Front Cover
 Gene selection, interaction and...
 Dynamics of banana bunchy top within...
 Integrated management of 'Tibaglon',...
 Control of storage diseases of...
 Control of banana fruit rots by...
 Phytopathological note: Rust of...
 Abstracts of papers presented during...
 Back Matter
 Back Cover

Group Title: Journal of Tropical Plant Pathology
Title: Journal of tropical plant pathology
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00090520/00039
 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: July-December 1996
Frequency: semiannual
Subject: Plant diseases -- Periodicals -- Philippines   ( lcsh )
Plants, Protection of -- Periodicals -- Philippines   ( lcsh )
Genre: periodical   ( marcgt )
Dates or Sequential Designation: v. 1, no. 1 (January 1965)-
General Note: Title from cover.
General Note: "Official publication of the Tropical Plant Pathology."
 Record Information
Bibliographic ID: UF00090520
Volume ID: VID00039
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
    Gene selection, interaction and pyramiding for blast resistance in rice
        Page 61
        Page 62
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
        Page 71
        Page 72
        Page 73
        Page 74
    Dynamics of banana bunchy top within commercial populations of banana (musa sp.) cv Lakatan
        Page 75
        Page 76
        Page 77
        Page 78
        Page 79
        Page 80
        Page 81
        Page 82
    Integrated management of 'Tibaglon', a bacterial fruit rot disease of cooking bananas under farmer's field
        Page 83
        Page 84
        Page 85
        Page 86
        Page 87
        Page 88
        Page 89
        Page 90
        Page 91
    Control of storage diseases of yam (dioscorea alata L.)
        Page 92
        Page 93
        Page 94
        Page 95
        Page 96
        Page 97
        Page 98
        Page 99
        Page 100
        Page 101
    Control of banana fruit rots by alum
        Page 102
        Page 103
        Page 104
        Page 105
        Page 106
        Page 107
        Page 108
        Page 109
        Page 110
        Page 111
        Page 112
        Page 113
        Page 114
        Page 115
        Page 116
        Page 117
    Phytopathological note: Rust of plumeria acuminata Ait. and Canna indica L.
        Page 118
        Page 119
        Page 120
        Page 121
        Page 122
        Page 123
    Abstracts of papers presented during the 27th anniversary and annual scientific meeting of the Philippine phytopathological society, inc. in Davao City, May 7-10, 1996
        Page 124
        Page 125
        Page 126
        Page 127
        Page 128
        Page 129
        Page 130
        Page 131
    Back Matter
        Page 132
    Back Cover
        Page 133
        Page 134
Full Text

~II I' I

Official Publication of The Philippine Phytopathoogical Society, Inc.


Vice-President AGUSTIN B. MOLINA, JR.
Business Manager RUSTICO A. ZORILLA
Board Member ANA A. EUSEBIO
Board Member NARCEO B. BAJET
Immediate Past President RIZALDO G. BAYOT


OSCAR S. OPINA Editor-in-Chief
RIZALDO G. BAYOT Associate Editor
TEODORA O. DIZON Associate Editor





'Plant Breeding and Biotechnology Divisi,
; 2Soil and Crop Science Department, Texas
.0, USA; 3USDA-ARS, Route 7, Box 999, Im

Key words: gene pyramiding, gene selectic

'With the breakdown of several maj
known as gene pyramiding was recommend
indicated interaction of the genes, thus in,
necessarily equated to better resistance.
resistance (Pi-ql, Pi-q5, Pi-q6 and Pi-b2) w
recombinant inbred lines. Using the mol
gene, lines with 0, 1, 2, 3, and 4 genes we
using three parameters: area under dise
percent diseased leaf area (% DLA) and
blast (SES rating). Results showed both di
interaction. Pi-q6 significantly affected Al
ql contributed significant variation for
affected all parameters but not Pi-b2. In n
other major genes but not Pi-b2 gene. Ri
the best fitting combinations has only three
and Pi-q6 for AUDPC and % DLA, and
rating. These results suggest that gene sel,
to be considered before gene pyramiding.

Blast resistance is one of the major dise
ctives in rice breeding in both tropical
temperate countries. The causal
nism, Pyricularia grisea Cav., is rec<
vn for its genetic instability, allowing it gen
overcome genetic resistance of host one
ts (Shull and Hamer 1994). In spite of



n, PhilRice, Maligaya, Munoz, Nu ,va
, & M University, College Static FX
-s Road, Beaumont, TX 77713, USA.

n, resistance, rice, rice blast

>r genes, combination of genes
led. Recent reports, however,
reased number of genes is not
Four major genes for blast
-re tagged from a population of
cular markers as tag for each
e evaluated at the blast nursery
se progress curve (AUDPC),
standard Evaluation System for
ect gene effect and gene x gene
FDPC and SES rating while Pi-
LUDPC and % DLA. Pi-q5
ost cases, Pi-q6 interacted with
gression analyses revealed that
genes. These were Pi-ql, Pi-q5
'i-q5, Pi-q6 and Pi-b2 for SES
action and their interaction have

plant resistance has been the most
:tive and economical control of the

Several approaches have been
mmended in utilizing major resistance
:s to avoid resistance breakdown and
of these is gene pyramiding. The basic

62 1996 Phil. Phytopath. 32(2):61-'7

assumption is that combination of majc
genes promote better resistance, an additive
effect of the genes involved. Seven
reports, however, indicated interaction c
genes and more recently the negative
interaction of the genes (Wang and othei
1994; Brown and others 1996) and intel
locus interaction of loci present in differed
chromosomes (Lark and others 199;
Zamir and Eshed 1995) suggesting thi
good gene combination has to be identified
and their interaction be evaluated.

In this study, the recombinar
inbred lines (RILs) evaluated were derive
from two parental genotypes (Lemont an
Teqiag), each having resistance to 2-5 racc
of blast pathogen. This population
provided a unique opportunity to study th
genetics of resistance to different races c
the pathogen and to evaluate pyramid
genes in the resistant new genotype:
Teqing and Lemont have at least four an
two genes, respectively (Tabien 1996
These were found effective against 2-
races and were found independent gene:
Based on the RFLP mapping: describe
herein, combinations of these genes, wei
identified using molecular markers an
evaluated at the blast nursery.


Phemetyping of RILs

A population of 245 RILs (F
arranged in a completely randomized desi
(CRD) with three replications was. prepare
for ea4 of the five races: IC-17, IB-49, II
54, I(-1, and'IE-1. A set for each rac
was seded at weekly.interval in 25 x 35
10 cm galvanized flats with field soil ar
was maintained inside the greenhouse.
20 ml snore suspension with cell count

and M-201 as a susceptible check at 17-2
days after seeding (DAS). All inoculate
flats were kept inside the dew chamber for
16-18 hr and then transferred in th
greenhouse until scoring time. Reaction c
the RILs to each race was evaluated 8 da)
after inoculation (DAI). Average scores c
0-3 were considered resistant while average
scores of 4-5 were considered a

The same set of RILs was planted i
small field plots following Marchet
(1983). All entries arranged in randomize
complete block design (RCBD) with there
replications were seeded in small plo1
having spreader rows along the windwar
side to enhance spread of spores to nearby
lines. The. parents, Lemont and Teqin
were seeded every 20th row while ever
two test entries were separated with M-20
as susceptible check. Percent diseased je;
area (% DLA) was taken at 19 days.aft<
seeding (DAS) and every week thereaft<
for five weeks while a weekly Standar
Evaluation System (SES) rating for bla:
was started at 20 DAS and continued ft
five weeks. Area under disease progre,
curve (AUDPC) was computed from the !
DLA data following Shanner and Finne

Genotyping of RILs

Genomic DNA of each of the 24
RILs (Flo) was isolated from fresh
) harvested leaves of 30-day old greenhou,
Grown seedlings. Extraction of DN
Followed the protocol of Li and othe.
- (1995b) while DNA digestion using EcoR
EcoRV, Xbal, and Hind II
electrophoresis, and Southern blottir
Followed standard procedures (Chittend<
Sand others 1994). Half of the probi
F nreviouslv used by Li and others (1995b)

1996 Phil. Phytopath. 32(2):61-74 63

sorghum probes, 64 rice anchor probes
from Cornell (Causse and others 1994) and
all rice landmark probes from Japan
(Kurata and others 1994) were also
evaluated. Labeling of probes was done
using [32p] d CTP, following random primer
method (Feinberg and Vogelstein 1983).
Hybridization, washing, autoradiography
and scoring were done as previously
described (Li and others 1995b).

Framework Linkage Map and Mapping
Major Genes for Blast Resistance

Framework linkage map was
established using Mapmaker Version 3.0
(Lander and others 1987) and LOD value
of 6.0 and recombination fraction of 0.25.
All map distances were in Kosambi
centimorgans (cM). The framework map
was based on data from, 219 lines that each
provided score on a minimum of 102 (80%)
of the RFLP markers. Discrete greenhouse
phenotypic data on resistance or
susceptibility to five races were analyzed
using Chi square test to localize the major
gene. To further evaluate location of the
genes, the average ratings of each line
(score of 0-5) were analyzed using
Mapmaker/QTL (Lander and others 1987).

Selection and Evaluation of Lines with
Different Number of Major Genes for
Blast Resistance

RFLP markers flanking or
bracketing the genes were used to estimate
the presence or absence of the resistance
gene(s) in each inbred line. Based on this
information, field phenotyping data for
groups of RILs having zero, one, two,
three, and four genes were analyzed.
Means were compared using Fisher's LSD
at 5%. Digenic interactions were evaluated
using two way ANOVA while higher
interaction was analyzed using regression
functions (SAS Institute 1988).


The Framework Linkage Map and
Location of Major Genes

The genetic map (Fig. .1) based on
219 RILs and 167 loci molecular markers
covered a total of 1749 cM and has an
average interval length of about 10.5 cM
between markers. Markers segregation
ratios in this population were closer to
Mendelian expectations than in many
previous inter-specific rice populations.
Only eight markers (6%) weke found highly
skewed and five of these were clustered in
a segment of chromosome 6. The marker
location and' relative distribution was
similar to an interspecific rice map (Causse
and others 1994) and a nearly perfect match
with that determined from an earlier
generation of the same Lemont x Teqing
cross (Li and others 1995a). Among 50
Japanese markers (JRGP) mapped, 16 were
located in different chromosomes probably
due to detection of duplicated loci while the
remaining 34 were mapped at nearly the
same location within the chromosomes as
reported (Kurata and others 1994).

Based on chromosomal location and
X2 tests, there were four major resistance
genes in this RIL population and these were
localized in chromosomes 2, 6, 11 and 12
(Fig. 2). The resistance allele on
chromosome 2 (Pi-q5) effective against IC-
17, IB-49, IE-1 and IG-1 originating from
Teqing was between RZ446a and RG520.
This location was very near the estimated
location of Pi-b mapped using RAPDs
(McCouch and others 1994). The
resistance allele (Pi-ql) on chromosome 6
against IC-17, IB-49, and IE-1 that
originated from Teqing was located
between markers C236 and RZ508. Six
najor genes near RG64 were previously
reported on topmost segment of
;hromosome 6 (McCouch and others

4 6 7 9

-C112 -"
-RG236 12
RZ801 15
RZ14 2
G944x -
RG957 14
_RG462 -
RG348b I~
CD0455 14
-RZ776a 16
-CDO348a -
RG811a 21

RZ382 14
.RG532 5-
RG140 8-
88 13-
r 2-
131 12
.RG472 34

-G402a CD0385
:: C285 12
-RZ762 7 RQ7
-C76 1IL 20
-RZ2516 7 RG30
RZ2 -RG29

-G89 6
-RG520a 12]
RZ446a 30
-RG654 -
-RG256a 13-
RZ260a 17
RZ273 14
_RG139 5-
C624 20

.-045 11

RG437 -
-RZ476a 15
_RZ599 2=
-RG83a 10

RG418b HU39a -
R662x Z590b 17
056 -IG214
CD087 -- 379a 4
-RZ538a 14

JiZ761 5 11
CD0337 1
746 RG13 12
RZ474 -
20 15

075 -CDSR9
"Z403 7-4
03 14
C74 "RG346
RG100 23
G341b 25
RG944 -
-C636 15
RG348a 5-
RG104a 11 -
-C515 5-

8 7_
G2123a 6-

-- 23.
C225c 9





0103 5"

-C397 8-

.CD0457 -
-CDO226b -
-RZ777 9-
-RZ386b 9-
CDO82a 6-




-RZ400 f-
-CD098 12
*RG752 17
RG1094f 8
-RG561 13


: b
-. -

RZ536a 12
- 8-
RG1109 16_
"RZ537b 22

- RZ797b

- RG16

- RZ781
RZ53a 4



- G402c





Figure 1. Framework rice linkage map consisting of 167 RFLP markers based from 219
recombinant inbred lines of Lemont x Teqing cross. Orientation of each chromosome
follows Causse and others 1994; numbers between markers are map distances in cM
(Kosambi), markers with asterisk are skewed: *=>70% Teqing allele, **=>70%
Lemont allele.




- R0424




1 2 3

10 11 12


O Pi-qS

- RZ446a

- RG654
- RG256a


I I RZ260a



- G2123b

- C236






- CD0497


- L457)

O Pi-b2

- RZ536a

--- RG1109


RZ397 Pi-q6
G1G1084 I
1.2 -- L102


Figure 2. The intervals into which four major genes for blast resistance (Pi-ql, Pi-qS, Pi-q6, Pi-b2)
were estimated to reside orr chromosomes 2, 6, 11 and 12 relative to markers of.the
framework rice linkage map derived from recombinant inbred lines from Lemont x Teqing.

- ~RG653a 0 Pi-ql

- RZ508


66 1996 Phil. Phytopath. 32(2):61-74

1994; Pan and others 1996). However, the
Pi-q 1 gene was estimated at the bottom half
of chromosome 6, thus appears to be a new
gene for blast resistance. The markers
associated with Pi-ql were all skewed to
Teqing alleles, thus caution is warranted in
interpreting the precision at which this
particular gene can be mapped. Recent
reports on genes mapped using skewed
markers were found associated with
another marker or were relocated in
another chromosome (Inukai and others
1996). The gene in chromosome 11 (Pi-b2)
that originated from Lemont might be
allelic to reported genes linked with
RZ536a (Yu and others 1991; Inukai and
others 1994). Pi-l(t) was found 14 cM
from RZ536 and Pi-k was 4.7 cM from Pi-
19t). The Lemont gene (Pi-b2) found
effective against IB-54 and IG-1 was
estimated to be Pi-kh (Tabien 1996) and
this was supported by the mapping results.
Probe RZ536 was associated with both Pi-
b2 and Pi-l(t) hence, these could also be
the same genes. Allelism tests will be
necessary to provide conclusive identity of
the above gene(s) identified on
chromosome 11. The blast resistance gene
on chromosome 12 (Pi-q6) was located
between RG869 and L102. Based on the
flanking markers, Pi-q6 is likely to be the
Pi-4(t) gene found closely linked to RG869
and RZ397 (Mew and others 1994). This
gene could also be the gene from "Hong
Jiae-Zhan", or gene Pi-62, from "Yashiro-
mochi" reportedly linked to RG869 and
RZ397 (Zheng and others 1995; Wu and
others 1995). Allelism tests can clarify the
identity of Pi-q6.

Field Performance of Some Gene

Marker data allowed genotype
estimation at all four mapped resistance loci
in 122 RILs. The four genes segregated

independently as reflected by the Chi-
square for four genes (P< 0.001).
Although lines having 0, 1, 3, and 4 genes
were all observed, some gene combinations
were absent or very rare, e.g. only one line
had the gene from chromosome 12.

