated potato dextrose agar
(PDA), composed of 250g potato, 20g
dextrose and 15g agar per liter of water and
Dl medium, which contained 15g mannitol,
5gNaNO 6g LiCI, 0.002g Ca(NO)2 4I20,
0.2g MgSO4H2O, 0.1g bromthymol blue, and
15g agar per liter of water. The preparations
were incubated for a minimum of one week at
room temperature. Single colonies that grew
on each plate were transferred to a fresh
culture medium and maintained on PDA slants
and sterile distilled water. The other half of
the remaining suspension was inoculated
on sliced carrot roots placed in a sterile petri
dish lined with sterile filter paper at room
temperature. The suspension was also
inoculated on wounded tomato seedlings
covered with plastic bags overnight and
incubated under greenhouse conditions. The
set-ups were monitored for gall and hairy root

Soil samples were thoroughly mixed.
Approximately 10g of soil were suspended in
90 ml of sterile distilled water. The resulting
soil suspensions were plated on PDA and Dl
media, and inoculated on sliced carrots and
tomato seedlings. Bacterial colonies that grew
on the plated media were transferred to fresh
media and sub-cultured until pure cultures were
obtained. The inoculated carrot slices were
monitored for hairy root formation while the
seedlings were examined for both gall and
hairy root development.


The bacterial isolates from galls, roots,
and soil samples were tested for pathogenicity
using carrot slices placed in petri dishes and

N.L Opina, J.E. V~~ilaadC.PoaiVoue3JueDcm r199 9

one-month-old tomato seedlings (VC- 11
variety) grown in pots with sterile soil. The
stems of the seedlings were wounded using a
sterilized scalpel. Inoculation was done by
placing a loopful of bacterial cell suspension
obtained from a 24-hour-old culture grown on
PDA into the freshly-wounded test plants.
Plants inoculated with sterile distilled water
after wounding were used as control. The
inoculated plants were covered with
polyethylene bags for 24 hours and incubated
under greenhouse conditions. The development
of galls or hairy root symptoms on seedlings
was monitored for two months, while hairy root
formation on carrot slices was monitored for
four weeks. Reisolation of the causal bacterium
from inoculated plants showing symptoms of
Agrobacterium infection was done to confirm
the identity of the isolates.

Characterization of the Isolates

Morphological and Cultural Characters.
Cultures of the unidentified bacterial isolates
were gram stained and examined under the
microscope. Their growth in culture medium
was likewise described.

Biovar Classification. Tumor-forming
bacterial isolates were classified into biovars
following the diagnostic tests described by
Moore et al. (1988): production of 3-
ketolactose; growth in NaCI; growth at
different temperatures; action on litmus milk;
production of acid from sucrose and erythritol;
production of alkali from malonic acid, L-
tartaric acid, propionic acid and mucic acid;
reaction to ferric ammonium citrate and
oxidase; and utilization of L-tyrosine and

Opine Catabolism. Opines can serve
as a sole carbon and nitrogen source for
Agrobacterium harboring the appropriate
plasmids. Different Agrobacterium strains and
their corresponding plasmids catabolize

different opines. To screen for opine utilization,
the basal medium containing 7.2g K2HPO4,
2.8g KH2PO4, 0.2g MgSO4 7H20, Ilmg
CaCI2 2H20, 5mg FeSO4 .7H20, and 2 mg
MnCl. 4H20 per liter (pH 7.2) with 5mM
sterilized opine was inoculated with a bacterial
suspension from a 24-hour-old culture. Basal
medium supplemented with 5 mM glucose and
5 mM ammonium sulfate was used as check.



Tests on the collected plant and soil
samples showed that A. rhizogenes is not
present in the country (Table 1). However,
crown gall disease of rose, caused by
Agrobacterium tumefaciens, was observed in
four provinces of Luzon, namely Benguet,
Camarines Sur, Cavite, and Laguna, but not in
the Visayas and Mindanao provinces surveyed.
The incidence of crown gall disease ranges
from 1 to 30%, the highest being in Alfonso,
Cavite. The galls were found only on the stem
and crown of old rose plants more than three
years of age. Munnecke et al. (1963) noted
that gall symptoms appeared in rose plants 18
months after inoculation. Thus, galls are usually
observed only in old rose plants in the field.
Galls were also observed in "agoho"
(Casuarina equitofolia) in Albay but no
Agrobacterium was isolated.

Isolation and Pathogenicity

Bacterial isolates and suspensions from
plant and soil samples did not induce hairy-
root or tumor formation when inoculated on
carrot root and wounded tomato plants. Rotting
caused by bacteria and fungi was observed
on the carrot slices. However, eight bacterial
isolates from galled roses induced tumor
formation in tomato and tobacco plants 14 to
56 days after inoculation (Table 2). The most

N.L. Opina, J.E. Villa and C. Protacio

Volume 35 June-December 1999 19

20 Survey, isok gruDu~LwIuflI ~p~i*g~ III UI~ ruhnppI

lafios, Laguna. In contrast to the other namely At-1, /
solates, it was able to induce tumor-formation reactions in all
. early as 14 davs after inoculation. classification

-rornung isolaUes irUm
:ed on "kalachuchi"
)erris elliptica plants,
t isolates induced
Inoculated plants even
The appearance of
ig time in some plant
bacterium of the crown
was reisolated from
ted tomato and tobacco
iculation into the same
e induced typical gall
y (1972) reported
s that can induce both
rmation. He further
refaciens isolated from
on tomato and carrot
origenic on broad bean
len and Holding (1974)
t in ATr TT 11T32r

y smcinuoiu uoUvai I
ing characteristics: gi
ic action on litmus milk;
icrose; no alkali product
,-tartaric acid, propioni(
positivee response on fe
:; and positive reacti
rer, these isolates also r
d on the following rea
ctose production; absen
iCl; production of acid
ilization of citrate and L

lolates At-2 and At-7 w
option of biovar 1 than to
ig only in L-tyrosine uti
nd At-8 resembled bio'
1, differing only in L-tar

men u

JV1l LIUN U.aI.L- I -L UALi ...LA -.. A--

___ ..

20 Survey, isoh

groVoaienurmI species III ue rinllppt

ce. genus Agrobacterium and tumorigenesis.
Annu Rev. Microbiol 29: 377-405.

YOT RG. 1993. Bacterial crown gall: A new 1963. Hairy root (Agrobacteriumrhizogenes)
disease of rose in the Philippines. Philipp. offield roses. Phytopathology 53: 788-799.
Phytopathol.29: 1-6.
Phoal91-6MOORE LW, KADO CI, BOUZAR H. 1988.

LEN ON, HOLDING AJ. 1974.Agrobacterium Agrobacterium, pp. 16-36. In:. N. W Schaad
Conn. pp. 264-267. In RE. Buchanan andN. E. (Ed.). Laboratory Guide for Identification of
Gibbons (Eds.). Bergey's Manual of Plant-PathogenicBacteria. APS Press, Amer.
Determinative Bacteriology. The Williams and Phytopathol. Soc., St. Paul, Minn., USA
Wilkins Co., Baltimore. 1268pp. SPENAAS NGTKOEZC,SCELLJ.
LEY J. 1972. Agrobacterium: intragenic 1987. Independent and synergistic activity of
relationships and evolution, pp. 251-159. In H. rol A, B, and C loci in stimulating abnormal
P. Mass-Geesteranus (Ed.). Proc. Third growth in plants. EMBO J.6:3891-3899.
International Conference onPlant-PathogenicLBART F 1989
Bacteria, Wageningen, The Netherlands.
Agrobacterium rhizogenes as a vector for
LEY J, TIJTGAT R DE SMEDT J, MICHIELS transforming higher plants. Microbiol. Sci. 4:
M. 1973. Thermal stability of DNA: DNA 24-28.
hybrids within the genus Agrobacterium. J.
GenMicrobiol. 78:241-252. ZAMBRYSKI P. 1988. Basicprocessesunderlying
Agrobacterium-mediated DNA transfer to
ANNE PJ, KERRA, NEW PB. 1970. Crown gall plant cells. Annu. Rev. Genet. 22: 1-30.
of stone fruit II. Identification and
nomenclature ofAgrobacterium isolates. Aust.
J. Biol. Sci. 23: 585-595.

