• TABLE OF CONTENTS
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 Front Cover
 Table of Contents
 Front Matter
 Effect of nitrogen on bulb rot...
 Diversity of selected isolates...
 Identification of fungi from decaying...
 Analysis of spatio-temporal dynamics...
 Phytopathological note: Canna indica:...
 Abstracts of papers presented during...
 Back Cover














Group Title: Journal of Tropical Plant Pathology
Title: Journal of tropical plant pathology
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Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00090520/00049
 Material Information
Title: Journal of tropical plant pathology
Series Title: Journal of tropical plant pathology.
Alternate Title: Journal of Philippine phytopathology
Philippine phytopathology
Physical Description: v. : ill. (some col.) ; 26 cm.
Language: English
Creator: Philippine Phytopathological Society
Publisher: Philippine Phytopathological Society
Place of Publication: Philippines
College Laguna
Publication Date: January-December 2007
Frequency: semiannual
regular
 Subjects
Subject: Plant diseases -- Periodicals -- Philippines   ( lcsh )
Plants, Protection of -- Periodicals -- Philippines   ( lcsh )
Genre: periodical   ( marcgt )
 Notes
Dates or Sequential Designation: v. 1, no. 1 (January 1965)-
General Note: Title from cover.
General Note: "Official publication of the Tropical Plant Pathology."
 Record Information
Bibliographic ID: UF00090520
Volume ID: VID00049
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
    Table of Contents
        Table of Contents
    Front Matter
        Front Matter
    Effect of nitrogen on bulb rot incidence in onion during storage
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
    Diversity of selected isolates of peronosclerospora spp. causing sugarcane downy mildew
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
    Identification of fungi from decaying plant material and screening for their antibacterial activity in Samal Island
        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
    Analysis of spatio-temporal dynamics of abaca mosiac and possible disease risk scenarios in Eastern Visayas
        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
        Page 54
        Page 55
        Page 56
        Page 57
    Phytopathological note: Canna indica: Host of banana bunchy top virus
        Page 58
        Page 59
        Page 60
        Page 61
        Page 62
    Abstracts of papers presented during the 39th pest management council of the Philippines conference held at Asturias Hotel, Puerto Princesa City, Palawan on May 05-09, 2007
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
        Page 71
        Page 72
        Page 73
        Page 74
        Page 75
        Page 76
        Page 77
        Page 78
        Page 79
        Page 80
    Back Cover
        Page 81
        Page 82
Full Text

ISSN 0115-0804


JOURNAL OF TROP


ICAL


January-December 2007








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Editor-in-Chief Christian Joseph R Cumagun
Associate Editors Teresita U. Dalisa)
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Circulation Manager Teodora O. Dizon


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JOURNAL OF

VOLUME 43 NUMBER 1








Effect of nitrogen on bulb rot incidence ir
R.T. Alberto, D.T. Eligio, S.E. Santiagc


Diversity of selected isolates of Peronos(
mildew
F.M. Dela Cueva, A.A. Gumarang, C.B.


Identification of fungi from decaying plan
antibacterial activity in Samal Island
M. M. Parungao, R.A.M. Ponteres and S

Analysis of spatio-temporal dynamics of
scenarios in Eastern Visayas
C. S. dela Cruz and A.R. Raymundo


Phytopathological Note: Canna indica: H
T. 0. Dizon and E. G. Dinglasan


Abstracts of papers presented during the
Philippines Conference held at Asturias I
May 05-09, 2007


3PICAL PLANT PATHOLOGY

JANUARY-DECEMBER 20C


CONTENTS





i during storage
S.A. Miller 1-(


oora spp. causing sugarcane downy

al and E. G. Dinglasan 10


riall and screening for their

Tan 25

Mosaic and possible disease risk

39


banana bunchy top virus
58


'est Management Council of the
Puerto Princesa City, Palawan on
63










EFFECT OF NITROGEN ON BULB ROT INCIDENCE IN ONION DURING
STORAGE

R.T. ALBERTO', D.T.ELIGIO', S.E. ;ATIAGO2 and S.A. MILLER3


College of Agriculture, Centi

2Science Research Speciali.
Institute, Maligaya, Munoz,

3Professor, Department of P
Environmental Science, OAI


evaluarea usi
of 'Yellow Gr


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ral Luzon Sta

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Nueva Ecija

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vith no nitrogen (N) application (
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IUUI LI C L I I I I LD VVILI I LII I 1. II LUJLCI IIUIIIIU I VI vi UILJ, I JI J- I I1JIG
replications and laid out in 2 x 4 x 100. Bulb rot incidence was
ffrotri-l in DCf'Rn Cnrr nitrnnon nhoarnadrl and rarnrdrdrl woAklv fnr







irce of inoculum and further 100kgN/h and 50kgN/ha. Overs
itamination of the samples. observations still showed the there
iciple of Koch's postulates was levels of N application as well a
awed to test for the the control resulted in the sam


IqVIUV ,LljU ktU LI IV I It f.

RESULTS AND DISCUSSION

Bulbs of 'Yellow Granex' were
firmer and harder than those of
Red Creole' but higher total
soluble solids were noted in 'Red
Creole'. Both varieties, however,
showed comparable titritable
acidity- an indication that N levels
had no influence on the said
parameters (Table 1). 'Yellow
Granex' had higher yield than Red
Creole, suggesting that the former
Nas not responsive to N treatment
and higher yield was obtained from
the treatment with no N added to
the soil. Application of 50 to 100 kg
N/ha in 'Red Creole' also
increased yield over the control but
increasing N level to 200 kg/ha
resulted in a marked decrease in
yield.
At room temperature (270C)
storage, the disease progress of
bulb rot was faster in 'Yellow
Granex' than in 'Red Creole' as
shown by the 100% rotting of bulbs
in just four weeks of storage at all
levels of N (Figure 1). It also
showed that 0 kg/ha, 50 kg/ha,
100kg/ha of N application have
similar bulb rot incidence as
200kgN/ha. 'Red Creole', on the
other hand, lasted up to the 11th
week of storage and all became
infected only on the 12th week.
On the eleventh week, the
highest bulb rot incidence was
observed in 200kgN/ha followed by


ncidence in all of the treatments
[Figure 2). This could be attributed
:o the phenolic compounds: catechol
and protocatechuic acid produced by
-ed onions. Both compounds are
Nater-soluble and when moisture is
Present, these chemicals diffuse into
:he water and prevent germination of
ungal conidia of the pathogens. In
:he presence of these compounds,
:he conidia burst and thus no
infection occurs (McDonald, 2006).
Nhite onions do not produce these
compounds, and thus, susceptible to
infection.
Cold temperature storage
effectively retarded the incidence of
bulb rot in both varieties. Though
Yellow Granex' still showed
vulnerability to the disorder even in
:he cold storage (especially during
:he second to third week), bulb rot
ncidence is at a much lower range
:0.11% to 0.36%) when compared to
room temperature storage (Figure 3).
It is also at this stage where bulbs
from the treatment applied with 200
susceptibility to the disease.
'Red Creole' was more
resistant to rot causing pathogens
inside the cold room. Incidence of
bulb rot was only noticed in
200kgN/ha during the second to third
week of storage (Figure 4) and no
onger observed, thereafter. The
practice of the farmers of irrigating
the field a day before harvest to pull
the onions with ease and poor post
harvest handling which pre-disposed







father bulbs to rot pathogen were
most likely the reason that triggers
infection during the early part of
storage in the cold room. But it is the
very low temperature in the cold
room retarding the pathogens'
activity and resulting to a
decreasing trend in bulb rot
incidence in the succeeding weeks
of storage (McGregor, 1986).
Aspergillus flavus was the
most predominant bulb-rot causing
pathogen in 'Red Creole' under room
temperature (27'C) storage. It was
detected at high population in all the
treatments (75 85 %) especially in
the control bulbs and on bulbs
applied with 50 to 100 kg N/ha
(Figure 5). Other pathogens detected
though at lower levels were A. niger,
Burkholderia cepacia and Fusarium
spp. They all occurred in bulbs
applied with 200kgN/ha. The same
pathogens were also observed in
'Yellow Granex' in all levels of N
application and in a much higher
population level than 'Red Creole'.
The most predominant of which was
A. niger (Figure 6). Its population
was highest in bulbs applied with
50kg N/ha followed by control and
bulbs applied with 100kg N/ha.
Among the treatments, the three
other rot pathogens were higher in
the bulbs applied with 200kg/N/ha.
At cold storage, only 'Yellow
Granex' that showed sensitivity to
the disease. Though its occurrence
is relatively low, it was observed in
all levels of N application. However,
only two bulb rot pathogens was
found to be associated with the
rotting of the bulbs, namely:
Fusarium spp. and B. cepacia. No
rot pathogens were observed in Red
Creole (Figure 7).


'Yellow uranex is nut
responsive in terms of yield to
nitrogen application but application
of 50 kg N/ha in 'Red Creole'
obtained the highest yield. Hence,
results of this study can help farmers
lessen the amount of N application to
reduce production costs and higher
income. Too much application of N
makes the onion bulbs more
succulent which enable the pathogen
to penetrate the tissues with ease
most especially in Yellow Granex.
(Lantin-Rosario et.al. 1997). It was
noted that bulb rot can effectively be
controlled at cold storage conditions
in both varieties irrespective of N
levels applied.
Irrespective of levels of N
applied, storage life of 'Yellow
Granex' under room temperature
was only four weeks hence it is not
suited for long time storage. At cold
storage, incidence of bulb rot was
highest on the 2nd to 3rd week of
storage at 200kgN/ha. Storage life of
'Red Creole' at room temperature
was 11 weeks. At cold storage,
highest incidence of bulb rot was
also recorded in bulbs applied with
200kgN/ha during the 2" to 3rd week
of storage. Overall levels qof bulb rot
incidence in all the treatments,
however, were still very low as
compared to room temperature
storage.
At room temperature and cold
storage and regardless of levels of N
applied, 'Red Creole' was found to
be more resistant than 'Yellow
Granex' to bulb rot due to delayed
infection by post harvest pathogens.
On the other hand, 'Yellow Granex'
is a tolerant variety as it gave
considerable yields despite being







more susceptible than the 'Re<
Creole'.
At room temperature storage
A. flavus was the most predominan
pathogen in 'Red Creole' while A
niger in 'Yellow Granex.'

LITERATURE CITED

HOFFMAN, M.P., C.H. PETZOLD1
and A.C. FRODSHAM. 1996
Integrated Pest Managemen
tor Onions. Cornel
Cooperative Extensior
Publication. Cornel
University, Ithaca, N.Y. 78 p.

LANTIN-ROSARIO, T., W.L. KLINE
and S. KLINE. 1997. Onior
Production for Export. Growth
with Equity in Mindana(
Program (GEM). 76 p.

MCDONALD, B.A. 2006. Lecture
notes in plant pathology
Federal Institute o
Technology, ETH-Zentrum
Zurich, Switzerland.

MCGREGOR, B.M. 1986. Pes
Control in Tropical Onions


Tropical Developme it anc
Research Institute. London
United Kingdom. 107 p.

SCHWARTZ, H.F. and S.K
MOHAN. 1996. Compendiurr
of Onion and Garlic Diseases
American Phytopathologica
Society Press. St. Paul
Minnesota, USA. 54 p.

ACKNOWLEDGEMENT

This research was supported by the
Integrated Pest Managemen
Collaborative Research Suppor
Program (IPM CRSP) which wa,
funded by USAID Grant No. LAG-G
00-93-00053-00 with Virginia Tecl
as management entity, Philippine
Rice Research Institute as leach
institution and University of th(
Philippines Los Bahos, Centra
Luzon State University, Leyte State
University, Ohio State University
Pennsylvania State University an(
Asian Vegetable Research anc
Development Center as collaborating
Institutions.









Table 1. Yield and quality attributes of bulbs of Yellow Granex and Red
Creole as influenced by different levels of N.


Variety N levels Yield Texture Hardness Total Titritable
(kglha) (t/ha) (mmlsec) Soluble Acidity
solid (%)
(Brix)


Yellow Granex Control
50
100
200


22.20a
20.30b
20.30b
20.30b


3.46
3.52
3.92
3.87


0.17
0.18
0.20
0.19


0.06
0.07
0.08
0.09


Red Crole Control 12.50c 2.32 0.12 12.0 0.07
50 17.22a 4.32 0.22 13.0 0.09
100 13.33b 2.84 0.14 12.5 0.09
200 11.67c 2.71 0.14 14.0 0.09
1Means in column with the same letter are not significantly different at 5%
level of DMRT.


C 5)fli -


100





Week,


IOOp.,/h -w 200ki/h;l





2001./ g/h
Ok (/hi
CoFnt rol


1.1 .4l(i


Bulb rot incidence (%) in 'Yellow Granex' as influenced by N
levels under room temperature storage. Dry Season 2003.


Figure 1.


--



























Figure 2. Bulb rot incidence (%) in 'Red Creole' as influenced by N
levels under room temperature storage. Dry Season 2003.


0 4
S03

S0-i
4


Z i .1 5 7
W? .k '*


fol it f <,t


~ i;;i~ I, I)


Figure 3. Bulb rot incidence in 'Yellow Granex' as influenced by N levels
under cold temperature storage. Dry Season, 2003















0 *.


Week*


-igure 41 Bulb rot incidence in 'Red Cre
cold temperature storage. Dry





at A. / I f a A, nnter 8. n.'


to .
80 ..1.; ^' ;_

.o
40



Control 50
Rate Of Nitrogen


Figure 5. Occurrence of bulb rot path(
N levels under room temp(
letter (outside the parenthe
each treatment while bars
parentheses) are not sigr
(P=0.05). Dry Season, 2003


-' I '1 '!, ):/ .-I







10. "

S10 It1 12


is influenced by N levels under
;on, 2003





I Furstrtln Itpp,








i
00 200
ition (kg)


n 'Red Creole' as influenced, by
a storage. Bars with the same
are significantly different within
the same letter (enclosed in
it different among treatments

























by N levels under room temperature storage. Bars with the same
letter (outside the parentheses) are significantly different within
each treatment while bars with the same letter (enclosed in
parentheses) are not significantly different among treatments
(P=0.05). Dry Season, 2003.


wA fv tm 'e 8a tp Ftrfriul tp .









Control 50 100 200
Rate of Nitrogen Appitcation (kg)



Figure 7. Occurrence of bulb rot pathogen in 'Yellow Granex' as influenced
by N levels under cold temperature storage. Bars with the same
letter (outside the parentheses) are significantly different within
each treatment whilebars with the same letter (enclosed in
parentheses) are not significantly different among treatments
(P=0.05). Dry Season, 2003.







CAUSING SUGAR

F.M. DELA CUEVA, A.A.
and E.G

Institute of Plant Breeding-Crop Science 4
Philippines at Los Baihos

Research supported by a grant from the I
(PHILSURIN) and the Institute of Plant Bi
Agriculture, UPLB, College, Laguna.


Peronosclerospora spp.
were differentiated using spon
reaction (PCR). Symptomatic s
commercial production areas i
Batangas, Pampanga and Caga
in the morphological and mI
measurement of collected sp
significant variations in their si;
Identity of the isolates
PCR with the Peronosclerospo,
ERIC and BOX primers ger
isolates but REP and ERIC prir
on location. Composite analysis
primers showed that population
genetic diversity and genetic
subpopulations of the same loc


Key words: Peronosclerospora, down



INTRODUCTION

Sugarcane downy mildew caused b)
Peronosclerospora spp. is one of the
most destructive pathogens o
sugarcane (Saccharum officinarum L.
throughout the world particularly in thE
tropical and subtropical regions. (Duct
et al., 1987). The most prominent
feature contributing to thE
destructiveness of these pathogens i,
the production of secondary inoculun
i.e. conidia in huge numbers allowing i


E DOWNY MILDEW

IARANG, C.B. PASCUAL
3LASAN

r, College of Agriculture, University of the


iine Sugar Research Institute
g-Crop Science Cluster, College of



ing downy mildew of sugarcane
phology and polymerase chain
:ane leaves were collected from
Iros Occidental, Davao del Sur,
Spores were collected and used
ilar studies. Examination and
of the pathogen revealed no
j shape across locations.
confirmed using spore DNA in
nus Specific (PGS) primer. REP,
d polymorphic bands among
differentiated the isolates based
DNA fingerprints from the three
>m Negros Occidental had high
"gence was also found among



Jew, rep-PCR primers



single infected plant to pose a threat
an entire planting area or regic
(Weston, 1923). These diseases ai
also often the limiting factor in crc
production in developing countries ar
preclude the planting of otherwise
preferred varieties (Micales et a
1988).
Downy mildew of sugarcane
the Philippines is caused by t
species of Peronosclerospora \







rioo). utner reports Inc
species miscanthi (splitting-t
;pontanea as well. Differ
populationn between P. philij


~Ul~ LI .I
ype) and
,nces in


Duck et al. (1987). Previous studies on
lost-plant resistance in the Philippines
used either P. sacchari (Jereza, 1983)
or P. philippinensis (Sampang, 1988).
-lowever, the relationship among
Peronosclerospora species is still
being questioned.
The separation of P.
:hilippinensis and P. saccharin should
)e re-evaluated because of their
similarity in sporulating capacity, host
ranges (Bonde and Peterson, 1983;
Exconde et al., 1968) and
norphologies (Bonde et al., 1984).
identification was based only on
norphological characters, which are
very much affected by environmental
conditions. Moreover, genetic
variation among the isolates of the
wo species has not been reported
and the molecular characterization of
Deronosclerospora spp. on
sugarcane in the Philippines has not
been studied.
This study was performed
using molecular techniques to
determine whether variations existed
among the different isolates of the
Peronosclerospora spp. that infect
sugarcane. Information generated
from this analysis can be useful in the
'ormulation of effective disease
management strategies particularly in
the deployment of resistant varieties
of sugarcane.


MATERIALS AND METHODS

Isolate collection
Young sugarcane leaves infected
only with downy mildew were


tiI.C u, u I UIIIo IIL.LVoU Of Iu
washed with sterile distilled water
Prior to incubation, leaves were again
washed with sterile distilled water and
incubated in a black plastic bag in the
dark for approximately 8 hours at 16-
25C and high relative humidity
Leaves were flushed with sterile
distilled water to wash the
conidia/conidiophores into a 50 ml
conical tube. The spore sample was
then stored at -20 oC until the time for
DNA extraction.