Data analyses revealed significant
direct effects and interactions of these
genes. Pi-q6 significantly affected AUDPC
and SES ratings but not % DLA, while Pi-
ql contributed to variation in AUDPC and
% DLA, but not SES ratings. Pi-q5 was an
important determinant of all three
parameters but Pi-b2 was not 'associated
with any of the three parameters. For
AUDPC, significant interactions were
found for Pi-ql x Pi-q5, Pi-q5 x Pi-q6, and
Pi-ql x Pi-q6 combinations while only Pi-
q5 x Pi-q6 was significant for % DLA. Pi-
q5 x Pi-q6 and Pi-ql x Pi-q6 were
significant for SES ratings. For three
parameters, Pi-q6 interacted significantly
with another gene while Pi-b2 did not. The
model with significant interaction had R2
values ranging from 20%-29%. Multiple
regression analyses revealed that the best
fitting combinations were Pi-q5, Pi-ql and
Pi-q6 for % DLA and AUDPC (R2=0.25)
and Pi-q5, Pi-q6 and Pi-b2 for SES rating

These results suggest the
importance of both the direct effect of a
gene and its .interaction with other genes.
Although the R2 values were relatively low
for major gene effect, these genes and their
interaction can explain 20-25% of the
variations observed in % DLA, AUDPC,
and SES rating. The remaining variation
could be due to QTLs or unidentified major
genes as indicated by significant variation
found among lines not containing the four
mapped major genes (Table 1). Analysis of
this group showed significant differences
for all three traits with very high R2 values
of 87-96%. The minor genes or other

1996 Phil. Phytopath. 32(2): 61-74 67

Table 1. Eight lines estimated to have no mi
absence of RFLP marker for Pi-ql
performance in the blast nursery.


TQ72 18.60
TQ77 8.67
TQ167 21.51
TQ176 3.13
TQ226 9.57

TQ234 14.75
TQ267 17.48
TQ289 10.58
Lemont 5.64
Teqing 2.70

M-201 24.50

Critical LSD 2.70

% DLA SES Rating

63.00 6.33
28.33 5.67
56.33 6.67

.00 6.00

1.67 8.00
-.33 7.67
i.33 7.00
.33 5.67
1.33 2.67

0.00 9.00


0 1770 ruin. rnytupaim. J A&J;Ui- I

nes therefore contribute a substantial
mount to the total variation in field

Table 2 shows the mean and the
variations of the RILs having 0 to 4 genes.
he lines estimated to contained four major
enes (Table 3) had highly significant
variation for all traits and the genotypes
would explain 87-96% of the variation.
similarly, the lines estimated to have singly
lapped major gene (Table 4) had highly
gnificant variation for each of the three
aits. Some lines having the same single
ene also exhibited a range of responses at
>e blast nursery. In particular, RILs
containing Pi-ql alone had variable resistance
cpression. The least frequent single gene
as Pi-q6 but'their performance seems to be
ke best single gene. For lines estimated to
ave two tagged major genes (Table 4), all
it three of the lines had Pi-ql and more than
ff had Pi-ql and Pi-q6. All lines had very
nall AUDPC, % DLA and low SES rating
)mpared to M-201. The lines estimated to
ive three genes (Table 5) had. also
gnificant variation in all three parameters
ith R2 ranging from 85-96%.

Combining genes has been
icouraged since the reported breakdown of
ajor genes. The above results, however,
lowed that gene combinations had
significant effect on variation at the blast
irsery. Gene selection and their interaction
ive to be considered before gene
tramiding. Some gene combinations may
)t significantly increase resistance as
ported in cotton (El-zik and Bird 1970) and
Lrley (Brown and others 1996). Although
veral resistance genes favored increased
distance to blast as shown in decreasing
rerage AUDPC, % DLA, and SES ratings
am lines having one to three genes,
creasing the number of genes

iurtner (I.e. to tour) mignt not increase
resistance as shown by our results.

Major genes identified using single
races in the greenhouse may not perform wel
at field conditions. The same observatior
was noted for two genes from Moroberekar
found effective against five races of blasi
pathogen during greenhouse tests. The
differential response was attributed to a
possible wide array of genes from the
resistant parent effective against complex)
populations of pathogen. Differential
response of major gene was also reported or
apple scab (Gardiner and others .1996)
Apple lines considered weakly susceptible
and weakly resistant had the same major gene
for apple scab resistance. Reduction ir
resistance, however, was attributed to the
absence of resistance modifying genes.

Breeding Implications in Using
Major Genes

Major blast genes can be combined,
as is being done for three genes, Pi-l(t), Pi-
2(t), and Pi-4(t) being pyramided at IRRI
(Mew and others 1994). The resulting lines
are expected to be better than single gene
lines. This might be true if the major genes
.will act in additive fashion as is generally
expected. However, caution has to be
considered in combining genes with recent
reports on interaction of loci present in
different chromosomes (Lark and others
1995; Zamir and Eshed 1995), and our
preliminary results on significant interactions
in some major gene combinations. Negative
interaction was detected in our data and these
observations had been noted in RILs of rice
(Wang and others 1994) and in Fi plant of
cotton (El-zik and Bird 1970). Plants with a
combination of three genes were more
susceptible than those having two major
genes for resistance to bacterial blight of

1996 Phil. Phytopath. 32(2): 61-74

Table 2. Mean and standard deviation of AUDPC, % DLA and /SES rating of lines with
zero, one, two, three, and four major genes for blast resistance estimated using
absence or presence of RFLP markers for Pi-ql, Pi-q5, Pi-q6 and Pi-b2 showed
decreasing mean values up to three genes but not four genes.

Group Mean Standard Mean Standard Mean Standard
deviation deviation deviation

One gene 4.33 2.73 21.13 14.92 4.85 1.87
Two genes 3.96 3.61 20.57 18.59 4.73 1.93
Three genes 3.49 2.71 16.86 13.21 4.61 1.80
Four genes 4.42 3.98 22.31 19.98 4.90 1.96
No gene 4.86 3.57 25.00 21.22 6.08 0.89

Table 3. The 14 lines estimated to have 4 major genes for blast resistance based on the
presence of RFLP markers for Pi-ql, Pi-q5, Pi-q6, and Pi-b2 showed variable
performance in the blast nursery.

Line/Cultivar AUDPC : % DLA SES Rating

TQ45 0.11 0.33 3.00
TQ80 6.83 38.67 6.00
TQ92 16.89 54.67 7.33
TQ101 4.74 22.67 6.00
TQ160 8.89 49.33 7.00

TQ169 3.63 14.67 4.33
TQ182 1.58 12.33 3.00
TQ189 3.17 27.00 4.00
TQ202 4.91 18.67 6.00
TQ204 0.32 1.00 2.33

TQ257 1.12 6.67 2.33
TQ263 10.06 15.00 7.33
TQ283 0.63 2.33 2.67
TQ341 12.00 22.00 6.00
Lemont 5.64 24.33 5.67

Teqing 2.70 13.33 2.67
M201 24.50 100.00 9.00

Critical LSD 2.21 13.57 1 24

70 1996 Phi. Phytopath. 32(2): 61-74

Table 4. Selected lines estimated to have one and two major gene for blast resistance
based on the presence of RFLP markers for Pi-ql, Pi-q5, Pi-q6, and Pi-b2
showed variable performance in the blast nursery.

Line/Cultivar Estimated Gene AUDPC % DLA SES Rating










Pi-q5 and Pi-ql
Pi-q5 and Pi-ql
Pi-q5 and Pi-ql

Pi-q5 and Pi-ql
Pi-q5 andPi-b2
Pi-q5 and Pi-b2
Pi-q5 and Pi-b2
Pi-ql and Pi-q6

Pi-q5 and Pi-b2
Pi-q5 and Pi-b2
Pi-ql and Pi-q6
Pi-ql and Pi-q6
Pi-ql and Pi-q6

Pi-q5 and Pi-q6
Pi-q5 and Pi-q6
Pi-q5 and Pi-b2
Pi-ql, Pi-q5, Pi-q6
















Critical LSD 2.42 13.12 1.34








1996 Phil. Phytopath. 32(2): 61-74 71

Table 5. Lines estimated to have three major gene for blast resistance based on the
presence of RFLP markers for Pi-ql, Pi-q5, Pi-q6, and Pi-b2 showed variable
performance in the blast nursery.





Estimated Gene
Pi-ql, Pi-q5, Pi-q6
Pi-q1, Pi-q5, Pi-q6
Pi-ql, Pi-q5, Pi-q6
Pi-ql, Pi-q5, Pi-q6
Pi-ql, Pi-q5, Pi-q6
Pi-ql, Pi-q5, Pi-q6
Pi-ql, Pi-q5, Pi-q6
Pi-ql, Pi-q5, Pi-q6
Pi-ql, Pi-q5, Pi-q6
Pi-ql, Pi-q5, Pi-q6

Pi-ql, Pi-q5, Pi-b2
Pi-ql, Pi-q5, Pi-b2
Pi-ql, Pi-q5, Pi-b2
Pi-ql, Pi-q5, Pi-b2
Pi-ql, Pi-q5, Pi-b2
Pi-ql, Pi-q5, Pi-b2
Pi-ql, Pi-q5, Pi-b2
Pi-ql, Pi-q5, Pi-b2
Pi-q 1, Pi-q5, Pi-b2
Pi-ql, Pi-q5, Pi-b2

Pi-ql, Pi-q5, Pi-b2
Pi-ql, Pi-q6, Pi-b2
Pi-ql, Pi-q6, Pi-b2
Pi-ql, Pi-q6, Pi-b2
Pi-ql, Pi-q6, Pi-b2
Pi-ql, Pi-q6, Pi-b2
Pi-ql, Pi-q6, Pi-b2
Pi-q 1, Pi-q6, Pi-b2
Pi-q5, Pi-q6, Pi-b2
Pi-q5, Pi-q6, Pi-b2

Pi-q5, Pi-q6, Pi-b2
Pi-q5, Pi-q6, Pi-b2
Pi-ql, Pi-q5, Pi-q6

Critical LSD 2.21 13.27 1.50









SES Rating




1994; lablen and others 1997).
Strategic pyramiding of major genes A technique for radiolabelling DNA
and QTL combination, considering both restriction fragments to high specific
race specificity and temporal patterns of activity. Anal Biochem 132: 6-13.
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that previously hindered selection for detailed map around an apple scab
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disease resistance classes both carry Vf
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BROWN AHD, GARWIN DF, BUNDON Development of pre-isogenic lines for rice
JJ, ABOTT DC, READ BJ. 1996. The blast resistance by market-aided selection
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on disease levels, yield and quality of Theor Appl Genet 93: 560-567.
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1996 Phil. Phytopath. 32(2): 61-74 73

Mapmalker: an interactive computer
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MANSUR LM, ORF J. 1995. Interactions
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Proc Nat Acad Sci USA 92: 4656-4660.

Characterization of quantitative trait loci
(QTLs) in cultivated rice contributing to
field resistance to sheath blight.
(Rhizoctonia solani). Theor Appl Genet
91: 382-388.

PARK WD. 1995b. Identification of two
major genes and quantitative trait loci for
heading date and plant height in cultivated
rice (Oryza sativa). Theor Appl Genet 91:

MARCHETTI MA. 1983. Dilatory
resistance to rice blast in USA rice
Phytopathology 73: 645-649.

ZEIGLER RS. 1994. Mapping blast
resistance genes in rice. In: Zeigler RS,
Leong SA and Teng PS (eds.). Rice blast
disease. CAB Inter, Wallingford, England,
pp. 167-186.

HUANG N. 1994. Fine mapping of major
genes for blast resistance. Inter Rice Res
Notes 19: 4-5.

TANISAKA T. 1996. Identification of new

blast resistance gene in the indica cultivar
Kasalath using Japanese differential
cultivars and isozyme markers.
Phytopathology 86: 1071-1075.

SAS INSTITUTE INC. 1998. Additional
SAS/STAT Procedures: Release 6.03 SAS
Tech Report SAS Institute Inc. Cary, NC.
179 p.

effect of nitrogen fertilization on the
expression of slow-mildewing resistance in
Knox wheat. Phytopathology 67: 1051-

SHULL V, HAMMER JE. 1994. Genomic
structure and variability in Puricularia
grisea In: Zeigler RS, Leong SA and Teng
PS (eds.). Rice blast disease. CAB Inter,
Wallingford, England, p. 65-68.

TABIEN RE. 1996. Utilization of
recombinant inbred lines in tagging blast
resistance genes for marker assisted
selection scheme in rice. Ph.D. Thesis.
Texas A&M University, College Station,
TX 77843, USA. 190 p.

Mapping dilatory genes for rice blast and
their temporal expression at the blast
nursery. Theor Appl.Genet (submitted).

NELSON RJ. 1994. Rflp mapping of genes
conferring complete and partial resistance
to blast from durably resistant cultivar.
Genetics 136: 1421-1434.

Towards cloning a blast resistance gene by
chromosome walking. Abst. Third


International Rice Genetics Symposium.
Oct. 16-20, 1995, Manila, Philippines. p.

TANKSLEY SD. 1991. Tagging genes for
blast resistance in rice via linkage to RFLP
markers. Theor Appl Genet 81: 471-476.

ZAMIR D, ESHED Y. 1995. An
introgression line population of

1996 Phil. Phvtnnath. 32(21'75-12 75


O. S. OPINA and 1

Respectively, Professor and Former
Pathology, University of the Philippines Los

Key words: banana, banana bunchy

The ability of banana buncl
infected mother plants to daughter I
month old banana mats. Results she
plants showing different severity of
This indicated that when the infei
symptoms, the BBTV has already
high titre to effect infection in the si
top (BBT) in 2-year old banana or
suggest that the incidence of BBT de
the inoculum source. BBT is disper
primary source ofinoculum. The sp,
Y = -0.168-0.143X, where: Y repre,
scale and X as linear distance in mel
this model of BBT spread, the likely
particular distance from the source c
or distance at which BBT incidence
at least 50 m away from the inocult
and relatively isolated banana orcha
onset of BBT epidemic started at eig
development can be described by 1
infection is estimated at 0.140 per v
adjacent plants or of close proximity
focal pattern of BBT spread is not sl



Undergraduate Student, Department of Plant
afios, College, Laguna.

p, epidemiology, Lakatan, virus

top virds (BBTV) to move from
mts (suckers) was examined in a 9-
wed that suckers taken from mother
symptoms were infected with BBT.
ed mother plant shows discernible
anslocated and attained sufficiently
kers. The spread of banana bunchy
lard was also examined. The data
reases with increasing distance from
d at a very short distance from the
ial spread is defined by the equation:
nts disease proportion in logarithmic
rs from the inoculum source. Using
ood of getting infected suckers at a
i be assessed. The isolation distance
approaches to zero is estimated to be
i source. From a newly established
with strict sanitation practices, the
t weeks after planting. The epidemic
gistic model. The apparent rate of
ek. New infections usually occur in
Primary inoculum source. A typical
rply defined six months after disease

If4 1009 Ol DD .,16.1<-k 2I1\. FYe

Norte, Davao del Sur, South Cotabato and planting materials that are introduced in
Misamis Oriental (PCARRD 1985). new banana plantation can serve as foci
Although banana exports come mainly from infection and secondary BBT spread with
commercial plantations, bananas are also the plantation can be mediated by t
grown all over the country as backyard banana aphids. Unless aphid vectors a
crop. promptly controlled, the disease can 1
expected to spread rapidly within t]
The traditional export of fresh plantation. Long distance movement
Cavendish makes the banana industry an BBT can therefore be efficiently prevent
important dollar earner which significantly by using virus-free planting materials. T1
contributes to the country's economy use of tissue cultured plantlets offers a ve
(PCARRD 1985). However, the Philippine attractive solution against BBT, but due
banana industry is now under threat from their inavailability and prohibitive co!
other Asian countries and the Latin farmers are constrained to use corms ai
Americas. One problem is the high cost of suckers as planting materials. Thus, spre,
production resulting from labor cost that of BBT may still continue unless a system
hindered the industry's competitiveness or guidelines be developed to help identi

the Philippine banana used
U~-I ---r o-4rl-+ -. --_

to dominate and notentiallv e.arrvino RRTV on that thpv r

1996 Phil. Phytopath. 32(2): 75-82 77

suckers of neighboring banana mats; c)
describe the temporal and pattern of spread
of BBT within a commercial banana