22 Survey, isolation and characterization of Agrobacterlum species in the Philippines

Table 1. Results of surveys for the presence ofAgrobacterium spp.

Province and Town Host Plant Crown gall Hairy root
incidence (%) incidence (%)

La Trinidad

Baguio City
Manolo Fortich
Camarines Sur
Naga City

Davao del Sur
Tugbok District
Davao Oriental
Iloilo City
Iloilo City
Hocos Sur
Los Bailos
La Union
Mountain Province
Nueva Ecija

Tomato, beans
Roses, chrysanthemum, kalanchoe
Roses, tomato, beans

Rose, chrysanthemum and carnation
Rose, dahlia, kalanchoe

Chrysanthemum, carnation, carrots
Rose, apple

Rose, tomato, carrots
Rose, tomato, carrots

Rose, tomato
Rose, tomato

Rose, tomato


Chrysanthemum, kalanchoe







Apple, grape, pear, plum, lychee,




Table 2. Pathogenicity test of different bacterial isolates on tomato.

Area of collection Number of isolates Pathogenic
Tested isolates

La Trinidad, Benguet 24 1
Naga City, Camarines Sur 7 0
Silang, Cavite 4 0
Cabuyao, Laguna 5 2
Los Bafios, Laguna 10 5

Table 3. Growth characteristics ofAgrobacterium tumefaciens isolate using different tests and
differential reactions of the biovars of the genus Agrobacterium

DIAGNOSTIC TEST At-1 At-3 At-4 At-5 At-2 At-7 At-6 At -8 1 2 3

Growth in 2% NaC + + + +
Growth at 350C + + + + + + + + + V- V
Growth at 37*C ig ig ig ig ig ig + +
Action on litmus milk Alk Alk Alk Alk Alk Alk Ac Ac Alk Ac Alk
Acid from sucrose + + + + + + + + + V
Acid from erythritol + + + + + + + -
Acid from melezitose + -
Alkali from malonic + + + +
Alkali from L-tartaric + + +
Alkali from propionic V -
Alkali from mucic acid + + +
Citrate utilization + + + + + + V- + +
Ketolactose production + V
Ferric ammonium citrate + + + + + + + -
L-tyrosine utilization + + + + + + + + -
Oxidase reaction + + + + + + + + V- V
Opines: nopaline + + + + + + + +
S+ = 80% or greater positive reaction/ growth, = 80% or greater negative reaction/ growth, Alk = Alkaline, Ac = Acid,
ig = inhibited growth, V= Variable 21-79% positive, a + or after V indicates the majority reaction were significant
b At-1 = Los Bafios, Laguna, At-2 = Los Baiios, Laguna, At-3 = Los Bafos, Laguna,
At-4 = Los Bafios. Laguna, At-5 = La Trinidad, Benguet, At-6 = Cabuyao, Laguna,
At-7 = Cabuyao, Laguna, At-8 = Cabuyao, Laguna

N.L. Opina, J.E. Villa and C. Protacio

Volume 35 June-December 1999 23



Portion of the MS thesis of the senior author submitted to the Graduate School, Univ
of the Philippines Los Bafios (UPLB), College, Laguna. Supported by the Philippine Count
Advanced Science and Technology Research and Development (PCIERD) and T;
Agricultural Development Corporation, Panabo, Davao del Norte, Philippines

'Former graduate student and 2Associate Professor, Department of Plant Pathology, U
College, Laguna, Philippines

The progression of major banana diseases, including Sigatoka, moko,
Fusarium wilt, and bunchy-top, were studied in monocropping and
multicropping systems. Although differences were observed in disease
severity or incidence, these were not statistically significant under the
conditions of the experiments in the case of the first three diseases.
The component crops in the multicropping system had no critical
influence as they were still at an early stage of growth. In the case of
bunchy-top, incidence was higher in the multicropping system apparently
due to the planting of other crops, which may have disturbed the aphid
vectors forcing them to be dispersed and in the process transmitting
the virus to other plants.

INTRnDITCTION hiahcht rank-incr hnannnnn nnrtinc rrinnn

Banana is Asia's most important con-
tribution to the international fruit industry. In

A. L Umadhay and D. Raymundo Volume 35 June-December 1999 25

iusae and Mycosphaerella musicola Leach monocrop and as a part of a multicropping
nd M. fijiensis Morelet, respectively, scheme.
trthermore, M. musicola appears to be
ermaphroditic (single ascospore or conidium
ultures producing protoperithecia and MATERIALS AND METHODS
permogonia) and self-sterile. This was
roven to be functional in the disease cycle Experimental Site
nd the cause of the characteristic tip-spotting
ymptom (Leach, 1941, 1946). These diseases Monocropped and multicropped production
re widely spread in commercial plantations systems were selected at the Mauro's Farm
ftriploid AAA types of dessert varieties like in Calinan proper and Brgy. Lacson,
hiant Cavendish, Dwarf Cavendish, Lakatan, respectively in Calinan District, Davao City,
lorado, Gros Michel, and Grand Naine. Southern Philippines The monocropped
furthermore, the AAB types can also be system was planted with the local banana
infected (Meredith and Lawrence, 1970). cultivar Lakatan while the multicropped
igatoka causes premature death of large areas system involved the same cultivar in an
f the leaf surface, if not the entire leaf, thus intercropping scheme with durian, citrus (cv.
dxucing the total photosynthetic area of the Szinkom and King Mandarin), and coconut. In
lant. This results to plant debility, reduced each cropping system, four areas -were
eight and slow maturation of the fruit selected and used as replications. Each
Buddenhagen, 1968). In extreme cases, replication measured 50x50 m2.
igatoka caused temporary or permanent
collapse of local banana industries (Meredith, Temperature and rainfall data were
970). In the Philippines, particularly in monitored throughout the period of the
4indanao, black Sigatoka is so serious in experiment through weather stations located
commercial Cavendish cultivars that the at the nearby farms of the Davao Pineapple
necessity of aerial spraying of fungicides Corporation (DAPCO) for multicropped
hanging from 23 to 30 cycles a year has system and ofthe Philippine Coconut Authority
irreased the cost of control annually (Roneros (PCA) and Philinnine Fruits. Incorporated

severity, on the other hand, was assessed for The infection rate of the monocyc
the localized disease Sigatoka. In this case, diseases Moko and Fusarium wilt v
percent severity of lesions was estimated estimated by using the model of Vander Ph
relative to the total number of leaves per plant (1963):
(Leach, 1946). The location of each leaf r = 1 (log 1 logL )
assessed on the plant was indicated by t2-tI 1-x2 1- x
numbering the leaves from the youngest open
leaf subtending the heartleaf to the oldest Similarly, for polycyclic diseases such
upright leaf (Leach, 1946; Stover, 1971). Sigatoka and BBT, infection rate v
Assessment of the disease in its earliest stage computed using this formula:
was also done by taking into account the r = 1 (log log __ )
position on the plant of the youngest leaf t2-t, 1-x2 1-X1
having yellow streaks and minute spots.
Before Sigatoka assessment was done, ten where r = apparent infection rate;
two-month old banana plants per replication t, = initial disease observation:
were selected and used as samples for t2 = final disease observation;
assessment throughout the period of the x, = percent disease at t; and
experiment. Selection was done randomly in x2 = percent disease at t2
both the monocropped and the multicropped log = natural logarithm
cropping systems. The temporal development
of Sigatoka was monitored at weekly intervals
from June to September 1997. RESULTS

Weekly records of meteorological data Diseases Found in the Two Croppinl
were compared with corresponding disease Systems
assessment records for a period of 4 months
to determine possible correlation between Three major banana diseases identified
weather factors and disease severity, the two cropping systems were Sigatol
Likewise, disease management and farm bunchy top, and Moko. Others found w,
practices were also noted. the virus diseases banana bract mosaic a


'emporal dynamics of banana disea!