Total genomic DNA extraction from
conidia/conidiphores

The total genomic DNA used as
templates of PCR were extracted
using the min-prep extraction method
developed by Saghai-Maroof et al
(1984) and Yao et al. (1991) with
some modifications. Spore
suspension was pipetted into a 1.5 ml
microfuge tube and centrifuged at
5,000 rpm for 2 minutes in an
Eppendorf 5417C centrifuge. The
supernatant was discarded and
another aliquot spore suspension was
added and centrifuged as above until!
the spore pellet reached the 0.3 ml
mark of the microcentrifuge tube
The spore pellet was then
completely suspended in extraction
buffer through gentle inversion of the
tube for 5 min. Twenty-five microliters
of 20% sodium dodecyl sulfate (SDS)
vlv was added and mixed as above
prior to incubation at 65 oC for 10-30
min. After incubation, 80 pl 5M NaCI
was added and mixed thoroughly for
5 min. CTAB solution (10% CTAB in
0.7M NaCI) was added to the tube,
mixed very well and incubated at 65
oC for another 10-30 min. Chloroform-
isoamyl-OH (24:1 v/v) was added







after incubation and mixed very well
by rocking the tube for 5 min. After
which, the tube was centrifuged for 5
min at 12,000 rpm. After
centrifugation, the resulting aqueous
phase was collected and transferred
to a new sterile 1.5 ml microcentrifuge
tube.
The chloroform-isoamyl-OH
(24:1 v/v) extraction step was
repeated and the resulting aqueous
layer was transferred to a new sterile
1.5 ml tube. One volume of ice-cold
isopropanol was added to the tube
and was mixed thoroughly by gentle
rocking of the tube until the DNA
precipitate was visible. The tube was
then centrifuged at 12,000 rpm for 5
min. Isopropanol was poured off and
DNA was washed with 500 pi ice-cold
70% ethanol (EtOH) with gentle
inversion of tube followed by
centrifugation at 12,000 rpm for 20
sec. Ethanol was removed and the
DNA pellet was briefly air-dried in a
laminar hood, after which, the DNA
pellet was dissolved in 20-50 pl sterile
HPLC-H20 at room temperature.
RNAse A (10 mg/ml) was added at 5
pl per 50 pl DNA solution and
incubated at 37 oC for 1 hr. The DNA
was then re-precipitated and
resuspended in 2050 pl HPLC-
H20.The concentration of the purified
DNA stock was determined by
running the sample through a 0.7%
agarose gel at 100 volts for 30 min. A
working stock was prepared with
concentration adjusted to 10 ng/pl
and then stored at 4 C until use.


PCR amplification and conditions

Peronosclerospora Genus Specific
(PGS) pr-mer. PCR was performed
using 20 pl of reaction mixture


containing (as tinal concentrations) 1i
PCR buffer, 2.5 mM MgC12, 40 pM
each dNTP (total of 160 pM), 1 U ol
Taq DNA Polymerase (Invitrogen,
Carlsbad, CA, USA), 0.1 pM each
forward and reverse primer (PGS'
and 20 ng template DNA. The therma
cycle conditions were as follows: 1
cycle at 940C for 1 min (Initia
denaturation); 30 cycles each at 94C
for 1 min, 530C for 2 mins, and 720C
for 2 mins; then followed by a 720C
final extension for 5 mins. Reactions
were carried out in a PTC-10C
Thermal Cycler (MJ Research, Inc.).

Rep primers
Three rep primers (REP, ERIC anc
BOXAIR) (Versalovic, et al., 1994)
were used as follows:
Primer Sequence Repetitive
Extragenic Palindromic (REP)
REP1R-1 5'-IIIICGICGICATCIGGC-3'
REP2-1 5'ICGICTTATCIGGCCTAC-3'

Enterobacterial Repetitive Intergenic
Consensus (ERIC)

ERIC15' ATGTAAGCTCCTGGGGATTCAC-3'
ERIC2 5'-AAGTAAGTGACTGGGGTGAGCG-3'
BOXA1R 5'-CTACGGCAAGGCGACGCTGACG-3

A 20 pl reaction mixture fo
each primer included (as fina
concentrations): 1x Gistcher Buffe
(GB), 160 ng BSA, 10% DMSO, 2.f
mM dNTP's, 50 pmoles each primer
2 U Taq DNA Polymerase and 50 n
DNA extract as template. Therma
cycle conditions for ERIC an(
BOXAIR primers were: 95C initial
denaturation for 7 min; 40 cycles
each at 94C for 1 min, 53C for '
min and 65C for 8 min; followed by c
65C final extension for 15 min. Fo
REP primers, the cycle conditions






tl S: IUa llUWs. O %, lu I IniII, FU
rcles each at 940C for 3 sec, 92C
r 30 sec, 40C for 1 min and 65C
r 8 min; followed by a 65C final
(tension for 8 min.


garose gel electrophoresis of
CR products

CR products were separated
rough agarose gel electrophoresis.
two-percent (2%) weight to volume
arose gel (SIGMA Chemicals, MD,
SA) was used for PGS and rep
-imers, in 0.5x TBE buffer (0.9M Tris
- 8.0, 0.9M Boric Acid and 0.5M
DTA pH 8.0).
PCR amplified products using
GS primers were separated on a
UPID II electrophoresis apparatus
S50V for approximately 1.5 hrs. PCR
-oducts from rep primers were
3parated on a GIBCO-BRL
horizontal electrophoresis apparatus
.ife Technologies) at 95V for 5 -7
-s. Gels were stained with ethidium
-omide (0.5 pg/ml) after
lectrophoresis, visualized in a UV
ansilluminator and documented for
and analysis. A 1 kb plus DNA
idder (Invitrogen, Carlsbad, CA,
SA) was included as size marker in
ie middle and on both ends of the
el.

lata analysis

or each isolate, the bands generated
y the three rep primers were
corded as "1" when present and "0"
then absent. All the data records
om all three primers for all isolates
employed in this investigation were
combined in a two-way table. The
;AHN clustering method (NTSYS,
:xeter publishing, Ltd., Setauket, NY,


. VV L) V A LrJ JI 1I LI 1u I~ IGILuW,
>y an unweighted paired group
method with arithmetic averages
UPGMA) based on Simple Matching
imilarity coefficient (Dice, 1945).


RESULTS AND DISCUSSION

isolate collection

sugarcane leaves showing no
disease other than the typical
symptoms of downy mildew (Figure
A) were collected from sugarcane
Growing areas in Batangas,
'ampanga, Tarlac, Negros
accidentall and Davao del Sur (Table
). Twenty-one isolates were
collectedd from Negros Occidental,
line from Batangas, six from
'ampanga, five from Tarlac and four
rom Davao del Sur. The isolates from
Jegros Occidental were gathered
rom six commercial growing areas.
)avao isolates were collected from
wo sites in Hagonoy, Davao del Sur.

Morphological characterization of
Peronosclerospora spp.

[he conidiophores of
'eronosclerospora spp were hyaline
and dichotomously branched (Figure
IB). Spores were also hyaline and
varied in shape. Some were elongate
)void and some were round
:ylindrical and slightly rounded at
apex. Sizes of the spores varied from
15-17 x 35-41 pm but were still within
he range (17-21 x 27-39 pm) for
Peronosclerospora spp. Cagayan
solates had the longest spores while
:he Batangas isolates had the
smallest spores.
The variation could be due to
differences in environmental factors







and tne genotype OT me nost Tron
which the isolates were collected. II
was observed that within an area
spore morphology varied depending
on the variety of sugarcane. This
observation is in agreement with tha
of Rao et al., (1984) who noted tha
morphology of the conidia varied witt
host genotypes. The size anc
appearance of conidia anc
conidiophores of Peronosclerospor
spp. also vary depending or
environmental conditions at the time
of collection, the mounting fluid use<
during microscopic examination anc
the person making the observatior
(Duck et al., 1987; Bonde anc
Peterson, 1983). The results indicate
that morphological traits of the fungu.
cannot be used alone in the
classification and identification o
species of Peronosclerospora fungi.

Total genomic DNA extraction fron
conidia/conidiophores

Contaminating fungi and othe
saprophytes in the leaves were
eliminated by carefully selection(
leaves that were free from other folia
diseases and surface disinfecting the
samples using l 0% sodiun
hypochlorite. Sporesr were collect(
from both leaf surfaces of the infected(
foliage but more spores were
gathered from the undersurface.
This is the first report of DN/
isolation from conidia an<
conidiophores of Peronostlerospon
spp. of sugarcane without the use a
liquid nitrogen. Genomic DNA wa,
successfully extracted and yielk
ranged from 20-120 ng/pl from a total
volume of 50pl DNA solution. DNI
quality was further enhanced when i
was re-precipitated twice using 0.


VUl oIV IYNld~l aI u dli qual vu .
absolute ethanol after RNAse
treatment. Ensuring the purity c
genomic DNA i.e., without an
contaminating RNA and/or protei
artifacts from conidia and c
conidiphore extraction, is crucial i
the success of PCR using rep primer
(REP, ERIC and BOX). Observin
this stringency is especially crucii
when using REP primers.

PCR amplification using PG
primers

Using PGS primers obtained fror
Centro Internacional de Mejoramient
de Maiz y Trigo (CIMMYT), Mexico L
one of the authors, the identity of th
spore-isolated DNA was ascertained
Amplified PCR products
approximately two -hundred thirl
base pairs (230 bp) from genom
DNA were resolved on a 2% (wh
agarose gel (agarose D1, low EEC
(Figure 2). Bands of the same siz
were visualized from sample isolate
and none on the negative contrc
sterile distilled water. Amplificatic
from the genomic DNA of 65 isolate
confirmed that they all belonged 1
the genus Peronosclerospora.
The significance of the PG
primer was previously exploited
breeding experiments for maiz
downy mildew resistance conducted
at the Institute of Plant Breedinj
College of Agriculture, UPL
(AMBIONET Report, 2002). Using tl
PGS primer, Peronosclerospora we
detected in samples withoi
characteristic symptoms of dowr
mildew.






Rep-PCR amplification of
Peronosclerospora spp. genomic
)NA

Repeated conserved sequences
correspondingg to BOX, ERIC and
REP elements allowed the
amplification of genomic DNA of 25
solates of Peronosclerospora spp.
Each primer set gave repeatable and
Distinct patterns of PCR products
hangingg from few to many fragments
)f different staining intensities and
molecular sizes. Rep-PCR generated
155 bands of different electrophoretic
nobility (Figure 3A). The lengths of
amplified bands ranged from 0.20
ol.5kb kb. ERIC-PCR generated 217
)ands but of slightly shorter lengths
0.20-1.20 kb) (Figure 4A). BOX-PCR
generated 169 bands with size
hanging from 0.20-0.70 kb. The
results showed that each primer
targeted different segments of the
ungal DNA, hence, there was
,ariation in the number of bands
generated and size of amplified
products.

Cluster analysis of the Rep-PCR
fingerprints

Separate dendrograms for BOX,
ERIC and REP were constructed
sing polymorphic patterns
-epresenting the most parsimonious
-elationship between isolates
JPGMA-SAHN cluster analysis of
REP primer-amplified products
revealed 22 haplotypes which were
grouped into six clusters, at 70%
similarity level (Figure 3B' The first
najor cluster (VI) was comprised of
seven isolates that were collected
rom different sugarcane growing
areas in Negros Occidental. Four


isolates came from Silay City, two
from Victorias City and one from
Manapla. The second larger group
comprised of six isolates that were
collected from different towns. The
four isolates from Davao del Sur
diverged to form a single cluster (IV).
Analysis of ERIC primer-
amplified bands revealed 14
haplotypes with three major clusters
at 70% similarity level (Figure 4B).
The major cluster (I) was comprised
of 13 isolates collected from six sites
in Negros Occidental while the four
isolates from Davao del Sur formed
one cluster. This trend echoed that of
the REP-primer analysis.
BOX primer-amplified bands
generated 20 haplotypes and formed
six clusters (Figure 5A and 5B).
Cluster V was the most predominant
group which was comprised of nine
isolates. Unlike REP and ERIC, this
primer could not differentiate isolates
from Davao.
The dendrograms showed that
at 70% similarity level, the groupings
of isolates were almost similar for
REP and ERIC primers. The isolates
were grouiped according to the place
of collection, with minor
rearrangements in each primer. All
four isolates from Davao showed
distinct profile as compared with
Negros isolates hence, they were
grouped into one cluster for both
primers. BOX primer was not able to
differentiate Davao from Negros
isolates.
The BOX primer (De Bruijn et
al., 1992) is generally recommended
because it generates robust
fingerprints, and yields a highly
complex fragment pattern. The REP
primer set generates a lower level of
complexity, but still yields







reproducible and differentiating
fingerprints. ERIC primer set is more
sensitive to sub-optimal PCR
conditions, such as the presence of
contaminants in the DNA
preparations but also generates
highly discriminatory patterns. In this
study, BOX primer did not generate
distinct grouping of isolates and thus,
cannot be recommended for further
diversity analysis of
Peronosclerospora isolates.
It was interestingly noted that
isolates Ne14-17, 19-21 consistently
fell into one group regardless of the
primers used. These isolates came
from municipalities of Silay, Victorias
and Manapla which are in close
proximities with one another.
Likewise, the same observation was
gathered from isolates Neg4, Neg9
and Neg10 that were collected from
Victorias and Manapla as well but
consistently belonged to another
group. This shows that variation
exists within and among isolates from
one municipality or specifically from
one hacienda. These differences
could be attributed to the movement
of planting materials from one place
to another which could have led to
the introduction of the pathogen.
Peronosclerospora sp. persists in
infected canepoints, hence, can
easily be transferred from one place
to another.

Composite Rep-PCR cluster
analysis

Combined SAHN cluster analysis of
the different bands produced by the
three rep primers generated 25
haplotypes on Peronosclerospora
spp. isolates. The haplotypes were
grouped into three clusters at 70%


similarity level (Figure 6).
Cluster analysis of the poolec
DNA fragments clearly separated thE
isolates collected from different
sugarcane areas in Negro,
Occidental and Davao del Sur. The
isolates from Negros were divide(
into two major clusters.
The results clearly showed tha
different sets of primers generated
different clustering patterns at 700A
level of similarity (Table 2). Si;
clusters were recorded when REP
PCR primer set was used, three front
ERIC-and four from BOX-PCR. There
were some isolates that showed
consistent grouping but it was
observed that the number an(
arrangements of isolates within c
cluster varied depending on the set o
rep-PCR primers.

Genetic diversity o
Peronosclerospora spp

The genetic diversity values of the
populations of Peronosclerospora sp(
based on analysis using separate an<
composite rep-PCR is presented ir
Table 3. The REP primer generate<
22 haplotypes and seven of the
isolates belonged to cluster VI
Fourteen haploytpes were recorded
from ERIC primer and 13 out of 2,
isolates were grouped in cluster I
BOX primer produced 20 haplotype,
and eight isolates were grouped ir
cluster I. A total of 25 haplotypes witt
three clusters was generated where
composite cluster analysis was used
Majority of the populations belong tc
cluster I. The level of genetic diversity
(H) based on Nei (1976) or
composite analysis gave a value o
0.74, suggesting tha
Peronosclerospora spp. causing







genetically diverse pathogen.

CONCLUSION

lorphological and molecular analysis
if different isolates of
'eronosclerospora sp. causing
ugarcane downy mildew were
conducted. Spore morphology varies
within an area depending on the
enotype of sugarcane from which
ie spores were collected. PCR using
iree rep primers (REP, ERIC and
!OX) was applied to determine the
enetic variation of the different
solates of the pathogen causing
owny mildew of sugarcane. The
entity of the isolates was verified
sing the PGS primer. The results


LITERATURE CITED


,MBIONET REPORT, 2002.
Marker-Assisted Selection for
the Transfer of Downy Mildew
Resistance in Philippine
Maize Inbreds -A Research
Project Component of the
Asian Maize Biotechnology.
Network (AMBIONET).

!ONDE, M.R. and PETERSON,
G.L. 1983. Comparison of
host ranges of
Peronosclerospora
philippinensis and P. sacchari.
Phytopathology 73:875-878

ONDE, M.R., DUCK, N.B. and
PETERSON, G.L. 1984.
Morphological comparison of
Peronosclerospora sacchari
from Taiwan with P.
philippinensis from the


W- IV kI IU L LI l IlJIUCL I IIJIII II| UI aUO
Occidental were different from the
Davao isolates. Interestingly, there
was a high variation .among the
Negros isolates.
These findings may have an
impact in the deployment of varieties
n different production areas. Further
studies, however,- involving more
diverse collection of isolates must be
done to assess the variation of the
Peronosclerospora spp. isolates.
Recommendation regarding the kind
of varieties to be used in a particular
area can be easily made when the
pathogen profile in each area is well
characterized. However correlation
betweenn the pathogenic and
molecular traits of the pathogen
should be further determined


Philippines. Phytopathology
74:755.

'E BRUIJN, F.J. 1992. Use of
repetitive sequences and the
polymerase chain reaction to
fingerprint the genome of
Rhizobium meliloti isolates
and other soil bacteria. Appi
Environ. Microbiol. 58: 2180-
2187.

ICE, L.R. 1945. Measures of the
amount of ecological
association between species.
Ecology 26: 297-302.

UCK, N. B., M. R. BONDE, G. L.
PETERSON, and A.
BEAN.1987. Sporulation of
Peronosclerospora sorghi,
Peronosclerospora sacchari,
Peronosclerospora
philippinensis on maize.
Phytopathology 77: 438-441.







EXCONDE, O.R.,J.V.ELEC and
B.A. ADVICULA.1968. Host
range of Sclerospora
philippinensis Weston in the
Philippines. Philipp. Agr.
52:175-188

JEREZA, T. S. 1983. Observation on
the reaction of promising
clones (1979-79) series to
downy mildew of sugarcane.
Phil. Phytopathol. 19: 5.

MICALES, J. A., M. R. BONDE,
and G. L. PETERSON. 1988.
Isozyme analysis and
aminopeptidase activities
within the genus
Peronosclerospora.
Phytopathology. 78: 1396-
1402.

NEI, M. 1976. Estimation of average
heterozygosity and genetic
distance from a small number
of individuals. Genetics
89:583-590.

NTSYS 2.1 Software, Exeter
Publishing, Ltd., Setauket,
New York. 2002 by Applied
Biostatistics, Inc.

RAO, B.M., H.S. PRAKASH, and
H.S. SHETTY. 1984.
Relationships of cultures with
sporulation and morphology of
asexual propagules of
Peronosclerospora sorghi on
maize. Int. Journal of Trop.
Plant Dis. 2(2):175-180.

REYES, T. T., L.T. EMPIG and C.
ATIENZA. 1974.
Morphological and
Physiological studies on the


Peronosclerospora sacchari
(Miyake) and Ustilago
th
scitaminea. Proc. 5 Crop Sci
Soc Phil. P. 253.

SAGHAI-MAROOF, M. A., K.
SOLIMAN, R. A.
JORGENSEN, and R. W.
ALLARD. 1984 Ribosomal
DNA spacer-length
polymorphisms in barley:
Mendelian inheritance,
chromosomal location and
population dynamics. PNAS
81: 80148018.

SHAW, C. G. and F. R. HUSMILLO.
1982. Assessment of yield
loss due to downy mildew of
sugarcane caused by
Peronosclerospora
philippinensis (Weston). Phil
Phytopathol. 18: 4.

SHAW, C. G. and F. R. HUSMILLO.
1983. Yield loss estimate due
to downy mildew of sugarcane
caused by Peronosclerospora
sacchari (Miyake). Phil.
Phytopathol 19: 4

VERSALOVIC, J. M. SCHNEIDER,
F. J., DE BRUIJN and J. R.
LUPSKI.1994.Genomic
fingerprinting of bacteria using
repetitive sequence based
polymerase chain reaction.
Methods Mol. Cell. Biol.5:25-
40.

WESTON, W. H. 1923. Sclerospora
of maize. J. Agric. Res.
n'o- ')2n "-70


YAO, C. L., C. W. M
FREDERIKSEF


AGILL, R. A.
I, M. R.