BBT Incidence on Banana Suckers from
Mats of Symptomatic Mother Plants

The experiment was conducted in a
newly established banana orchard planted
to Lakatan. Nine-month old banana mother
plants naturally infected with BBT were
identified and grouped according to the
severity or stage of symptom development.
The first group consisted of mother plants
with early BBT symptom noticeable only
on the candle or the rolled leaf (Scale 2),
second group, symptom noticeable on the
candle leaf and the first expanded leaf
(Scale 3); third group, symptom noticeable
on the candle leaf, first and second
expanded leaf (Scale 4); and fourth group,
symptom noticeable on three or more
expanded leaves (Scale 5). Mother plants
showing no apparent symptom of BBT
were served as control (Scale 1). All
suckers from the identified infected and
healthy (control) mother plants were
carefully dug, segregated and labeled
according to stage or age. BBT infection
was assayed using growing-on test.
Suckers were planted in potted soil, grown
under insect-proof glasshouse, fertilized
and watered whenever necessary. The
banana suckers were monitored for
symptom development. Incidence of BBT
was determined using the following
formula: Incidence (%) = No. of BBT-
infected suckers / Total No'. of Suckers X
100. Incidence of BBT on suckers taken
from mother plants with different severity
of infection was summarized and compared,

Spread of BBT within Banana

The experiment was conducted in a
BBT-infected banana orchard planted to 2-
year old Lakatan. Banana plants showing
advanced symptoms of BBT and serving as
point sources of infection in the banana
orchard were identified. Planting materials
(suckers) were gathered randomly at
concentric circles with various distances (0
to 6 m) from inoculum poi.t source. BBT
infection was assayed using growing-on
test. All suckers were planted randomly in
greenhouse plots, regularly sprayed with
insecticides, fertilized and watered
whenever necessary. Tissue cultured
plantlets were randomly planted within the
plots to determine the presence of
secondary spread or background infection
of BBT within experimental plot. The
banana suckers were monitored for
symptom development. Likewise,
incidence of BBT was determined and
summarized according to distance from
inoculum source. Severity of infection was
plotted with distance from inoculum
source. Disease gradient and model of
spread were derived using regression

Spread of BBT in Time and Space

The spread .of BET in time and
space was determined in a relatively
isolated, and newly established banana
orchard planted to tissue cultured plantlets
of Lakatan. The planting plan of the whole
area was prepared to indicate the exact
position of each banana plant. After field
transplanting, each plant was monitored for
BBT infection at weekly intervals. Plants
showing typical symptom of BBT was
recorded and immediately removed to
simulate the recommended sanitation

78 1996 Phil. Phytopath. 32(2):75-82

practices. The spread of BBT within the
orchard was mapped-out to reveal the
pattern of spread and apparent infection
rate was determined using logistic models
(van der Plank 1963).


BBT Incidence on Suckers from Mats
With Symptomatic Mother Plants

The ability of BBT to move from
infected mother plants to daughter plants
(suckers) was examined. Results showed
that all the suckers taken from symptomatic
mother plants regardless of severity of
infection were infected with BBT (Table 1).
BBT symptoms were first manifested on
older suckers and later to the younger
suckers. In all cases, infected suckers
showed typical BBT symptoms within three
months after planting. Suckers taken from
mats with symptomless mother plants did
not show any symptom of BBT after four
months of observation. The results suggest
that once the mother plants showed early

Table 1. Incidence of banana bunchy top on
suckers taken from mother plants
showing different severity of infection.

Severity' Incidence (%)

Scale 1 (Control) 0

Scale 2 100

Scale 3 100

Scale 4 100

Scale 5 100

'Snyptom severity of mother plant: no apparent
symptom, scale 1; symptom appearing only on candle or
rolled leaf, scale 2; on rolled leaf and first expanded
leaves, scale 3; on two expanded leaves, scale 4; and on
three or more expanded leaves, scale 5.

symptom of the disease, the BBTV might
already have translocated and attained
sufficiently high titre to effect infection in
the suckers. This finding agrees with that
of Stover (1972) who stated that suckers
arising from diseased rhizomes rarely
escape infection. Studies indicate that virus
infection starts at the site of introduction
and spread slowly to surrounding. cells
through the plasmodesmata. If vascular
tissues are reached, the virus together with
the assimilates enters the sieve tubes and
spreads passively to plant parts such as
young developing roots/shoots, fruits and
other sinks (Gibbs and Harrison 1976; Bos
1983). Suckers which are largely dependent
on the mother plant for carbohydrates and
other assimilates serve as sinks and
therefore, most likely carry the virus once
the early symptom appeared on the mother

The results of the study showed a
concrete evidence that suckers taken from
infected mother plants regardless of
severity of symptom are already infected
with BBT and they should not be used as
planting materials. The utilization of
suckers from symptomatic mother plants as
planting materials will therefore facilitate
fapid and widespread distribution of BBT.

Spatial Spread of BBT

Results of growing-on test of
banana suckers collected from various
distances around the inoculum point
sources of BBT are presented in Table 2.
The data suggest that the incidence of BBT
showed a definite trend, decreasing with
increasing distance from the inoculum
source. All suckers taken from within the
mats of infected mother plants or point
sources were infected with BBT.
Increasing the distance from inoculum
source by 2, 4 and 6 m resulted in the

1996 Phil. Phytopath. 32(2):75-82 79

Table 2. Incidence of banana bunchy top (BBT)-
infected suckers taken from various
distances from inoculum point sources.

Distance (m) BBT Incidence (%)

0 100

2 21.4

4 15.4

6 12.5

decrease in BBT incidence
and 12.5%, respectively.

to 21.4, 15.4

Plotting the disease incidence over
distance in linear scale showed a steep
hollow curve, decreasing rapidly at first
near the source, then flattening out as the
distance increases (Fig. 1). The steep curve
is interpreted to mean that BBT is
dispersed at a very short distance from the
primary source of inoculum while the
flattening of the curve as distance increases
from the source indicates background
infections or some of the infection units did
not come from the primary source (Gregory
1968). The slope of the curve is a measure
of BBT gradient, however, hollow curve is
difficult to interpret because the slope
changes from point to point along the
curve. Thus, logo of infection was plotted
against linear distance to substantially
straighten the curve (Fig. 2). Linear
regression analysis indicated that the
regression line is defined as Y = -0.168-
0.143X, where V represents disease
proportion in logarithmic scale and linear
distance in meters from the inoculum
source as X. The regression coefficient, -
0.143 is an estimate of BBT gradient under
the condition existing within the banana
orchard. In general, the values of disease
gradient are within the magnitude of-1 and
as the values become nearer to zero,
secondary infections are expected to occur

[ 1 2 3 4 1 6 7

Figure 1. Plot of disease proportion and distance
from inoculum point source in linear
scale showing a typical steep hollow

0 __________

D- 0.s8

I 2 4j a a

Figure 2. Plot of disease proportion (x) in
logarithmic scale and distance from
inoculum point source in linear scale.

or some infection units are dispersed
exceptionally far from the primary source.
Cammack (1958) assessed diseased
gradients around inoculum point source of
Puccinia polysora Underw. at various time
intervals. He found out that at 10, 20 and
30 days after exposure the disease gradients
were -2.618, -1.06 and -0.313, respectively.
This indicates that on the 30th day,
secondary rust infections have occurred. It
should be stressed that a two-year old

80 1996 Phil. PhvtoDath. 32(2):75-82

by insects have flatter gradients possibly
due to the ability of the vectors to disperse
the pathogen randomly away from the point 0.0001 50

Knowledge of spatial spread of located within 50-1000 m and -no BBT
plant disease is relevant in many aspects. It incidence on the 19 plantations beyond
can be used as a basis for cropping plans, to 1000 m. In a related study, the mean
trace a source of inoculum, to improve distance of new infections from primary
design of experiments such as fungicide or sources in an established plantation was
varietal trials, to provide insight in disease 17.2 meters. About two-thirds of new
control through crop isolation and others. infections was within 20 m and 1% within
In this particular study, the spatial spread of 86 m (Dale 1987). The predicted levels of
BBT was established primarily to determine infections using the established BBT model
distances from primary sources of inoculum of spread were not consistent with the
where planting materials like suckers be observations of Dale (1987). The
taken to obtain acceptable level of difference may be attributed to the

equation, suckers taken at
concentric circles around t

about 6 m or conditions favoring movement of aphid

1996 Phil. Phytopath. 32(2):75-82 81

Table 4. Incidence of banana bunchy top in a newly
established and relatively isolated banana

Number of Disease
Time (weeks) infected Proportion
plants (%)

8 2 0.005
9 4 0.010
10 7 0.017
11 13 0.033
12 17 0.040
13 18 0.046
14 20 0.051
15 24 0.061
16 25 0.064
17 25 0.064
18 25 0.064
19 26 0.066
20 28 0.071
21 28 0.071
22 28 0.071
23 29 0.074

Total No. of 390

Lakatan was presented in Table 4 and
illustrated in Fig. 3. The onset of BBT
epidemic started 8 weeks after planting
(WAP) and the level of disease increased
steadily up to 23 WAP despite strict
roguing of infected plants. Plot of disease
proportion against time showed a sigmoid
curve, typical of polycyclic disease. Using
logistic growth model, the apparent rate of
infection (r) which was determined by
regressing logit of disease proportion
against time was estimated at 0.140 unit per
week (Fig. 4). The development of BBT in
the banana orchard was relatively slow
compared with other virus diseases.
Magdafita and others (1989) determined
the epidemic potential of papaya ringspot
and estimated an average rate of infection
of 0.74 per week based on logistic growth
model. The contrasting ability 'of both
diseases to cause explosive epidemic may
be attributed to the differences in virus-
vector relationship and behavior of vectors.





0 5 10 Is 20 24
TIME ( Wee )

Figure 3. Disease progress curve of banana bunchy
top in a newly established banana
orchard (cv Lakatan) under strict
sanitation practices.


Y -5.32+O.14X
2 = 0.68



0 5 10 15

20 2s

Figure 4. Plot of disease proportion (x) transformed
logit [In(x/l-x)].

Papaya ringspot virus (PRSV) is
transmitted nonpersistently by several
species of aphid vectors (Opina 1968) while
BBTV is transmitted specifically and
persistently by an aphid, P. nigronervosa
(Wardlaw 1935). The slow BBT progress
could also be attributed with strict
sanitation practices in the orchard.
Similarly the rate of PRSV was reduced by
three-fold and epidemic onset was delayed
by 15 weeks when crop isolation and rigid
sanitation was practiced (Magdalita and

others 1989). The pattern of BBT spre.
within six-month observation showed th
BBT was established randomly in tl
orchard from few foci of infections me
likely introduced through infected plant
and rarely from background infection
New infections usually occur in adjace
plants or of close proximity to prima
sources of infection. The observati<
agrees with that of Dale (1987) wl
demonstrated that about two-third of ne
infections was within 20 m from tl
inoculum source. A typical local pattern
spread in the orchard, however, was n,
sharply defined within six months becau:
of slow disease spread primarily due
strict sanitation practices.


BATESON MF, DALE JL. 1994. Banar
Bract Mosaic Virus: Characterizatic
using potyvirus degenate PCR primer
Arch. Virol. 140: 515-527.

BOS L. 1983. Introduction to plai
virology. United Kingdom: Longma
Group Limited. 160 p.

CAMMACK RH. 1958. Factor affecting
infection gradients from a point source <
Puccinia polysora in a plot of Zea may,
Ann. Appl. Biol. 46: 511-523.

DALE JL. 1987. Banana bunchy top: A
economically important plant virus disease
Advances in Virus Research. Floridi
Academic Press Inc. 301-309.

The spread of virus diseases in .the potat
crop. Agr. Res. Council Rept. Ser. 7.

1996 Phil. Phytopath. 32(2):75-1

1 GIBBS A, HARRISON B. 1976. Pla
t virology: the principles. London: Edua
SArnold (Publishers) Ltd. 292 p.
spatial distribution of insect-borne pla
t virus diseases. Ann. Appl. Biol. 36: 47
y 482.
SGREGORY PH. 1968. Interpreting pla
r disease dispersal gradients. Ann. Re
SPhytopathol. 6: 189-212.
SEpidemiology of papaya ringspot in tl
Philippines. Philipp. Phytopathol. 25: 1-1

OPINA OS. 1986. Studies on a new vin
disease of papaya in the Philippines. Foc
Fert. Technol. Center Bull. 33 Taiwa

SPCARRD. 1985. The Philippin
i Recommends for Banana. Technic
Bulletin Series No. 66: 136.

SINGH RS. 1972. Plant Diseases. Ne
SDelhi: Oxford and IBH Publishing Co, 48(

STOVER RH. 1972. Banana plantain an
abaca diseases. Com. Mycol. Inst., Ke:
Surrey, England. 316.

VAN DER PLANK JE. 1963. Plar
diseases epidemic and control. New Yor
and London: Academic Press. 349.

WARDLAW CW. 1935. Diseases c
banana and of the Manila hemp plan
London: MacMillan and Co., Ltd. 321

1996 Phil. Phytopath. 32(2):83-91 83


G. C. A

This study was conducted in collal
Livelihood Project of University of the Philii
ERP), UP Diliman and the Local Governmer

'University Researcher, Institute o
Philippines Los Bahios, College, Laguna.

Key words: banana, 'bugtok', d



ration with Comprehensive Education and
ines Extension and Research Program (UP-
of Valencia, Negros Oriental.

Plant Breeding (IPB), University of the

I I '

84 1996 Phil. Phytopath. 32(2):83-91

'Tibaglon' is a disease caused by plantations have resources, organization,
the bacterium Pseudomonas solanacearum and technology to manage the disease.
EFS. The same disease was reported by Cheap, practical strategies to manage the
Roperos in 1965 and he called it 'bugtok'. disease are available but implementation
In 1969, Zher and Davide observed the and operationalization under farmers' fields
infection of this pathogen in 'Saba' in are lacking.
Negros Oriental and the local name was
'tibaglon' or 'tapurok'. Diseased plants It was the objective of the study to
yield fruits that show dark, dry rotting in develop a practical and operational disease
the pulp. When cut cross-sectionally, the management system against a bacterial
rotting may be revealed as concentrated at disease of bananas caused by P.
the center of the pulp, although may move solanacearum and evaluate the adaptability
outward, too. Infected fruits are unfit for oftnese strategies in small to medium scale
human consumption. Usually under severe banana fruit.
infection, all fingers in the bunch are
infected rendering the whole bunch useless.

Pseudomonas solanacearum MATERIALS AND METHODS
attacks many varieties of bananas,
including the Cavendish type. It is believed Survey of Occurrence and Distribution
to have been brought to the Philippines of the Disease
through seed pieces used as planting
materials in commercial plantations A comprehensive survey on the
(Roperos and Magnaye 1991). In occurrence and distribution of the, disease
Cavendish plantations, the disease is known 'tibaglon' in cooking bananas was done in
as 'Moko'. Symptoms of 'Moko' include 14 barangays within the municipality of
chlorosis of leaves, wilting and fruit Valencia, Negros Oriental. The parts of
rotting. In the case of 'tibaglon' or the plants affected and characteristic
'bugtok' almost always only the fruit symptoms of the disease were recorded.
rotting symptom is manifested, not the Sample of the different plant parts were
wilting symptom. As such, it was earlier collected for isolation of the pathogen in
believed that 'tibaglon' or 'bugtok' are the laboratory for diagnostic confirmation
___ I_ .1!,W -:--- ,* _r D _P +I- A;-n-n T-;A -n-- A-f thb Atlaaaca

The taxonomy and biology of the
causal organism are well established
(Buddenhagen and Elasser 1962,
Buddenhagen and Kelman 1964; Hayward
.1964; Soguilon and others. 1995). Modem
molecular works to identify and
characterize strains of P. solanacearum of
bananas have been conducted (Cook and
others 1991; Seal and others 1993;
Raymundo 1997). In commercial
plantations, significant amount of money is
- <* - -

number of bunches harvested. A bunch is
considered infected when at least one hand
is showing the characteristic rotting in the

Integrated Management of Bacterial
Disease 'Tibaglon'

Fifty farmer cooperators were
identified. The following disease
management tactics were evaluated under
farmPr' f4pldlc-

1996 Phn. rhytopath. 32(2):83-91 85

1. Normal farmers practice. No

2. Early debudding. The male
buds were removed as soon as
2 false hands appeared in the

3. Sanitation. Bi-weekly removal
of dead and hanging leaves.

4. Debudding and sanitation.
Combination of treatments 2
and 3.

5. Debudding, sanitation and
disinfestation of tools.
Treatments 2 and 3 plus the
bolos used for debudding, and
cutting dry leaves were
disinfested with 5% sodium
hypochlorite (chlorox).

