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S INCIDENCE OF BACTERIAL WILT IN FLORIDA ON TOMATO LIN S OBTAINED ROM
THE ASIAN VEGETABLE RESEARCH AND DEVELOP CENTER.
Lines of tomato plants selected for resistance to bacterial wilt (Ps7auaoomonas
solnacearum E. F. Smith) at the Asian Vegetable Research and Development Center
(AVRDC), Tainan, Taiwan were transplanted in the summer into a field naturally
infested with the pathogen at the Agricultural Research Center, Fort Pierce,
Florida. Although none of the lines were as resistant as Hawaii 7997, CRA-66E or
PI 126408-6-Bk, many were as resistant as Saturn, a resistant variety developed
by the North Carolina Agricultural Experiment Station. A few of the lines were
as susceptible as the non-resistant Florida commercial varieties, Florida MH-1
and Walter. Fruit size of the AVRDC lines was small when compared to fruit of
commercial varieties grown in Florida.
Bacterial wilt of tomato is an important disease in the warmer regions of
the world. The disease causes losses each year in localized areas of some tomato
farms in south Florida. No resistant variety is available for commercial use in
south Florida. As part of a program to develop resistant varieties for use in
Florida, tomato lines hybridized and selected for resistance to bacterial wilt by
the Asian Vegetable Research and Development Center, (AVRDC), Tainan, Taiwan were
screened in a field naturally infested with Pseudomonas solanacearum E. F. Smith,
at the Agricultural Research Center, Fort Pierce (ARC-FP).
Materials and Methods
Seed of tomato lines were sown in 1:1 horticultural vermiculite shredded
sphagnum peat moss, with nutrients added, in seedling trays. The seedlings were
grown in the greenhouse for two weeks, then transferred to outdoor benches for
two more weeks before transplanting. The plants were then transplanted into
Oldsmar fine sand where losses of Florida M-1 due to bacterial wilt had ranged
from 84 to 99% in previous tests (1, 2).
The first planting, an unreplicated observational trial, included 14 lines
from AVRDC, and the resistant variety Saturn as a check. The number of plants
set in the field September 12, 1977 ranged from 16 to 43 per line. Bacterial
wilt incidence was counted on November 23.
The second planting transplanted to the field on June 2, 1978 included 10
accessions from AVRDC. There were four replications of eight plants per repli-
cate in a randomized complete block design. The plants were set two rows per
bed, 18 inches between plants down row. Tomato varieties highly tolerant to
P. solanacearum indigenous to the ARC-FP, Hawaii 7997, CRA -66E, PI 126408-6-Bk
and Saturn (2), and the susceptible varieties Florida MH-1 and Walter (1, 2)
were used as comparisons.
1/ Associate Professor, University of Florida, Institute of Food and Agricultural
Sciences, Agricultural Research Center, Fort Pierce; Assistant Professor, UF,
IFAS, Agricultural Research and Education Center, Bradentait and Associate
Professor, UF, IFAS, Agricultural Research and Education Center, Homestead.
The third planting was transplanted to the field on July 6, 1978. It included
plants from seeds of seven selections of AVRDC lines made from planting 1. The
experimental design was the same as in planting 2. Hawaii 7997 was planted as the
tolerant check and Florida MH-i and Walter as the susceptible checks.
In plantings 2 and 3, the incidence of bacterial wilt was recorded weekly
beginning four weeks after transplanting$ The mean number of days plants survived
in infested soil in each replicate was calculated by the following formula:
nlt1 + n2t2 +*..nitl + iT
S = mean number of days plants survived in field
n, = dumber of plants killed up to ti
t1 = days after piahting that weekly reading was made, minus 3.5 days
n2 = number of plants killed between t1 and t2
N number of plants surviving at time of final weekly reading
T = days after planting that final weekly reading was made, plus 3.5 days
n = number of plants per replicate
Time of weekly reading, minus 3.5 days was used to obtain an average time of
death for plants killed between weekly readings. T was arbitrarily set at 3.5
days after the final reading, This assumes that plants surviving at the final
weekly reading survived for 3.5 days more,
Results and Discussion
In planting 1, the percent of plants in the AVRDC lines that survived until
November 23, 1977 ranged from 11 to 1007. (Table 1). Fruit of all AVRDC lines
were small compared to fruit of commercial Florida lines, and some lines had
pear-shaped or oblong-shaped fruit. Most plants had good to excellent fruit set.