J~u.ILJ, i. w VVPIn. U IIU r. J.
WU. 1991. Detection and
Identification of


able 1. Isolates of Peronosclerospora s

folate C
Code

1 Neg Brgy. Rizal, Haciend
1 Negl Occidental
2 Neg2 Saravia, Negros Occ
3 Neg3 Hacienda Sta. Cruz,
4 Neg4 Hacienda Florencia,
5 Neg5 Hacienda Lourdes, 1
Hacienda Luisita, Ka
6 Neg6 Occidental
7 Neg7 Hacienda Bayabas, (
8 Neg8 Hacienda Bayabas, (
9 Neg9 Hacienda Bariw, Mar
10 Neg10 Hacienda Camba-o,
11 Negl11 Hacienda Manaco 5,
12 Negl2 Hacienda Carmelo, 1
13 Neg13 Hacienda Basag, Sa
14 Dvol Guihing, Hagonoy, C
15 Dvo2 Guihing, Hagonoy, D
16 Dvo3 Don Mariano Osmef
17 Dvo4 Don Mariano Osmei
18 Neg14 Hacienda San Diego
19 Neg15 Hacienda San Diego
20 Neg16 Hacienda Lourdes, E
21 Neg17 Hacienda Manalo 5,
22 Neg18 Hacienda Lumbia, El
23 Neg19 Pusod, Cuaycong, N
24 Neg20 Pusod, Cuaycong, N
25 Neg21 Hacienda Solatorio, I


Peronosclerospora sacchari in
maize by DNA hybridization.
Phytopathology 81: 901-905.


id their collection sites.

action site
luina, Silay City, Negros

aa
-ias, Negros Occidental
ias, Negros Occidental
la, Negros Occidental
i, Cadiz City, Negros

City, Negros Occidental
City, Negros Occidental
Negros Occidental
s Occidental
os Occidental
a, Negros Occidental
Negros Occidental
del Sur
del Sur
gonoy, Davao del Sur
gonoy, Davao del Sur
SCity, Negros Occidental
( City, Negros Occidental
;ity, Negros Occidental
City, Negros Occidental
jalona, Negros Occidental
Occidental
Occidental
pla, Negros Occidental







Table 2. Isolates of Peronosclerospora spp. and their corresponding fingerprint
patterns obtained from rep-PCR analysis.


Collection site


Rep-PCR
REP ERIC

I I


BOX
I


- Composite
Rep-PCR


Brgy. Rizal, Hacienda Maquina, Silay City,
Negl Negros Occ.
Neg2 Saravia, Negros Occidental
Ne3 Hacienda Sta. Cruz, Victorias City, Negros
Neg3 Occ.
Hacienda Florenci2, Victorias Ci.y, Negros
Neg4 Occ.
Neg5 Hacienda Lourdes, Manapla, Negros Occ.
Hacienda Luisita, Kadnaan, Cadiz City,
Neg6 Negros Occ.
Ne7 Hacienda Bayabas, Cadiz City, Negros
Occ.
Hacienda Bayabas, Cadiz City, Negros
eg cc.
Neg9 Hacienda Bariw, Manapla, Negros Occ.
NegO Hacienda Camba-o, Victorias City,Negros
Ngl0 Occ.
Neg11 Hacienda Manalo 5, Silay City, Negros Occ.
Negl2 Hacienda Carmelo, Saravia, Negros Occ.
Negl3 Hacienda Basag, Saravia, Negros Occ.
Dvol Guihing, Hagonoy, Davao del Sur
Dvo2 Guihing, Hagonoy, Davao del Sur
Dv3 Don Mariano Osmeia, Hagonoy, Davao del
Dvo3
Sur
Dvo4 Don Mariano Osmeia, Hagonoy, Davao del
Sur
Hacienda San Diego, Silay City, Negros
Negl4 Occ.
Occ.
Hacienda San Diego, Silay City, Negros
Ogcc.
Neg16 Hacienda Lourdes, Silay City, Negros Occ.
Neg17 Hacienda Manalo 5, Silay City, Negros Occ.
Hacienda Lumbia, EB Magalona, Negros
Negl Occ.
Pusod, Cuaycong, Victorias City, Negros
Negl9 cc.
Occ.
Neg0 Pusod, Cuaycong, Victorias City, Negros
Neg20 Occ.
Ne Hacienda Soatorio, Manapa, Nc.os cc.
Neg21 Hacienda Solatorio, Manapla, Neqros Occ.


Ill I

II I
II


V II I

VI III IV

VI III IV


V I III IV III

V I III IV Ill
V I III IV III


isolates







Table 3. Total genetic diversity (H) o
and composite analysis of fi
composite analysis.

Haplotypes
Primer
Number Predor
Predonr

REP 22 VI (*
ERIC 14 I(1:
BOX 20 1(8

Composite 25 I (1:





















Figure 1.Typical symptoms of st
sugarcane plant (A). (
conidiophores (B)


onosclerospora spp. based on seperati
prints generated by rep-PCR primers ar


Genetic
Diversity
t Types Values (H)

rates) 0.85
ites) 0.67
tes) 0.84

ites) 0.74




















ane downy mildew on young infecl
ia attached to intact sterigmata a





























Figure 2. PCR-amplified proc
Peronosclerospora isc























Figure 3. Banding patterns in agar,
corresponding UPGMA der


(-230 bp) from DNA of the
using the PGS primer







B

I-----












jel of REP-PCR products (A) and th
'am of the 25 isolates (B)































Figure 4. Banding patterns in agarose gel of ERIC-PCR products (A) and the
corresponding UPGMA dendrogram of the 25 isolates (B)


N97
DW84


Figure 5. Banding patterns in agarose gel of BOX-PCR products (A) and the
corresponding UPGMA der"rogram of the 25 isolates (B)





24



____-gl
---.-lINBg2
SL--r---'g3


!1 L--.-- -----Neg8
SNeg
'---- -J--- N099







Dro2
Neg14
i I Neg16


Ij I--- Neg39

-- Negl2
Neg7
Dvol
|Dvo2

Dvo3


Wg19


NBgl5
Ig20

000 05 050 0.75
Coeffianlt



Figure 6. UPGMA (Unweighted Paired Group Method with Arithmetic Averages)
dendrogram from composite data of the three rep primers (REP, ERIC and
BOX) from the 25 isolates of Peronosclerospora spp.







IUrN I IIA I IUN UP- rUNUl I-KUI
SCREENING FOR THEIR ANTIBA(

M.M. PARUNGAO, RA.M

apartment of Biology, College of Arts anm
nila, Pedro Gil St., Ermita, Manila




Plant litter in tropical rainf(
sources of medically important ai
biocontrol agents. Decaying plar
randomly selected tree species ii
Island, Davao del Norte. Fungi w
material by plating serial dilutions c
Extract Agar (MEA). A total of 70
screened for antibacterial activity a!
carotovora and Ralstonia solanace
Eight isolates produced zones of i
solanacearum. Antibiosis may t
metabolites that inhibited the gro
These eight isolates were identified
Acremonium sp., Trichoderma v
Cladosporium cladosporioides, an(
the greatest potential, producing tt
the fungal isolates against tw
effectiveness against E. carotov
attributed to several toxic metaboli
maltoryzine, cyclopiazonic acid, anc

Keywords: antibacterial, disk diffusik
solanacearum

INTRODUCTION

igi undergo various fermentative
cesses which result in the production
secondary metabolites that are
nificant in the search for new
ibiotics. This is especially significant
many antibacterial agents used to
at human infectious diseases are
idered ineffective with the rise of
Itidrug resistant strains. It is
;essary to identify new antibiotics
)ugh previously unexolored targets to


CAYING PLANT MATERIAL AND
HAL ACTIVITY IN SAMAL ISLAND

ITERES and SJ.M. TAN

ances, University of the Philippines





; harbors fungi that are potential
tics and agriculturally significant
materials were collected from 10
* forest of Babak District, Samal
isolated from the collected plant
tato Dextrose Agar (PDA) and Malt
ial isolates were subcultured and
t plant bacterial pathogens Erwinia
using the Disk Diffusion Method.
tion against E. carotovora and R.
ue to the production of toxic
of the bacterial plant pathogens.
;liocladium sp., Aspergillus oryzae,
Geomyces sp., Fusarium sp.,
)pulariopsis sp. A. oryzae showed
gest zones of inhibition among all
ant pathogenic bacteria. Their
and R. solanacearum may be
iat it produces such as kojic acid,
tropropionic acid.

ethod, Erwinia carotovora, Ralstonia


ensure that effective drugs will remE
available in the future (Nogueira, 2006
Antibiotics which harness tl
natural defensive strategies of fur
against these pathogens will grea
benefit humans (Stamets, 2002). T-
makes tropical rainforest plant litter
potentially rich source of undiscovert
fungal species which could be utilized
the production of medically imports
antibiotics that could inhibit the grow
of pathogenic bacteria.







rlani Dactenae painogens suCr
Erwinia carotovora and Ralstonia
anacearum cause many serious
eases of plants throughout the world;
lough the number of diseases they
ise is significantly less than those
ised by fungi and viruses (Kennedy
j Alcom, 1980). Traditionally, the
itrol of these plant pathogenic
cteria has relied heavily upon
3micals and pesticides the misuse
which has led to excessive
/ironmental pollution and the spread
plant diseases in natural ecosystems.
One alternative to These
smicals and pesticides is the use of
:robial antagonists such as fungi to
)press diseases. Tropical rainforest
?r could also prove to be an untapped
irce of fungal species that could be
ized in the production of agriculturally
)ortant biocontrol agents that could
actively suppress diseases caused by
nt pathogenic bacteria (Pal and
rdener, 2006).
This study aims to determine the
:ential of fungi to show evidence of
ibitory activity against plant
:hogenic bacteria. These fungal
lates were obtained from decaying
nt material from thp forests nf Rahak


151an0, LUavaU UUI Iul n e. I I1i trrluwltu
of fungal species present in the ar
can provide, the concerned authority
with greater, rec.;on "': conserve a
sustainably revelor the forest area.

MATERIALS AND METHODS

Profile of sampling area

This* study primarily dealt .with fut
found on decomposing plant litter in t
landward forests in the Mangrovett
Project of the Departm-nr
Environment and Natural Resourc
(DENR) located in Barangay San Isid
Babak District, Island Garden City
Samal in Davao del Norte Seve
factors determine the rate
decomposition of plant litter. The
include the physical and chemic
composition of the litter, t
decomposer organisms present, and t
abiotic factors such as moisture, r
solar radiation, and temperature in t
environment (Swift et al, 1979; Williai
and Gray, 1974). The province of Day
del Norte has a relatively unifo
temperature of 27C. The high
temperature occurs in April, while t
in\A/oCt ftomnrotfl irIt hoI\A/t n "acr aPmir






leaf and twig waL placed individually in was isolated, such that Fungi 1 isolate,
resealable plastic bags. from Tree 1 will be tagged as isolate F
Fungi were induced to sporulate T1. All fungal isolates of the first trei
by placing two sterile cotton balls were assigned codes before proceedin!
moistened with distilled water upon to the next set of fungi isolates from th<
arrival in the laboratory in Manila. second tree. The first fungal isolate c
Samples were incubated for a period of the succeeding tree was assigned
one week to one month at room code immediately following the code c
temperature. the last fungal isolate of the previous
A 25 g composite sample or tree.
decaying plant material for each of the
ten tree species was prepared. Serial Screening for antibacterial activity
dilutions for each of the ten composite
samples were prepared up to 108. Kirby Bauer Test against plan
Each of the dilutions was subjected to bacterial pathogens
spread plating on two selective media:
acidified Potato Dextrose Agar (aPDA) The two plant pathogen isolates: Erwini
and all plates were then incubated at carotovora and Ralstonia solanacearur
room temperature for a period of four were provided by Dr. Marina P. Natura
days to one week. The plates were Crop Protection Cluster, University c
observed for the presence of fungal the Philippines Los Baihos Lagunm
growth at the end of the incubation Isolates were plated on Nutrient Agc
period. (NA). Broth cultures of the two isolate
were prepared by inoculating test tube
Isolation of fungi from decaying plant containing Tryptic Soy Broth (TSB). The
materials broth cultures were incubated at roon
temperature for 24 hours. The
PDA plates of the nine serial dilutions methodology used to test fc
from each of the 10 tree species were antibacterial activity against humal
examined for the growth of fungi. Each pathogens was also carried to test fo
unique fungal colony was noted, and a antibacterial activity against the plar
portion of the selected fungus together pathogens.
with the agar substrate was taken and
inoculated growth-side down individually Characterization and identification o
onto prepared acidified PDA slants Fungi
placed in vials. The slants were
prepared by placing 20 mL of acidified Characterization and identification c
PDA in vials and then allowed to cool fungal isolates were based on colon
until hardened. morphology, hyphal features, and the
Each fungal isolate was assigned arrangement of spore and spore-bearini
a code with the first irunai isolate from structures.
the first tree being designated Fungi 1, Hyphal features and sporn
the second isolate Fungi 2, and so on. morphology for each of the fungs
Each fungal code is followed by a tree isolates were examined using the slid'
code. The tree code is the number culture or agar block culture technique
designated to the tree where the fungus After an incubation period of three days





28

the cover slips were ready to be (Artocarpus blancoi Merr.). Noting the
mounted onto a glass slide with a drop trees from which the fungal isolates
of lactophenol. This technique allowed were obtained ensured that the trees in
for the spores and spore-bearing the area served as the substrate on
structures to be clearly visualized, and which these fungi thrive.
the identity of the fungal isolate to be
determined up to the genus level. Screening for antibacterial activity
After the initial identification of the
fungal isolates via hyphae and spore The Kirby-Bauer Test was performed to
characterization, colonial morphology determine if the molds isolated from the
was then observed by inoculating each forests of Babak District, Samal Island,
of the fungal isolates onto plates of Davao del Norte are a potential source
Potato Sucrose Agar (PSA). This of antibiotics that will be effective
medium allowed the fungal isolates to against the representative -m-
exhibit their respective growth patterns negative plant pathogens: Erwir.t.
and pigmentations characteristics carotovora and Ralstonia solanacearum.
which allowed for the verification of All isolates were subjected to
identities of the fungal isolates as antimicrobial activity testing against the
determined from the prepared agar two Gram-negative plant pathogenic
blocks, bacteria. After an incubation period of
24 hours at 270C, eight out of the 70
RESULTS isolates were found to produce zones of
inhibition against the two bacteria.
Ten tree species were randomly Seven out of the eight isolates produced
selected in the forests of Babak District, zones of inhibition against E carotovora
Samal Island, Davao del Norte. Plated and R. solanacearum (Table 1).
serial dilutions from the 10 plant Most of the isolates showed
composite samples were expected to higher inhibitory activity against
yield two types of fungi: molds and R. solanacearum than E. carotovora. as
yeasts. Molds appear wooly, hairy or indicated by the presence of larger
cobwebby owing to their filamentous zones of inhibition against R.
nature while yeasts appear as opaque, solanacearum than E. carotovora (Table
solitary or small aggregations of cells 1). The wider zones of inhibition
(Frobisher et al., 1974). No yeast recorded against R. solanacearum
isolates were recovered, however, showed only a weak positive
Of the 70 fungal isolates, four reaction. Minute colonies of R.
were from Balete (Ficus stipulosa), three solanacearum were still able to grow
were from Talisai (Terminalis catapa), within the recorded zones of inhibition.
six were from Piagao (Xylocarpus The narrower zones of inhibition
moluccensis), five from Aluman recorded against E. carotovora showed
'Lutjanus argentimaculatus), 11 from a strong positive reaction. There was no
3ago (Shorea quiso), nine from Apatot visible growth within the zones of
Morinda citrifolia), eight from Sto. Niio, inhibition produced.
2 from Anonang (Ehretia acuminata), Isolate F58 T8 however,
even from Anibong (Oncosperma produced a wider mean zone of
lillarium), and five from Antipolo inhibition against E. carotovora (10.75







1 -7 0, P uuuCLtu wiuC Lul |b ui eiyrgi isolates IS variaoDe ( aDe Z).
in against E. carotovora (11.5
it failed to produce any zones of DISCUSSION
in against R. solanacearum.
F31 T6 produced the widest Isolation of fungi from decaying plant
zones of inhibition against E. material
ora (13.75 mm) and R.
'earum (18.75 mm). Fungi thrive in dark, moist environments
The recorded zones of inhibition rich in organic material. Ideal
R. solanacearum were temperature conditions for fungi range
able to that measured for the from 10-50C (Alexopoulos, 1996). An
Control (19 mm), tetracycline example of such an environment is the
). The zones of inhibition forest of Babak District, Samal Island,
id by the fungal isolates against Davao del Norte. The average
tovora however, could not reach temperature of the forest is 27"C and
lalf the size produced by the rainfall is evenly distributed throughout
control, tetracycline (5pg/mL). the year (Peters, 1994). The favorable
Af inhibition were monitored after conditions for the growth of fungi make
)d of 48 and 72 hours to the forest of Babak District, Samal


1996),


)lant pathogenic Boddy, 1988). Initial cl
acterized and the 70 isolates reveal
Jral morphology, mostly comprised of
)ore and spore- This group of fungi oc(
:opoulos, 1979). and facultative, wea







a of these fungi specificity. The use of Gram-positive
apidly in culture plant pathogenic bacteria as rAst


et al.(2005; Tang, et al. (2005) Six out of the eight isolates were
r^air4 + 4 urir4rlrf i irtri;fr^i i +r% c!Vir ia rnr4r nnft iv;f xii i4


common amor


ra. R. solanace


s of fungi such a:
scomycetes.
Only 70 isolates
the total plant mal
was significantly
er of leaves collei
n for the small nun
ied is that isolation
s stored at room t
veeks declined line
303). This was the
amnlar whin.h word-


,gomycetes

e obtained
I collected.
than the
(>100). A
of isolates
s in airdried
>erature for
(Paulus et
ie case for
it inr lhntiri


due to R. solana
he necessary mec
ct or neutralize thi
by the isolates.
)late F58 T8 was fo
ihibitory activity
ra than R. solanm
ra may be more SL
bolites produced b
ared to R. soianacei
)late F49 T8 proc
;vk;k;4;,r 141 C4


earum not
ianisms to
antibiotics

ind to show
against E.
cearum. E.
sceptible to
this isolate
rum.
uced large
t nnninqt F


solanacearum. E


'ere isolated in
ie autumn as
cio et al., 2004)
e cooler. Yeast


produced by this isolate as co
R. solanacearum. R. solanace
possess a means of resistant
the produced metabolites.


carotovora (13. i mr
o solanacearum (18.75
it effectiveness against the
?. may have been due to the
0 one or several toxic metab
I- a mode of action that
?. specific against both plant
The recorded zone
d against R. solanace
*a comDarable to that mea


itai ulle lCuI 11. I I r of1 1 lllCAy ~i- ( J' v- l. v- ll vl 1/ IIIIIIt/s lr g eYj
lited number of test organisms (5pg/ml). However, these larger zone
-. L -- I - __J --:II. . : .. ... .... - ... .....