- Umadhay and D. Raymundo Volume 35 June-December 1999 27

dich later became chlorotic in terms of temperature and rainfall
oms included yellow, light percent severity in both the systems
n stripes, generally along insignificant (Table 3).
e general mosaic. For
sions were surrounded by In the monocropping system,
pale brown, oval patches, practices observed were close distance
o several centimeters in high density planting. The distance be
he leaf lamina, particularly hills in rows and columns of 2 meters c
ins and in association with overlapping of leaf canopies. Remoi
disease on the other hand diseased leaves, or deleafing, was pra
gh its minute dark brown but old and cut leaves were left in the
ch gave the leaf a sooty Additional field observations included imq
ough texture. In disease drainage, a possible cause of water lo1
plants were infected with and improper provision of nutrit
ses. Furthermore, BBT, supplement. In the multicropping system
) were found on a single same practices were observed. Durir
a case of BBT, Sigatoka period under study, intercropped plants
T occurring together. at the early stage of growth.

elopment in Time Banana Bunchy-Top
ka Disease
The assessment of BBT epi(
recent of the banana plants development in the two systems was pre
,served to be infected with in Table 4 and illustrated in Figures 3 :
percent severity in both The initial source of inoculum was rel
is high (Table 1) and when high affecting 6.40% and 8.44% of thi
e show a sigmoid curve banana population and 16.8% and 29.
olycyclic diseases (Figs. 1 the final assessment in monocroppin
mocropping system, the multicropping systems, respectively. Ap
ve increased steadily over rate of infection (r) inthe monocropping s
i the multicropping system was estimated at 0.0082 per unit/day (
; curve increased gradually while inthe multicropping systemthe r is (
1.05% up to 28 days and per unit per day (Fig. 4). The develop
ed from 29.05%to 39.36% BBT was relatively slower inthe monocr
I assessment. Ninety-one than in the multicropping system.
sessment, percent severity
60.03%. Disease progress Moko Disease

28 temporal dynamics of banana dlsea5

'infection (r) were 0.0113 and 0.0124 system. The increase of Sige
t per day for the monocropping and likewise, may have resulted
upping systems, respectively (Figs. 5 & uniformity and improper cult
observed in the area such as imp
which causes waterlogging,
Fusarium Wilt planting, improper nutrition
poor sanitation practice,
er 120 days of observation, a low susceptibility. Poor drain
m wilt incidence was observed in the affected Sigatoka chiefly throul
opping system with 3 out of 466 plants humidity conditions within tl
corresponding to an infection rate of High planting density oftentii
per unit per day (Fig. 7). In the overlapping of leaf canopy tha
)pping system, 2 out of 190 plants were a microclimate favorable
with a rate of 0.0070 per unit per day development (Roperos and Ma
This is largely determined by th
moisture, whether derived fron
irrigation, evaporates (Rotem ar
DISCUSSION Major commercial varieties of
are highly susceptible to Sigatc
disease Development in Time 1970). According to Shillin
Sigatoka Disease lacatan, which is the tallest n
Cavendish group, is highly s
Rate of disease increase was not Sigatoka. It was suggested tha
intly different between the two cropping as height of plant, rate of lei
This could be due to the very high length of leaf etc. may affect
ioculum found in both systems at the of the leaf, impaction of leaf spi
ing of the observation. Likewise, consequently, amount of disease
h there were intercropped plants in
i bananas in the multicropping system, In this experiment, three w
:re still very young except for a few rain with intermittent low rain
t trees that were planted far from favored high infection rate. T.
ier and consequently did not appear to during heavy rainfall were prol
disease development significantly. through heavy raindrops while t
ng to Shillingford (1975), shade from showers raised the relative hu
onuts inhibits dew formation which favored sporulation. According,
;pore dissemination and germination. (1970), the increased incident
s growing in partial shade or under a during and after rainy periods a
.-.-. ml,, r,-, n ~n ,,mr, r~t ,lP1, 4:rPP m lr o4 K l r .1 K .


'emporal dynamics of banana disews

Volume 35 June-December 1999 29

ributors to total inoculum. temperatures exceed 21C and rainfall is
perithecia increase and the maximum (Stover, 1964). Further
rease in areas with the highest infection declined when temperatures fell b
est rain-free periods. Lowest 21 C, although rainfall was still abundant
:cia production in Honduras
ring the dry months of April One of the criteria in determining dis
I and 1965, followed by a rise severity is the mean position of the your
ig on the rainfall following the leaf spotted (YLS). The younger the pi
eason in May. In contrast to are infected the higher disease severity
dochia production can be high be. In this experiment, the position of
of rain provided dewfall is youngest leaf spotted (YLS) of banana pl
in long hours of leaf wetness inthe monocropping and multicropping sy,
. Conidia were the more ranged from 4.05 4.8. According to L
in disease build-up and spread (1941), lakatan is highly susceptibleto Siga
; were primarily for spreading disease and the first visible stage of spol
r long distances, sexual ('streaks') usually occurs on about the fo
and for surviving periods leaf of unsprayed plants while in the spr,
onidial activity. In contrast, plants, youngest leaf with spots ranged f
eved that ascospores were the 4.7-6.9. On more susceptible cultivars,
ource of infection. Maximum incubation period is shorter and mature les
luction is rain-dependent, appear on younger leaves. According
use of the necessity for Shillingford (1975), Lakatan has the sloi
rtilization by compatible rate of leaf emergence compared with o
r, 1963). Rain is essential for varieties. This could be the reason why in
;charge of ascospores. experiment, Lakatan plants regardless of
idia production and dispersal, cropping system adopted, were seve:
by rain, occur abundantly with affected with the disease at an early stag
Thus, even in the absence of leaf development.
e crops of conidia can be
ig in infection of young plants Banana Bunchy-Top
i the taller infected plants.
is of high humidity follow Percent disease incidence of bunchy
heavy spotting may develop in the multicropping system was higher tha
the monocropping system. This could be
to improper cultural practices and con
i temperatures for maximum measures practiced in the area. Vectors
-re 26.540C and 25.600C in sources ofinoculum were abundant inthe

plants, infection continued because not all Temperatures between 30-35C increase 1
infected plants could be located and destroyed incidence and onset of bacterial wilt althou
at each inspection. Another possible cause of not all strains of the pathogen are affect(
higher infection in the multicropping system High water table due to heavy rainf;
was the planting of other crops, which may accumulates high soil moisture that far
lp_--rr Imar1 a r^-lP~dan 1 ----lA i A -rlllllh ft c


Moko Disease

Percent incidence ofmoko disease and t
rate of infection were almost the same in t
two cropping systems. Possible cause
observed during the conduct of the study w
the negligence or ignorance of the farmer abc
moko. Infested knives were used duril
roguing of diseased plants in the field. Likewi!
moko-infected plants were cut and le
scattered in the area. High amount ofinoculu
was clearly available in the area and t
bacterium could have spread rapidly with t
aid of man, insects (Hunger, 1901), tool
nematodes (Lucas et al., 1955) and rain. HiW
disease incidence could also be due to the cic
distance of plants allowing direct contact a
root-to-root spread of the pathogen. Und
high soil moisture conditions, the wiltbacterit
emerges or is released from the roots
infected plants and can spread to roots
adjacent healthy plants in soil, particularly wh
root systems are intermingled (Kelman a
Sequeira, 1965). Other factors that may le
to high disease incidence are variety
susceptibility, plantation location (Buddehagt
1961) and field practices like the use ofinfest
knives (Rorer, 1910; Sequeira, 195M
According to Buddenhagen (1961), moko w
serious in plantations of 'lacatan' bananas
southeastern Trinidad because the soil is acic
heavy clay and the plantation is situated in
hilly area of tropical rain forest.

Environmental conditions, such
temperature and rainfall, usually favor t

splash infested soil on fresh wound surface
where the wilt bacterium can easily gain acce,
to the vascular bundles of the banana plai
(Sequeira, 1958).

e Fusarium Wilt

s The low incidence and infection rate (
t Fusarium wilt observed in this study could I
g due to a low source of inoculum present in tl
, area. However, Roperos and Atabug (198;
t reported the sporadic occurrence of Fusariu
I wilt in several plantations in Davao province
e The occurrence of Fusarium wilt could hai
e been affected by soil conditions of the are
, According to Reinking and Manns (1932
1 the time of the first appearance of disea.
: depends on inoculum potential and soil facto
I favoring infection. According to Buddenhag(
r (1968), the impact of Fusarium wilt in tl
I Americas has been so great that this diseax
F has been ranked with catastrophic plai
F diseases such as wheat rust and potato bligl


, effects of soil types and moisture levels (
bacterial wilt disease of groundnut (Arach
hypogaea). Pertanika 6:26-31.