6. Debudding, sanitation, tool
disinfestation and bagging.
Treatments 2, 3, and 4 plus
bagging with polyethylene bag
as soon as the raceme and
hands were formed.

Disease incidence were recorded by
farmers by counting affected bunches
relative to the number of bunches
harvested. Disease incidences .were
recorded before the implementation of the
management practices, and then six months
and one year after the initiation of the

Before the implementation of the
demo-trials, an intensive training activities
were conducted among farmers, including
the active participation of the Local
Government Units (LGU), particularly the
Municipal Agricultural Officer (MAO).
Group discussions on diagnosis of the
disease were done. Lectures were done to

make tarmers understand the nature and
cause of disease. Emphasis was done to
explain how the disease is transmitted from
plant to plant. The control tactics that
were evaluated in the dem"o-trials were
explained to the farmer cooperators as well
as the MAO. They were also trained to
assess infection and record keeping. The
MAO was the regular supervisor for the
implementation of the demo-trials.


Survey of Occurrence and Incidence

The survey was done in 14
barangays on Valencia, Negros Oriental
with 163 farmers participating in February,
1996. The disease was found to occur in
all the barangays surveyed with disease
incidences ranging from 60-92% (Table 1).
The highest disease incidence was observed
at Balayag-manok with 92%, followed by

90% in L
and Balili

ptong, Bong-ao, Ea


incidences, respectively. Higher
ices were observed in barangays
I at the northeast and southeastern
s of the municipality, adjacent to the
'Dumaguete where the disease was
diagnosed and reported in 1969 by
nd Davide. The disease incidences
-ower in barangays located at the
- of the municipality. Traditionally,
barangays depend much on 'Saba'
tion as their source of livelihood,
ng the fruits to nearby towns, even
u and Manila. However, with the
ing incidence of 'tibaglon' this
of livelihood has been seriously
ned. Of the infected bunches a
)f 80-100% of the fingers are unfit

86 1996 PhiL Phytopath. 32(2):83-91

Table 1. Incidence of 'tibaglon' in several barangays in Valencia, Negros Oriental, taken
before the implementation of disease management program.

Barangays Number of Observed Disease Incidence (%)
Farms Mats Bunch Finger

1. Mampas 12 1350 84 95
2. Balugo 15 2420 89 95
3. Jawa 10 1090 86 100
4. Liptong 13 1975 90 95
5. Balayag-manok 24 2660 92 95
6. EastBalabag 12 1140 90 95
7. Balili 12 1406 89 100
8. Bongbong 10 1230 82 90
9. Pulang-bato 15 1780 61 80
10. Cadiocan 10 1190 60 80
11. Bong-ao 9 760 89 95
12. Calayugan 9 870 88 95
13. Palinpinon 6 580 87 95
14. West Balabag 6 840 87 95

Total 163 19291 1174 1305
Mean 84 93

1770 rnil. riylyoputn. j3hI)jO3Y1 of

rnciu 3yulptus.nuaul1u

In the field, it is difficult to the
untrained eyes to determine early
symptoms. Unlike the symptoms of
'Moko' which include leaf chlorosis and
leaf wilting, 'tibaglon' affects the male bud
first then the fruit. The earliest symptom of
an infected bunch is noted as blackened,
wrinkled and loose flowers from the male
bud (Fig. 1). When ihe petiole of the male
bud is cut, the discolored vascular tissues
are evident. The disease progresses and
eventually affects the fruits. The apical
fingers are more severely affected than the
basal fingers. Affected fruits exhibit dry
rotting and discoloration of the pulp which
is reddish to dark brown in color. The
discoloration is more intense in the central
tissue of the fruit (Fig. 2). When cut cross
sectionally, the discolored rotten tissues are
concentrated at the central part. The
browning of tissues are also observed in
fruit pedicels and peduncles. The bacteria
which attacked the fruit must have been
transported systematically to the pedicels
and peduncles. In very few severe cases,
browning is also observed in the
pseudostem and corms. There are very few
plants encountered showing symptoms at
the base of the pseudostem and corms.
Affected plants showing discoloration of
the pseudostem and corms also exhibit
yellowing and slight wilting ofithe leaves.
There is lesser discoloration observed
farther away from the fruit. These
observations clearly demonstrate that the
pathogen causing 'tibaglon' is transmitted
by insects and inoculated through the floral
parts of the plant.

Figure 1. Symptom of bacterial fruit rot in male
inflorescence of 'Saba'. Note black
male flowers and the characteristic
loose inflorescence.

Z,~ fWm :iI

Figure 2. Internal reddish brown rotting symptom
of 'tibaglon' in mature, green 'Saba'

1 '4"- f, -

88 1996 Phil. Phytopath. 32(2):83-91

To confirm the diagnosis of the
disease, isolation of the bacterium from the
rotten tissues was done. Cultural and
morphological characteristics of the
bacterium isolated were round, convex
colonies with pink centers and white
margins. The colonies observed resembled
those of the "SFR" (small, fluid, round)
strain of the bacterium, P. solanacearum,
the same bacterium causing 'Moko' disease
of bananas. The pathogen causing the
disease can be recognized readily by colony
characters expressed in Kelman's
tetrazolium medium. Recent DNA studies
)y Raymundo (1997) confirmed that
:bugtok', another local name of 'tibaglon'
is caused by the same bacterium causing
'Moko'. Soguilon and others (1994) also
observed thit the 'Moko' isolate is
morphologically similar to that of 'bugtok'

Earlier report indicating that the
organism causing 'Moko' maybe a different
strain from that causing 'bugtok' or
'tibaglon' because of differences in
symptomatology, maybe explain by the fact
that the inoculation site for 'Moko' is
different from that of 'bugtok' or
'tibaglon'. The inoculation sites for
'bugtok' or 'tibaglon' are the male flowers,
since farmers do not normally remove the
male buds early enough, if not at all.
Insects transmit the bacterium through
feeding on the male flowers. On the other
hand, 'Moko' which is the same bacterial
disease in commercial Cavendish
plantations, exhibits the wilting and
chlorosis symptom, because the inoculation
sites maybe through the roots, or at the
basal portion of the plant due to mechanical
transmission through pruning or
desuckering, a regular commercial cultural
practice. Also, in commercial plantations,
the male buds are cut off as soon as the
false hands appear and bagging fruits with
polyethylene bag is a normal practice for

fruit protection. Thus, infection by the
bacterium through the flowers are
practically insignificant in Cavendish
commercial plantations.

Disease Management Demo-trials

The effects of the .different
management practices in the reduction or
prevention of spread of the bacterial
disease 'tibaglon' in the municipality of
Valencia are shown in Table 2. Results of
the study indicated that all the management
practices were evaluated alone or in
combination were effective in reducing
infection spread of 'tibaglon'. The
reduction in disease incidence was greater
when the management practices are
integrated. As -more practices were
combined, the reduction of the disease was
greater. The effect of the different
management practices became more
apparent with time. Higher reduction in
disease incidence was achieved one year
after implementation of the practices
compared with six months.

The simple removal of the male
buds resulted in the reduction of the
disease incidence from 91% at the start of
the study to 52% and 22%, after six
months and one year, respectively. This
represented a 76% control of the disease
after one year of implementation.
Debudding provides a simple and practical
approach to the reduction of the disease,
since it involves the elimination of the
source of inoculum as well as inoculation
sites as insects are attracted to feed on
male flowers. Sanitation, done by the
removal of dried leaves hanging on the
plants is another simple method of
reducing disease incidence. The consistent
removal of dried leaves every two weeks
had resulted in the reduction from 86%
down to 65% after 6 months and 40%
after one year. The practice had resulted

Iyo rnn. rnytopamn. jz zp:a-y

Table 2. Percent incidence and control of 'tibaglon' before implementation, six months
and one year after implementation of management practices1.

% Incidence % Control
Management Practices month month
0 6 12 0 6 12

1. Untreated control 82.0 89.0 96.0 -
2. Debudding 91.0 52.0 22.0 43.0 76.0'
3. Sanitation 86.0 65.0 40.0 24.0 54.0"
4. Debudding + Sanitation 82.0 39.0 11.0 53.0 86.0c
5. Debudding + Sanitation
+ Disinfestation of fruits 88.0 34.0 6.0 .61.0 93.0b
6. Debudding + Sanitation
+ Disinfestation of fruits
+ Bagging 78.0 23.0 0.0 70.0 100.0"

'Data were taken from 50 farms. Means followed by different letters are statistically different using
DMRT at 5% level of significance.

T U iyo run. r1yUpalu. JArJ.OJ-YI

to 54% control of the disease after one The success of the program, while
year. A higher percentage of control was based on technical concept, depended
achieved in debudding than sanitation. The much on the cooperation and support given
combination of the two tactics, however, by the LGU. The sincere support of the
gave a highly significant control of Mayor and MAO of Valencia, Negros
'tibaglon' than when used separately. The Oriental and even teachers, made this
combined practice of debudding and program successful. Operational disease
sanitation resulted to the reduction of control strategies were available, LGU's
disease incidence from 82% at the start of were ready to operationalize them and the
the study to 39% and 11% six months and result was a successful management of an
one year later, respectively. The reduction economically legitimate problem of
meant 53% and 86% control of the disease farmers.
6 months and one year, respectively. The
integration of disinfection of tools used in
cutting fruits, buds and dried leaves with
debudding and sanitation gave better effect. LITERATURE CITED
The disease was reduced tremendously
with percentage of control as high as 93%
one year after the implementation. The BUDDENHAGEN WI, ELASSER TA.
inclusion of bagging in the integrated 1962. An insect spread bacterial wilt
program for the eradication of bud rot in epiphytotic of Bluggoe banana. Nature.
cooking banana fruits attained 100% 194: 164-165.
control of the disease after one year. The
use of bagging, however, was considered BUDDENHAGEN IW, KELMAN A.
by farmers as impractical considering the 1964. Biological and physiological aspects
height of cooking bananas and this would of bacterial wilt by Pseudomonas
entail an additional expense for them, not solanacearum. Ann Rev Phytopath. 2:
to mention the future problem of disposal 203-230.
of this plastic bags when used extensively.
Early elimination of infected plants was not COOK D, BARLOW E, SEQUIERA L.
included as major component on the 1991. DNA probes as a tool for the study
integrated program to eradicate 'tibaglon' of host-pathogen evolution: The example
because of difficulty to identify 'tibaglon' of Pseudomonas solanacearum. Pages
infected plants at early stage of 103-108. In: Advances in Molecular
development. Besides, farmers would still Genetics of Plant-Microbe Interactions. H.
use some of the fingers that are not Hennecke and D.P.S. Verma, eds. Kluwer
infected, in an affected bunch. Sanitation Acad. Publishers, Dordrechs. The
and early debudding apparently are very Netherlands.
practical means of managing the disease.
They are also easy to implement and the HAYWARD AC. 1964. Characteristics of
effect on control is significant. The farmers Pseudomonas solanacearum. J of Appl
are so convinced of the results, that Bacteriol. 27: 265-277.
practically the whole municipality is now
implementing the program. This RAYMUNDO AK. Genetic analysis of

1004 Phil Phwtnnoth 1701-9r1Q

92 1996 Phil. Phytopath. 32(2):92-101



Portion of a ViSCA-funded project cot
mnd Training Center, ViSCA, Baybay, Leyte.

'Associate Professor, Philippine Root C
ind 3Science Research Assistant, Department 4
Agriculture, Baybay, Leyte.

Key words: Botryodiplodia theobromc
disease, yam

The effectiveness of chemical,
combination of these control measures ir
was determined using two storage meth
or conventional method had no significar
yam varieties varied in their response to
responded positively to T2 (mechani
(mechanical trimming + fungicides + w
(hot water treatment); VU-2 to T2 ant
untreated tubers of Kinampay and VU-
compared to those applied with the mos
Higher percentage germination of tuber:
(untreated). Significant interaction effi
control measures as well as their comb
were generally sensitive to curing, fungic


The edible roots of yam (Dioscorea
data L.) are popular source of carbohydrates
n Southeast Asia and Africa. In the
'hilippines, yam is usually grown in small
latches of land or as a backyard crop (Pido
987). With increasing production, problems
associated with storage may arise. During
torage, yam tubers undergo a high degree of
deterioration caused by physical damage,
microbial infection, endogenous physiological



lucted at the Philippine Root Crop Research

)p Research and Training Center; 2Professor,
F Plant Protection, Visayas State College of

,control measures, Fusarium solani, storage

physical and mechanical control or a
minimizing storage rot disease of yam
Ids. Storing under either modified pit
effect on rot of yam tubers. Different
different control measures. Kinampay
il trimming and wood ash), T3
od ash), T4 (fungicide alone) and T5
T3 and Ace 007 to T5. However,
had a lower severity of rot disease
effective disease control treatments.
was likewise noted in T2, T3 and T6
,ts of variety, storage methods and
nation were also noted. Yam tubers
le and hot water treatments.

action, and fluctuating storage temperature
Booth 1974). According to Noon (1978),
4ostharvest deterioration through attack by
microorganisms is considered as the major
ause of loss of yam tubers during storage
nd marketing.

None of the measures recommended
or the control of these losses such as
refrigeration, curing, chemical treatment, and
radiation has been widely adopted. In
addition, attempts to develop cold storage

1996 Phil. Phytopath. 32(2):92-101 9;

technologies for the tubers have been Hot Water Treatment. Ten n
abandoned because the tubers are susceptible snore suspensions of B. theobromae and I

reducing if not completely eliminating
postharvest losses. This study was therefore
conducted to determine the effectiveness c
chemical, physical and mechanical control o
a combination of these control measure
under different storage conditions i
controlling storage diseases of yam.


In Vitro Bioassay.

Funniridal TrPntmpnt In vifri

immersed in hot water at each of the
temperatures (44, 47 50, 53, 56 and 60C) foi
each time interval (10, 20, 30, 40, 50 and 6(
min), using a constant temperature watei
bath. After exposing the pathogen to th4
designated temperature and time interval, th<
spore suspensions were poured in Petri dishe:
containing previously cooled PDA. Thi
control or check was provided by pouring
untreated spore suspension into solidified
PDA in Petri plates. The plates were their
incubated at room temperature and funga
growth and developments were noted after 4i

94 1996 Phil. Phytopath. 32(2):92-101

T4 Fungicide alone Tubers RESULTS AND DISCUSSION
were dipped in a bath of
benomyl suspension at the Fungicidal Test In Vitro
manufacturer's recommended
rate (200 ppm) for 10 min. Table 1 shows the mycelial growth of
B. theobromae and F. solani as affected by
T Hot water Tubers were different fungicides. Of the six fungicides
immersed in hot water at evaluated against B. theobromae, only
480C for 10 min. using a benomyl completely inhibited the growth of
constant temperature water the fungus after 2 days of incubation. For F.
bath. solani, Captan, Benlate and Dithane M-45
were found significantly inhibitory to the
T Control Untreated tubers. growth of the pathogen. Other fungicides
tested were ineffective in controlling the
The treated and control tubers were mycelial growth of the two pathogens.
then placed in net bags and stored for 4
months under modified pit and conventional Table 1. Mycelial growth in plated potato dextrose
storage methods. In the first storage method, aar of B theobromae and F. soani as
a pit (1 x 1.5 x 1 m) was dug. Small bamboo affeed application of dierent
poles served as flooring within the pit. The
set-up was about one foot above the ground. LENGTH OF MYCELIUM
The pit was covered with a wire screen and FUNGICIDE 48 HADP (mnm)
enclosed with a shelter. The same shelter was R teobromae F. solani
utilized in the conventional method with
Control 35.00 6.00
tubers in net bags hang about 2.5 m above the Benlate 0.00 0.47
ground. Fungitox 2.67 1.01
DithaneM-45 14.30 0.50
The initial weight of tubers was Cupravit 14.80 5.09
recorded 2 days after harvest for all Caplan 17.95 0.39
treatments except for T1 that was taken right Viigran Blue 25.10 6.21
after harvest. Likewise, the final weight was
determined after 4 mo of storage. 'Average of three replicates; HADP hours after disc
Tubers were observed monthly until
the fourth month of storage for possible The results suggest that some of the
development of disease. At the termination of chemicals tested were not effective in
the experiment, tubers were halved controlling the growth of B. theobromae and
longitudinally and the reaction of yam F. solani while others were toxic only to a
accessions/genotypes to rot pathogen was single specific pathogen. For instance,
noted following the disease rating .scale Benlate was found inhibitory to the growth of
described earlier both B. theobromae and F. solani while
Captan and Dithane M-45 were toxic to F
The treatments were laid out in a solani alone.