.......









rrnrnsqnI ;n nqmll tn ha nc fnllrnuc


n*erpreted a


colonies within


oloqv revealed that isolate F11 T3


T . --- --- -W -11 1 1 1 | VI I I* | IfI I M4 IJ4. I ILJ %0 I U JI ? V
carotovora showed a strong positive organic matter. They are
reaction. There was no visible growth spreading colonies and may or m
within the zones of inhibition produced. exhibit coloration from the r
The zones of inhibition produced by the culture. They possess erect, penic
fungal isolates however, could not reach like conidiophores that are
even half the size produced by the branching. Brush-like, flask-
positive control, tetracycline (5pg/mL). phialides arise from the te
Since the zone of inhibition produced branches of a conidiophore. The
was less than standard, the test are colorless, pink or green. (
organisms were deemed to be resistant Fungus, 2006).
(Mayer, 2006). The unique tannish pigmel
Zones of inhibition were exhibited by isolate F61 T9 define
monitored after a period of 48 and 72 fungus as Scopulariopsis
hours to determine if antibiosis Scopulariopsis species are soil
progressed. However, there was no and plant debris dwellers. They
measurable increase in the size of the felt-like texture and exhibits light
inhibition zones produced against E. or buff tan coloration. The reve
carotovora and R. solanacearum. This either colorless or brownish.
was due to the overgrowth of mycelia for conidiophore terminates in
some isolates. The overgrowth of phialides in which chains of colorl
mycelia could not be controlled, as dark spores are borne. Occasi
some isolates were fast growers. In chlamydospores can be observed
other isolates, all antibiotics produced produce trimethyl arsine and dii
were able to diffuse to the furthest arsine, the most toxic forms of a
distance after a period of just 24 hours. (Doctor Fungus, 2006). Arsenic h
Four out of eight isolates ability to induce growth inhibition
exhibiting inhibitory action against the cycle arrest and activation of api
two plant pathogens were isolated from pathways (Karasavvas, et al., 2001
Tree 8 or Anonang (Ehretia acuminata). Isolate F51 T8 was fou
The occurrence of such may be due to belong to genus Geomyces, whii


inal
)res
ctor

tion
this
sp.-.
angi
ave
awn
? is
The
nort
S or
ally,
hey
thyl
inic
the


are


C ~ __




32

Isolate F58 T8 was verified as isolated from the soil. They are
Cladosporium cladosporioides. It is a moderately fast growing, glabrous to
slow to moderately growing fungus that velvety to cottony fungi. Colonial
exhibits olive green to black velvety coloration ranges from white, yellow,
colony. The reverse is usually dark pink or pale grey. Solitary and erect
green to black in color. It is phialide, arising directly from hyphae,
characterized by intercalary or terminal bears cluster of spores, either in balls or
swellings of the conidia in which one- in chains (Doctor Fungus, 2006). The
celled, greenish spores in chain are obsolete synonym for this genus is
borne (Doctor Fungus, 2006). C. Cephalosporium due to their ability to
cladosporioides F58 T8 was found to produce a group of antibiotics called
show more inhibitory activity against E. cephalosphorins. Cephalosporins are
carotovora than R. solanacearum. E. antibacterial agents that disrupt the
carotovora may be more susceptible to peptidoglycan layer of bacterial cell wall.
the cercosporins produced by the mold The fast growing isolate F49 T8
as compared to R. solanacearum. was identified as Trichoderma viride.
Cercosporins could have rendered This species is usually green, white or
greater oxidative damage to the DNA, yellowish in both front and reverse
lipids and proteins (Daub, 2007) of E. culture. Concentric rings, which are
carotovora as compared to R. developing conidia, with patches of
solanacearum. white, blue-green or yellow-green are
Isolate F57 T8 was identified as sometimes observed. Whorls of short
Fusarium. Species of Fusarium are phialides, either solitary or in clusters,
natural inhabitants of plants and soil. that bear unicellular spores
They exhibit a variety of colonial characterizes this species (Doctor
coloration. The front and reverse culture Fungus, 2006). T viride F49 T8
can come in white, lavender, red, tan, produced large zones of inhibition (11.5
salmon, yellow or purple hue. They are mm) against E. carotovora but was
usually spreaders that are wooly to unable to produce any zones of
cottony in texture. The conidiophore, inhibition against R. solanacearum. E.
either solitary or branching, bears sickle- carotovora may be more susceptible to
shape spores. They have found to the trichodermin, trichotoxin and
produce mycotoxins such as fumonisins, trichorzin (Nielsen, 2002) produced by
zearalenones and trichothecenes the fungus as compared to R.
(Doctor Fungus, 2006). Trichothecenes solanacearum. Trichodermin may have
are toxic sesquiterpenoids that are more potently inhibited the peptidyl-
potent inhibitors of protein synthesis, transferase activity required for the
different trichothecenes interfering with elongation andlor termination (Wei et
initiation, elongation and termination al., 1974) in E. carotovora, while R.
stages. They have been used as solanacearum may possess means of
antibacterial, antifungal, antiviral and resistance against this mode of action.
insecticidal agents (Bennett and Klich, Trichoderma also produces a variety of
2003). antibiotics, several of which have
Isolate F33 T6 was identified as antifungal properties (Demain and
Acremonium. Species of such are Solomon, 19F5).
generally saprophytes and commonly







Tne characterization of the CONCLUSION
Iony, spore and hyphae of isolate F31
revealed its identity as Aspergillus Ten tree species were randon
rzae. A. oryzae is a fast growing selected in the forest of Babak Distri
igus that exhibit flat white colony with Samal Island, Davao del Norte. PI(
ges of green that depicts the spore composite materials were prepared
d spore bearing structures. The each of the tree species, and the
nidiophore terminates in a swollen were subjected to serial dilutions. T
sicle in which phialides are borne. serial dilutions were spread plated
ort phialides bear dense, radial PDA and MEA to allow the growth
ains of greenish to yellowish spores molds and yeasts. A total of 70 mc
actor Fungus, 2006). A. oryzae F31 isolates were produced. No ye,
exhibited the greatest mean isolates were acquired as no yea,
libition zones against E. carotovora were found to grow on the cult
3.75 mm) and R. solanacearum plates.
(.75 mm). Its effectiveness against Each isolate were plated on PI
th plant pathogens may be attributed to promote the growth of active
several toxic metabolites that it growing mycelia. The actively growi
ducess: kojic acid which is known to mycelia were bored into agar dis
ssess antibacterial properties, which were used in the Kirby Bai
iltoryzine with its high toxicity rating of Tests performed to screen for t
5o of 3mg/kg (lizuka, 1974), and b- antibacterial activity of the isolat
ropropionic acid which causes against E. carotovora and
%versible succinate dehydrogenase solanacearum.
libition (Environmental Protection The screening for t
ency, 1997). antibacterial activity of 70 isolates frc
All eight isolates that inhibited the decaying plant material of Samal Isla
;ted plant pathogens were yielded no isolates that produced zon
aracterized as Deuteromycetes. of inhibition against the Gram- positi
uteromycetes occur as saprobes, soil human pathogens Enterococc
igi and facultative, weak parasites of faecalis and Streptococcus pyogenes.
ints (Alexopoulos, 1979). The isolates The screening for t
re taken from decaying plant antibacterial activity of 70 mold isolat
iterial. The plant materials were from decaying plant material of San
ked up off the ground at the time of Island yielded eight mold isolates tt
npling, hence, the presence of some produced zones of inhibition against t
I fungi among the fungal isolates in Gram-negative plant pathogens
s study (Ellis, 2006). Characterization carotovora and R. solanacearum. Sev
the mold isolates also confirmed their isolates produced zones of inhibit
tibacterial activity, as antibiotics are against both E carotovora and
)duced by many members of solanacearum, while an isolc
uteromycotina (Moore-Landecker, produced zones of inhibition against
31). carotovora only. The mold isolate F
T6 exhibited the greatest antibacter
activity in terms of the zones of inhibit
produced against E. carotovora (13.







i) and R. solanacearum (18.75
n).
The eight isolates that exhibited
ibacterial activity against E.
otovora and R. solanacearum were
notified as Gliocladium sp. F11 T3,
opulariopsis sp. F61 T9, Geomyces
F51 T8, C. cladosporioides F58 T8,
sarium sp. F57 T8, Acremonium sp. F
T6, T. viride F49 T8, and A. oryzae
1 T6.


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I CIUl: I IVIclI I UI I 1 UI I11 II III IJ I IU I I U I
against Erwinia carotovora and Ralston

Fungal Isolates
E.
F11-T33
F31 T6
F33 T6
F49 T8
F51 T8
F57 T8
F58 T8
F61 T9
Positive Control
(Tetracycline -5 pg/ml)
Negative Control (distilled
water)
Mean of four replicates.


CIILI .L I IUUI 0 UI VIVI I I luI I01 loWulaIC
'anacearum.

ean zones of inhibition (mm)1
tovora R. solanacearum
00 12.00
75 18.75
!5 14.00
50 0
)5 9.00
25 17.25
75 8.50
50 12.25
00 19.00

i 0
























I


J'-


green
nk / red deep red flat to moderately hyaline long in chains / sc
cottony fast rod clumped
together
(mass)
yellow bright cottony moderately hyaline short clustered sc
yellow fast rod (ball)
reenish White cottony fast yellow- round solitary/ s(
green clustered
reenish dark flat to moderately yellow- round in chains sc


Texture Growth Color

cottony / moderately hyaline
powdery fast
velvety / moderately hyaline
powdery fast
cottony fast hyaline


rouna soil
shoi
round soli
c
round soli
c






ANALYbIS UH bP'A I IU-1 tlMVUKAL UYNAMIGUS UF ABAUA MIVOSAIL
AND POSSIBLE DISEASE RISK SCENARIOS IN EASTERN VISAYAS



C.S. DE LA CRUZ1 and A.D. RAYMUNDO2

Former Graduate Student, UPLB, presently Superintendent, Regional Integrated
Agricultural Research Center, Balinsasayao, Abuyog, Leyte, Philippines; and 2Cluster
Director and Professor, Crop Protection Cluster, College of Agriculture, UPLB, College,
Laguna

Supported by the Philippine Council for Agriculture, Forestry, and Natural Resources
Research and Development (PCARRD), Department of Agriculture-Bureau of
Agricultural Research (DA-BAR), National Research Council of the Philippines (NRCP),
and Fiber Industry Development Authority (FIDA).



Abaca mosaic incidence increased with time and was highest in
Amguhan. Apparent infection rates of the disease were 0.03, 0.02, and
0.05 plants per month in Sapa 1, Sapa 2, and Amguhan, respectively. The
disease increased 1.8 times or almost doubled in 12 months after a one-
time eradication activity. A 3.9 average of abaca mosaic re-growths per
hill was observed as a result of unsuccessful and incomplete hill
eradication of abaca mosaic-diseased abaca hill or mat. It appeared that
eradication is no guarantee for an effective disease control if it is not
sustained. Annual percent disease increases were 8.8 and 16.07% for
Sapa and Amguhan, respectively. With these rates, the likelihood of the
abaca plantations in the two barangays being wiped out is high. No
direct effect of weather factors on disease incidence was observed.

Random movements of various aphid vector species of abaca mosaic


Ph.P. 138,315.90, respectively. Rate
and 0.04 farms per month for Sa
these rates, it was estimated th
plantations in the two barangays w(
The fast rate of disease increase
awaiting the abaca industry in El
should be fast enough to keep I
eradication of all possible sources
surveys are necessary to avert a rel

Keywords: abaca, mosaic, infection ral


increase in prevalence were u.ub
nd Amguhan, respectively. With
ie remaining unaffected abaca
e all infected in three years time.
dicates a possible catastrophe
i Visayas. Eradication activities
with disease spread. Complete
oculum, periodic inspection, and
ride catastrophe.

.k analysis, disease eradication







INTRODUCTION


The Manila hemp or abaca indust
continues to be one of the maj,
pillars of the country's economy
The Fiber Industry Developme
Authority (FIDA, 2000) has report<
average yearly export earnings
US$77.8 million generated fro
processed products like fib(
cordage, pulp, yarns, fabrics, ai
fiber crafts. For abaca fiber alone
export earnings averaged US$18
million a year from 1990 to 199
Export revenues from this crop ha'
been significantly increasing sin,
1990.
Low productivity is the prima
problem of the industry in meetil
increasing prospects ai
opportunities. FIDA (1997) attribute
this low productivity to the continue
presence of abaca mosaic ai
bunchy-top diseases in most of tl
abaca growing areas of the country
The devastating effect of tl
abaca mosaic virus (AMV) disea
on fiber production has been
lingering problem besetting tl
abaca industry in the Philippines.
has ravaged plantations
Mindanao, the Bicol Region and
other parts of the country, and is n(
threatening areas of the Easte
Visayas Region, particularly Bayb
and other municipalities of Leyte.
Castillo et al. (1954) studi
abaca mosaic spread under differs
conditions and found out that t
average monthly rates of spread
AMV in six-month-, one-year-, tw


year-, and three-year-old plantatior
are 2.46, 3.77, 2.16 and 0.E
percent, respectively; in are,
interplanted with corn, 7.97 per cer
and in those sprayed wi
insecticides, 0.91 per cent; while
plantations where the disease
plants were removed and vacant hil
replanted with healthy ones, 0.34 p
cent.
Aside from the reported aph
vectors of AMV (Ocfemia and Celin
1938; Celino, 1940; Celino ar
Ocfemia, 1941; Gavarra and Eloj
1964, 1966, 1969; Gavarra, 197-
disease development is influence
by a number of factors. Kent (195
reported that interplanting of co
with abaca causes a market
increase in the amount and rate
spread of mosaic. In some case
100% infection could be observed
one year. The corn not only acti
as a reservoir for the virus but al:
was one of the most favorable he
plants for the breeding of the apl
vectors. Likewise, Castillo et
(1954) noted that the rapid spread
mosaic is further hastened whi
corn is interplanted with abaca. Ke
(1954) emphasized further th
planting canna and other weeds ai
grasses around abaca may have tl
same effect, in that, they may ser
as virus sources and as breedii
hosts for aphids. Apparently,
soon as the weeds are cut or ha
matured, the aphids move to tl
abaca.
The distribution of a pli
disease in space oftentimes shows
definite trend, either increasing







decreasing in a particular direction
such that when infection values are
plotted against distance traveled, a
sloping line called gradient is
obtained (Gregory, 1968). This
gradient is part of the chain of events
in the infection process resulting to
an epidemic as affected by various
factors that operate during the
process of which insect movement,
among others, is paramount in many
virus diseases. Studies on the
quantitative aspects of disease
gradients are rare (Cammack, 1958)
and none has been done on the
mosaic' disease, one of the two
destructive virus diseases of abaca
(FIDA, 1997). Despite its importance
to the abaca industry,
epidemiological studies on the
mosaic disease relative to
understanding the mechanism of
disease spread under field
conditions are practically non-
existent. Likewise, although the role
of aphid vectors in the transmission
of the virus has been studied
(Retuerma, 1982; Kent, 1954; and
Gavarra and Eloja, 1966),
information on disease spread is
limited.
The spatial pattern of virus-
infected plants is complex (Madden
et al., 1987) and the spatial variation
of epidemic development is often
dynamic (Stein et al., 1994). When
such is well documented, it can be
valuable in disease management.
For instance, when the disease
gradient is known, control by
isolation from a source of inoculum
can be easily planned. Additionally,
when these spatial patterns are
analyzed in temporal forms (Madden


and Hughes, 1995), the results can
be of immense importance. In abaca,
t can be in the establishment of
/irus-free nurseries as a component
n a national eradication program to
manage the disease. Abaca
nurseries to be established can be
situated within the isolation distance
:o prevent contamination from known
noculum foci. It is, likewise, possible
from these analyses to predict the
development of disease such that
relevant management strategies,
particularly eradication, can be
implemented in a timely manner to
prevent or limit the spread of
disease.
This study was conducted to
determine the temporal and spatial
dynamics of the abaca mosaic virus
disease in Baybay, Leyte and to
predict the possible risk to the
Eastern Visayas region in a scenario
where a sustainable disease
management strategy is non-
existent.

MATERIALS AND METHODS


Two barangays or localities in
3aybay, Leyte, Eastern Visayas
were selected in monitoring the
epidemic development of AMV
disease. These were Barangays
Amguhan and Sapa, two of the
earliest AMV disease-infected areas
n the municipality. Barangay Sapa
was divided into Sapa 1 and Sapa 2,
which were areas that have
undergone one-time FIDA-
;ponsored AMV disease eradication,
which consisted of cutting down all
4MV-infected plants in a hill and all







infected hills in a plantation, followed
by injection of herbicide into a plastic
straw inserted at the core of the CL
portion of the stalk.


Temporal dynamics of abac
mosaic

In each area, three 10 x 10 m
quadrants with AMV-infected plant
were randomly selected. The AM\
infected plants served as foci of th
disease within a quadrant. Eac
quadrant was situated in a separate
abaca plantation within th
barangay. A total of nine quadrant
were monitored for the entire
experiment. Initial disease
incidences were recorded tw
months -after the abovementione
eradication activity after which th
monthly AMV disease incidence wa
monitored for 12 months.
Disease incidence in eac
quadrant was monitored monthly b
counting the number of disease
plants. Percent disease incident
was computed as a ratio of th
number of mosaic-infected plants i
a quadrant and the total number (
plants in the quadrant. Diseas
progression in terms of infection rat
was estimated using Vanderplank
model (1963) as follows:



r= 1 Ing l X2 loge,
t2-tl 1-X2


where:


r = apparent rate of infection
tl = initial time of disease observation
t2= final time of disease observation
loge = natural logarithm
xi = percent disease incidence at ti
X2 = percent disease incidence at t2

The number of sucker re-
growths was counted in ten
randomly selected eradicated abaca
hills in the different abaca plantations
in the two barangays two months
after the eradication activities to
determine if increase of AMV
disease re-growths has occurred.
Monthly weather data on
temperature. rainfall wind velocity,
wind direction, wind speed and
relative humidity were obtained from
the nearest station of the PAGASA
AgroMeteorology Station at the
Visayas State College of Agriculture,
Baybay, Leyte. Correlation analyses
of the data with the temporal
progression of the disease were
done.

Spatial dynamics of abaca mosaic

This part of the study was conducted
in the same two barangays where
the total abaca area and number of
abaca plantations were 272 has and
200 farms in Barangay Sapa while
Barangay Amguhan has 272.8 has
and 250 farms, respectively. The
different plantations were considered
as experimental units.
The different mosaic foci were
ascertained during an initial survey
of the different abaca growing
barangays comprising the
municipality of Baybay, Leyte. In the
test barangays, the earliest mosaic-







identified to serve as disease foci.
From these foci, spatial development
of disease was monitored for 12
months


Determination of areas affected by
mosaic

During the initial survey, the total
area of abaca farms in hectares
affected by mosaic was determined.
Subsequently, the total cumulative
area affected until December 2000
was ascertained through 3-month
surveys. The total area affected by
the disease during the last month of
survey was taken as the final area
affected for a particular barangay.