S ALLEN RN. 1978. Spread ofbunchy top disease
: established banana plantations. Aust.
l Agric. Res. 29: 1223-1233.

BRUN J. 1947. La maladie de Sigatoka (
s cercosporiose du bananier (Mycosphaerel
: musicola Leach Cercospora musae Zimm

K.M. L Umadhay and D. Raymundo Volume 35 June-December 1999 31

BUDDENHAGEN IW. 1961. Bacteria ofbananas:
history and known distribution. Trop. Agric.

BUDDENHAGEN IW. 1968. Banana diseases in
thePacific area. FAOP1. Prot Bull. 16: 17-31.

GUYOTH, CUILLEJ. 1958. Essai de prevision des
attaques de Cercospora en Guadeloupe. Fruits
d'outremer. 13: 85-94.

HAYWARD AC. 1991. Biology and epidemiology
of bacterial wilt caused by Pseudomonas
solanacearum. Annu. Rev. Phytopathol. 29:

HUNGERFWT. 1901. Deslijmziekteveroorzaakt
door Bacillus solanacearum Smith, Oversicht
der zieklen en beschadigingen van het blad bij
DeliTabac. Meded's Lands Plantentuin 47: 20-

JOHNSON A. Host list offungi etc. recorded in the
South East Asia and Pacific Region. Musa spp.-
banana; Musa textiles abaca. Tech. Docum.
F.AO. PL Prot. Comm. S.E. Asia 26:1-3.

KELMAN A. 1953. The bacterial wilt caused by
Pseudomonas solanacearum, N. Carolina Agr.
Expt Sta. Tech. Bull. 99,194 pp.

KELMAN A, SEQUEIRA L. 1965. Root-to-root
spread of Pseudomonas solanacearum.
Phytopathology 55: 304-309.

LEACHR. 1941. Bananaleafspot,Mycosphaerlla
musicola, the perfect state of Cercospora
musae Zimm. Trop. Agric. 18:91-95.

LEACHR. 1946. Bananaleafspot (Wcosphaerella
musicola) on the Gros Michel variety in
Jamaica. Kingston, Jamaica: Government

MEREDITHDS. (1970). Bananaleafspotdisease
(Sigatoka) caused by Mycosphaerella
musicola Leach. Phytopathological Papers,
No. 11. CommonwealthMycological institute.
Kew, Surrey, England. 147 pp.

streak disease of bananas (Mycosphaerella
fijiensis): susceptibility of cultivars. Trop.
Agric. 47:275-287.

ROPEROS NI ATABUG RG. 1985. Status ofMoko
and Panama diseases of banana in the
Philippines, pp. 106-112. In Proc. Intern.
Seminar-Workshop on Banana and Plantain
Research and Development.

ROPEROS NI, MAGNAYE LV. 1991. Status of
banana diseases in the Philippines, pp. 52-66.
InR V Vdlmayor B. E. Umali, and C. P Bejosano
(Eds.). Banana Diseases In Asia and the
Pacific: Proc. Regional Technical Meeting on
Diseases Affecting Banana and Plantain in
Asia and the Pacific, Brisbane, Australia, 15-
18 April 1991.

RORERJB. 1910. Abacterial disease of bananas
and plantains. Proc. Agr. Soc. Trinidad and
Tobago 10:109-113.

SEQUIERA L. 1958. Bacterial wilt of bananas:
Dissemination of the pathogen and control of
the disease. Phytopathology 48: 64-69.

SHILLINGFORD CA. 1975. Varietal susceptibility
of bananas to infection by Mycosphaerella
musicola in sprayed and unsprayed plots.
Trop. Agric. 52:157- 165.

SIMMONDS JH. 1933. Bananaleaf spot Progress
report. QueenslandAgric. J. 39:21-40.

SIMMONDS JH. 1939. Influence of seasonal
conditions on the development of Cercospora
leaf spot of the banana with special reference
to the control programme. Queensland Agric.
J. 52:633-647.

STAHEL G. 1937. Notes on Cercospora leafspot
ofbananas (Cercosporamusae). Trop. Agric.

STOVER RH. 1964. Leaf spot ofbananas caused
by Mycosphaerella musicola: factors
influencing production of fructifications and
ascospores. Phytopathology 54:1320-1326.

K.M. L Umadhay and D. Raymundo

Volume 35 June-13ecember 1999 31

32 Temporal dynamics or banana diseases

SlTUVEK KH. Y196. Leaw spot or oananas cause
by Mycosphaerella musicola: perithecia and
sporodochia production in different climates.
Trop. Agric. 45:1-12.

VAl lvCKVtmJ--iAN M. IYOJ. naxl vIL lSeaSCS.
Epidemics and Control. Acad. Press, New
York. 349pp.

K.M. L Umadhay and D. Raymundo Volume 35 June-December 1999 33

Table 1. Weekly percent disease severity of Sigatoka on lakatan
bananas (average often plants per replication) of the two
cropping systems in Calinan District, Davao City.

Monocropping System
Percent disease severity
of leaf area infected

Multicropping System
Percent disease severity
of leaf area infected


K.M. L, Umadhay and D. Raymundo

Volume 36 June-December 1999 33

Table 2. Average youngest leaf spotted (YLS
June 29 September 7, 1997 in Calir

0 1 2

Monocropped 4.06 4.34 4.51
Multicropped 4.05 4.34 4.51
*determined by identifying the youngest leaf

of ten Sigatoka-infected lakatan bananas per replica,
i District, Davao City.

Time (weekly)
3 4 5 6 7 8

4.67 4.83 4.31 4.59 4.36 4.29
4.66 4.83 4.31 4.59 4.34 4.30
ving yellow streaks and minute spots.

Table 3. Correlation coetticient of Sigatoka, bun
wilt diseases between percent severity ai
environmental factors.

Variables temperature rain
A. Sigatoka disease
%severity 0.054 0.0'
infection rate 0.031 0.0(

%incidence 0.116 0.2!
infection rate 0.234 0.41

C. Moko
%incidence 0.052 0.1,
infection rate 0.088 0.21

D. Panama
%incidence 0.070 0.11
infection rate 0.007 0.1

Infection rate was computed by using Vander Plank's model
No significant differences were observed in all parameters us

y top, moko, and Fusarium
incidence and

I temperature rainfall

0.001 0.051
0.255 0.063

0.029 0.067
0.247 0.207

0.001 0.015
0.019 0.200

0.063 0.061
0.065 0.079


L uuuuJ r~ ~ -~~---

illpuGla uyoUaInllcs u u banana a

Table 4. Total number of infected plants and ]
'Lakatan' bananas (different ages) in
at Calinan District, Davao City.

Days after date Rainfall Tempe
Initial Rating (1997) (inches) (o(
0 18-May 2.65 26.
22 22-Jun 0.09 25.
36 6-Jul 0.23 25.
50 20-Jul 0.49 26.
64 2-Aug 0.07 26.
78 17-Aug 0.21 26.
92 31-Aug 0.75 26.
106 14-Sep 0.40 26.'
120 27-Sep 0.79 25.

Rainfall Tempe
(inches) (oC
0 18-May 0.97 24.!
22 22-Jun 0.01 24.!
36 6-Jul 0.12 24.(
50 20-Jul 0.26 24.'
64 2-Aug 0.00 25.(
78 17-Aug 0.07 24.1
92 31-Aug 0.00 24.'
106 14-Sep 0.53 25.(
120 27-Sep 0.38 24.(

recentt disease incidence of banana bunchy top (BBT
)th cropping systems from May 18 September 27,

Iture Total number Total number Percent i
of plants of infected plants incid

I 466 25.25 6.2
) 466 44.00 9.2
S466 50.75 11.
S466 55.25 12.
S466 59.75 13.
S466 63.00 13.
S466 66.25 14.
I 466 70.00 15.
S466 76.50 16.

ture Total number Total number Percent c
of plants of infected plants incidi

S190 16.00 8.4
S190 29.25 15.1
190 38.25 19.'
190 42.25 21.!
190 44.25 23.
190 46.50 24.
190 49.00 25.'
190 51.75 27.,
190 56.00 29.'