1996 PhiL Phytopath. 32(2):92-101 95

It is noteworthy to mention that
fiungicidal test in vitro is not a reliable
indicator of fungicide performance in vivo
since it does not consider the suscept-
pathogen-chemical interaction. Heyn and
others (1965) likewise explained that certain
fungicides hydrolyze much faster in vitro than
when applied to plants. Thus, it has been
recommended that several media be used to
negate the probable occurrence of reaction
between the active ingredients of fungicides
and the specific nutrients of a particular

Effect of Hot Water Treatment on the
Growth ofB. theobromae and F. solani

Growth of B. theobromae and F.
olani was completely inhibited at
temperatures higher than 47C. Both
pathogens could thrive at 44 and 47C (Table

Severity of Rot Disease as Influenced by
Variety, Control and Storage Methods

Among the three varieties, Kinampay
gave the lowest disease severity score
followed by VU-2 and Ace 007 (Table 3).
Nfo significant difference in disease severity
score was noted between the latter two
varieties; Ace 007 gave a significantly higher
percentagee germination than Kinampay and
/U-2 (Table 4).

In terms of germination, tubers
mechanically trimmed and dipped in wood ash
T2), mechanically trimmed + Benlate + wood
ish (T3), and the untreated (T6) gave
significantly higher percentage termination
han the rest (Table 5). Yam tubers were
generallyy sensitive to curing, chemical

Yam tubers cured for 2 days under
sunlight (Ti) gave a significantly higher
disease severity score than the other control
measures. The other treatments (T2 to T6)
did not differ significantly in the disease
severity scores. The higher moisture loss in
cured yam tubers may be considered an
important factor that contributed to the high
disease severity. Such moisture loss could be
partly responsible for the greater susceptibility
of stored tubers to infection by rot pathogens.
This result concurs with the findings of
Goodlife and Heale (1977) on stored carrots,
Furthermore, Mozie and Okoro (1990)
reported that the number of cork cell layers
formed during wound healing in yam tubers
appears to be related to the light quality used
for irradiation treatment during curing. They
noted that throughout the storage period of
40 weeks, those cured in red light recorded
30% rotting whereas tubers cured in yellow,
green, and blue light chambers exhibited no
rotting. Hence, it is possible that the
wavelength and quality of light used in curing
of yam in this study failed to stimulate the
neristematic activity of the cork cambium in
wound repair or healing, resulting in increased
disease severity of cured tubers. Analysis of
variance further revealed significant
interaction between control measures applied
md yam variety on rot disease severity.

Rot disease severity score was
significantly lower in variety Kinampay
applied with the following treatments:
mechanically trimmed + wood ash (T2);
mechanically trimmed + Benlate + wood ash
T3); dipped in Benlate alone (T4); hot water
T5) and untreated (T6) (Table 7). On the
either hand, Kinampay tubers cured under
sunlight for 2 days (TI) gave the significantly
highest disease score. This can be attributed
3 higher moisture loss observed in cured

__ 1996 Phil. Phytopath. 32(2):92-101

Table 2. Effect of hot water treatment on the 1

Temperature (C) 10 :

44 +1 + +
47 + + +
50 -
53 -
56 -
60 -

'+= growth was observed; -= nogrowth wasobserved

Table 3. Disease severity of rot disease in yam
different control measures and/or var

Control Method2 Kinampay

Ti 9.0 a
T2 3.0 gh
T3 3.7 fg
T4 2.0 h
T5 3.3 fgh
T6 3.3 fgh

'In a column or row, means followed by a conur

2Control methods: T1 = curing; T2 = mechanical t
dipping Benlate + wood ash; T4 = dipping in Benl;

-owth ofB. theobromae (A) and F. solani (B).

Time Interval (min)
i 30 40 50 60

+ + + + + + + + +

ubers at 4 months after storage as influenced by

VU-2 ACC 007 Mean

6.3 be 6.0 bc 7.1 a
L.7 def 6.7 be 4.8 b
1.3 efg 6.3 bc 4.8 b
6.0 bed 6.0 bed 4.7 b
7.0 b 3.3 fgh 4.5 b
5.3 cde 6.3 be 5.0 b

n letter are not significantly different at 5% level.

mming + wood ash; T3 = mechanical trimming +
e alone; T5 = hot water; T6 = control.

1996 Phil. Phytopath. 32(2):92-101

Table 4. Mean percent germination of three yam varieties.

Variety / Accession Germination1 (%)

Kinampay 59.2 b
VU-2 53.3 b
Ace 007 80.0 a

'Means followed by a common letter are not significantly different at 5% level. DMRT.

Table 5. Percentage germination of yam tubers as affected by different control methods.

Control Method' Germination (%)2

Ti 50.0 b
T2 73.3 a
T3 73.3 a
T4 58.3 b
T5 60.0 b
T6 70.0 a

'Ti = Curing; T2 = Mechanical trimming + wood ash; T3 = Mechanical trimming + dipping in Benlate + wood
ash; T4 = Dipping in Benlate; T5 = Hot water (480C for 10 min.); T6 = Untreated (control).

2Means followed by a common letter are not significantly different at 5% level. DMRT.

98 1996 Phil. Phytopath. 32(2):92-101

Modified Pit Conventional

Ti 7.7 a 6.5 b
T2 4.3 def 5.2 cd
T3 5.0 cde 4.5 def
T4 5.9 be 3.4 f
Ts 5.2 cd 3.9 ef
T6 3.9 ef 6.1 bc

hIn a colunm or row. means followed by a common letter are significantly different at 5% level, DMRT.

ST1 = Curing: T, = Mechanical trimming + wood ash: T3 = Mechanical trimming + dipping in Benlate +
ash: T4 = Dipping in Benlate: T5 = Hot water (48C for 10 min.); Tg = Untreated (control).

Table 7. Disease severity in yam tubers four months after storage as influenced by val
control measures and storage methods.'

Control Method2 Modified Pit Conventional Pit
Kinampay VU-2 ACC 007 Kinampay VU-2 AC(

Ti 9.0 a 7.0 abed 7.0 abcd 9.0 a 5.7 cdef 5.0(
T2 3.0 gh 5.0 defg 5.0 defg 3.0 gh 4.3 efg 8.3
T3 3.0 gh 5.7 cdef 6.3 bcde 4.3 efg 3.0 gh 6.3 1
T4 3.0 gh 5.7 cdef 9.0 a 1.0 h 6.3 bcde 3.0
T5 3.7 fg 9.0 a 3.0 gh 3.0 gh 5.0 defg 3.7 1
T6 3.7 fg 3.0 gh 5.0 defg 3.0 gh 7.7 abc 7.7

Mean 4.34 6.48 6.06 4.06 6.40 5.

'In a column or row, means followed by a common letter are not significantly different at 5%

2Control methods:' T = Curing; T2 = Mechanical trimming + wood ash: T3 = Mechanical trimm
dipping in Benlate + wood ash: T4 = Dipping in Benlate alone; Ts = Hot water (480C for 10 min);



1996 PhiL Phytopath. 32(2):92-101

Mech. Mech. [Dip in
trimming trimming fungicide
+ ash + dip alone
in fungicide

Figure 1. Effect of different control measures on weight loss of three yam varieties.

Hot water

increase in disease severity score.

-In variety VU-2, significantly lower
disease severity was obtained in tubers
mechanically trimmed and dipped in wood ash
(T2), mechanically trimmed + Benlate + wood
ash (T3) and untreated (T6), while higher
disease severity scores were recorded in
tubers treated with the other control
measures. With Ace 007, a significantly
lower disease severity score was observed
only in tubers treated with hot water (Ts)
while the rest gave significantly higher disease
severity scores.

The results suggest that different
varieties of yam varied in their response to
different control measures applied. With
Kinampay [T4) = dipping in benomyl alone]
and VU-2 [T3) = mechanical trimming +
dipping in benomyl solution], the most
effective control measures applied gave
significantly lower disease severity scores
comparable to untreated tubers.

Neither modified pit nor conventional
storage methods did not significantly affect
rot disease severity and percentage
germination of yam tubers. However, storage
methods and control measures showed
significant interaction effect on rot disease
severity (Table 6). Yam tubers stored under
conventional method and mechanically
trimmed + Benomyl + dipped in wood ash
(T3), dipped in Benomyl alone (T4) and
treated with hot water (Ts) obtained the lower
disease severity scores compared to
mechanically trimmed tubers, dipped in wood
ash (T2), mechanically trimmed + Benomyl +
wood ash (T3), and the untreated (T6).

These findings showed that under the
menventinnA qtnroat mpthnd cnntrnl

1996 Phil. Phytopath. 32(2): 92-101

measures due to a lower disease severity
rating even in the control. On the contrary,
application of control treatments to yan
tubers under modified pit storage resulted to
higher disease severity. This must be due to
the complexity of interactions between
environmental conditions inside the pit and
the physiology of the treated corms that need
further detailed investigation.

Significant interaction effects on rot
disease severity was also observed on variety,
storage methods and control measures used
(Table 7). A significantly lowest disease
severity score of 1:0 was obtained in
Kinampay stored under the conventional
method and dipped in Benomyl solution; the
highest disease severity score of 9.0 was
noted in all three varieties stored in
conventional and modified pit but applied
with different control measures. For instance,
tubers of Kinampay cured and stored both in
modified pit and conventional storage
methods gave disease severity score of 9;
likewise with tubers of VU-2 treated with hot
water and stored under modified pit. In Ace
007, tubers dipped in fungicide and stored
under modified pit gave the same disease
severity score of 9.0.

Loss in Fresh Weight

Figure 1 shows the changes in
percentage weight loss of three yam varieties
applied with the different control measures
and stored using the conventional and
modified pit storage methods. Cured
Kinampay tubers stored in conventional and
modified pit gave the highest loss of fresh
weight while those treated with hot water
showed the lowest weight loss. In addition,
untreated tubers of Kinampay showed lower
loss in fresh weight both under modified pit

1,yo rnm. rnytopatn. jz(Z): YZ-IUI 101

from the tuber. certain N-carboxymethyl-dithiocarbamic acid
derivatives. Ann Appl Biol 56:399-409.

MOZIE, O, OKORO NN. 1990. Effect of
LITERATURE CITED light irradiation on wound "curing' in white
yam (Dioscorea rotmudata Poi) tubers. Trop
Sci 30:373-378.
BOOTH RN 1974. Postharvest
deterioration of tropical root crops: Losses NOON RA. 1978. Storage and market
and their control. Trop Sci 16:49-63. diseases of yams. Trop Sci (U. K.).
GOODLIFE JP, HEALE JB. 1977. Factors
affecting the resistance of stored carrot roots PIDO NL. 1987. Crop characteristics,
to Botrytis cinerea. Ann Appi Biol 85:163. production and storage. In: Pido NL, Pepino
MB, Editors: Ubi: A guide to its culture and
HEYN AJ, CARTER GA, ROTHWELL K, Phil Root Crop Information Service,
WAIN RL. 1965. Investigations on PRCRTC, Baybay, Leyte. 78 pp.
fungicides XII. The fungicidal activity of

102 1996 Phil. Phytopath. 32(2): 102-117

r--------~--- --- -- ---- --0----- D~~

VTRODUCTION conditions. Postharvest losses in frui

l t1 IIaLUI. uI lapiu iipuCnll anl u vCuml cu at .L'-tU/O 11 InupIpIaI %vuuIiLIIlm
senescence of tropical fruits reflect the (Daniels 1990).
.. rP .... ... . _.. -__

1996 Phil. Phytopath. 32(2): 102-117 103

pollution in the air, soil and water, chemical characterized by hyaline, apparently
control of postharvest commodities are unpigmented mycelia and few
discouraged by environmental protection microsclerotia. As low as 0.4 meq Al/100
agencies. Moreover, the emergence of g (36 ug/g) in the culture medium
fungicide-resistant strains of pathogens are significantly reduced mycelial growth of P.
reducing opportunities to devise fungicide- capsici (Muchove and others 1980).
based control strategies. The widespread Similarly, Meyer and others (1994) noted
and continuous application of benomyl that germination of endoconidia and
resulted in the development of resistant chlamydospores of Thielaviopsis basicola
strains of Lasiodiplodia theobromae (Pat) decreased significantly when exposed to 5
Griff. And Maubl. and Colletotrichum ppm Al while radial growth was suppressed
musae (Berg. and Curt) Arx. in banana on agar amended with 10 ppm Al. In vitro
fruits reported from Central American germination and reproduction of P.
plantations (Slabaugh and Grove 1982). parasitica was inhibited by aluminum
Benoynyl resistant strains of C. (Weaver and Shew 1992, Benson 1993).
gloeosporioides have been reported also
from mangoes in Thailand (Farungsang and In the Philippines, Borromeo (1983)
Faruntang 1992). Hence, there is an urgent studied the effectiveness of alum against
need to develop an alternative to harmful Erwinia carotovora subsp. carotovora, the
synthetic fungicides that does not cause of soft rot of cabbage. He reported
compromise community expectations of that 15% alum is promising to control the
fruit quality. The use of alum [K Al (S04)2 bacterium. He also noted that alum
12H20] in plant disease cotitrol is one sprayed towards the butt end before
alternative, packing reduced the incidence of soft rot in
The important characteristic of
alum such as very low pH value and high Banana is the most important
microbial toxicity of Al3 ion attracted the tropical fruit with respect to acreage and
attention of scientists to use it in disease production. Postharvest diseases of banana

those caused by Phytophthora

104 1996 Phil. Phytopath. 32(2): 102-117

The objectives of this study was to
determine the ability of alum to control
these postharvest rots and to characterize
the activity of alum as it is affected by
inoculum concentration and time of


Collection of pathogens and preparation
of inoculum

Banana fruit rot pathogens, L.
theobromae and C. musae, were isolated
from infected banana fruits collected from
the Los Baflos public market. The isolates
were purified and maintained in PDA
medium at room temperature.
Pathogenicity tests were carried out in ripe
banana fruits. The pathogens were re-
isolated from the infected fruits and

Sterile distilled water was added to
5-day old slant cultures of C. musae. The
surface of the culture was gently scraped
using a sterile needle. The suspension was
decanted through a double layer of sterile
gauze cloth into a 25 ml glass vial. The
pycnidia from 15-day old slant cultures of
L. theobromae were crushed over a glass
slide containing a drop of water.i The
suspension was decanted as before. The
concentration of the spores was determined
with the aid of a hemacytometer following
standard procedure (Sharvelle 1961).

Germination and germ tube elongation

The effects of alum on the
oarmination and germ tube elongation of L.

theobromae and C. musae were determined
in microtiter plate wells. Spore
suspensions of 104 and 105 conidia/ml were
used in this study for L. theobromae and C.
musae, respectively. Each well of the plate
was filled with 50 ul conidial suspension
and 50 ul alum solution. Finally, 20 ul
potato dextrose broth was added to
provide nutrients for growth. The
concentration of alum in the total liquid
volume was maintained to the desired level.
Inoculated plates were wrapped with
aluminum foil and stored at room
temperature in a plastic box which provided
optimum RH. After 8 hr of incubation,
plates containing L. theobromae were taken
out from the box to determine germination
and germ tube elongation. Plates with C.
musae were incubated for 24 hr. Twenty ul
of 10% glutaraldehyde was added to each
well to arrest further growth during the
measuring process. The number of
germinating spores and germ tube
elongation were measured as before.