Estimated yield of mosaic-affected
areas and abaca yield loss
determination

The estimated yield of affected areas
was computed by multiplying the
final mosaic-affected areas (has.) by
the average fiber yield (kg/ha) in the
area.
Yield loss was estimated by
the using the yield loss model Y =
3.53 + 0.92X where Y is the percent
yield loss and X is the final disease
incidence (De la Cruz, 2001). The
final disease incidence was
computed using Vanderplank's
model (Vanderplank, 1963). Total
yield loss was derived as the product
of the percent yield loss per hectare
and the estimated yield of affected
areas in each site.


in Sapa and Amguhan indicating the
initial mosaic-infected plantations as
foci and subsequent newly infected
plantations within the barangays
were prepared. At 3-month intervals,
survey was made to determine the
newly infected abaca plantations in
each barangay. New mosaic
infections were indicated by a
different color in the map to
determine the direction of the
spread. In each survey, uninfected
abaca plantations during the
previous survey were examined.
Disease prevalence based on
the number of mosaic-infected abaca
plantations was also determined
using the following equation:



No.of mosaic-infected
% disease plantations/barangay
prevalence -x100
prevalence Total number of abaca
plantations/barangay
RESULTS


Temporal dynamics of abaca
mosaic

The temporal progression of AMV
disease differed in each site after the
one-time eradication program
(Figure 1). Disease incidences
progressively increased in the three
sites from January until December
2000.
Disease incidence was higher
in Amguhan compared to the other
two sites. Sapa 1 had generally
higher disease incidences compared







ranged from 4.58 to 14.96, 3.92 tF
11.11, and 12.33 to 28.40 % in Sap,
1, Sapa 2 and Amguhar
respectively, with apparent infection
rates of 0.03, 0.02, and 0.05 pe
month, respectively (Table 1). Thi
latter site also showed the highest
percent disease incidence increase
of 16.07% while 10.38 and 7.19 03
were recorded in Sapa 1 and 2
respectively
The one-time eradicatior
activity, though successful in some
cases, resulted in unsuccessful hil
eradication as more AMV-infectec
suckers ranging from 1 to 5 re
growths per hill, with an average o
3.9 re-growths, were observed ir
many cases (Figure 2 and Table 2)
Usually, when a farmer did thi
eradication, he tended t<
incompletely eradicate a hill b
leaving some AMV-infected abac
that were about to mature ani
appeared to have still prospects fo
inclusion in the forthcoming harvest
This practice has contributed to thi
increase of AMV-infected sprouts
Re-growths in AMV-infectei
eradicated hills usually manifest thi
typical symptoms of the disease
These new young infected plant
were also found to harbor aphids.
Analysis of correlation
between disease incidence and eacl
of the weather factors in the are;
failed to establish any definite
relationships. Although the
correlation between disease
incidence and all factors, excep
wind speed, were positive, thi
coefficients (r) were not significant
(Table 3).


I I I 1 III -I I Yl .o
estimated number of 515,050 and
517,700 abaca hills in Sapa and
Amguhan, respectively. The
corresponding percent disease
increase per year was 8.8 and
16.07%. With this trend, 45,324.4
and 83,194.39 AMV- diseased abaca
hills are expected to occur annually.
The effect, therefore, on plantations
in these two barangays and possibly
in adjoining areas, can be
devastating if no corresponding
intervention were to be implemented.


Spatial dynamics of abaca mosaic

The spread of mosaic in the two
sites was generally ra 'dom. The
number of infected abaca plantations
in a barangay increased with time. In
both barangays, new mosaic
infections in plantations were
gradually noticed three months after
the FIDA-sponsored eradication
activity and subsequently increased.
Apparently, after the eradication,
inoculum sources of the virus were
drastically reduced as a result of the
cutting down of diseased abaca
plants. Thereafter, new and more
mpsaic-infected suckers emerged
and eventually contributed to the
pool of inoculum sources available
for transmission by vectors. After
one year, few plantations in the two
sites remained uninfected. Disease
was not observed in only 66 and 86
out of 200 and 250 abaca plantations
in Sapa and Amguhan, respectively,
after a year. The spread is
anticipated to continue until such
time that most plantations in the







>arangays will become infected.
Subsequently, adjoining barangays
nay become infected.
In Barangay Sapa, incipient
infection was more or less distributed
among the plantations of the
>arangay. Initial disease prevalence
vas 49%. Newly infected plantations
or the months of March, June,
September, and December were
03, 111, 117, and 134, respectively,
vith percent disease prevalence of
11.5%, 55.5%, 58.5%, and 67.0%.
In Amguhan, disease foci
iere also distributed throughout the
entiree abaca plantations of the
iarangay. Initial disease prevalence
/as 53.6%. The numbers of newly
ifected plantations were 139, 146,
54, and 164 with 55.6%, 58.4%,
1.6%, and 65.6% percent disease
prevalence, respectively.
The spread of the AMV
disease in both sites was not
Inidirectional. At each sampling
me, newly affected abaca
lantations occurred randomly within
!ach site regardless of distance to
ie nearest focus in the field.
The initial average levels of
disease incidence in Sapa and
jmguhan were 3.41 and 4.79%,
respectively (Table 4). The rates of
crease in prevalence were 0.06
nd 0.04 units per month for Sapa


f area affect
Atal area aff(


by the disc


a, the


ercentages of disease incidence of
.04 and 6.73, respectively for Sapa
nd Amguhan (Table 5). This
situation resulted in an estimated
)tal yield loss of 8,050.14 and


,684.22 kg valued at P143,902.52
nd P138,315.96 respectively for
apa and Amguhan.


DISCUSSION

MV' disease incidence increased
ith time and was highest in
mguhan. Apparent infection rates
id percent incidence increase
allowed the same pattern in the
ree sites. Weather factors were not
orrelated to the incidence of the
sease.
The average monthly percent
sease incidence increase of 0.94%
this experiment is higher
)mpared to the reported 0.34%
monthly incidence increase (Castillo,


)re removed and repianth
,althy ones. Thresh (1974)


between plants varies widely
:cording to the type of virus, crop,
ivironment, and mode of
ansmission.
A range of 1 to 5 or an
terage of 3.9 AMV-diseased re-
owths per hill was observed in
successful and incomplete hill
adication. This number was taken
'o months after a one-time
adication drive, thus an increase is
:pected as abaca sucker
oduction increases through time
actual observations revealed that
successful and incomplete hill
adication occurred because the
adication technique ray have
ime limitations beyonur control,
ich as under dosage arid reduced
irbicide efficacy as a- rest of







inadvertent spillage, rain or
evaporation and other factors.
Underground suckers about to
emerge from the soil may have also
escaped chemical treatment.
Additionally, as most of the members
of the eradicating team were farmers
paid on daily basis and required to
eradicate specified quota of number
of eradicated disease abaca hills,
there appeared to be a tendency to
work fast and unknowingly miss or
inaccurately trace the path of the
advanced group doing the actual
cutting of the diseased plants.
These instances are believed to be
contributory factors to unsuccessful
clump/hill eradication. In ofher
instances, farmers who volunteered
to eradicate AMV-infected plants in
their own plantations- usually
deviated from the correct procedures
by not cutting some diseased plants
in a hill especially if the diseased
plant is about to mature and can still
be harvested. The result, likewise, is
incomplete hill eradication.
These conditions resulted in
considerable" increases in the
number of diseased plants in the
abaca plantations. In this study, the
disease increased 2.27, 1.83 and 1.3
times for Sapa 1, Sapa 2 and
Amguhan, respectively. On the
average, the disease increased 1.8
times or almost doubled in twelve
months after the eradication activity.
This is a clear indication therefore
that a one-time eradication scheme
is not an insurance that the disease
will decrease. After unsuccessful hill
eradication, young sucker re-growths
are enhanced as a natural
compensatory reaction of abaca


plants to perpetuate. These young
suckers, at the 3-leaf stage, are ideal
infestation sites of aphids based on
actual field observations. The
disturbances and actual cutting down
of diseased abaca plants probably
stimulated the aphids to form winged
forms which are efficient in
transmission of the virus to healthy
plants. O'Loughlin (1962) pointed out
that unfavorable conditions on the
host plant, such as wilting or
overcrowding of aphids, lead to the
production of winged forms.
Magnaye (1979) pointed out that
periodic defoliation of Caladium spp.
as host of Pentalonia nigronervosa
may contribute to the migratory
tendencies of the alate form of the
_..-._l~ ... .L- A . L L ...L -


a plans
ias and Ve


rowing nearvD


penoas, wnicn produce wilting II
plants, are factors that tend ti
accelerate the formation of wini
buds in aphids. Schaefer (1938
also found out that the number c
alate produced by Acyrthosipho,
onobrychidis Kalt was inversel
proportional to the ability of the plar
to support its population; starvation
on smaller plants produced mor
alate. When AMV-infected plant
harboring aphids were cut as a resu
of eradication activities, the plant
dried up and eventually died. Thus
the aphids are deprived of foo,
source that might trigger them ti
produce alate forms as a survive
mechanism allowing transfer to ne\
living and healthy plants, there
transmitting the virus.







evidently, a tast spread ot the
disease is occurring among plants
within the plantations as a result of
ie availability of virus inocula and
phid vectors. It has been reported
earlier that aphid vectors of the
mosaic virus such as R. maidis are
lore mobile because they produce
lore alate forms (Gavarra, 1977).
*his presumably hastens faster
ispersal of the virus. These
conditions are primary reasons for
ie need to implement rapid
radication of all possible sources of
irus inoculum and a continuous
monitoring and eventual eradication
f AMV-diseased abaca plant re-
rowths and other inoculum sources
i order to attain eventual eradication
f the disease. The eradication
cheme has to be refined in order to
void the limitations and drawbacks
f the method.
The number of diseased
ibaca hills, estimated at 45,324.4
nd 83,194.3, to occur annually,
respectively in Barangays Amguhan
nd Sapa is significant. The
nportance of a sustained and sound
*radication program for the proper
management of the disease can not
ie overemphasized in this regard.
"he immediate curtailment of the
disease in Eastern Visayas to save
ne threatened abaca industry in this
region should be an immediate
priority. implementation of
continuingg eradication activities
>ased on periodic inspection to
ascertain the recurrence of the
disease should be done without
lelay. It is a must, likewise, to
,duCate farmers on the correct
proceduress in disease eradication


ir importance in the sL
,ment of the disease.
. total of 12 aphid
Den reported to trans


stained

species
ryI h^


,"VnIIu, I Zoo ,liInu, IU,,I y' I l IU .
nd Ocfemia, 1941; Gavarra and
loja, 1964, 1966, 1969; Gavarra,
977). Considering this number, fast
pread of the disease is expected.
or instance, the corn aphid is a
respective vector of the abaca
losaic virus. In some areas of the
baca plantations, corn plantings
'ere observed especially as main
rop in "slash and burn" systems that
light produce large quantities of
orn aphids during the cropping
eriod. It was very likely that after
arvest, these aphid populations, if
here were any, could easily transfer
) abaca plants and thereby transmit
ie mosaic virus.
The apparent random pattern
f. mosaic spread in abaca
lantations in the two sites suggests
iat complex factors might be
evolved in the process. The flight of
ectors is random and this may
explain the observed pattern of
disease spread. Thresh (1974)
pointed out that the rate of virus
pread between plants varies widely
according to the type of virus, crop,
environment and mode of
transmission. Since disease foci
tere observed to be iairiy distributed
it the start of the survey, it is thus
expectedd that. sources of virus
ioculum were available throughout
ie field.
The aforementioned
situation has been observed in other
)athosystems. Cornwel; (1958) and







Strickland (1951) reported that ACKNOWLEDGMENT
seasonal trends in the rate and
pattern of spread of cacao swollen The concepts and ideas
shoot virus are due to differences in presented in this work emanated
the size and activity of populations of from the FIDA- UPLB NAFC project
the mealybug vector. Moreover, the on "Epidemiology of Abaca Virus
actual rate of spread between trees Diseases" under a program entitled
depends on such factors as the "Sustainable Research and
number and proximity of the main Management of Abaca Diseases in
sources of infection and the mode of the Bicol and Eastern Visayas
spread (Thresh, 1974). Regions". The support of the
The established disease foci Philippine Council for Agriculture,
during the initial survey were Forestry, and Natural Resources
randomly distributed all over the Research and Development, the
plantations. This situation did not Department of Agriculture-Bureau of
allow for a definite pattern or Agricultural Research, and the
gradient of disease spread in the two National Research Council of the
areas to be established However, Philippines for the PhD work of the
results suggest that the disease is senior author is likewise
continuously increasing spatially. acknowledged.
The disease has affected 212 has in
Sapa and 201.8 has in Amguhan
corresponding to total yield losses of LITERATURE CITED
8050.14 and 7,684.22 kgs,
.spectively. The absence of an
intervention could be disastrous to CAMMACK R.H. 1958. Factor
the Eastern Visayas region, similar affecting infection gradients
to what has already happened in the from appoint source of
Bicol Region (Raymundo et al., Puccinia polysora in a plot of
2001), Zea mays. Ann. Appl. Biol.
The rate of disease increase 46:186-97.
within sites was high. This is
indicative of a need to implement a CASTILLO B.S., AGATI A. and
management strategy, such as OTANES F.Q. 1954. Studies
eradication, fast enough to keep on the rate of abaca mosaic
nace with this rate All sources of spread under different














































LJvcV luJpillI i i. I ulI J- I iv. i .I, v .. I
Department of Agriculture, Philipp. Agric. 37:555-591.
Quezon City. Philippines


CELINO, M.S. and G.O. OCFEMIA
1941. Two additional insect GAVARRA, M.R. and A.L. ELOJA.
vectors of the mosaic of 1964. Experimental
abaca or Manila hemp plant transmission of the abaca
and transmission of its virus to mosaic virus by Toxoptera
corn. Philipp. Agric. 30:70-79 citricidus Kirk.. Philipp. J. Pit.
Ind. 29:47-54.
^'Mn^MltAHi I a 0 4 CincO


1966. Further sti
insect vectors of
mosaic virus.
transmission of
mosaic virus


s of
lopy
teen
Res.


49:61







MADDEN, L.V., LOUIE R. and J.K.
KNOKE. 1987. Temporal and
spatial analysis of maize
dwarf mosaic epidemics.
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MAGNAYE, L.V. 1979. Studies on
the identity and relationship of
the abaca ar banana
bunchy-top virus in the
Philippines. fM.S. Thesis]
College, Laguna, Philippines:
University of the Philippines
Los Baihos. (Available at the
UPLB Library)

OCFEMIA, G.O. and M.S. CELINO.
1938. Transmission of the
abaca mosaic. Philipp. Agric.
27:593-608.

O'LOUGHLIN, G.T. 1962. Aphid
trapping in Victoria I. The
seasonal occurrence of
aphids in three localities and a
comparison of two trapping
methods. Aust. J. Agric. Res.
14:61-69.

RAYMUNDO, A.D., CIPRIANO,
B.P., GARCIA, S.,
BORROMEO. R., TAPALLA.
P., BAJET, N.B., SUMALDE,
A.C. and N.G. FABELLAR.
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diseases in the Bicol and
Eastern Visayas regions,
Philippines. Philipp. Agric.
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RETUERMA, M.L. 1982.
Simultaneous and sequential


transmission of abaca-mosaic
and banana-mosaic to abaca
(Musa textilis Nee) by Aphis
gossypii Glover. Philipp.
Phytopathol. 18:48-55.

SCHAEFER, C.W. 1938.
Physiological conditions which
produce wing development in
the pea aphid. J. Agric. Res.
57:825.

STEIN, A., KOCKS, C.G., ZADOKS,
J.C., DRINKING, H.D.,
RUISSEN, M.A. and D.F.
MYERS. 1994. A
geostatistical analysis of the
spatio-temporal development
of downy mildew epidemics in
cabbage. Phytopathology
84:1227-1239.

STRICKLAND, A.H. 1951. The
entomology of swollen shoot
of cacao. II. The bionomics
and ecology of the species
involved. Bull. Entomo. Res.
42:65-103.

THOMAS, I. and E.J. VEVAI. 1940.
Aphis migration. An analysis
of the results of five seasonal
trapping in North Wales. Ann.
Appl. Biol. 27:393-405.
THRESH, J.M. 1974. -Temporal
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Annu. Rev. Phytopathol.
12:111-128.


VANDERPLANK, J.E. 1963.
Diseases: Epidemics
Control. Acad. Press,
York, 349 pp


Plant
and
New












--Amguhan


30 -




25 -




20


15




10 -


SI I I 1 I I I I I I I
1 2 3 4 5. 6 7 8 9 10 11 12
Month


Figure 1. Increase of abaca mosaic virus disease in Barangays
Sapa and Amguhan, Baybay, Leyte, from January to
December 2000.


----Sapa 1


---Sapa 2






Table 1. Percent disease incidence (%) and apparent infection rate (r) per month of
abaca mosaic in 3 sites in Baybay, Leyte.


BarangaylSite


Sapa 1



Sapa 2


Initial disease
incidence
(%)


4.58



3.92


Final disease
incidence

(%)


14.96



11.11


12.33 28.40


0.03



0.02


Amguhan


0.05

















- j


within a hill (A) after herbicide treatment. Abaca mosaic-
infected re-growths ranging from 1 (B), 2 (C), 3 (D), 4 (E) and


MIFF


B


a C



























5 5 3


2

2





55

ible 3. Correlation coefficients (r) between disease incidence and weather
factors at different sites in Baybay, Leyte.



Correlation coefficients with incidence
Site
Rainfall Relative TemperatureWind
Humidity Max. Min. speed


Sapa 1 0.12ns 0.55 ns 0.26 ns 0.08 ns -0.63 ns

Sapa 2 0.06ns 0.48ns 0.30ns 0.18ns -0.59 "

Amguhan 0.28 ns 0.49 ns 0.12 ns 0.02 ns -0.42 ns

not significant







Table 4. Number of abaca farms, rate of increase in prevalence per monti
average mosaic incidence in Brgys Sapa and Amguhan, Baybay, Lei



Number of Disease Incidence (%) Rate of
Barangay Abaca increase ii
Farms Range Average' Prevalence



Sapa 200 0.99-54.05 3.41 0.06

Amguhan 250 0.99-56.66 4.79 0.04



1Computed based on the number of mosaic-infected hills over the total number
hills x 100 during the initial survey

2Computed based on the initial percent prevalence and final percent prevalence
each barangay from January to December 2000









Table 5. Cumulative area (ha) affected by abaca mosaic and yield loss in Brgys. Sapa
Leyte from January to December 2000.


and Amguhan, Baybay,


Area


Area
Barangay Aete
Affected
(ha)


Sapa


165.75


Amguhan 166.05


Average


165.90


Initial
% Disease
incidence


3.41





4.79






4.10


Area
Affected
(ha)


212.0





201.8


Final


%
Disease
incidence


Average Estimated
Yield Total Yield1
(kg/ha) (kg)


6.04 1,060.68 224,864.16


6.73 1,060.68 214,045.22





206.90 6.39 1,060.68 219.454.69


% Yield
Loss2
(per/ha)


3.58





3.59





3.59


1 Computed by multiplying average yield per hectare by final area affected by the disease.
2 Based on the regression model Y= 3.53 + 0.92 X, where X is final disease incidence and Y is % yield
loss. The model assumes that AMV-infected abaca plants are totally discarded and no yield is produced.
3 This is on the assumption that only 50% is the actual loss since abaca mosaic-infected plants do not
sustained 100% loss.
4 Computed by multiplying the prevailing price of abaca fiber (PhP18.00/kg).in Baybay, Leyte at the time of
the experiment by the total yield loss in each barangay.


Total
YieldLoss3
(kg)


8,050.14





7,684.22





7,867.18


I


- -


________________,...........;---:-------------------


Loss
Value4
(PhP)


144,902.

52



138,315.

96



141,609.

24







Phytopathological Note:

CANNA INDICA: HOST OF I

T. O. DIZONl.Ia

Research Associate Professor and Univ
Science Cluster-Institute of Plant Breedi
Philippines at Los Bahos, College, Laguna



This study was conduct,
ornamental plant in the Philippines
Symptoms developed on inoculated
transmission and Enzyme Linkem
confirmed that Canna is a host of E
samples indicated that the vJus is
tissues.



INTRODUCTION

Banana bunchy top is the most
serious virus disease of banana as well
as abaca in the Philippines. The disease
is caused by banana bunchy top virus
(BBTV) and is transmitted by an aphid
vector, Pentalonia nigronervosa, by
vegetative planting material, but not by
mechanical inoculation (Magee, 1927).
The disease reduces yield or in severe
cases, highly infected plants do not
produce banana fruits. The disease on
banana as well as abaca has been
existed and reported as early as 1950s,
until this time. Little work has been
done to totally eradicate or minimize this
disease in the Philippines.