,vluullul ulu u. \rlr-~

Table 5. Average total infection and percent disease,
(different ages) in both cropping system fror
District, Davao City.

Time Rainfall Temperature Total num
(days) (inches) (OC) of plants

0 2.65 26.31 466
22 0.09 25.90 466
36 0.23 25.68 466
50 0.49 26.22 466
64 0.07 26.55 466
78 0.21 26.10 466
92 0.75 26.00 466
106 0.40 26.00 466
120 0.79 25.55 466

Rainfall Temperature Total num
(inches) (OC) of plants

0 0.97 24.90 190
22 0.01 24.90 190
36 0.12 24.60 190
50 0.26 24.70 190
64 0.00 25.00 190
78 0.07 24.80 190
92 0.00 24.90 190
106 0.53 25.00 190
120 0.38 24.60 190

Icidence of Moko on lakatan bananas
lay 18 September 27, 1997 at Calinan

Total number Percent
of plants disease incidence

10.00 2.15
12.75 2.77
19.25 4.33
24.00 5.31
29.25 6.38
35.25 7.69
37.00 8.09
39.50 8.62
40.75 8.89

Total number Percent
of plants disease incidence

3.25 1.73
4.75 2.37
5.25 2.58
7.75 3.87
10.00 5.03
12.00 5.23
13.50 6.68
15.00 7.49
16.50 8.27

38 Temporal dynamics of banana diseases

E 0.50
g 0.40
) 0.30

-o 0.10

0 20 40 60 80 100
ime (days)


r = 0.0248
0.00, o,
x -0.20 e100
Time (days)

Fig. 1. Disease progress curve of the actual disease proportion
(A) and logit-transformed disease proportion of Sigatoka
disease in monocropping system (B). Apparent infection
rate,r, was computed by using Vander Plank's model
for polycyclic diseases.

K.M. L Umadhay and D. Raymundo

0 20 40 60
time (days)

80 100

Fig. 2. Disease progress curve of actual disease proportion (A)
and logit-transformed disease proportion of Sigatoka
disease in multicropping system (B). Apparent infection
rate, r, was computed by using Vander Plank's model
for polycyclic diseases.




x -0.20
_ -0.40




time (days)

Volume 35 June-December 1999 39

40 Temporal dynamics of banana diseases

"E 0.12
0 0.10
0 0.08
0.00 i i
0 50 100 150
time (days)

50 100 10


x -0.60 r 0.0082




Fig. 3. Disease progress curve (A) and logit-transformed
disease proportion of bunchy top in monocropping
system(B). Apparent infection rate, r, was
computed using Vander Plank's model.

r\ QC_ ______


I. 0.25

0.00 --- i
0 50


1 50
r = 0.0115






Fig. 4. Disease progress
disease proportio
(B). Apparent inf
using Vander Pla

100 150

100 1!


rve (A) and logit-transformed
fBBT in multicropping system
ion rate, r, was computed by
s model.

42 Temporal dynamics of banana diseases


O 0.02
0 50 100 150
time (days)


x 0.03 r= 0.0113
o 0.02
0 50 100 150

Fig. 5. Disease progress curve (A) and logit-transformed
disease proportion of moko disease in monocropping
system (B). Apparent infection rate,r, was
computed by using Vander Plank's mode for
monocyclic diseases.

K.M. L Umadhay and D. Raymundo Volume 35 June-December 1999 43

e o.os
f 0.05

o 0.03
0 i t i I i i-i i 1I , ,
0 50 100 150
time (days)


0.03 r= 0.0124
0.025 a
0 50 100 150
time (days)

Fig. 6. Disease progress curve of the actual disease proportion
(A) and logit-transformed disease proportion of moko
disease in multicropping system (B). Apparent infection
rate, r, was computed by using Vander Plank's model for
monocyclic diseases.

panama mono


0 0.003
0 -:- i : ; i i i -
0 50 100 150
time (days)


r =0.0042 o a 0
x 0.002
o 0.0015
0 50 100 150
time (days)

Fig. 7. Disease progress curve of the actual disease proportion
(A) and logit-transformed disease proportion of Fusarium
wilt in monocropping system (B). Apparent infection
rate, r, was computed by using Vander Plank's model
for monocyclic diseases.


Oral Presentation

Yield loss model of Fusarium wilt of cotton Fungi as a growth enhancer of in-vitro
caused by Fusarium oxysporum f. sp. cultured orchids. MB Brown. BIOTECH,
vasinfectum Synder and Hansen. LC UPLB, College, Laguna.
Cano, OS Opina, and AB Molina Jr. Several Ascomycetous and Basidiomy-
Department of Plant Pathology, UPLB, cetous fungi were effective as growth
College, Laguna. enhancers of different varieties of in vitro-
This study was conducted to develop yield cultured orchids. Inoculants were in the form
loss and seedcotton yield models for Fusarium of finely-chopped fruiting bodies, mycelia, and
wilt of cotton caused by Fusarium oxysporum sclerotial bodies. The effectiveness of parti-
f. sp. vasinfectum. cular fungi to enhance plant growth depends
on the varieties of orchids and form of fungi.
Pre-determined levels of incidence of
Fusarium wilt at various crop stages exerted Host index of plant diseases in the
significant effect on the seedcotton yield of Philippines-Third Edition. NG Tangonan.
cotton varieties. For a variety resistant or Department of Plant Pathology, USM,
tolerant to Fusarium wilt like CRDI-I, as the Kabacan, North Cotabato.
infection increases yield loss increases. Such The third edition of the book, Host
loss can be explained by the high disease Index of Plant Diseases in the Philippines,
incidence at the seedling, boiling and flossing covers additional entries ofhost plants and new
stages which can be best described by the records of their diseases (1992-1998). In
following models: Y = 9.08 + 0.868 X,, Y = addition to the existing list, there are now a
11.40 + 0.737 X4 and Y = -2.65 + 1.052 X, total of3,065 diseases affecting 457 plant hosts,
where Y is percent seedcotton yield loss and representing 115 families, 391 genera and 556
X,, X4 and X, are disease incidence at seedling, species. The kinds of pathogens included are
boiling and flossing stage, respectively. For a alga (67), bacteria (160), fungi (1,903),
non-tolerant variety such as UPL-C2, the nematodes (662), parasitic flowering plants
relationship was best described by Y =.7.19 + (21), and viruses/viroid (292). PhilRice and
0.871 X, and Y = 10.00 + 1.072 X, where X, USM published this third editionin 1999.
and X3 are the incidences at seedling and
flowering stage, respectively. Identification of Phytophthora sp. causing
leaf blight of Cordyline terminalis Kunth,
The single-pointandmultiple-pointmodels, varietal screening and chemical control
which were derived using least square under field conditions. JI Orajay.
regression techniques, proved useful in the Department of Plant Pathology, UPLB,
satisfactory estimation of seedcotton yield from College, Laguna.
disease incidence. Thus, these can now be Three isolates of the organism causing
used to estimate seedcotton yield and yield leaf blight of Cordyline terminalis (ti plants)
losses caused by Fusarium wilt. were obtained from diseased samples collected,

46 Abstracts

from three sites, namely Lucban, Quezon, If done every 3-4 days, disease control was
Institute of Plant Breeding (IPB), and maintained at higher than 90% throughout the
Department of Horticulture, UPLB. seven weeks. In the case of Ridomil, all the
Observations/measurements on the growth intervals tested contained the disease very
response to particular temperatures, mating effectively. The number of infected leaves
reactions and morphology of asexual and increased just slightly, and disease control was
sexual structures revealed that all of them were maintained at higher than 90% except during
Phytophthora infestans var. parasitica the first two readings for 7-day and 14-day
Water (syn. P parasitica Dast.). intervals.