Growth of the pathogen

The effects of alum on the mycelial
growth of L. theobromae and C. musae
were determined by incorporating alum into
PDA medium. The alum powder was
added into the medium before pouring into
Petri plates. The plates were inoculated
with a 5 mm-diameter disc taken from the
edge of one-day old cultures of L.
theobromae and two-day old cultures of C.
musae. Plates were then incubated at room
temperature and radial growth was
measured every 24 hr.

The addition of a small amount of
alum in the PDA medium made it highly
anidir The conwth of the test nathonen

1996 Phil. Phytopath. 32(2): 102-117 105

was severely inhibited in the amended
medium. To determine the cause of
inhibition, whether it is due to Al" toxicity
or adverse pH value, an experiment was
carried out. The pH of the alum amended
medium was adjusted at 6.5 by the addition
of KOH to the medium before pouring into
the plates. The plates were inoculated,
incubated and the radial mycelial growth
was measured as before.

Disease inhibition

To determine the effect of alum on
disease inhibition, banana fruits of ripening
grade 5 (Lizada and others 1990) was used
throughout the tests. Fruits were surface-
disintegrated by immersion in 10%
commercial bleach for 5 min, air dried and
was placed in plastic trays for one hour
before inoculation. Two wounds (5 mm
wide and 2 mmdeep) were made in each
fruit. Immediately after wounding, 20 ul of
an aqueous standardized spore suspension
of either L. theobromae or C. musae were
pipetted into each wound site. The conidial
suspension was allowed to air dry at
ambient temperature. Then each wound
was treated with 20 ul alum solution.

The concentration of alum was
varied to determine its potential in
controlling the disease. In the case of L.
theobromae, the tested alum concentrations
were 2.5, 5.0, 7.5, 10.0, 12.5 and 15.0%
while for C. musae the concentrations were
2, 4, 6, and 8%. Inoculum levels of 5,000
and 1,000 conidia/ml were used for each

ed with plastic sheet for 2

the inoculated sites were measured after 2
and 4 days for L. theobromae and C.
musae, respectively.

Time of application of alum

To determine the appropriate time
of alum application relative to inoculation,
ripe banana fruits were treated with alum
before, simultaneous with, and after
inoculation. The treatments were
application of alum 4 and 2 hr before
inoculation, simultaneous application, and 2
and 4 hr after inoculation. Banana fruits
were disinfested and wounded as before.
Each wound was treated with 20 ul alum
and 20 ul spore suspension of L.
theobromae (1,000 conidia/ml). The
concentrations of alum tested were 10.0,
12.5 and 15.0%. Inoculated fruits were
incubated at room temperature. Rot
development was monitored as before.


Germination and germ tube elongation

The germination of both L.
theobromae and C. musae spores was
significantly affected by alum. Results
indicated that. germination of L.
theobromae was inversely related with
alum concentration (Fig. 1). Minimum
germination (4.15%) was noted at 15.0%
alum. The two-celled spores of the

106 1996 Phil Phvtonath. 32(2): 102-117

15.0% alum. There was no significant
difference in germination of spores treated
with 2.5 to 10.0% alum.

The germ tube elongation of both
pathogens was remarkably affected by alum
treatment. The shortest germ tube of L.
theobromae was recorded at 15.0% alum
(Fig. 2). Germ tube length of spores
treated with 5.0 to 15.0% alum did not
exhibit significant difference. Like
germination, the germ tube elongation of
the pathogen was inversely related with
alum concentration. The germ tubes of C.
musae were also severely affected by alum;
as low as 1.0% alum severely inhibited
germ tube growth. There was no
significant difference in germ tube length of
spores treated with 2.5 to 15.0% alum.

At lower concentrations (up to
2.5% alum) L. theobromae spores
produced few, short and severely branched
germ tubes. Immediately, after
germination, some of the germ tubes
appeared disintegrated. This disintegration
started at 2.5% alum and the frequency was
increased with the increased in alum
concentration. At 10% alum and above, all
germ tubes were disintegrated. Germ tube
disintegration was also noted in C. musae
spores but the pathogen was able to
n-nA,,,. nnP n.- hl- l n-+, J- ,.- .


0 1 U S 10 Is

Figure 1. Effect of alum on germination of
Lasiodiplodia theobromae and
Colletotrichum musae after 8 and 24
hours, respectively.

I : -
I 00 --- - -

0 1 U 5 10 11

Figure 2. Effect of alum on germ tube elongation of
Lasiodiplodia theobromae and
Colletotrichum musae after 8 and 24
hours, respectively.

1996 Phil. Phytopath. 32(2): 102-117 107

0 4% alum. The pathogen was unable to The colony diameter at higher alum
colonize at 0.5% alum. Insignificant concentration was quite large but the
increased growth of the fungus compared growth of the pathogen was sparse and the
to alum-free control was recorded at low colony was thinner. As the concentration
alum concentrations of 0.05 and 0.1%. of alum increased, the colony became more
Significantly higher growth of the fungus sparse and thinner and the color of the
was recorded at 0.05 and 0.1% alum after 2 colony changed from light brown to dark
days of incubation. Higher alum brown. The growth of the pathogen in the
concentrations (0.2% and above) strongly presence of alum was characterized by
inhibited colony diameter with very minimal more sparse mycelium compared to the
growth at 0.5%. The pathogen was unable control. Frequent branching of mycelium
to colonize the 0.6% alum-amended was noted at 5.0% alum.
medium even after 2 days.
The growth of '. musae was
The growth of C. musae was significantly affected in the alum amended
significantly reduced in alum amended medium at pH 6.5. Likewise, the colony
culture medium and was inversely related diameter was inversely related to the alum
to the concentration of alum in the medium concentration in the medium (Fig. 7). The
(Fig. 5). Growth was completely inhibited growth of the fungus at 5.0% alum was
at 1.25% alum even after a longer visible only after 3 days of incubation. The
incubation of 4 days. A longer incubation colony became thinner at higher alum
period was needed by the pathogen to concentrations. The color of the colony
grow on higher alum concentration of 0.75 changed from pinkish to creamy white.
and 1.0%. There was no significant The pathogen produced less spores
difference in colony diameter at 0.75 and compared to the alum-free control.
1.0% alum after 3 and 4 days. The
pathogen produced only thin colony in the Aluminum hydroxide [Al (OH)3] gel
medium amended with higher alum was formed when potassium hydroxide
concentration. (KOH) was incorporated into the alum
amended culture medium. At 5.0% alum,
Mycelial growth in medium at pH 6.5 the medium became completely white due
to gel formation. The opaque medium
Althir-nh 1 / n-~hAr-m. ~ f ta ilA itn h 'am! trannrnrPnt vuhan thp nothnopn

noted at 0.1% alum but this was not
significantly different from the alum-free
control. A similar trend in growth was
recorded after 2 days of incubation (Fig. 6).

Alum significantly inhibited L.
heobrotmae rot development in artificially
inoculated banana fruits. Higher
concentrations of alum exhibited greater

hob IL90 Io ri. rnytopamn. JL(I): IUL-II /


100 -

80 -


40 -

20 -

0 4i
0 0.05 0.1 0.2
Concentration of a

Figure 4. Growth of Lasiodiplodia theol



E 80
V 5o

I 60



0 0.25 0.5

Figure 5. Growth of Colletotrichunm j

01 day
82 daya

0.3 0.4 0.5 0.6
lum (%)

ronmae at various concentrations of alum.

S---- day
'02 day
S13 day
14 day

0.75 1 1.25
tion of alum (%)

nusae at various alum concentrations.

1996 Phil. Phytopath. 32(2): 102-117

01 day


0 0.1 0.5 1 2 5
Conxcentration of alum (%)

Figure 6. Effect of various alum concentrations on the
theobromae at pH 6.5.

T T T4

T T .'_ T



growth of Lasiodiplodia




Figure 7. Effect of alum on the growth of Colletotrichum musae at pH 6.5.

u Iu


0 0.1 0.5 1 2
Concentration of alum (%)

~L .L- _i


J J .


110 1996 Phil. Phytopath. 32(2): 102-117

inhibition. At a high inoculum level of inoculum levels of 5,000 and 1,000
5,000 conidia/ml, a significant reduction in conidia/ml although the size of rot was
disease development was recorded in fruits smaller at the lower inoculum levels (Fig.
treated with as low as 2.5% alum (Fig. 8). 11).
Disease development was inversely related
to alum concentration. The pathogen was Time of application of alum
not able to produce any disease symptom in
banana fruits treated with 7.5 to 15.0% Fruits that had been treated with
alum after 48 hr of incubation. At higher alum 2 hr before inoculation with L.
alum concentrations of 12.5 and 15.0, theobromae showed better protection than
disease symptom was visible only after 72 those treated 4 hr prior to inoculation
and 84 hr of incubation, respectively. The (Table 1). Likewise, fruits treated with
pathogen produced rot with a diameter of alum 4 hr after inoculation provided greater
14.22 mm at 15.0% alum after 84 hr when disease inhibition than those treated 2 hr
the control fruits were completely rotten. after inoculation or simultaneous pathogen
The results suggest that the activity of alum introduction. Treatment of alum 2 and 4 hr
was fungistatic rather than fungitoxic. after inoculation caused suppression of
disease symptoms up to 3 days and small
At lower inoculum level of 1,000 rots were noted only after 4 days of
conidia/ml, the size of rotten tissue was less incubation.
compared to that at higher inoculum levels.
Disease inhibition was inversely related to
concentration of alum. At 10.0 and 12.5% DISCUSSION
alum, disease symptoms were visible only
after 60 and 72 hr, respectively. There was Spore germination and germ tube
no disease development in banana fruits elongation of L. theobromae and C. musae
treated with 15.0% alum even after 84 hr were not completely inhibited 15.0% alum
(3.5 days) of incubation (Fig. 9). in the substrate but were significantly
reduced. These observations support
r\:__-- --~. ^L-, At :_ -1--,,1,

1996 Phil. Phytopath. 32(2): 102-117 111

0 2.5 5 7.5 10 12.5 15
Concentration of alum (%)

0 2.5 5 7.5 10 12.5 15
Concentration of alum (%)

Figure 8. Effect of alum on rot of banana fruits caused by Lasiodiplodia
theobromae at two inoculum level (A) 1,000 and (B) 5,000

Figure 9. Effect of various alum concentrations on banana rot 3.5 days after inoculation
with Lasiodiplodia theobromae (1,000 conidia/ml).


996 Phil. Phytopath. 32(2): 102-117 113





215 T---------------



0 2





O 2

Figure 1. Effect of alum on rot in banana I
inoculum level (A) 5,000 and (B)

M4 ady
05 day
M6 day

4 6 8

M4 day
-6 day

4 6 8
Df alum (%)

ruits caused by Colletotrichum musae at two
1,000 conidia/ml.

114 1996 Phil. Phytopath. 32(2): 102-117

Table 1. Inhibition of rotting in banana fruits as affected by alum treatment and time of
inoculation with Lasiodiplodia theobromae.

Elapsed Time Conc. of Rot Diameter (mm)
Treatment Between Alum after'
Treatment (hr) (%) 3 days 4 days

Alum followed 4 10.0 6.25 17.00
by pathogen 12.5 1.25 6.25
15.0 0.00 4.73

2 10.0 4.50 14.08
12.5 2.00 5.00
15.0 1.64 4.75

Simultaneous -10.0 5.41 11.85
application 12.5 2.58 4.58
15.0 0.00 3.60

Pathogen followed :2 10.0 0.00 2.66
by alum 12.5 0.00 2.70
15.0 0.00 0.00

4 10.0 0.00 2.41
12.5 0.00 0.00
15.0 0.00 0.00

Control 30.87 46.50

SEach figure is an average of 12 replicates.

1996 Phil. Phytopath. 32(2): 102-117 115

The radial growth of L. theobromae
was suppressed at 0.6% alum while C.
musae was suppressed at 1.25%. C musae
was able to produce few normal germ tubes
in 15.0% alum indicating that L.
theobromae is more sensitive to Al than
was C. musae.

The growth of both pathogens was
severely inhibited by small amounts of alum
in the culture medium. However,
appreciable growth was noted with 5.0%
alum when the pH of the medium was
adjusted to 6.5. This clearly indicated that
Al toxicity was much greater at low pH.
Meyer and others (1994) reported that
toxicity of Al towards T basicola was
much greater at pH 4.8 than at 5.6 to 6.0.
As pH decreases, a higher percentage of Al
is in the highly toxic Al]3 form. As pH
increases above 5.0, Al" makes up a very
small proportion of soluble Al; the
predominant Al occurs as aluminum
hydroxide (Ritchie 1989).

At higher concentrations of alum
the colony color of both pathogens was
changed. A similar interference in pigment
development in V. albo-atrum due to Al
toxicity was reported by Orellana and
others (1975). Higher alum concentrations
(0.5% and above) inhibited spoire
production of C. musae. Deluca and Shew
(1988) also reported reduction in sporangia
production of P. parasitica var. nicotianae
at 30 ug Al/g of culture medium.

The active compound of alum is
most likely the Al 3 ion. Other reports
indicated that the Al+3 ions, .not the
associated anions, are responsible for
suppressive effects shown by Al (Borromeo
1983). Meyer and others (1994) also noted

that Al from different sources had similar
inhibitory effects on germination and
growth of T. basicola. Al3 ion obstruct
normal cell metabolism as it has high
binding capacity with protein and long
chain polysaccharides (Henderson and
Easton 1980).

Alum was more effective at a lower
inoculum level of 1,000 than at 5,000
conidia/ml for both pathogens. It is clear
that the fungicidal activity of alum
decreased when inoculum level increased.
Thus, when inoculum levels are high, a
higher dose of alum is recommended.

Banana fruits treated with alum
after inoculation with the pathogen
exhibited greater disease reduction than
simultaneous treatment or treatment before
inoculation with L. theobromae. Results
indicated that alum was effective even if
applied after the pathogen had initiated the
infection process in the host tissues. This
may be due to the high sensitivity of
germinating spores or newly emerged germ
tubes and hyphae than dormant spores was
observed in in vitro studies.

Alum appears to lose its
effectiveness over time. The- loss of
effectiveness of alum may be due to the
inactivation of the active component of
longer exposure. Al3 ion which is
recognized as the toxic form to different
organisms may form complexes with
organic compounds in the cell (Henderson
and Easton 1980). Some organic
compounds of the fruit tissue precipitate or
chelate A"3 ion (Ritchie 1989) and thus
may inactivate possible defense mechanism
against the pathogen. These reactions
reduce the A"3 ion and expose the fruit to


fungal attack. Borromeo (1983) als
reported that treatment of alum 6 hr after
inoculation provided better protection i
cabbage core against E. carotovora subsy
carolovora than treatment with alum 6 I
before inoculation. The full potential c
alum should be determined over a wide
range of application time.

All the germ tubes of I
iheobromae were disintegrated at 10 t
15% alum as was observed in in vitr

produce disease syn
after a long incu


BENSON DM. 1993. Suppression c
Phytopthora parasilica on Catharanthus
roses with aluminum. Phytopathology 83

BORROMEOES. 1983. Characterization
and postharvest control of Erwinii
carotovora subsp. carotovora infecting
cabbage. M. S. Thesis, UPLB, College
Laguna. 86 o.

,ms in banana fruit

1996 Phil. Phytopath. 32(2): 102-117 117

LI-I.AII-rt v iv .. v ,- rt-iN i .a I It.I noD
Changes during ripening in banana. In
Hassan A. Pantastico E, editors. Banana
fruit development, postharvest physiology
handling and marketing in ASEAN
ASEAN Food Handling Bureau, Kualh
Lumpur, Malaysia, p. 65-84.

1994. Inhibition of germination an<
growth of Thielaviopsis basicola b,
aluminum. Phytopathology 84: 598-602.

MORTUZA MG, ILAG LL. 1995. Effec
of temperature and humidity on thi
germination and growth of Lasiodiplodit
theobromae, cause of stem-end rot o
mango. Phil Phytopath 31: 1-8.