The existence of BBTV not only in
the Philippines but in other countries
where BBTV has been reported could be
attributed to the presence of alternate
hosts of the virus. Species of Musa


ANA BUNCHY TOP VIRUS

SDINGLASAN

Research Assistant, respectively, Crop
college of Agriculture, University of the




determine if Canna indica, an
host of banana bunchy top virus.
s by aphid Pentalonia nigronervosa
munosorbent Assay (ELISA) test
The presence of BBTV on the leaf
ble of multiplying in the Canna leaf




(Magee, 1927), W. ieolutina (Thomas and
Dietzgen, 1991), it ornata have been
reported to be inteawed with BBTV. Aside
from these Musa species, other weeds
and crops that can be found in banana
and abaca production areas are reported
to be host of the virus or can be
colonized by the aphid vector, P.
nigronervosa. Among these crops is
Canna indica or the 'Bandera Espahola'.
Su et al. (1993) obtained positive ELISA
reactions from BBTV-inoculated Canna
indica and the recovery of the virus to
banana was demonstrated. However,
Geering and Thomas (1997) found no
evidence that Canna indica is a host of
BBTV in Australia. Similar results were
reported by Magee (1927). In the
Philippines, there has been no study to
confirm that Canna indica is a host of
BBTV.

The objective of this study is to
determine if Canna indica, an ornamental
-1--I ; & L- nL,;1;:- -; -- -, ; 1- e







IVIn I 1cruFlL.O MIVU ImVE I InfIJU

growing of test plants

"anna seeds of cultivar Tropical Yellow
iere brought from Tokyo, Japan,
rough the courtesy of Dr. Keiko
Iatsuaki of the Tokyo University of
agriculture The seeds were sown in
plastic pots containing baked soil
ubstrate (garden soil, sand, coir dust at
:1:0.5 ratio). One seed was planted per
lot. Plants were placed inside a
compartment enclosed with opal screen
i a screenhouse. Watering was done as
necessary.

tearing of aphids (Pentalonia
uigronervosa)

The vector P. nigronervosa, were reared
in BBTV- infected banana plants. Plants
vith the aphids were grown in the
greenhouse and enclosed with mosquito
let to prevent movement of the aphids.
,phids rapidly multiplied on the banana
plants.

inoculation with banana bunchy top
iirus

firuliferous nymphs and adult aphids
,ere individually 'picked with brush and
laced on the foliage of Canna plants.
:or the test, four treatments, based on
he number of aphids per plant, were
lone as follows: 1 5 aphids per plant,
S- 10 aphids per plant, 3 15 aphids
)er plant, 4 20 aphids per plant. Eight
plantss were used for each treatment. A
controll consisted of uninoculated Canna
ilant was used for comparison. All
controll plants were placed in a separate
"ompartment provided with opal screen
o prevent contamination. All inoculated
)lants were evaluated for the presence
f ..


CLIGM LUtL

All the inoculated plants including the
ininoculated plants (control) were
evaluated for the presence of BBTV
using Enzyme Linked Immunosorbent
Assay (ELISA) three months after
inoculation. Leaf sections close to the
lower part of the leaf were used for
evaluation. Sections were taken the four
plants, replicated twice, from each
treatment. Then all the sections were
. I


r%- lis -


Symptom Development

All the Canna plants regardless of
whether they were inoculated with 5, 10,
15 or 20 aphids, were infected with the
disease. All the inoculated plants
exhibited various symptoms. These
symptoms were evident about 2 months
after inoculation. Some of the
symptoms were the following: whitish
flecks on the foliage (Fig.1A), crinkling
the leaves and thickening of the veins
(Fig. 1E), rosetting resembling a bunchy
appearance of the petiole (Fig. 1D) and
whitish streaks on the lower portion of
the leaf (Fig. 19 and E). It was also
observed that the color of some leaves
was dark green and they were brittle.
The uninoculated plants were healthy
and did not produce typical symptoms of
banana bunchy top (Fig. 1F). These
symptoms were observed in all
treatments used.






Uecemberlusz. INiBA'/A~V-'Nt: :
Los Banos, Philippines, pp. 69-
102.


GEERING, A.D.W. and J.E. THOMAS.
1997. Search for alternative hosts
of banana bunchy top virus in
Australia. Australasian Pant
Pathology 26: 250-254.


MAGEE, C.J.P. 1927. Investigation on
the bunchy top diseases of the
banana. Council for Scientific and
Industrial Research, Melbourne,
86 pp.


SU, H.J., F.Y. WU and L.Y. TSAO.
1993. Ecology of banana bunchy
top virus disease. In: Valmayor,
R.V., Hwang, S.C., Ploetz, R, Lee,
S.C. and Roa, NV (eds).
Proceedings: International
Symposium in Recent
Developments in Banana
Cultivation Technology, Taiwan
Banana Research Institute,
Chiuju, Pingtung, Taiwan 14-18
December 1992.
INIBAP/ASPNET: Los Banos,
Philippines, pp. 308-312.


THOMAS, J.R. and R.G. DIETZGEN.
1991.Purification, characterization
and serological detection of virus-
like particles associated with
banana bunchy top disease in
Australia. Journal of General
Virology 72: 217-224.


ILIA I est

There was an increase in the mean
reading from 5 to 20 aphids per plant in
the ELISA test conducted on
uninoculated as well as inoculated plants
(Table 1). The presence of BBTV on
inoculated plants from the four
treatments indicated that the virus
particles have multiplied in the Canna
plants. Low number of aphids, five
aphids per plants, is capable of initiating
rapid multiplication of the virus in the
Canna leaf tissues. The uninoculated
plants or the control had the lowest mean
values.


CONCLUSION

Based on symptoms developed on
inoculated plants and ELISA test, it is
therefore confirmed that Canna is a host
of BBTV. The presence of BBTV on the
leaf samples indicated that the virus is
capable of multiplying in the Canna leaf
tissues.

LITERATURE CITED

ESPINO, R.R.C., L.V. MAGNAYE, A.P.
JOHNS and C. JUANILLO C.
1993. Evaluation of Philippine
banana cultivars for resistance to
bunchy top and Fusarium wilt. In:
Valmayor, R.V., Hwang, S.C.,
Ploetz, R, Lee, S.C. and Roa, NV
(eds). Proceedings: International
Symposium in Recent
Developments in Banana
Cultivation Technology, Taiwan
Banana Research Institute,
Chiuju, Pingtung, Taiwan 14-18






Table 1. Results of the ELISA test conducted on Canna BBTV-inoculated plants.

Overnight after substrate
addition
Treatment Leaf A B Mean Result


Five aphids per plant

Ten aphids per plant

Fifteen aphids per plant


Twenty aphids per plant


Control (-) (No aphids)
Control (+) BBTV


Samples

2,3,4,5

6,7,8,9

10, 11, 12,
13

14, 15, 16,
17


0.844

0.432

0.572


0.328

0.955

0.773


0.872 0.753


1 0.234 0.263
0.924 3.284


0.586

0.694

0.673


0.813


0.263
2.104


2.104





































D E




Figure 1. Symptoms of banana bunct
bunchy top virus. A-E inoculated w


p on inoculated Canna caused by banana
BTV, P- uninoculated (control).







ABSTRACT
Presented During the 39th I
Philippines Conference held at Astu
on May


Oral Presentation


Molecular sequencing and
phylogenetic analysis of sweet
potato chlorotic stunt virus (SPCSV)
in some sweet potato growing areas
in the Philippines. JA Panopio, LM
Dolores, GM Yebron and AC Laurena,
ISAAA, International Rice Research
Institute (IRRI), Los Banos, Laguna and
Crop Science Cluster-Institute of Plant
Breeding (CSC-IPB), College of
Agriculture, UPLB, College, Laguna

Sweet potato virus disease (SPVD), the
most important virus disease of sweet
potato (Ipomoea baatat (L) Lam.), is
caused by the synergistic interaction
between whitefly-transmitted crinivirus
Sweet Potato Chlorotic Stunt (SPCSV)
and the aphid-transmitted potyvirus
Sweet Potato Feathery Mottle Virus'
(SPFMV). The presence of SPFMV,
SPCSV and Sweet Potato Chlorotic
Fleck Virus (SPCFV) using CIP
(International Potato Center)-developed
NCM ELISA kit was detected in some
sweet potato commercial growing areas
in the country. Double infection of
SPFMV and SPCSV was found to be
the most prevalent, causing the SPVD in
these areas.
The SPCSV was isolated from
the complex virus using whitefly-
transmission into propagation host (1.
setosa and I. nil) and typical symptoms
of vein clearing and sunken vein were
observed on the diseased susceptible
plants. Reverse-transcriptase
polymerase chain reaction (RT-PCR)
resulted to the positive amplification of
the 460bp heat shock protein 70
hnmnlnn ie II. -er7nth\l frnnmnf finr +he


:PAPERS
management Council of the
otel, Puerto Princesa City, Palawan
I, 2008


Syasain (Bataan), Tranca (Laguna),
Tanato' (Bataan), ViSCA (Leyte) and
Nagbunga (Zambales) isolates using
primers specific to non-East African
strains. Molecular sequencing of the
partial Hsp70h gene of isolates Ablang
(Tarlac), Rang-ayan (Tarlac), Syasain
(Bataan), Tranca (Laguna) and Tanato
(Bataan) resulted to 99.3-100% and
97.2-100% homology based on
nucleotide (nt) and derived amino acid
sequences, respectively. All isolates
obtained from Central Luzon were found
to be 100% similar based on the
deduced amino acid sequence.
Phylogenetic analysis of the
partial Hsp70h gene indicated that all
the Philippine SPCSV isolates obtained
belong to the non-East African (NEA)
strain group of SPCSV. Comparson of
the partial Hsp70h sequence of Lhe four
isolates tp previously described
sequences of Hsp70h of East Africa
(EA) and NEA strains generated nt
homology between 74.2-77.8% and
derived amino acid similarity of 89.1-
92.5%.
The high sequence variation of
EA and NEA SPCSV strains is not only
relevant in the improvement of indexing
methods of planting materials for
quarantine measure but should also be
considered in planning sustainable
control strategies against SPVD and for
deploying various forms of resistance in
sweet potato breeding program.

Field evaluation and frequency of
Fertilizer application as control
options against coffee rust. JR Rint
and YA Ilagan, Cavite State University,
Indang, Cavite

DrawiviAn e *ef. .i \r l\fI 4 *ih4 mrnnhli,







with good water managemer
effectively controlled disease infectic
among the coffee seedlings. This findir
was verified in the field using the fn
bearing coffee plants. Hence, the stu(
was conducted to evaluate the effect i
frequency of fertilizer application
controlling coffee rusts on fruit bearir
coffee plants.
Using a Randomized Comple
Block Design, fruit bearing Liberica ar
Excelsa coffee varieties, planted in a 0
hectare of land, were randomly selected
at the rate of 15 plants per treatmer
replicated three times.
The fertilizer was applied a
spray for foliar application during d
season at the rate of 2 tablespoons pi
16 liters of water and as granular for sc
application during wet season at the ra
of 150 grams per tree. Five treatment
were used, namely: no fertilize
application and fertilizers applied at 2,
6 and 8 week-intervals.
The data gathered were tot
number of leaves, number of your
developing leaves, number of buds p,
branch, number of rust spots per le<
percent of plants infected by tP
disease, damage index on coffee le
due to infection, phytotoxicity on plan
due to treatment application, mez
monthly relative humidity ar
temperature.
The intensity of rust infectic
increased as the frequency of tt
fertilizer application increased. The
was an increase in the number of le
spots and number of leaves on tt
plants that were sprayed with fertilizer
bi-weekly intervals while those sprays
every 4 and 8 weeks have less
number of leaf spots. The incidence
the rust infection was minimal during tt
rainy season.
Fertilizer alone did not lessen tt
incidence of rust infection but tt


varieties fertilized at monthly interval
had the least number of spots per leaf
after 9 months of treatment. Liberica
had the least number of leaves infected
with rust when fertilized every 6 weeks
and Excelsa when fertilized every 2
months.

Reaction of eight carrot cultivars to
root-knot nematode, Meloidogyhe
incognita. NB Pedoche, LM Villanueva
and D de Waele. Benguet State
University, La Trinidad, Benguet,
Philippines and Katholieke Universiteit
Leuven, Belgium

The root-knot nematode, Meloidogyne
incognita is one of the most damaging
parasites of vegetables. Eight
commercial carrot cultivars (Daucus
carota L.) were evaluated under
greenhouse condition for resistance or
susceptibility to M. incognita, Benguet
population. Plants were inoculated with
1500 nematode eggs collected from
'Apollo' tomato (Lycopersicon
esculentum) roots with 1% NaOCI. The
degree of galling was assessed 8 and
16 weeks after inoculation. Host plant
reaction was classified as immune,
highly resistant, resistant, moderately
resistant, intermediate, moderately
susceptible, and highly susceptible
based on resistance index by Kouame
el al, 1998 {RI=4 (gall2 + egg2)].
Inoculation of. 1500 eggs/pot
significantly affected the growth and
yield of eight carrot cultivars 8 and 16
weeks after inoculation. Based on the
host response index, cultivars Caroline,
Chunhong and Lucky Kuroda were
intermediate; Argo Super Kuroda and
Royal Chantenay were moderately
susceptible and New Kuroda, New
Kurodagosun and Victoria were
susceptible to M. incognita. Identification
of varieties with some degree of
resistance could be useful in designing
integrated disease management







Temporal differentiation of rice
tungro bacilliform virus (RTBV) field
population in response to plant host
resistance gene. JT Niones' and AD
Raymundo2. 'Philippine Rice Research
Institute (PhilRice), Midsayap, North
Cotabato and 2Crop Protection Cluster
(CPC), College of Agriculture, UPLB,
College, Laguna

To determine the role of host genotype
in generating temporal variation of the
rice tungro bacilliform virus (RTBV)
populations, the genetic structure of
infecting virus within and between host
genotypes was analyzed in a collection
of natural field isolates from virus
resistant and susceptible lines over
three cropping seasons. RTBV genetic
variation was evaluated through
polymerase chain reaction (PCR)
amplification and subsequent enzymatic
Alu I-based restriction digestion of
RTBV coat protein gene 1 fragment. In
the total restriction digestion of RTBV
coat protein gene 1 fragment. In the
total population, eight distinct Alu I-
based coat protein RTBV genotypes
were identified and used as indicators
for virus diversity. The number of coat
protein RTBV genotypes detected in
single host genotypes varied from one
to eight with a few dominating and
persisting over the whole sampling
period of 18 months.
In general, RTBV populations
appear to be stable in genetic
composition over three cropping
seasons. The overall RTBV genetic
diversity values observed among host
genotypes did not significantly change
from season to season. However,
apparent observations showed that
tungro virus resistant Matatag line,
exerted selection pressure on the RTBV
virus population. This selection
eventually may allow the proliferation of
virulent variants and in time might
'breakdown' resistance. Over the
camnlinn timo wnin ic rocic-nt f nrl


nilar RTBV genotypes but different
rBV genotypes predominated in these
us resistant lines, indicating that host
notype may have exerted selection
assure.

Ironomic, serological and
molecular evaluation of BC2 papaya
progressed with PRSV-P resistance.
SSipr', AGC Sajise', GA Beligan', AC
lurena2, NH Tan Gana2, RA Drew3 and
A O'Brien3. CSC-IPB, College of
iriculture, UPLB, College, Laguna,
school of Biomedical and Molecular
fences, Griffith University, Nathan
impus, Brisbane 4111, Queensland,
istralia. Email:moninasiarO(vahoo.com

line with the objective of developing
a first PRSV-P resistant papaya plants
rough conventional breeding, second
ickcross (BC2) generations were
aluated and characterized using
rological, agronomic and molecular
chniques. The BC2 is product of
progressing the PRSV-P trait from the
paya wild type Vasconcellea
ercifolia to Carica papaya.
It was observed after three and a
If months of exposure to natural
section, 27 out of the 30 BC2 plants
eady showed infection of the virus
sed on visual inspection but after the
rological evaluation, results revealed
at only 10 out of the 30 plants tested
're positive to the virus. The mild
mptom observed during the first few
)nths after field transplanting did not
egress in some plants, which proved
e result of the serological test.
Fruit quality evaluation of the
elected BC2 plants was the focus of the
ronomic aspects of the study. In
neral, the fruit weight ranged from
9.5 1266.1 grams. Fruits have firm
Ilow orange flesh, with mild papaya
oma. The TSS (B) values ranged
im 11.33 12.83, which corresponded
"cM^a mnrfI,- rr --n -s *r








introgression of the resistant trait frc
V. quercifolia to C. papaya. TI
fingerprints showed marked divergen
of polymorphic band patterns betwei
resistant and susceptible F1 intergene
hybrid lines and susceptible I
intergeneric hybrid lines and B
progenies. The method successful
differentiated C. papaya genotypes frc
its wild relative, V. quercifolia.
The promising result of B
generation produced by convention
breeding could provide a sustainat
approach in the restoration of tl
Philippine papaya industry previous.
devastated by the disease.

Biological and molecul
characterization of a potyvir
infecting oil palm (Elaeis guineensi,
EG Dinglasan2, NH Tan Gana3, I
Salumbides1, FM dela Cueva2, /
Laurena3, MB Palacpac' and M
Agbagala'. Plant Quarantine Servic
Bureau of Plant Industry, Los Bari
Laguna'; Plant Pathology Laborato
Plant Genetic Resources Division2 a
Biochemistry Laboratory, Cr
Biotechnology Division3, CSC-IF
UPLB, College, Laguna

Naturally infected oil palm (Elai
guineensis) exhibiting characters
symptoms of virus infection such
chlorotic ringspot, mosaic, streaks, a
stunting were collected from oil pa
nurseries in Bukidnon. Infected leave
were classified based on symptom
reacted positively to SCMV-spec
antibody. The leaf samples were us
for viral isolation, biologic
characterization, and total DI
extraction. Virus transmission studio
revealed that the virus can
mechanically transmitted to corn (2
mays), sorghum (Sorghum bicol
suaarcane (Saccharum officinarum) a


naturally infected and mechanically
inoculated plants had strong positive
reactions to sugarcane mosaic virus
(SCMV) antibodies. Total RNA were
extracted from leaves of infected oil
palm, and the mechanically infected
corn and sorghum. RT-PCR was done
using Superscript II to generate the
cDNA. Primers sets for amplifying
protein gene of potyviruses were used
namely, potyvirid primers developed by
Gibbs and Mackenzie (1997),
sugarcane mosaic (SCMV) by Yang et
al. (1997), and sorghum mosaic (SrMV)
by Yang et al. (1997). PCR using the PT
primers obtained amplicons indicating
that the virus behng to the genus
Potyvirus. PCR using the SCMV primers
also yielded amplicons which further
suggested that the infective potyvirus
could likely be a strain of SCMV.