Eleven ti plant cultivars were evaluated Occurrence and transmission of banana
for their susceptibility to the Lucban isolate. streak badnavirus in the Philippines. LV
Tip cuttings of these cultivars were planted Magnaye, LE Herradura, A Lobres and
in artificially infested media, and observed for M Alforque. Bureau of Plant Industry-Davao
five weeks. Seven of them, namely "Willies National Crop Research and Development
of Gold", 'Wilson", "White Rain", "White Center (DNCRDC), Bago-Oshiro, Davao City.
Ade", "Pink Top". "Salmon" and "Gluaca" Banana streak badnavirus, a serious virus
were very susceptible. "Sagilala" and disease affecting bananas in Africa, was first
Hawaiian Compacta" (with slender leaves) observed in the Philippines on cultivar Mysore
showed mild infection while "Brown" and (Inangel) in the Southeast Asia banana
"Green Cylonti" were not infected throughout germplasm collection at DNCRDC in 1994.
the observation period. Consequently, three other varieties from the
Papua New Guinea (PNG) accession were
Seven commercial fungicides were recorded to have the disease. Survey results
evaluated in a field trial during the wet s nationwide conducted from 1994-1997 showed
eason for their efficacy against leaf blight, that the disease is present in Capiz, Isabela,
Tip cuttings of "Lemon Lime" were planted, Zamboanga, Samal and Sto. Tomas, Davao del
sprayed immediately with fungicides at Norte infecting local cultivars.
their recommended rate and observed for
seven weeks. All the fungicide treatments Transmission tests at BPI-DNCRDC
significantly reduced the number of infected using sugarcane and citrus mealybug produced
leaves. They also slowed down disease positive infection on Lakatan and Butuhanplant-
development in varying degrees. The systemic lets with acquisition feeding time and infection
fungicides Acrobat, Aliette, and Ridomil feeding time of 24 hr. On inoculated Lakatan,
showed exceptional disease control. Daconil first symptoms became apparent after 17-25
exhibited activity comparable to the systemics days. Characteristic symptoms patterns ob-
during the early part of the experiment, served were bright yellow streaks on the lamina
Towards the end, it decreased its activity, and which eventually form into a mosaic pattern.
along with Dithane and Vitigran Blue, provided The chlorotic streaks/stripes progressed to
moderate control. Captan showed relative poor necrosis during the advanced stage.
activity throughout the experiment.
New species and records of saprophytic
The effective spray interval ofAliette and fungi on culm of Bambusa and
Ridomil MZ was also determined. For Aliette, Dendrocalamus. TU Dalisay, KD Hyde
spraying must be done at least once a week to and TH Bulimia. Department of Plant
effectively maintain the disease at low level. Pathology, UPLB, College, Laguna; The

ume 35 June-December 1999 47

versity of Hong Kong, Pokfulam Road, swellings that are diagnostic symptoms of root-
ig Kong. knot disease. Studies of its biology in Yellow
Microscopic examination of dead culms Granex revealed that second stage juvenile
species of Bambusa and Dendrocalamus caused root infection through the root tips 2
Fungi yielded 83 fungaltaxa, comprising 48 days after inoculation, with apparent root galling
ihomycetes, 24 ascomycetes, 10 in 7 days. Its life cycle from infective larvae
lomycetes, and one basidiomycete. to egg takes only 19 days. The pest occurred
enteen taxa were new to science. The in all rice fields in San Jose City and in 74% of
new species of Ascomycetes are onion fields in 82 barangays in four Luzon
cophila bambusae Umali & KD Hyde, provinces. Host range studies in the
philippinensis Umali & K.D. Hyde, greenhouse indicated that several weed species
rulatascus angustispora, A. bambusae, serve as alternate hosts and some vegetables
gnardia makilinensis, G. philippinensis, are potential rotation crops in rice-onion
ltia dendrocalami, Anthostomella cropping patterns.
vifissura, A. longipileata, and A.
lippinensis while the three new Management of Fusarium wilt of cotton
lomycetes are Asteromidium bambusae, (Gossypium hirsutum L.) caused by
indallia bambusae, Pseudothyrium Fusarium oxysporum f. sp. vasinfectum
\gkongensis. Four new species of Synder and Hansen. LC Cano, OS Opina
ihomycetes were Diplococcium and AB Molina, Jr., Department of Plant
drocalami Goh, KD Hyde & Umali, Pathology, UPLB, College, Laguna.
naniella bambusae Umali & K.D. Hyde. This study evaluated the effects of
'iconia bambusae, and Phaeoisaria different crop and weed species and cropping
'ippinensis. Fungi which have not been systems on the population build-up of
frded previously on Dendrocalamus were Fusarium oxysporum f. sp. vasinfectum
odictys, Cladosporium, Corynespora, (Fov) in the soil and appraises disease
rvularia, Podosporium, Gliomastrix management systems for Fusarium wilt of
phomycetes); Annulatascus, Bertia, cotton. The population of Fov was lowest in
fothia, and Microthyrium ascomycetess); potted soil planted to corn and highest in plots
zosphaera and Hapalosphaeria grown with weeds. Cotton and mungbean
elomycetes); and Hyalopcynis favored the increase or survival of Fov in the
sidiomycete). On the other hand, more than soil. The number of Fov was lower in the soil
hyphomycetes, four ascomycetes, and planted to CRDI 1 compared with UPL -
*e than four coelomycetes were newly C2. The population ofFov in naturally infested
>rded on Bambusa. soil was suppressed when corn was used as
previous crop. Plots previously grown to
foidogyne graminicola: a nematode pest peanut, mungbean and weeds such as
n rice to onion. E Gergon, V Judal, C Cenchrus echinatus, Eleusine indica,
vina, R Gapasin and J Halbrendt. Euphorbia heterophylla, Ipomoea triloba,
lippine Rice Research Institute, Mufioz, Amaranthus spinosus and Cyperus rotundus
eva Ecija, ViSCA, Baybay, Leyte; favored the survival of the pathogen. The
nsylvania State University, U.S.A. number of Fov was significantly reduced in
Meloidogyne graminicola, a nematode the soil planted consecutively with corn. The
t of rainfed and upland rice ecosystems, results suggest that cotton variety did not exert
sing root-knot in onion, is reported for the a direct effect on the population of Fov and

discernible relationship between the population fungal pathogens tested for pathogen
of Fov and Trichoderma spp. CRDI 1 out showed high aggressiveness on bulbs of
yielded UPL C2 when they are planted in onion varieties except for P terrestris
Fusarium- infested area. The yield advantage Fusarium sp. 1. Pathogenicity tests u
of CRDI 1 can be partially attributed toits greenhouse conditions showed low incid
ability to resist ortolerate Fusariumwilt. Higher ofpre-emergence damping-off on onions i
populations of Fov were associated with inoculated with P terrestris, Fusarium
standard inorganic fertilizer practices and and a combination of P. terrestris
relatively lower populations of Fov were Fusarium sp. 2. High incidence was obse
associated with bio-organic fertilizer fortified on onions inoculated with combinations o
with Trichoderma inocula. Plants treated with three Fusarium species, followed
standard inorganic fertilizer practices gave the Fusanum sp. 2 and the combination <
lowest incidence of Fusarium wilt, plant terrestris and Fusarium sp. 3. The incid
mortality and highest seed cotton yield, of bacterial wilt in San Jose City was hit
eggplant growing areas.
Management of soil borne diseases in rice-
irahrale fcwumc I>T Alh-rfn I T- if-. ,,l,,...,

Valdez, SE Santiago, LE Padua and.
Miller. Philippine Rice Research Instit
Maligaya 3119, Nueva Ecija; BIOTE4
UPLB, College, Laguna; Ohio State Univer
Ohio, U.S.A.
During a four-year continuous monito
of soil-borne diseases in rice-vegetable syst
in San Jose, Nueva Ecija, five diseases v
found seriously affecting rice and veget~
crops. These were seedling damping-of
onions caused by Fusarium sp.
Rhizoctonia solani, pink root of onions cat
by Phoma terrestris, bacterial wilt of eggp
caused by Ralstonia solanacearum
sheath blight of rice, caused Rhizocto
solani. In Bongabon, Nueva Ecija, soil-be
diseases of onions were pink root and bulb
of onions. Twenty out of forty seven on
growing sampling sites surveyed in Nueva E
were positive for pink root, while four ou
ten sites in Pangasinan and two out of e
sites in Nueva Ecija had pink root. Phc
terrestris from infected onion roots has t
isolated using corn meal agar and has b
confirmed using sterilized wheat straw.
solani, S. rolfsii and three species of Fusar
were also isolated from pink root-ifected ro