MUCHOVEJ RMC. 1980. Effect o
exchangeable soil aluminum and alkaline
calcium salts on the pathogenicity anc
growth of Phytopthora capsici from greer
pepper. Phytopathology 70: 1212-1214.

AL. 1975. Effect of soluble aluminum or
growth and pathogenicity of Verticilliun
albo-atrum and Whetzelinia sclerotiorun
from sunflower. Phytopathology 65: 202.

RITCHIE GSP. 1989. The chemical
behavior of aluminum, hydrogen and
manganese in acid soils. In: Rodson AD,
editor: Soil Acidity and Plant Growth.
Academic Press, San Diego, CA. p. 1-60.

Postharvest pathology of banana. In:
Hassan A, Pantastico EB, editors. Banana -
fruit development, postharvest physiology,
handling and marketing in ASEAN.
ASEAN Food Handling Bureau, Kuala
Lumpur, Malaysia. p. 104-116.

SHARVELLE EG. 1961. The nature and
use of modem fungicides. Burgess
Publishing Co., Minnesota, USA. 308 p.

Postharvest diseases of bananas and their
control. Plant Dis 66: 746-750.

Aluminum and a calmodulin antagonist
inhibit germination and reproduction of
Phytopthora parasitica var. nicotianae.
Phytopathology 82: 1088 (Abstr.).

Ia1 XflX AR EAU. 1K RAJ supftIa



'Research Associate Professor, Inst
University of the Philippines at Los Bafios,
Student, and 3Professor, Institute of Agri
Tsukuba, Ibaraki 305, Japan.

Key words: Canna indica, Co)
Puccinia thaliae, rust

Coleosporium plumeriae wz
disease is characterized by the form,
erumpent, hypophyllous, punctiforn
leaf. Urediniospores are subglol
verrucose with bluntly capitate
unconspicous, two or four, scatte
consist of minute spots with yel
Puccinia thaliae was found causing
of the leaves and the p.seudosterr
hypophyllos, scattered, minute, rou
Urediniospores are subglobose, ova
and thick, pores two, equatorial.
apex rounded, truncate or acumini
walls pale brown and thick at
Spermagonia, pycnia and aecia are t


Plumeria acuminata Ait. (=P.
acutifolia Poir.), locally known a,
kalachuchi, is one of the most popular
ornamental trees which are common)
found in parks and landscape
establishments over the country. It bear!



:ute of Plant Breeding, College of Agriculture
College, Laguna 4031, Philippines, 2 Graduate
culture and Forestry, University of Tsukuba

'osporium plumeriae, Plumeria acuminata,

Found causing rust in Plumeria. The
tion of powdery, bright yellow-orange,
uredinia on the abaxial portion of the
ose to angular, catenulate, coarsely
annulate tubercles, germ pores
ed. Lesions on the adaxial surface
ow color turning brown with age.
rust in Canna. It infects both surfaces
Uredinia are amphigenous, mostly
id to irregular, yellow to light brown.
e or pyriform, echinulate, walls hyaline
Teliospores are clavate to cylindrical,
te, slightly constricted at the septum,
he apex, pedicel short and hyaline.

beautiful, big flowers of various colors and
sizes which predominates especially during
summer months of the year. Canna indicc
L., locally known as Bandera Espafola, is
likewise popular landscape ornamental
plants. It has been introduced in the
country and commonly found along fences.
ornamental nurseries and parks. It bears

1996 Phil. Phytopath. 32(2):118-123 11

large. sort petals ot various sizes and

Kalachuchi rust has been first reported in
the Philippines by Tangonan and others
(1997) while (Caina rust by Divinagracia
(1985). They reported the incidence and
the characteristics symptoms of the disease.
With regards to the identification of the
pathogen, Tangonan and others (1997)
identified the rust fungus on kalachuchi as
(oleosporium pl)mnteriae Pat. The same
fungus has been attacking Plumeria in
Canada (Traquair and Kokko 1980) and
Hawaii (Ogata and Gardner 1992).
Identity of the Canna rust was not
confirmed as to the species name.
Divinagracia (1985) reported it as a certain
species of Puccini.

This study aims to provide
morphological description of the fungus
causing rustin Plumeria and Canna, and to
identify the species of Puccinia causing
Canna rust.


Plumeria and Canna leaves with
rust were collected in ornamental
screenhouse of the Institute of Plant
Breeding, UPLB, College, Laguna. The
characteristic symptoms were described.
Samples were dried and observed with light
and scanning electron microscope (SEM).
For SEM, air-dried uredinia and leaf tissues
were mounted in metal stubs, sputter
coated with Platinum-Palladium and
observed in S-4200 SEM operating at 15.

Hand sections of sori and spores
mounted in cotton blue lactophenol were
prepared and examined under the light

microscope. Photographs were taken The
morphology of the uredinia, urediniospore,
and teliospores were described.



Plumeria. Infected leaves showed
distinct rust pustules on abaxial portion ol
the leaves. Uredinia containing
urediniospores were powdery, bright
yellow-orange in color that turned brown
with age (Fig. la). Uredinia easily peeled
off when touched. Lesions on the adaxial
portion of the leaves were minute spots
with yellow color turning brown as the
lesions aged (Fig. Ib). Lesions often
coalesced forming bigger spots.

Canna. Distinct formation of
pustules (uredinia) consisting of
urediniospores, that were bright orange and
powdery were observed on both surfaces
of the leaves (Fig. 2a). Blackish telia were
sometimes observed around uredinia.
Uredinia easily peeled off when touched.
Spots sometimes coalesced forming bigger
lesions. On the adaxial portion of the
lesions aged, spots on the adaxial leaf
portion turned brown and sunken. Lesions
also appeared on the stalk or pseudostem
of the plant (Fig. 2b). Severe infection
caused drying of the leaves.

Morphology of the Spores

Plumeria. Uredinia with peridia
hypophyllous, punctiform, erumpent,
powdery, lacking peridium, orange yellow
to pale yellow (Fig. Ic and Id).
Urediniospores broadly elliptical to
subglobose or angular, catenulate, coarsely
verrucose with bluntly capitate, annulate
t1 ilhr- 1-PC r ..,o,-+te ,rn, n-*r*-

mi -ar ~B~~aP~ 1 1



Fig. 1. Coleospc
and adxih
under SE


'ium plumeriae on Plumeria acumini
(b) portions of the leaves, uredinia (
ie (SEM), urediniospores under light
A (f).

rn' i m

Fig. 2. Puccinia
and pseui
(e), telios]

haliae on Canna indica. Pustules on
)stem (b); uredinia under SEM (c an
3res under light microscope (f).


I -- - IF2 0 I- M I

122 1996 Phil. Phytopath. 32(2):118-12'

inconspicuous, two to four, and scattered
(Fig. le and If).

Canna. Uredinia amphigenous
mostly hypophyllous, rarely epiphyllous
scattered, minute, round to irregular
yellow to light brown (Fig. 2c and 2d)
Urediniospores subglobose, ovate o
pyriform, echinulate, walls hyaline anm
thick, pores two, equatorial (Fig. 2e)
Telia black, hypopyllous, minute, round
compact, subepidermal. Teliospore.
clavate to cylindrical, apex rounded
truncate or acuminate, slightly constricted
at the septum, walls pale brown and thici
at the apex, pedicel short and hyaline (Fig
2f). Spermagonia, pycnia and aecii


Based on the spore morphology
the rust fungus on Plumeria was confirmed
as C. plumeriae reported by Patouillard
(1902), Saccardo (1905) and.Gallegos and
Cummins (1981). This is the second report
of rust of Plumeria in the Philippines. The
infected leaves from the first report of this
disease was collected from Mindanao
areas, specifically in the vicinity of
Cotabato. In this report, the fungus was
observed in Southern Luzon specifically
Laguna area. Regarding its spread, there is
a possibility that Plumeria infected with C.
plumeriae from the Mindanao may have
been transported to Luzon. The rust of
Plumeria was first described on P. alba in
Guadaloupe Island, West Indies by
Patouilldrd (1902) as recorded mainly in
Central America. Recently, this rust has
been reported from South Pacific Islands,
Hawaii, Australia and Indonesia (Ogata and
Gardner 1992; Kakishima and others
1995). It was also reported in a
greenhouse in Canada (Tranquair and
Kokko (1980), Kakishima and others-

(1995) stated that this subsequent spread
in Southeast Asia and Japan is eminent.

Eight species of Plumeria including
P. acuminata (=P. acutifolia), P. alba L
and P. rubra L. have been reported as hos
plant (Kakishima and others 1995). In the
Philippines, we have observed sever
infection of P. acuminata with the rusi
fungus. Therefore, we suspect that man3
species and/or varieties of Plumeria will be

identified as Puccinia thaliae Diet. Thi:
fungus is reported for the first time in the
Philippines. The disease is very prevalen
wherever Canna is grown It is wide
spread especially in the tropics and this rus
has been reported on many species o:
Canna and Thalia (Sinevesan 1970
Hiratsuka and others (1992).


DIVINAGRACIA GG. 1985. Diseases ol
important foliage and flowering ornamental
plants. NRCP-UPLB Terminal Report,

Uredinales (Royas) de Mexico. Vol. II.
INIA, Culiacan, 492 pp.

NAKAYAMA K. 1992. Rust Flora of
Japan. Tsukuba Shuppankai, Tsukuba,
Japan. p. 762.

MACKENZIE EHC. 1995. A warning
against invasion of Japan by the rust


ingus, Coleosporium plumeriae, on
'lumeria. Forest Pests No. 521, Vol.
4(8): 1-5.

)GATA DY, GARDNER DE. 1992. First
-port of Plumeria rust, caused by
7oleosporium plumeriae in Hawaii. Plant
)is 76: 942.

ATOUILLARD N. 1902. Champignons
e la Guadaloupe. Bull Soc Mycol Fr. 18:

ACCARDO PA. 1905. Syllonge
ungorum. 17: 898.


iIVENESAN N. 1970. Puccinia thaliae.
'MI Description of Pathogenic Fungi and
bacteria No. 267.

977. Rust of Kalachuchi (Plumeria
cuminata Ait.) caused by Coleosporium
lumeriae Pat. USM R and D J 5: 1-4.

pore morphology in Coleosporium
lumeriae. Can J Bot 98:2454-2458.

124 I1o r1u. mnytupALu. Okkkie.-9-10i

Abstracts of Papers Presentea
During the 27h Anniversary and Annual
Scientific Meeting of the
Philippine Phytopathological Society
in Davao City, May 7-10, 1996

Suppression of Tungro with Added Dose
of Nitrogen. V. G. Sagun, Jr., E. P.
Paderes, and D. E. Paderes, PhilRice and

Rice tungro inoculated plants were
topdressed with added dose of nitrogen
from urea and ammonium sulfate at the
rate of 46 kg N/ha at two and three weeks.
Rice tungro inoculated plants were
topdressed with added dose of nitrogen
from urea and ammonium sulfate at the
rate of 46 kg N/ha at two and three weeks
interval in screenhouse and field
conditions to determine the effect on
disease severity, virus amount, and on
yield of rice.

Added dose of nitrogen regardless
of the source (urea or ammonium sulfate)
significantly increased plant height,
number of productive tillers, leaf nitrogen
level, panicle length, number of spikelets,
percent filled grains, and grain yield of rice
tungro-infected plants both in screenhouse
and field conditions. Grain yield
increment was 169-263% in the field. The
number of leaves and leaf area of rice
tungro-infected plants were not greatly
influenced by added N. However, plant
maturity was prolonged from one to two

1-LIan les1 inUlcaUeu a IcUULIUon uL
bacilliform virus by 29 67 percent and
spherical virus by 66-86 percent in the
greenhouse. In the field, reduction of
bacilliform virus was 12-62 percent and
63-80 percent for spherical virus.

Cost-benefit analysis showed a net
return of P16,930.50-P27,782.50 with a
cost-benefit ratio of 1.46-1.83.

Blast Development on the New Rice
Plant Type in Relation to Canopy
Structure, Microclimate and Crop
Management Practices. I. B Pangga, P.
S. Teng and A. D. Raymundo, IRRI and

A new rice plant type (NPT) is
being developed to further increase rice
yield. This study was conducted to analyze
blast development caused by Pyricularia
grisea on a NPT line, IR64454-81-1-3-2,
and IR72 in field glasshouse, and simulation
experiments using a leaf blast model,
BLASTSIM.2. The effects of applied
nitrogen levels and pant spacing on blast
development were determined in relation to
canopy structure and microclimate. In all
experiments, leaf blast severity was higher
on IR72 than on NPT at all nitrogen levels.
However, levels of field and glasshouse
collar blast incidence were higher on NPT
than on leaf wetness duration, higher
canopy relative humidity, and lower leaf
area and light interception in IR72 than in

1996 Phil. Phytopath. 32(2):124-131 125

canopy air temperature, and decrease in evaluated. The original bed was furrowed
mean tip angle, light interception, dew and planted without plowing the walking
amount, leaf wetness duration, and midday space between the planting rows.
canopy relative humidity. As the nitrogen
level increased, leaf area, light interception,
dew amount, canopy relative humidity and
leaf wetness duration increased, while A Procedure to Assess Temporal Risk of
midday canopy air temperature, and mean Tropical Rice Blast. S. B. Calvero, Jr., S.
tip angle decreased. M. Coakley and P. S. Teng, IRRI and
Oregon State Univ., USA.

One approach in disease
Disease Management Strategies in management is to avoid the time when
Tomato Under Minimum Tillage and conditions favor infection.. To assess
Continuous Cropping. F. P. Obrero and temporal risk of rice blast disease (caused
G. P. Tan, BRCI, Bukidnon. by Pyricularia grisea), we developed a
procedure where patterns in the relationship
The production of tomatoes by between blast proneness and time of sowing
Bukidnon Resources Co., Inc. (BRCI) has at three tropical sites in Asia were analyzed
two unique features: (1) irrigation through using multivariate statistical procedures. A
the drip system, and (2) application of matrix data set comprising of predicted leaf
fertilizers through the drip irrigation system and panicle blast severities as column
or 'fertigatio'n'. Expensive irrigable lands variables and 24 hypothetical sowing dates
and high cost irrigation system should be as row variables was constructed at each
efficiently utilized by reducing the cost of site to determine such patterns. Sowing
cumbersome land preparation and at the dates were grouped according to proneness
same time maintain high yield, of rice to blast using cluster analysis (CA).
Three groups of sowing dates at each site
A practical cropping system, then, were identified by CA. The proneness
consisting of two tomato crops with one characteristics of the groups were further
short crop in-between (2-3 months) is being described using principal component
developed under minimum tillage using analysis (PCA) by relating leaf and panicle
glyphosate plus ammonium sulfate. blast with weather factors. At Cavinti,
Philippines, it was revealed that 1R50 is
Early and late blight, rock-knot prone to both leaf and panicle blast if sown
nematode and powdery mildew appeared to from July to December, and to panicle blast
be prevalent in the area. Bacterial wilt was alone if sown from January to May. With
properly managed through resistant cv C22 at the same site, leaf blast infection
germplasms. A new disease, Allernaria is high during June to December, while
collar rot become a major one because of panicle blast infection is high during
continuous tillage were also present. January to mid-May and mid-August. At
the IRRI blast nursery with 1R50 and at
Cultural methods to manage Situing, Indonesia with C22, both leaf and
diseases are being done with encouraging panicle infections could be high all
results. A third tomato cropping throughout the year. However, panicle
continuously done in the same area with blast could be low during mid-November to
intercycle period of two months is being December at IRRI and during mid-February

orcnaras ati aoak

totabato revealed me occurrence or me
following fungal diseases: stem and root rot
Isolation and Pathogenicity of diseases and stem/trunl trunk canker caused
Phytophthora sp. from Tobacco and its by Phylopthora palhivora and leaf blight
Distribution in Tobacco Areas. L. R. caused by F,.sarium sp. and Rhizoctonia
Truong. NTA. sokmi The latter is the most recently
observed disease noted at Saguing,
A fungus identified as Phylophthora Makilala (Agbisit's Durian Farm) and at
sp. was isolated from wild tobacco. The Dagupan, Kabacan (Pamplona's Durian and
fungus grows slowly in potato dextrose Mangosteen Farm)
agar and produces papillate, lemon-shaped
sporangium. The colony is uniform to Typical symptoms are brown to
slightly radiate with irregular edges and dark brown map-like blighting that starts at
moderate aerial hyphae. Aerial hyphae are the tip or leaf margin It can become
coenocytic and granulated Subterranean extensive and could affect a large portion of
hyphae are nodose, swollen and irregularly the leaf causing it to dry-up similar to sun-
shaped. scalding effect.