Conidial state of Leiveillula taurica
(Lev.) Am. on pepper (Capsicum
annum L.). TU Dalisay and RFO
Peralta, CPC, College of Agriculture,
UPLB, College, Laguna

Masses of wh te powdery growth on the
lower leaf surface and yellowing on the
upper surface of Capsicum annum var.
Longum Bailey 'Jalapeno' and var.
Celica' were observed. Severely
affected leaves curled and plant became
defoliated. Colonies are epiphyllous,
brown with age. Conidiophores in
fascicles arise singly or in groups from
stomates, sometimes branched near
upper portion, 76.6-189.8 x 10.0-13.3 p
(X=146.9 x 9.7 p for 'Celica' and 130.0-
266.4 x 6.7-10.0 p (X-165.8 x 7.6 p) for
"Jalapeno', with one to three septa just
below the mature conidium. Conidia
appear to have network or ridges and
crests, borne singly or .-1 chain of two or
three, rarely cate.-ulate of two
morphological types namely cylindrical
or clavate to pyriform, smooth,
occasionally verrucose, hyaline,
unicellular. Cylindrical conidium







measure
(X=623


, A-7A Q y 1A i-9 7 11


66.6 x 13.3-20.0 (X=54.4 x 16.8 p) for
'Jalapeno' while clavate to pyriform
conidium measures 59.9-83.3 x 10.0-
26.6 p (X=70.2 x 17.9 p) for 'Celica' and
50.0-76.6 x 13.3-23.3 p (X=62.3 x 18.7
p) for 'Jalapeno'. The above
morphological characteristics are
associated with powdery fungus, a
conidial or imperfect state of Leiveillula
taurica.
Laboratory tests showed that
percent germination of conidia
significantly increased with an increase
in relative humidity. Temperatures
between 20-300 favoured increase in
germination. Further increase up to 40%
inhibited germination of spores.
Inoculated spore germinates as early as
2 hours after inoculation. Germ tube
occurs at its tip along its length.
Appresorium is formed upon contact of
the hypha with the leaf surface. Ten
days after inoculation, numerous fruiting
structure coming out from stomates
were seen.

Fungi associated with stem-end rot
of mango (Mangifera indica L.). TU
Dalisay and RFO Peralta, CPC, College
of Agriculture, UPLB, College, Laguna.

Fungi consistently isolated from rotten
mango fruits from Pangasinan, Davao,
Cebu, Zambales and Laguna were
Lasiodiplodia theombromae Pat.,
Colletotrichum gloeosporoides Penz.,
Phomopsis mangiferae Ahmad, and a
species of Pestalotiopsis. C.
gloeosporoides dominated the seed
tissues coming from Panganisan and
Davao with occasional occurrence of
species of Pestalotiopsis and P.
mangiferae, L. theombromae were
always isolated from samples coming
from Cebu with one sample that
harboured C. gloeosporoides. Fruits
from Laguna and Zambales have P.
manaiferae as the associated fruit rot


is conclusive due to limited number of
;amples subjected for isolation;
however, chances that they were
present on rotted fruits were verified.
:athogenicity tests of fungi, exhibited
certain degree of rot on fruits. Initial
legree of rotting inflicted by L.
heombromae, C. gloeosporoides, and
. mangiferae were not different. But on
he '6h day of observation, L.
heombromae caused 30% fruit rot.
.east rotting was observed on C.
rloeosporoides (3.3%) and P.
nangiferae (5.0%). Sunken and
constricted black lesions were observed
in fruits inoculated with C.
floeosporoides while a spreading rot
vas noted on' fruits affected by L.
heombromae and P. mangiferae. The
matter, however, produced a slow
readingg rot. Pestalotiopsis sp. failed to
produce rot. Perhaps it was isolated as
Ssaprobe but not as a true causal
)rganism of fruit rot.
The fungi were inoculated singly
ir in combination to evaluate
compoundedd effects on severity of rot.
theombromae inoculated alone
caused 100% fruit rot while only 6.2%
Ind 9.0% rot were observed on fruits
loculated with C. gloeosporoides and
. mangiferae, respectively. Mixtures of
ungi exhibited various degree of rotting.
Zot seemed to have aggravated
consistentlyy if L. theombromae was
combined. Combinations of different
ungi with L. theombromae caused
bout 96 to 100% rot on the 141h day of
observation. Rot was observed as early
is 6th day after inoculation while in
combinationss without L. theombromae,
percentt fruit rot reached to only 12%. It
;eemed therefore, that L. theombromae
vas more responsible in causing severe
ot than the rest. L. theombromae
loculated alone caused 17% rot as
iarly as 6 days after and 100% at 14
lays incubation.








management of panicle blight
disease in rice. PS Torrena, PhilRice,
Midsayap, North Cotabato

A study to document areas infected with
panicle blight in North Cotabato
Province, identify the pathogens
associated with the disease, and
establishment of management options
was conducted at PhilRice MES, Bual
Norte, Midsayap, Cotabato.
Five municipalities (Kabacan,
Libungan, Midsayap, Pigcawayan and
M'lang) where inbred varieties were
planted and found susceptible to panicle
blight, particularly variety PSBRc78,
were reportedly infected.
A complex of three bacteria
(Burkholderia glumae, Acidovorax
avenae and Pseudomonas
fuscovaginae) and fungi (Fusarium sp.,
Curvularia sp. and Altemaria sp.) were
isolated from the seed samples.
B. glumae was pathogenic to
four varieties tested in the pathogenicity
test. Symptoms included wilting or
drying of seedlings, sterility,
discoloration of spikelets during the
reproductive phase.
Screenhouse test showed that
rice plants applied with organic herbal
nutrient (OHPFR) had the lowest
percentage of severity infection of
44.44% but not significantly different
from indigenous micro-organisms from
fermented rice (IMOFR), indigenous
micro-organisms from fermented rice +
fermented plant juice (IMOFR+FPJ),
indigenous micro-organisms from
fermented rice + lactic acid serum
(IMOFR+LAS), lactic acid serum (LAS)
and organic herbal nutrient (OHNM) with
means of 61.11%, 50.00%, 55.56%,
50.00% and 55.56%, respectively.
Of the 50 rice entries evaluated
under screenhouse condition, only three
cultivars (PSB Rc18, NSIC Rc122 and


Characterization and identification of
prevalent races of Xanthomonas
oryzae pv. oryzae in major inbred and
hybrid rice growing areas in the
Philippines.' MaGM Babb', JG
Castres', MaJC Duque1, LM Perez', GB
Amar', JT Niones2, LM Borines3, A A
Dela Cruz1, EO Espejo3, J Duque2,
Truong Hoai Xuan' and FA dela Pefra',
'PhilRice- Central Experimental Station,
Science City of Muioz, Nueva Ecija
(*Author for correspondence; email:
glnababbd)pphilrice.gov ph); 2Midsayap
Experimental Station, Bual Norte,
Midsayap, North Cotabato, and
Department of Pest Management,
3Leyte State University (ViSCA),
Baybay, Leyte

Collection of Philippine X.o.o (PXO)
isolates was conducted in major inbred
and hybrid rice growing areas of the
Philippines. The different isolates
collected were inoculated to the seven
bacterial blight near isogenic lines (BB-
NILs). The virulence pattern of the
isolates on the BB-NILs were compared
to the virulence pattern of the PXO
races on the NILs to determine the race
of each isolate. In Northern Luzon, most
of the isolates follow the reaction
patterns of races 9 or 5, race 3b, race 1,
and some races 4 and 8. In Eastern
Visayas, isolates with virulence pattern
similar to race 8 is more prevalent in the
region than the other races. Some
isolates showed virulence patterns of
races 3a, 3b, 5 and 7, and only one
isolate showed a virulence pattern
similar to race 2. In Southern Mindanao,
majority of the isolates had the same BB
disease reaction pattern with Race 9.
The rest of the isolates just slightly
resembled with other BB races; their
disease reaction is the same with five to
six of the differential lines but not to the
seven NILs.
It is recommended that the
reaction patterns of the different isolates
be verified by inoculatina them aaain to







reactions are not very clear, although
these phenotypic data could give us an
idea of the possible races present in the
region. It is necessary to have a
molecular analysis for further
characterization of the races present.

Distribution and occurrence of the
rice blast fungus, Pyricularia grisea
in the Philippines. FA dela Pefra and
MAS Manalo, PhilRice, Science City of
Munoz, Nueva Ecija

Blast sample collection was done in
several rice growing areas from 2004 to
2006 to determine the distribution and
occurrence of Pyricularia grisea, the rice
blast fungus in the Philippines. Leaves
showing blast lesions or panicles with
panicle/neck blast sym[toms were
collected from farmers' field in Luzon
(Nueva Ecija, Pangasinan, Isabela,
Benguet, Camarines Sur, Tarlac,
Bulacan, Ilocos Sur, Ilocos Norte and
Oriental Mindoro), Visayas (Leyte, Iloilo,
Aklan, Bohol and Biliran Province) and
Mindanao (Agusan del Sur, Zamboanga
del Sur, Zamboanga City and South
Cotabato). Identification was based on
symptoms, structure of the conidia,
colony characteristics and pathogenicity
tests. The samples from the same
variety within the same
barangay/municipality through the
farmers' fields were treated as one.
Moreover, samples from lines were not
considered in this paper. Due to time
and financial limitations, collection was
not done in all reported areas with rice
blast occurrence. Distribution of P.
grisea in the Philippines was mapped
depending on the geographical location
where it was collected.
There were 146 blast samples
gathered from different varieties.
RpvAntv nine (77 1 war rofllarrt from







is targeted primarily in high value crops treatments for control of plant parasitic
includes nurseries, vegetable and fruit neniatodes on cotton (Gossypium
tree plantings. Midas 50:50, a 50:50 hirsutum). Aldicarb (Temik 15G) applied


mixture of iodomethane and chlorpicrin,


approved by the U.S. Environm
Protection Agency for an experim
use permit in grower f
lodomethane alone and 50:50 mi
was tested in two separate field
nn^ <-* ..j.__i_- / -. -_ _ \


and the other for contn
nematodes (Rotylenchus
northern Florida U.S.A.
Broadcast equivalent
iodomethane 50:50 were
of 112, 168, 224, 280 a
while the 50:50 product %
392 Ibs. /acre. Imme


:ently stan
ental abar
ental for tl
ields. root-
xture renif
trials, Colu
control nem
form (Bay
is) in thioc
2006. avail
nf thick


in-furrow at 5.62 ko/ha has


lent that include
sed by cotton grower
I manage the souther
idogyne incognita
chus reniformis), an
foplolaimus columbu,
seed-applied system
ice), which include
atode management,
producers in 2007. I
'TA Cmnl"re, Dol


-- -L. -. ---- I .i a -..







Oribiana, CA Relevante and CH recombination and limited gene flow.
Balatero, CPC, College of Agriculture, High host specificity of each formae
UPLB, College, Laguna and East West specials is due to their non- vegetative
Seed Co., Bulacan compatibility. The nature of the diversity
encompassed within a formae specials
Vegetative compatibility groups (VCGs) has a direct significance on the
were determined for 57 F. oxysporum prospects for disease control through
isolates from Momordica charantia L. genetic resistance. It is recommended
(bittergourd) and Lagenaria sicerara that vertical or race- specific resistance
(Mol.) Standley (bottle gourd) using in plant shoqid be used in managing
nitrate-non-utilizing (nit) mutants. Of Fusarium wilt of bittergourd and
these, 24 isolates that sectored bottlegourd
frequently in chlorate medium were
genetically unstable and not further Aggressiveness and genetic
used in the experiment. Sixty one nit structure of the seedbome pathogen
mutants were generated from F. Gibberella fujikoroi Sawada
oxysporum f. sp. momordicae isolates Wollenweber causing bakanae
with their respective frequencies: nit1 disease in rice. CJR Cumagun, K
(31), nit3 (11), nitM (19). Twenty five nit Aguilar, EB Gergon and AT Angeles,
mutants were generated from F. CPC, College of Agriculture, UPLB,
oxysporum f. sp. lagenariae isolates College, Laguna and PhilRice, Science
with their respective frequencies: nit1 City of Muioz, Nueva Ecija
(13), nit3 (5), nitM (7). F. oxysporum f.
sp. momordicae populations have Forty-six Fusarium strains from Laguna
higher frequency of reversion to wild (13) and Nueva Ecija (33) weralOated






were obtained. Majority of the isolates extraction involved. A novel method of
(35) induced similar mean amount of detecting rice tungro viruses in rice leaf
disease as measured by seedling height sap samples by one-step reverse
while five brought about significant transcriptase PCR (RT-PCR) without
differences in the two varieties across nucleic acid extraction, thereby reducing
two trials showing variety x isolate cost, was pioneered by this study. This
interaction. Significant genotypic procedure exploits the rapid adherence
variation for aggressiveness (P=0.05) of the viruses unto the walls of the PCR
was found in both varieties with medium tube at cold temperatures and the
heritabilities (0.54-0.55) due to immediate release of RNA or DNA at
significant isolate-environment higher temperatures. CDNA synthesis
interaction and error. The most converts the RNA genome of RTSV and
important sources of variation across the mRNA of RTBV into cDNA. The
two trials were isolate and isolate- subsequent PCR process in the same
environment interaction, accounting for tube amplifies the cDNAs alongside with
34% and 42% of the total variation for the RTBV DNA genome. The method
aggressiveness trait. Aggressiveness of produced results comparable to ELISA
40 isolates on the two varieties was but superior when it comes to cost and
highly correlated (r=0.76), but speed. At the same time, it is a lot
correlations between trials were easier and safer to perform than other
moderate (0.44-0.50), suggesting that PCR-based methods of detection
aggressiveness is affected by the primarily due to the elimination of RNA
environment. Ability to undergo sexual and DNA extraction. It is also optimized
reproduction and saprophytic phase in to be low-cost to about P50 or less per
seeds and soil of some isolates of G reaction. The method thus breaks the
fujikuroi could account for high misconception that PCR-based
quantitative variation in aggressiveness, detection of viruses needs to be
The aggressive isolates that have been complex and expensive. The procedure
found stable could be used in evaluating currently works well in detecting RTBV
for disease resistance. High quantitative and RTSV individually by one-step RT-
variation in aggressiveness of G. PCR. Efforts to optimize it to detect the
fujikuroi could explain the resurgence of two viruses simultaneously' in one
bakanae disease in rice field in Nueva reaction multiplexingg) are now
Ecija. underway, by designing and screening
for suitable PCR primers, to even make
Simultaneous detection by one-step this innovation more powerful. This
reverse transcriptase PCR (RT-PCR) presentation highlights the results of the
of rice tungro spherical virus (RTSV) one-step RT-PCR including any other
and rice tungro bacilliform virus developments leading to the one-step
(RTBV) from rice leaf samples. RL multiplex RT-PCR detection of the
Ordonio and GO Romero*. PhilRice, tungro viruses.
Science City of Muroz, Nueva Ecija
e cin r io ( is Marker-aided backcrossing of
Polymerase chain reaction (PCR) is bacterial blight resistance genes in
long known to be very sensitive and hybrid rice maintained and restorer
accurate for detecting viruses as an hid rice min ainer and restorer
alterative to Enzyme-linked lines. LM Borines, EO Espejo, R
alternative to Enzyme-linked Torillas, CM Vera Cruz and ED Redorna,
Immunosorbent Assay (ELISA). Tr ias, C Vera Cr and E Rei),
Levte State University (ViSCA),







major limitation to nyria rice
duction in the Philippines is the
1ceptibility of hybrids and component
s to bacterial blight (BB) caused by
rthomonas oryzae pv. oryzae (Xoo).
>roving the resistance of the hybrid
component lines to BB is necessary
ore they should be extensively
ployed to attain target yield.
This study was conducted to: 1)
aluate the reaction of Mestizo hybrids,
ir B and R lines to PXO races, 2)
corporate bacterial blight resistance
ies, to B and R lines via marker-
ed backcrossing and 3) confirm the
'sence of introgressed Xa genes in
progeny of each backcross
aeration through phenotyping with
agnostic Xoo races and molecular
irker analysis.
Mestizo hybrids, their B and R
:s, IRBB61 donor, and checks were
anotyped using ten PXO races.
irker-aided backcrossing from
3B62 donor (with Xa4/7/21) to each B
d R line was done to introgress target
nes. The resistance genes in the
vanced lines were confirmed using
agnostic PXO races and analyses of
The reaction of Mestizo hybrids,
ir B and R lines to PXO races except
58025B was similar to IRBB4
licating the presence of Xa4
instancee in five out the six Mestizo
brid maintainer and restorer lines.
distancee genes Xa7 and Xa21 were
:orporated together with Xa4 to BCsF2
>geny of IR34686-179-1-2-1R,
30819-34-2R, IR62161-184-3-1-3-2R
d IR6888B. Resistance genes were
;o incorporated to BC4F1 progeny of
58025B maintainerr of Mestizol) and
38897B.
The lines containing gene
ramids had increased resistance to


ster Presentation


rvey and damage assessment on
iana cultivars infected with plant
-asitic nematodes in Davao del
r, Davao del Norte and Cebu
wvinces. RA Zorilla, TO Dizon, FS
a Cruz, Jr., MS Pinili, AG Castillo,
Reyes, SM Calderon, LC del Mundo,
ie Waele and I Van den Bergh, CPC
i CSC-IPB, College of Agriculture,
LB, College, Laguna and Katholieke
iversiteit Leuven, Belgium

rvey and root damage assessment of
iana cultivars infested with plant
*asitic nematodes were conducted in
vao del Norte, Davao del Sur and
bu Provinces. In Davao del Norte,
m five municipalities- surveyed
ipalong, New Corella, Tagum City,
>. Tomas and Panabo) 10 cultivars
m 44 root samples revealed cultivar
irado had the highest percentage of
ad roots (20.60%). Percent root
:rosis was highest on cultivar Pelipita
h 26.5%. Root galling index rating of
(trace with few galls) was obtained
m cultivars Lakatan and Mundo. In
vao del Sur, from 48 root samples
m five municipalities (Digos City,
gonoy, Podada, Kiblawan and Sta.
iz) cultivar Morado showed highest
rage dead roots (42.30%). Cultivar
lo gave the highest percent root
cross of 40.0%. No root galling index
31) rating was observed among roots
Elected in different municipalities.
On the other hand, survey
nducted in Cebu Province revealed
it from 122 root samples collected
m 10 municipalities (Argao,
ilaguete, Alcoy, Santander, Oslob,
bonga, Dumanjug, Sta. Cruz, Barili
d Carcar), 20 cultivars were infested








Sabang Puti obtained the high
percent root necrosis of 76%. In contre
cultivar Manila gave the lowest rc
necrosis of 5.75%. Based on the re
galling index cultivars Sulay Baguio ai
Gloria yielded mean RGI rating of
(<25% of roots galled), indicative of roi
knot nematodes.

Techniques for Panicle Bla
Evaluation. JP Rillon and MaSV Du(
PhilRice-Central Experiment Static
Science City of Mufioz, Nueva Ecija

Four assessment techniques were us
to determine the best evaluati
technique to identify the reaction of m(
popular varieties to panicle blast. The
are spray inoculation, spore injection
inoculation through wrapping of pani<
with cotton balls and under natu
infection. Three susceptible che
varieties 4IR50, IR72 and IR42) we
used. The highest percent sevc
panicle blast incidence was obtained
IR50 with 100.00% disease incidence
all inoculation techniques. For IRA
60% disease incidence was observed
spore injection, 68.80% in cott
wrapping, 66.70% in spray inoculati
and 66.40% under natural infection. F
IR42, 90% disease incidence wv
obtained through natural infection, 5(
through spore injection, and 34.7f
disease incidence in spray inoculatic
In inoculation by wrapping the pani
with cotton soaked in spore suspense
3.82% disease incidence was observe
Among the 37 popular varieties, NW
Rc19 had the lowest disease incider
with 42.26% in spray inoculation, 44/c
cotton wrapping, 65.00% in sp(
injection and 66.67% in natural infectii
NSIC Rc142 had the lowest disez
incidence with 100% in spore injectii
90.48% in cotton wrapping, 80.65%
spray inoculation, and 68% in natL
j; 4r.--ir, Qn,- ir n-*i inlnaiM-% horli


determined primary infection a
resistance to fungal penetration' It al
effectively established infection withe
wounding the panicle and ensure that
tissues of the panicle received inoculu
The spore injection and inoculati
through wrapping of panicle with colt
balls soaked- in spore suspensi
techniques can evaluate spread
pathogen within the panicle.