A showed antagonistic effects against all ol
e, seven soil-borne pathogens. On the potel
i, ofBacillus isolates as biological control age
y, Bacillus sp. 118 showed inhibitory eff
against all of the seven soil-borne pathog
ig In a rice hull burning experiment in San J
is soil-borne pathogens were not observed in I
re burned and unburned plots. Moreo'
le populations of colony forming units (CFU
af soil-borne fungi were lower in burned tha
id unburned plots. Compost application did
:d have any significant effect on the incidc
at ofpink root in both burned and unburned p]
id Preliminary results from the crop rotal
a experiment in Bongabon showed that the
ie ofpepper, rice, onion, peanuts as rotation ci
at reduced the incidence of pink root in onic
ja Survey and distribution of plant paras
)f nematodes associated with sugarcam
it some milling districts in the country.
'a Zorilla, National Crop Protection Cen
n UPLB, College, Laguna.
n A total of 245 soil samples from six su
?. mill districts and 41 farms from different s
m were collected, processed and analyzed at
s. Nematolov Lahoratnrv NCPC ITTPT.R

Volume 35 June-December 1999 49

The most predominant nematode species
found in all soil samples were Pratylenchus,
lesion nematode; Tylenchorhynchus, stunt
nematode; Helicotylenchus, spiral nematode;
Rotylenchulus reniformis, reniform
nematode; Meloidogyne, root-knot nematode
and Rotylenchus, spiral nematode. The other
nematodes found and their percent distribution
were Hemicycliophora, sheath nematode
(92%); Hoplolaimus, lance nematode (85%);
Criconemoides and Hemicriconemoides, ring
nematodes (56 and 51%, respectively);
Pratylenchus, pin nematode (40%) and
Longidorus, long nematode (25%).

Generally, during the dry months
(January-May, 1998), the nematodes found
were fewer in number compared with those
found during the rainy months of June to
December of the same year.

Distribution and mapping of Phytophthora
bud rot on coconut in the Philippines. RG
Abad, ES Poliquit, NSJ Bachiller and EC
Manohar. Philippine Coconut Authority, Bago
Oshiro, Davao City.
The distribution of Phytophthora bud rot
of coconut in the Philippines was determined
in 1995 through an actual survey on areas with
reported incidence of the disease. It was found
that the pathogen infected several coconut
varieties all over the country. Disease
incidence reached 4.1% or 11,130 palms killed
by the fungus in Davao del Sur, Davao del
Norte, and Davao City, having the highest
occurrence. The Malayan Yellow Dwarf x
West African Tall (MYD x WAT) hybrid
introduced in the Philippines was the most
susceptible with 2.7% incidence. Majority of
the affected palms were 3-15 years old.

To determine the spatial and temporal
distribution of the disease, a quarterly
monitoring for disease incidence was done in
three coconut areas in Mindanao. Results
showed that the disease occurred in multiple

foci and progressed from one focus to adjacent
palms. Infection rate ranged from 0.025 to
0.099 per unit per year in the 3 observed sites
with MYD x WAT hybrid having the highest
rate followed by MYD x Hijo Green Tall (HGT)
and Laguna Tall having the lowest incidence.
Across genotypes, infection rate was 0.143
per unit per year.

The apparent susceptibility of the coconut
cultivars with MYD as one of the parents is
supported by a 6-year data gathered in the 4
multi-location trial sites of PCA involving 13
entries of local tall varieties and hybrids.

Rainfall influenced disease incidence in
the MYD x HGT hybrid but not with the
MYD x WAT hybrid. The susceptibility of the
MYD x WAT can then be greatly attributed to
its genetic make-up.

Assemblage and distribution of endophy-
tic fungi in leaves of Bambusa tuldoides.
TU Dalisay, KD Hyde and TH Quimio.
Department of Plant Pathology, UPLB,
College, Laguna; The University of Hong
Kong, Pokfulam Road, Hong Kong.
The endophytic mycota in leaves of
Bambusa tuldoides were diverse. Thirty
seven fungal taxa were isolated, comprising
16 hyphomycetes (Alternaria alternate,
Alysidiopsis pipsissewae, Arthrinium
arundinis, A. phaeospermum, Botryconis
saccardoi, Cladosporium cladospoioides,
Dacytlaria triseptata, Fusarium sp. cf F
avenaceum var. avenaceum, Humicola
grisea var. grisea, Nigrospora sphaerica,
Periconia bambusae, Podosporium
elongatum, Trichothecium roseum,
Zygposporium gibbum), 4 coelomycetes
(Pestalotiopsis sp., Phoma euprena,
Phomopsis sp., Selenophoma
sacrophulariae, Stenocarpella minima), 3
ascomycetes (Chaetomium globosum,
Glomerella cingulata, and Sporormiella
minima), and 14 morphospecies. The mycelia

50 ADstracts

sterilia included four Xylariaceous taxa.
More isolates were recovered from the leaves
collected from the upper culm level than those
from the lower culm level. The isolates were
more abundant in the secondary vein of older
leaves. With the exception of mycelia sterilia
7 and 8, other unidentified taxa occurred at
low frequencies. Species of Fusarium and
Tnchothecium were dominant.

Diversity of saprophytic bambusicolous
fungi found in the Philippines and Hong
Kong. TU Dalisay, KD Hyde and TH
Quimio. Department of Plant Pathology,
UPLB, College, Laguna; The University of
Hong Kong, Pokfulam Road, Hong Kong.
The diversity of fungi on culms of
Bambusa spp. was high, with 1,590 collections
distributed among 51 species ofhyphomycetes,
22 ascomycetes, and 0 coelomycetes.
Dendrocalamus spp. yielded 507 collections
distributed among 20 species ofhyphomycetes,
4 ascomycetes, 3 coelomycetes, and
1 basidiomycete. The dominant hypho-
mycetes of Bambusa and Dendrocalamus
were Acrodistys, Padosposium, and
Cladosporium. The ascomycete families, the
Xylariaceae and Valsaceae were frequently
encountered. More collections were made in
the Philippines (1320), with a higher species
diversity (55 taxa) compared to Hong Kong
(777 collections and 50 taxa).

Poster Presentation

Efficiency of locally modified biorad
biolistics. SK Manohar and RT Imbao.
National Institute of Molecular Biology and
Biotechnology, UP Diliman, Diliman, Quezon
The coated particle DNA delivery system
using biolistic apparatus usually result in varying
rates of success, often a few transformations
only. This has necessitated different kinds of
modifications often involving additional
components and redesigning of circuitry. We

have come across a simple design reported m
the literature and explored the feasibility of
modifying on biolistics locally.

Adapting the method of R. Torisky et al.,
we are able to fabricate locally at low cost the
simple focusing device and use is routinely for
transformation protocols. The fabrication
design and efficiency of the focusing device is
discussed, to show the feasibility of obtaining
at least a ten-fold "positives" in bombardment

Pathogenicity of four Phythophthora
isolates to coconut and its intercrops
under controlled conditions. ES Poliquit.
Philippine Coconut Authority, Bago Oshiro,
Davao City.
Phytophthora isolates obtained from
coconut (Cocos nucifera L.), durian (Durio
zibethinus L.), and cacao (Theobroma cacao
L.) were cross-inoculated among these crops
to determine reciprocal pathogenicity and host
range ofthe pathogens. In addition, the isolates
were also tested on solo papaya (Carica
papaya L.) seedling and fruits.

All isolates were able to infect their
respective hosts as well as the other test hosts
namely: coconut seedlings and nuts, durian
seedlings, cacao pods, and papaya fruits and
seedlings. Statistically, there was no significant
difference in the virulence of the isolates on
the test seedlings of various hosts. On fruit
hosts, however, cacao pod rot isolate is the
only one that differed having the least degree
of infection among the isolates.

Among the test hosts, the Malayan Red
Dwarf nut was the most susceptible with 100%
infection by all isolates.

Root-knot disease caused by Meloidogyne
graminicola and its management in rice-
onion cropping systems. EB Gergon, V
Judal, C Ravina, R Gapasin and J

Volume 35 June-December 1999 51

Halbrendt. Philippine Rice Research
Institute, Mufioz, Nueva Ecija; ViSCA, Baybay,
Leyte; and Pennsylvania State University,
Meloidogyne graminicola, a nematode
pest of rainfed and upland rice ecosystems,
causes root-knot disease in onion. Extensive
survey showed that the pest is an active
parasite in many onion fields.