In planting 2, most AVRDC lines survived as long er longer than Saturn
(Table 2), Saturn was found to be tolerant in previous tests at the ARC-FP (1, 2)
but it has not performed well horticulturally. All of the AVRDC lines survived
longer than Walter, The difference in survival between Walter and five of ten
AVRDC lines was statistically significant. Although there was no statistical
difference, most of the AVRDC lines survived longer than did Florida MH-1,
In planting 3, one selection from AVRDC line Clld-0-1-2-0, survived signif-
icantly longer than did Walter and MH-1 (Table 3), The other selection of the
same line, however, was no better than Walter or Florida MH-1. Survival of most
selections of other AVRDC lines was slightly better than the two Florida varieties
but means were not significantly different (Table 3),
The results of these tests indicate that genes for resistance to P.
solanacearum indigenous to the ARC-FP are present in the AVRDC lines, The small
fruit size of the AVRDC lines, however, will probably limit the usefulness of
these lines to the Florida tomato industry,
1. Sonoda, R. M. 1977. Behavior of tomato lines, selected for resistance to
southern bacterial wilt, in a field infested with the pathogen.
Ft. Pierce ARC Research Report RL 1977-3.
R. M., and J. J. Augustine. 1977. Reaction of tomato lines selected
for resistance to southern bacterial wilt in a field naturally in-
fested with the pathogen, Results 1977. Ft. Pierce ARC Research
Report RL 1977-6.
Table 1. Survival of tomato lines transplanted into soil at the
Agricultural Research Center, Fort Pierce naturally infested
with Pseudomonas solanacearum E. F. Smith -
Accession Plants set % Surviving
__ __i__ ~ ___ ___
1/ Transplanted September 12, 1977. Bacterial wilt incidence recorded
November 23, 1977.
Table 2. Mean.day-f-arvivaland percent survival of tomato
accessions transplanted into soil naturally infested
with Pseudomononas solanacearum E, F. Smith at the
ARC-FP on June 2, 1978
Days of survival
% Survivors -
L 1 GS
CL 9-0-0-1 UG
CL Pd-0-3-6 UG
CL 143A-0-4B-1 UG
CL 123-2-4 UG
CL 8d-0-7-1 GS
CL 143B-0-6-p UG
I/ At 75 days after planting.
2/ Means in the same column followed by
nificantly different at the 57. level
the same letter are not sig-
(Duncan's new multiple range
-n ...n .
Table-3--Mean -days of-survival and percent survival of tomato accessions
transplanted into soil naturally infested with Pseudomonas
solanacearum E. F. Smith at the ARC-FP on July 6, 1978.
Accession survival 7 Surviving
Hawaii 7997 56.7 a2/ 62.5 a 3
C lld-0-1-2-0-1 41.1 b 18.8 b
L 124-2 34.3 be 21.8 b
C 122d-0-1-4-0-1 31.4 bc 15.6 b
C 122d-0-1-4-0-2 30.6 bc 18.8 b
C 11d0-1-2-0-2 29.5 bc 3.1 b
L 124-1 29.1 bc 12.5 b
Walter 26.2 c 6.2 b
CL 143-0-4B-1-00-00 26.0 c 3.1 b
Florida MH-1 25.5 c 0 b
I/ At 60 days after planting,
2/ Means in the same column followed by the sane letter are not
significantly different at the 5% level (Duncan's new multiple