Development of rice bli
management practices in rainf
lowland rice. MS Desamito, EM Vadi
GS Rillon and TH Xuai
Conr- ;.i.,. r "~, -: il or truonghoaixuan(i
philrice.qov.ph PhilRice-Central
Experiment Station, Science City
Muhoz, Nueva Ecija

Leaf blast and panicle blast caused
Pyricularia oryzae was them
prevalent and caused a serious thn
across study site in Brgy. Banti
Guimba, Nueva Ecija during this v
season 2006. High yielding rice varin
NSIC 130 was the most susceptil
having 50-80% panicle blast and 4:
unfilled grains resulting in crop loss
75% among three varieties planted
farmers across the site. N(
collaborator farmers who planted P
Rc 82 harvested about 5t/ha, exc,
one who got 50% its yield potential c
to neck blast and panicle blast infectil
Six farmer collaborators who were gi\
PSB Rc 82 seeds harvested fr
previous experimental setup treated v
the local antagonistic bacte
inoculants, had a negligible bl
incidence and got an average of 4.8-
t/ha.
Development of leaf blast in
rainfed lowland site started at 44 DA1
the three lowest leaf positions v
severity rating of 1-3. The combinat
of high relative humidity (90-95%), d4
:f n ann -\ r- ,-- .:;kll r-







nnanceu me iUdi Uldsb IltUII:U tLU
large and coalesce, and produce
onidia at the center of the lesions that
Iter induced the disease widespread.
ifected low leaves were dried up then
iere were no lesions developed on the
oung leaves until 74 DAT, the second
ycle of infection restarted, and the neck
last was seen at 81 DAT. By closely
recording the disease symptoms and
igns over seasons and different
varieties, the detective tool of the
disease will be gradually developed and
hared with farmer collaborators and
on-collaborators.

lutrient balance and disease
iteraction in irrigated lowland rice
Ecosystem. PS Torrefa, EM Valdez,
IS Desamito, MAS Manalo, RT Cruz
ind TH Xuan (Corresponding a1utio
"uonghoaixuan@philrice gov.ph).
'hilRice-Central Experiment Station,
Science City of Muioz, Nueva Ecija

)n-farm trials on site-specific nutrient
management using the recommended
ates of NPK, LCC- and MOET-base
Ind farmers' practices affecting rice
lisease infestation and grain yield were
conductedd in three farm fields
representative: 1) trained farmer (owned
i hectare field, affordable fertilizer and
abor input, transplanted crop
establishmentt with certified seeds of
ligh yielding varieties) and 2)
progressivee farmer (owned 4-ha farm,
and accessed to new technology input
i io-h e r.n im mcajrlr anrl hvhririd CumdF


ne s u1 ir-r, c
n LCC and M
practices we
treatment plot
after planting b


the tl
rere pre-c


event o


Dasea on me cut crop irom queuiraru o
5 sq m at 14% moisture content.
On farm trial by trained farmer.
The recommended NPK rate (90-45-45
kg/ha) and LCC and MOET tool (60-40-
65) were more balanced NPK than that
of the farmer practice (71-16-24 kg
NPK/ha plus 7 kg zinc sulfate) ahd
produced higher grain yield (5.10 5.60
t/ha vs. 4.64 t/ha). Similarly in the
second trial, LCC-base and MOET were
useful tool to reduce the farmer's
fertilizer input from 71-42-11 kg NPK/ha
to 49-22-92 kg NPK/ha to 49-22-92 kg
NPK/ha while produce a comparable
grain yield of 5.3 t/ha. Higher rate of N
(104-136 kg/ha) in combination with PK
at low rate 20-12 or 7-7 kg/ha induced
sheath blight affected area by 30%.
On farm trial by progressive
farmer. Direct seeded and transplanted
Mestizo 3 that were applied more with
the NPK recommended rate (90-45-45
kg/ha) or based on LCC and MOET tool
(65-45-45 or 50-15-55), produced higher
grain yield (6.2-6.9 t/ha) than that from
the farmer's practice one (108-25-25
and 138-32-32 kg NPK/ha with two
splits) while decreased the BLB severity.
In short, on-farm trials on the
nutrient 'requirement and disease
interaction by trained and progressive
farmer collaborators indicate a location-
specific. LCC and MOET were useful
tool to help farmers save at least 40%
NPK rate, sustained their grain yields of
inbreed and hybrid varieties and
reduced severity indexes of SHB, BIB,
and clean seeds.

Fungi in agricultural soils of
Benguet: Bane and boon to
commercial vegetable production.
LAD Lando, AL Nagpala, CD Ba-a and
JP Galeng, Department of Plant
Pathology, Benguet State University, La
Trinidad, Benguet







La Trinidad and Kibungan of Benguet.
The most abundant species isolated
was Penicillium (25). Following
Penicillium in descending order of
frequency were Fusarium (13),
Trichoderma (12), Paecilomyces (12),
Plasmodiophora brassicae (11),
Aspergillus (10), Mucor (9) and
Altemaria (4). The following were
isolated at least twice- Rhizopus,
Gliocladium, Colletotrichum. On the
other hand Botryotinia, Pythium and
Rhizoctonia were isolated once in the
sampling sites.

Efficacy of seed treatments on
control of bakanae disease of rice. AT
Angeles, EB Gergon and LR Pautin,
PhilRice, Science City of Muioz, Nueva
Ecija

The efficacy of different chemicals
(alum, benomyl, captain, mancozeb,
combination of benomyl and mancozebi
and 5% NaOCI), botanicals (Acapulco,
gumamela, Jatropha, kakawati, lagundi,
lemon grass, malunggay and neem), hol
water treatment, detergent and
Trichoderma sp. as seed treatment
against bakanae was evaluated.
Crude extract of botanicals were
prepared from leaves, bark, of fruits o1
plant materials and applied in two
concentrations (25% and 50%) while
chemicals were applied at 0.1g/100
seeds. The different treatment materials
were tested in the laboratory against the
bakanae organism (Fusarium fujikuroi)
collected from Pantabangan, Rizal using
paper disc method. The zone pi
inhibition was measured 2 days after
incubation at 270C. Likewise, the activity
of the different seed treatments were
applied to PSB Rc 82 seeds either
before or after soaking them in spore


Based on zone of inhibition fou
treatments benomyll, combination o
benomyl and mancozeb, 25% crude lea
extracts of lagundi and lemon grass
were significantly different from the
control indicating that benomyl was the
component effective against the
pathogen. In vitro study showed the
captain, mancozeb, benomyl, sodiun
hypochlorite (NaOCI) and crude extract:
from Jatropha seeds had significantly,
higher seed protection from bakana4
than the other treatments. Captan
mancozeb, benomyl and NaOCI
provided protection to the seedling:
from bakanae infection for 21+ days bu
the effect of benomyl was significantly'
lower than the NaOCI and mancozeb
Mancozeb, however, was fount
phytotoxic making it less desirable thai
benomyl. Crude extracts from neen
leaves and gumamela flower at botl
25% and 50% concentration, an<
Jatropha seeds, kakawate leaves an<
Acapulco leaves and fruits (25%
provided some degree of see<
protection against F. fujikuroi up to 1,
days from sowing.

Reactions of local and introduce(
banana cultivars and hybrids to blacl
Sigatoka and banana bunchy tol
virus. TO Dizon, FM dela Cueva, FI
dela Cruz Jr. and AB Molina. CSC-IPB
College of Agriculture, UPLB, College
Laguna and INIBAP c/o Khush Bldg.
IRRI, Los Banos, Laguna

Five local cultivars and six introduced
hybrids (FHIA lines) of banana wen
evaluated for their reaction to blacl
Sigatoka and banana bunchy top viru!
under field condition. Resistance wa:
evaluated by measuring the youngest
leaf spotted and disease severity inde:
at harvest stage for black Sigatoka an







Hw youngest leaf spotted, high severity
idex and index of youngest leaf spotted
nd low index of non-spotted leaves.
:ultivar Cardaba, although with low
youngest leaf spotted, had the lowest
disease severity index and index of
youngest leaf spotted. All introduced
ybrids, FHIA lines, except FHIA 02,
'ere found to be resistant. Resistant
ies had high youngest leaf spotted,
iw disease severity index and index of
youngest leaf spotted but high index of
on-spotted leaves. The reaction of
ardaba to black Sigatoka was
comparable with the FHIA lines.
For banana bunchy top, Cardaba
as found to have the lowest percent
icidence followed by Latundan. There
'as rapid increase of banana bunchy
)p disease on Cuarenta Dias and
akatan-Cavite, and slight increase in
avendish and Lakatan-Davao. Among
ie introduced hybrids, FHIA 18 did not
jccumb to the disease even after 18
months after planting. FHIA 01 had low
percentage incidence while FHIA 25 and
HIA 17 had high percent incidence. As
ampared with the local cultivars,
hybrids developed the disease at lower
ite.

luick ways to know your crops'
nportant diseases. CB Pascual, FM
ela Cueva, LM Dolores, NL Opina, TO
izon and EG Dinglasan. CSC-IPB,
college of Agriculture, UPLB, Collage,
aguna

he appropriate and effective disease
management strategies can not be
iade unless the cause of the disease is
afrectly detected and identified.
traditional identification of plant
athogens has been based largely on
lorphological criteria which are usually
fficult, requires skills and are highly
fected by environmental conditions.


tested or modified at the Institute of
'lant Breeding (IPB), UPLB for rapid
nd accurate disease indexing and
pathogen identification. Training
modules for these molecular and
erological methods are now available
it IPB.

performancee evaluation of
genetically transformed (T1) plants
or blight, bacterial blight and
temborer. RR Aldemita', ES
,vellenoza2, MM Rosario3, and RT
liranda3, Genetic Transformation
laboratory, Plant Breeding and
biotechnology Division, PhilRice -
:entral Experiment Station, Science
;ity of Murioz, Nueva Ecija

ligh yielding varieties with resistance to
common devastating diseases of rice
as been the foremost objective of rice
reeders. Due to limitations in the gene
ool and constantly mutating pathogens,
iis endeavor has been a great
challenge. Genetic transformation was
tilized to address the problem. Genes
)r resistance to blast and sheath blight,
acterial blight and stemborer were
itroduced to inbreds, hybrid parentals,
nd new plant type lines. A selectable
barker resistance evaluation was
conducted in the T1 generation using
electable agents: 50mg/L kanamycin,
Omg/L hygromycin, and the herbicide
IASTA (30 mg/L) which were used to
introduce chitinase/glucanase, Xa21,
nd pin2 genes, respectively, though
enetic modification. Green and
igorous seedlings were selected and
rown to maturity. Kanamycin resistant
nes (369 from 59 events of 14
enotypes), hygromycin-resistant plants
97 from 42 events of 6 genotypes), and
IASTA resistant lines (399 from 116
vents of 3 genotypes) were obtained in
iboratory and screenhouse








conditions. Resistance screening for 1
three traits was started in the I;
quarter of the year and will be contini
this year. Resistant lines obtained i
be further characterized for ag
morphological characteristics
consideration as a breeding material
as an improved variety.

Morphological characterization a
morphotometrics of UPLB, Day
and Quezon Radopholus sim,
(Cobb) Thorne populations of bana
(Musa sp.). MS Pinli', D de Waele2, J
Castillo3 and RA Zorilla3, 'Gradu
Research Assistant, IPB-KU Leuv
Belgium Project, 2Katholieke Universi
Leuven, Belgium, 3CPC, UPLB, Colle!
Laguna.

Three populations of banana burrow
nematode Radopholus similis fr
UPLB, Davao and Quezon proving(
were isolated and cultured asepticall
vitro using carrot discs at 28
Morphological comparisons revea
variability on taxonomic characters. 1
shape and size (length) varied wit
and among populations, except sin
type found in male UPLB R. simi
Populations from Davao and Que2
observed a pointed to truncate tail er
with or without annulations, where
broad to round to smooth terminus m
found in UPLB nematodes. Larg
female and male were.found in UP
with the total body length of 632.0 6
pm and 592.2 605.4 1pm, respectivE
Shortest female was observed
Quezon population with a total be
length from 592.2 631.7 p.m.

Yield performance of gami
irradiated banana cv Lakatan w
resistance to banana bunchy t
virus. TO Dizon, OP Damasco, E
Guittap, JS Estrella and LS Cayr
r~S.-IPR r.nllane of Anriciltiur IJPI


were evaluated for resistance to bana
bunchy top virus under greenhou
using artificial inoculation. Those tl
were resistant to BBTV were furtt
evaluated in the field under high disea
pressure. The fruits of putative resists
lines with symptoms appearing dur
the flowering to fruiting stage wf
harvested and the bunch weig
number of hands, number of fingers I
hand, length of the fingers anr tc
soluble solids were taken.
Based on the results, plants
putative resistant lines had lower bur
weight, smaller finger and less numt
of hands per bunch than the control
plants with no symptoms of the disea:
However, no differences were obser%
on the number of finger per hand a
the total soluble solids.

Variation of Peronosclerospt
species causing sugarcane dow
mildew by PCR using rDNA-1
Primer. CB Pascual, FM dela Cue
AA Gumarang, RT Luzaran and I
Dinglasan, CSC-IPB, College
Agriculture, UPLB, College, Laguna

Downy mildew pathogens
recognized as important disea;
causing organisms in the Philippin,
but they received rarely relatively lii
attention, especially the downy milde
in sugarcane. Even today, there ,
many important gaps on publish
information about their biology a
epidemiology.
To determine the exact iden
and characteristics of the downy mild
species in sugarcane, infected I'
samples at different stages of infect
were collected from Luzon, Visa)
(Cebu, Negros) and Mindanao. Ti
were examined and characterized us
conventional and molecular techniqL
to detect different species.
Results showed that there w








IUl f W"lt UUbUIV~au 11U011 t1yayall
plates followed by isolates from
ampanga and Davao. The smallest
>ore dimension was recorded from
egros (Victorias City) isolates. Bogo
plates did not produce conidia but
rmed oospores only. Positive
nplification from genomic DNA of all
electedd isolates using
eronosclerospora-genus-specific
'GS) primer confirmed that they all
along to the genus Peronosclerospora.
universal primers for internal
inscribed spacer region differentiated
e species of Peronosclerospora into P.
acchari, P. philippinensis and P.
liscanthi.

loculum potential of bakanae on rice
seds and its effect on yield. EB
ergon, AT Angeles and LR Pautin,
hilRice, Science City of Muiioz,
ueva Ecija

he influence of the initial inoculum of
akanae pathogen on the seed to the
assible infection carried on the next
wanting season and its effect on yield
as determined. Naturally infected
seds of rice variety PSB Rc 82
previously assessed for bakanae
fection during the 2006 dry season
ere collected from the National
cooperative Testing field plots.
representative seed lots (40 gm/plot)
ith varying degrees of infection (0%,
%, 10%, 15%, 20%, 30%, 40% and
0%) were cleaned of deformed,
iscolored and weed seeds, subjected
blotter and germination tests, sown in
x 2' seedbed trays, and 25 days after
awing, they were transplanted in 4m x
m plots using one seedling per hill.
akanae infection was obtained 14 days
After sowing and 7 days after
ansplanting until maximum tillering by
Hunting the number of hills infected. At
n1a=ct 1il inforftar nilnts wAfrp


)mpuIea. Yleia was oDiaineu rrum uil
Arriving plants and compared with yield
om randomly selected healthy plants
within the plot. Blotter and germination
,sts were also done on the harvested
eeds.
Results of agar testing showed
iat all seed lots used were infected with
. fujikuroi with infection variedly
singing from 12% to 70% with a mean
f 39.15%. Blotter testing also showed
eed infection ranging from 4% to 83%.
I both dry and wet season trials the
*vel of seed infection was not positively
slated with field infection during the
previous season.
Infected tillers per hill ranged
om 8% to 51%, with an average of
6%, an indication that bakanae can
?duce this much productive tillers/hill.
urviving infected hills yielded an
average of 5.99 g/hill compared to 23.9
/hill from the same number of randomly
elected healthy plants. Based on these
ata, the estimated yield loss per plant
ue to bakanae was 23%.

;otton seed treatment for nematode
management. JR Rich, KS Lawrence,
IV Barber and TW Katsvairo

he development and marketing of
ematicidal seed treatments is a
relatively new development and the
products have been initially targeted for
se on cotton seed. Avicta Complete
'ak, a product of Syngenta Corporation,
tas registered on cotton in 2006 and
widely used on the crop that year. The
eed treatment, Aeris from Bayer
corporation is now registered for use in
otton in 2007. Both products are
fixtures of chemicals that are
)rmulated to provide early season
uppression of nematodes, thrips, and
ingal seed pathogens. Avicta Complete
lak contains the nematicide abctemin
ilus thiamethoxam for thrips and
I - :







fungal seed treatment option availa
as well. Numerous field trials have be
conducted with these products over
past three years, and Avicta has be
included in over 150 university tri
while the newer Aeris was included o
30 trials. Results for nematc
management have been mixed
generally positive for deploying the
seed treatments as supplements
nematode management programs
use of these products vary by cot
production state due to differences
nematode species and populat
densities, crop rotations, edaphic fact
and economic consideration
Recommendations for integration
these new products into existing cot
nematode management programs in
states of Alabama and Florida U.S
have been formulated and will
presented.

Isolation and molecular identificati
of a whitefly transmitted virus fn
sweet potato virus "Kulot" comply
LM Dolores, JA Panopio and I
Yebron Jr. ISAAA and CSC-IPB, UPL

The sweet potato chlorotic stunt vi
(SPCSV) was isolated from the vi
"kulot" complex using white
transmission into propagation hosts


setosa and I. nil) and typical sympto
of vein clearing and sunken vein we
observed on the diseased susceptil
plants. The virus was purified
chloroform, n-butanol clarification a
differential centrifugation which ga
sharp virus bands in cesium chlori
gradient. Reverse-transcriptE
polymerase chain reaction (RT-PC
resulted to the positive amplification
the 460bp heat shock protein
homologue (Hsp70h) fragment for 1
Ablang (Tarlac), Rang-ayan (Tarla
Syasain (Bataan), Tranca (Lagun
Tanato (Bataan), ViSCA (Leyte) a
Nagbunga (Zambales) isolates us
primers specific to non-East Afric
strains. Molecular sequencing of 1
partial Hsp70h gene of isolates Able
(Tarlac), Rang-ayan (Tarlac), Syas
(Bataan), Tranca (Laguna) and Tan;
(Bataan) resulted to 99.3-100% a
97.2-100% homology based
nucleotide (nt) and derived amino a
sequences, respectively. All isola
obtained from Central Luzon were foL
to be 100% similar based on
deduced amino acid sequence.
This is the first report on
isolation and molecular cloning of
whitefly transmitted virus, SPCSV fr
sweet potato virus "kulot" complex in
Philippines.








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