Several management strategies were
evaluated against M. graminicola. Crop
rotation experiments proved that mungbean,
peanut, cucumber and pepper suppressed soil
populations ofM. graminicola. Replicated
on-farm trials showed that heat treatment by
burning rice hull reduced nematode populations
and increased onion yields. Mycorrhizae when
added as soil supplement significantly improved
onion seedlings height and emergence in
nematode-infested soil.

Screening of isolates for antibiosis against
cassava bacterial blight. MK Palomar, VG
Palermo and M Rosas. Department of Plant
Protection, ViSCA, Baybay, Leyte.
Seven unidentified bacterial antagonists
(B115, B12, B143, B127, B134, B135, and
B147) and Pseudomonas fluorescens at a
concentration of 104 cells/ml as well as
metabolites of Trichoderma harzianum,
exerted antagonistic effects towards
Xanthomonas campestris pv. manihotis.
Variations on the degree of antagonism
exhibited by the different isolates were
observed with P. fluorescens having the
highest at 11.35 mm, followed by B12, B143,
B134, and Trichoderma harzianum
metabolites with 10.25 mm, 5.08 mm, 2.41 mm
and 2.36 mm average inhibition zones,

The antagonistic or protective effect of
such antagonists was further tested in vivo
under screenhouse conditions. Dip treatments
with suspensions ofBll, B127, B134 and B143

registered 100% disease reduction on the
cutting of Golden Yellow cassava variety.
P fluorescens also performed better than the
other antagonists in preventing disease
infection by exhibiting maximum protection
compared to other treatments.

Antagonistic effects of Bacillus sp. (LEP-
118) against soil-borne pathogens in rice-
vegetable systems. RT Alberto, MV
Duca, SE Santiago, LE Padua, A Lapus,
RM Gapasin and SA Miller. Central Luzon
State Univ./Philippine Rice Research Institute,
Mufioz, Nueva Ecija; BIOTECH, UPLB,
College, Laguna; ViSCA, Baybay, Leyte; Ohio
State Univ., USA.
Out of 20 Bacillus strains tested, only
Bacillus sp. (LEP 118) showed antagonistic
effects on 7 soil-borne pathogens of onions.
Seventy two-hour old cultures of LEP 118
showed very apparent inhibition of Phoma
terrestris, Fusarium sp. 1 and Fusarium sp.
3 with inhibition zones of 9.17, 6 17 and 4.33
mm, respectively. Inhibition against Fusarium
sp. 2 was very apparent with 5.17 mm.
Antagonism was less apparent in Sclerotium
rolfsii and Rhizoctonia solani (Rw and Rr)
with only 1.5,2.67 and 2.5 mminhibition zones,
respectively. No inhibition zone was observed
in Ralstonia solanacearum. At 72 hours after
inoculation, maximum enzyme production took
place resulting in high antagonistic activity of
LEP 118.

Soil-borne diseases in rice-vegetable
systems. RT Alberto, MV Duca, SE
Santiago, and SA Miller, Central Luzon State
Univ./Philippine Rice Research Institute,
Mufioz, Nueva Ecija; Ohio State Univ., USA.
During four years of continuous
monitoring of soil-borne pathogens in rice-
vegetable systems in San Jose City, five were
found seriously affecting rice and vegetable
crops, pink root of onion (Phoma terrestris),
basal plate rot of onion (Fusarium oxysporum
f sp. cepae), white rot of onion (Sclerotium

Volume 35 June-December 1999



: of eggplant suggesting their efficacy as antagonists against
d sheath blight the rice root-knot nematode. Planting Tagetes
In Bongabon, sp. or Crotolaria sp. in nematode-infested soil
wing areas in is therefore feasible in managing the rice root-
ian, soil-borne knot nematode.
'ere pink root
rot (Fusarium Genetic engineering approach to develop

(Sclerotium cepivorum). Twenty out of forty Aldemita. Philippine Rice Research Institute,
seven sampling sites surveyed in Nueva Ecija Mufioz, Nueva Ecija.
were positive for pink root, while four out of In the Philippines, damage caused by
ten sites in Pangasinan and two out of eight diseases especially tungro, blast, bacterial
sites in Pangasinan and two out of eight sites blight and sheath blight is quite staggering. At
in Nueva Viscaya likewise had pink root. present, many investigations are geared
towards the development of fungal and viral
Antagonistic plants for the management disease resistance in rice. Wild prices have
of the rice root-knot nematode, been tapped as the genetic sources for disease
Meloidogyne graminicola, in rice-onion resistance and were used for breeding
system. RM Gapasin, EB Gergon, SA purposes. However, the conventional method
Miller, ML Judal, C Pile and CV Ranchez. of gene introgression to rice will take many
Department of Plant Protection, ViSCA, years of backcrossing before an improved,
Baybay, Leyte; Philippine Rice Research resistant variety can be obtained. A more
Institute, Muiioz, Nueva Ecija, Ohio State efficient method of gene induction is through
Univ., Ohio, U.S.A. genetic engineering.

Volume 35 June-December 1999 63

results on the use of new strategies in A. transplanting). Nitrogen fertilizer (45-0-0) was
umefaciens-mediated transformation of rice applied in two splits, 2/3 basal and 1/3 at early
ellss; the co-transformation system, and the panicle initiation. Phosphorous (0-18-0) and
presence of two binary vectors in one strain potassium (0-0-60) fertilizers at 40 kg/ha were
vill be presented. applied basally. Twenty-three day-old
seedlings of PSB Rcl4 were transplanted in
Effect of rice straw management practices the field at a distance of20 x 20 cm. Replanting
in pest incidence. FA dela Pefla, GB of missing hills was done 15-20 days after
Wmar, AT Angeles, GS Rillon, H Rapusas, transplanting. Other standard cultural
IP Rillon, RT Cruz, MD Malabayabas, JE management practices for land preparation
lill, and PC Sta. Cruz. Philippine Rice and water management were followed.
Research Institute, Mufioz, Nueva Ecija and The general assessment of pests was
international Rice Research Institute, Los done in four growth stages of the rice plant
3afios, Laguna. (mid-tillering, panicle initiation, soft dough and
General assessment of pests and maturity).
diseases was done in 60 plots of the Crop
Residue Management (CRM) Project of the Significant differences in leaf damage due
rrigated Rice Research Consortium (IRRC) to defoliators (whorl maggots and leaf folders)
luring the wet season of 1998. The CRM and other leaf feeders such as cutworms,
researchh aimed to document the effect of grasshoppers and semi-loopers were observed
various crop residue management practices during the early crop stages. At the later
n pest incidence and to generate information growth stages of the crop, stemborers and rice
hat will serve as basis in formulating bugs were the insect pests that caused
recommendations in different production damage. However, differences among
systems. treatments were not significant.

Rice straw management treatments One of the diseases observed, bacterial
vere as follows: S, = control (removal of rice leaf streak, was the most common at crop
traw with remaining stubble only); S, = late growth stages, at mid-tillering but with no

early incorporation of rice straw from previous
harvest (1 month before transplanting); S4 =
turningg of rice straw from previous crop and
corporation of ash (1 month before

differences among treatment means were
observed. Narrow brown spot and grain
discoloration were prevalent at early dough
and maturity stages, respectively.

i.. !Sfi^ : "* .'** .;* * p!"' is : -* *:*


1. Membership in the Philippine Phytopathological Society is prerequisite to publishing in Journal of
Tropical Plant Pathology or at least one author must be a member of this society. The Editorial Board,
however, may relax this rule for contributions of exceptional merit. It may also invite distinguished
scientists to contribute articles of interest to the Society.

2. Manuscripts must be reports of original research, excerpt of meritorious reviews, and should have not
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3. The manuscript should be typed on one side of 8 1/2 x 11 inch paper, double spaced throughout.

4. Papers other than Notes may be organized conveniently under: Title, Author(s), Author's position
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5. Acknowledgments should be placed at the end of the articles i.e. after Literature Cited.

6. In the text, citations should be by name-and-year system, e.g. Molina (1996), Ou and Nuque (1980).
With three or more authors, use and others (e.g. Ou, Nuque and Silva (1981) should appear Ou and
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