Isolation of the fungus was
facilitated by using water agar medium,
careful washing and drying of samples and Fruit Blotch of Watermelon (Citrullus
selection of Phylophlhora colony lanatus (Thunb.)J in Northeastern
Abundant sporangia were produced :in this Thailand: Etiology and Factors
medium 3-5 days after tissue planting Affecting Disease Development. P.
Virulence of the isolate was established Srichumpa-Pinyapong and M P Natural,
through soil, stem and leaf petiole UPLB.
inoculation techniques. It induced stem rot
on inoculated plants as early as 4 days after Thirty strains of the fruit blotch
inoculation. Variables symptoms on bacterium were isolated from three
naturally infected seedlings, young watermelon areas in Northeastern Thailand.
transplants and older plants were described. All isolates were Gram-negative, non-spore
P~hylophthora sp, was present ih the forming rods, about 0,9 x 1.8 u, having a
tobacco growing areas of Ilocos Norte, single polar flagellum. The colonies were
Ilocos Sur, La Union, Abra, Misamis convex, circular and entire. No fluorescent
Oriental, Iloilo and Quirino. pigment was produced in KB medium
Other morphological, physiological and
biochemical properties suggest that the
causal bacterium was Acidovorax avenae
Update on Fungal Diseases of Durian subsp. citrulli (syn. l'sueckdoonas
Orchards in Cotabato. N. G. Tangonan psuedoalalligenes subsp. cilrulli Schaad
and F Cr Cmahot IISM and others. 1978).

I -- L _^ -* Z 7 --c -4C AAA tr'

1996 Phil. Phytopath. 32(2):124-131 127

from naturally infected plants. However, Observation and indexing of the
watermelon seedlings of 10 hybrids with graft-transmissible diseases of citrus found
seeds soaked in bacterial suspension before in the highlands of Northern Luzon through
planting developed symptoms one week continuous orchard monitoring were
after. Disease incidence was 0.83%. reported. (Cirus tristeza and greening/
leafmottling were the two most important
Factors that affected development diseases affecting citrus. Other diseases
of fruit blotch in watermelon fruits were found were woody gall/vein enation and
inoculum concentrations, age of fruits, bud-union disorder of sweet orange on
wounds and variety, rough lemon rootstock.

Symptoms induced by citrus tristeza
virus include stem pitting stunting and small
Bacterial Wilt of Indian Tree (Polvalthia fruit production on sweet orange and on a
longifolia Benth and Hook). M. P. local mandarin cultivar called "gayuman"
Natural, UPLB. Likewise, greening/leafmottling disease
continues to be a threat in the highlands. It
Indian trees that were planted along causes a dibilitating effect on sweet orange
the highway of Calauan, Laguna showed and most mandarin cultivars. Co-infection
wilt symptoms. Microscopic examination with other diseases was common resulting
revealed.bacterial infection. Pathogenicity to a more rapid decline.
to tomato seedlings and hypersensitivity to
tobacco plants were tested. The tomato The incidence of the vector
plants wilted 5 days after stem injection. Diaphorina citri Kuway and preliminary
Hypersensitive reaction was observed less results on the search for mild strains for
than 24 hr after infiltration of bacteria on cross protection were also reported.
tobacco leaves. Nicotiana glutinosa but
not N. tabacum, Solanum melongena
(eggplant) also wilted. Incubation period
was more than 2 weeks. Genetic Polymorphism in Some
Australian Isolates of Pseudomonas
Cells were Gram-negative, rod- solanacearum Using Probes Developed
shaped, aerobic, non-space forming. Other from a Biovar III Strain. M. P. Natural
physiological and biochemical tests indicate and B. W. Holloway, UPLB and Australia.
that the pathogen is a strain of
Pseudomonas solanacearum E. F. Smith. DNA from 18 strains of P.
This is the first report of P. solanacearum, solanacearum were analyzed using probes
infecting a tree in the Philippines, and the developed from a cosmid bank of PSO 1000,
first report on Polvalthia longifolia. a biovar III strain causing bacterial wilt of
eggplant. The two biovar II strains differed
significantly from the biovar Ill and IV
strains. Almost always, no DNA fragment
Occurrence of Graft-Transmissible from Biovar II hybridized with the probes
Diseases of Citrus in the Highlands of used. If hybridization was present.
Northern Luzon, Philippines. J. M. hybridization occurred in different fragment
Ochasan and M. L. Amoy, BNCRDC, size. Within the bio\ar 11 strains.
Baguio City. polymorphism was also evident Bio\ar l

128 1996 Phil. Phytopath. 32(2):124-131

strains were almost similar to the Biovar III (DAC-ELISA) using antibodies against
strains. The probes that were developed BBTV from Australia. TAS-ELISA was
may be useful in identifying and detecting more sensitive in detecting BBTV antigen
field isolates ofP. solanacearum. than DAC-ELISA. TAS-ELISA positively
detected BBTV in 23.53% of 17 samples
whereas DAC-ELISA only detected
13.33% of 15 samples. The range of
Population Structure Analysis of positive values in TAS-ELISA and DAC-
Pseudomonas solanacearum Causing ELISA were 0.15 to 0.61 and 0.10 to 0.61,
Bacterial Wilt in Tomato Using RAPD- respectively.
PCR. N. L. Opina and L. S. Moreno, IPB-
UPLB. Monoclonal antibody ard rabbit-
anti-mouse conjugate was observed to be
Genomic DNA of the different effective at 1:3 and 1:200 dilutions,
biovars of P. solanacearum isolated from respectively with PBS-T-PVP for both
tomato were extracted using modified TAS-ELISA and DAC-ELISA.
CTAB method. The concentrations of the Absorbances decreased when
DNA recovered ranges from 100-500 ng/ml concentrations of monoclonal antibody was
which were estimated by comparing the increased. No conclusive data was
intensity of banding with the known obtained with varying concentrations of
concentration of undigested DNA. Twenty polyclonal antibody in DAC-ELISA.
OPERON kit D RAPD primers were Abaca (Musa textilis) showing bunchy top
applied to the P. solanacearum genomic symptoms assayed similarly reacted
DNA for PCR reaction. The generated relatedness of BBTV strain from Australia
DNA fragments were scored and analyzed to that of bunchy top viruses of banana and
using Numerical Taxonomy System abaca in the Philippines.
(NTSYS) Program. Several OPD RAPD
primers viz OPD-18, OPD-11,OPD01 gave
the best banding profile to analyze the
similarity and differences of the isolates A New Procedure for Developing
among and within biovars of P. Forecasting Models. S. B. Calvero, S. M.
solanacearum. Other primers gave very Coakley, A. Surin, C. K. Kim and P. S.
few to no banding. Teng, IRRI, Oregon State Univ., USA,
Thailand and Korea.

A new procedure for generating
Serological Detection of Banana Bunchy empirical forecasting models is presented
Top Virus (BBTV) in Musa spp. G. C. with rice-Pyricularia grisea (rice blast) as
Catacutan, A. A. Eusebio, N. B. Bajet and the pathosystem of interest. This procedure
J. E. Thomas, UPLB and Australia. employs the use of weather factor searching
computer software called WINDOW
Banana bunchy top virus (BBTV) PANE, path analysis (PA), and multiple
was detected in samples using direct linear regression (MLR) analysis. Data on
methods of enzyme-linked immunosorbent disease variables (such as leaf and panicle
assay (ELISA): triple antibody sandwich blast severity and incidence) on blast-
(TAS-ELISA), and direct antigen coating susceptible rice cultivars were obtained
from three blast hot spot sites in Asia:

lburi in Thailand during 1993-94, of susceptibility of IR72 was significantly
Leon in South Korea during 1974-89 (P=0.0001) higher compared to IR24.
,e as the response variables in the There was also a significant soil x rice
al models. Historical time-series genotype x race interaction (P=0.0046),
r data sets that include precioitation su2aesting that bacterial blight development

d (ms'), sunshine duration
radiation (MJ m-2) were
rom each of the three sites
he explanatory variables.
PANE program showed 1
weather factors were hiE
with the disease variables. I
revealed that not all of th
'e large direct effects on dise
nt. MLR models for large dii
fact nnrA th,.QA 127oFnnPr'.

>- and micro-element contents
[ave contributed to variatio
)ility of rice to bacterial blight.

on of Agricultural Wastes
ig Materials to Coi
de in Banana Comme
ion. E. 0. Membreve and

avinti, mean nematodes identified<

upIIIauUIIU uIi numllUer
citation > 84 mmd-' and
RH > 80% at Icheon. P

liophora, Meliodog
cotylenchulus. The

known to be as organic feeders.

Rice hull and sawdust can reduce
laphic Influence on Bacterial Blight the nematode population from soil and
sease of Rice Caused by Xanthomonas roots, while coirdust and the control
izae pv. oryzae. H. U. Ahmed, R. F. comparably increased nematode population.
Fonso, L. P. Nieva and C. C. Mundt,
RI. The frequency of plant parasitic
nematodes reduced also the ricehull and
A factorial experiment including soil sawdust treatment, while in coirdust and
m two locations (Calauan and IRRI), the control continuously increased.
o rice genotypes (IR24 and IR72), and
o Philippine races of the bacterial blight
:hogen (rades 2 and 3) was conducted in
Greenhouse to determine the effect of Screening of Breeding Lines, Hybrids
iphic factors on disease expression. and Open-pollinated Varieties of Corn
for Resistance to Philippine Corn Downy
Results indicate that the Calauan Mildew. N. G. Tangonan and F. A.
I was significantly (P=0.0007) more Sebastian. USMARC-USM.

130 1996 Phil. Phytopath. 32(2):124-

For 1995, a total of four trials were When applied in the fruits thro
conducted to screen 82 corn entries for dipping as protectant, it was found effect
resistance to downy mildew (DM) infection to suppress the invasion of the ca
caused by l'eroi.osclero.Vpora fungus.
philippiniensis. These entries from the
CIMMYT corn germplasm exhibited
variable reactions to downy mildew disease. Sheath Blight Intensity in Relation
Plants affected early by the disease Crop Residue Management. R.
succumbed within a month and those that Pamplona and T. W. Mew, IRRI.
survived bore unproductive ears. Findings
revealed that 9.76% were found resistant to A study was conducted to as:
DM infection. Moreover, 53.66% were the intensity of sheath blight of rice in
found intermediate and 36.59% were found rice cropping systems: continuous
susceptible. Furthermore, USM open- (RICE-RICE) vs. Aerated cropping pat.
pollinated varieties like USM Var 1, 3, 5 (RICE-MAIZE) at three nitrogen levels
and 7 were also found resistant whereas 50 and 100 kg N/ha) with early or
USM Var 8 and 10 were found incorporation of crop residue at the II
intermediate, USM Var 6 susceptible, Farm during the 1995 wet season. Fi
respectively. This study is part of the the assessment made on four stages of c
ongoing project on improvement and growth maximum tillering (49 DA
development of new hybrids and OPVs at booting (63 DAT); flowering (77 Di
USMARC-USM. and at milking stage (91 DAT) it
observed that in the fields of continue
rice, incidence and severity increased \
time at 100 kg N/ha. This was furthernm
Evaluation of 15 Medicinal Plant enhanced by early crop resi
Extracts for Fungicidal Property Against incorporation which remained high fi
Colletotrichum gloeosporioides Penz. early crop growth stages until maturity.
Causing Anthracnose on Mango Fruits. low nitrogen, 0 and 50 kg N/ha, howe'
W. M. Escopalao and J. C. Silvestre, USM. no noticeable difference in sheath bli
was seen whether crop residue '
Of the 15 medicinal plant extracts incorporated early. In rice aerated c
tested in vitro against C. gloeo.sporioides rotation system (RICE-MAIZE), she
only kamantique (fruit) and garlic vine blight incidence and severity were rela
(leaves) crude extracts inhibited the growth low in all nitrogen levels regardless of e
of the fungus based on the zone of or late crop residue incorporation.
inhibition which was comparable to
benomyl, the chemical check.
Transmissibility of Sarocladium ory
Kamantique (fruit) and garlic vine (SAWADA) from the Seed to
(leaves) extracts were further assayed for Seedling. F. D. Dugay, J. B Manandl
their effectivity at different dilutions. It T. W. Mew, IRRI.
was found that both extracts were effective
at 1:10 and 1:100 dilutions, comparable to A study was conducted
the chemical check, determine the transmission of Satroclaich

996 Phil. Phytopath. 32(2):124-131 131

oryzae causing sheath rot of rice from seed tr
to seedlings. Detection of the pathogen in tc
components of the germinating seeds and b
seedlings was done by sectioning the plant tr
parts and direct observation after staining. ((
In plant component sectioning, seeds and rr
seedlings were divided into different ci
components, plated in a semi-selective
medium and incubated at 300C for 7 days.
For microtome sectioning, cross and nr
longitudinal sections were made and tl
observed under the microscope. Sampling g
was done at 2-day intervals. It was found le
that the seeds harbored the pathogen on the ni
hull, endosperm and embryo. At the early -A
stage of growth, the inoculum was initially n
concentrated in the scutellum. As the rn
seedling grew, the infection in the scutellum h,
progresses to the coleoptile and to the first
leaf. Since these parts were overlapping
during the growth of the seedling, the
pathogen appears to cause infection RI
through contact. The presence of infection E
at the upper portion of developing .leaves F
and a healthy base and core of the S
germinating rice seed suggested that the
transmission of Sarocladium oryzae from
seed to other parts of the seedlings is (1
mainly through contact. E

A Database on Germplasm Screening for si
Sheath Blight Resistance. M. G. M. t(
Magbanua and T. W. Mew, IRRI. d
There is a total of 21,866 accessions m
which have data on sheath blight reactions p
and information on various agronomic d

lits. An analysis of this dataset was made
establish the relationship between sheath
ght resistance of these accessions and the
lits of the rice plants particularly culm
diameter, length, number), leaf length,
iturity and plant height (derived from
Im length plus panicle length).

About 88% are rated to be
moderately susceptible (SES=5) and more
in 85% of which have culm diameter
eater than 4 mm, over 45% have culm
igth higher than 120 cm, 72% with culm
mber ranging from 10 to 20 tillers, 80%
th leaf length ranging from 40 to 80 cm,
ore than 30% have a maturity period
nging from 135 to 170 days and 40%
ve plant height more than 140 cm.

itoon Stunting Disease Survey in
awaiian-Philippine Mill District. F. R.
ismillo, M. C. Alba and N. S. Meneses,

A survey on ratoon stunting disease
.SD) in sugarcane was conducted in
iwaiian-Philippine Mill District on July 16
31, 1995. The result confirmed the
esence of RSD in sugarcane varieties of
iwaiian-Philippine Mill District. The 24
garcane varieties in the district was found
exhibit different degree of nodal
coloration as macroscopic symptom of
e disease. However, no particular variety
is consistently RSD-free based on the
lase-contrast microscopy (PCM)

been published elsewhere. The decision of the Editorial Board to accept or reject manuscript is final

The manuscript should be typed on one side of 82 x 11 inch paper, double spaced throughout.

Papers other than Notes may be organized conveniently under: Title, Author(s), Author's position
address, Key words, Abstract, Introduction, Materials and Methods, Results, Discussion, (or Resi
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Acknowledgments should be placed at the end of the articles i.e. after Literature Cited.

In the text, citations should be by name-and-year system, e.g. Molina (1996), Ou and Nuque (19E
With three or more authors, use and others (e.g. Ou, Nuque and Silva (1981) should appear Ou
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