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Copyright 2005, Board of Trustees, University
Ft. Pierce ARC Research Report RL-1975-2
EFFECT OF TIME OF PLANTING ON INCIDENCE OF BACTERIAL WILT
ON TOLERANT AND SUSCEPTIBLE LINES OF TOMATO
R. M. Sonoda1/ l M L
Over a period of 20 years of cropping bacteria wilt incited by Pseudo nas
solanacearum E. F. Smith has increased and now caused heavgA sses in tomato
plantings at the Agricultural Research Center, Fort Pierce BC2iP976he i idence
of the disease in commercial plantings has been hea y only in localized are s on a
few farms. However, many of these farms are on vir poi1, or are fumigat d for
control of nematodes and soil-borne diseases. Seve l.edy lt in
home gardens in the Fort Pierce area have been observe
Tomatoes in the Fort Pierce area are usually planted twice each year, in the
winter with most seeding from late December to mid-January and in the summer from
late July through August. Transplanting is done several weeks later than field
seeding. Plants affected by bacterial wilt are noticed during both growing seasons.
High soil temperature and high soil moisture are two important environmental factors
affecting the development of bacterial wilt (1,3). Cooler and drier weather occur
near the end of the fall growing season and the beginning of the spring growing
The tomato varieties currently grown in Florida are not tolerant to P.
solanacearum. Of approximately 130 lines of tomatoes screened in the field at the
ARC-FP, only Saturn and Venus, two lines released by workers in North Carolina (2)
showed acceptable tolerance to the strains of P. solanacearum indigenous to the soils
at the ARC-FP (Sonoda, unpublished data). Line 727-6, a cross made by the late
J. M. Walter, showed slightly better tolerance to the pathogen than Florida com-
mercial varieties in field tests. The object of the current experiment was to
determine the interaction of time of transplanting and degree of tolerance on
Materials and Methods
Seed of four tomato cultivars or breeding lines were obtained from the follow-
ing sources: Saturn, Dessert Seed Co.; Walter, Asgrow Seed Co.; 727-6 (CAB 54-11-2-
Il-Bk-Bk-6) from J. P. Crill and 713-1 (CAB 54-10-2-1-l-Bk-Bk-l-Bk) from D. S..Burgii
The latter two are crosses made by the late J. M. Walter and selections from these
crosses made by Walter and Crill.
Seeds were sown in Jiffy Mix Plus(Cornell peat-lite type mix with a controlled
release fertilizer added) in plastic multipot flats in the greenhouse. Seeds of the
four lines were sown four times at two-week intervals. When seedlings were about
two weeks old, the seedlings were thinned to one plant per cell in the flat. The
flats were transferred to outside seed benches for two more weeks before trans-
The seedlings were transplanted into five 65 feet long rows in a 35 x 65 feet
area at the ARC-FP where 85% of susceptible tomato plants had been killed by
l/ Associate Plant Pathologist, University of Florida, Institute of Food and
Agricultural Sciences, Agricultural Research Center, Fort Pierce 33450.
bacterial wilt in a planting -immediately preceding the current test. The beds were
weeded and soil loosened with a hoe. Holes were made in the beds to accommodate the
tomato plants and the Jiffy Mix Plus attached to the roots. Each hole was drenched
before planting with 3/4 pint water containing 2 liters Difolatan 4 flow and 2.5 kg
Start-rite (analysis 10-52-8) per 100 gallons. The fungicide was used to prevent
transplant damp-off incited by Pythium aphanidermatum and Rhizoctonia solani (4).
Single plants with Jiffy Mix Plus attached to the roots were removed from multipot
flats and placed in the holes. The roots and base of the stem were covered with
soil and the area around the base of the stem drenched again with 1/4 pint of the
Difolatan-Start-rite mixture. Plantings in the field were made on 9-19, 10-1,
10-16, and 10-29, 1974. There were five replications of each tomato line and six
plants per replication for each planting date.
Mean weekly temperatures and weekly rainfall totals were highest in the period
following the first two field plantings (Table I).
Bacterial wilt symptoms were noticed three to four weeks following each
planting date. Saturn was much more tolerant to this disease than any other line
(Table 2). Very few plants of Saturn were affected by the disease. Losses were
heavy for Walter, 727-6 and 713-1 in the two early plantings but the losses de-
creased significantly in the later two plantings. No significant difference be-
tween Saturn and the other three lines in bacterial wilt incidence was observed for
the last planting, although a few plants of the three more susceptible lines showed
symptoms while Saturn did not. There was no significant difference between line
727-6 and the two other susceptible lines although for each planting date fewer
plants of 727-6 exhibited bacterial wilt symptoms.
The results of this experiment showed that the later the planting date in the
fall of 1974, the lower the incidence of bacterial wilt in all four lines of
tomatoes tested. Cox (1) reported similar results for a series of plantings made
from September 2 to November 1, 1961. A reduced incidence of bacterial wilt occur-
red when plantings were made after November 1. The decreasing incidence of bacteri-
al wilt with later plantings in the fall coincides with decreasing temperature and
The results also showed that the: ore tolerant the tomato line, the earlier the
planting date at which maximum stands occurred. Good stands of Saturn were obtained
even at the two earliest planting dates. Near maximum stand of Saturn was obtained
with the 10-16 planting. Saturn, however, lacks desirable horticultural character-
istics for use in south Florida. The growth of this line at the ARC-FP has been
heavily vegetative and fruit set has been poor. Near maximum stand was obtained
with line 727-6 with the 10-29 planting. A plant with tolerance near the level of
727-6 would not be of much value under the current commercial growing practicea-sn l
the Ft. Pierce Area as plantings are generally made by early September and planting
dates near the end of October would expose plants to hazards of frost.
Further crossing, screening and testing of tomatoes must be made to obtain
lines with tolerance equal to or better than Saturn, but with better horticultural
characteristics for use in fields with bacterial wilt strains similar to those
indigenous at the ARC-FP. J. C. Gilbert (personal communication) reports that
Saturn is not tolerant to P. solanacearum lines indigenous to Hawaii. Further
studies must also be conducted to determine if the Saturn genotype is tolerant to
strains of the bacteria present in other areas in the state.
1. Cox, R. S. 1961. Progress on the control of southern bacterial wilt on
trellis-grown tomatoes in south Florida. Fla. St. Hort. Soc. Proc.
2. Henderson, W. R. and S. F. Jenkins, Jr. 1972. Venus and Saturn. North
Carolina Ag. Exp. Sta. Bul. 444. 13 pp.
3. Kelman, A. 1953. The bacterial wilt caused by Pseudomonas solanacearum.
North Carolina Ag. Exp. Sta. Tech. Bul. 99. 194 pp.
4. Sonoda, R. M. 1972. Control of tomato transplant damp-off. Plant
Disease Reporter 56:840-842.
Table 1. Mean weekly temperatures an4
rainfall during experiment1/
1/ Recorded by instruments about
100 yards from
2/ Seven day periods from Wednesday through Tuesday.
Table 2. Percent of plants free of bacterial wilt symptoms
60 days after planting in Pseudomonas solanacearum
infested field at the Agricultural Research Center,
Date of Planting
Variety 9-19 10-1 10-16 10-29
Walter 3.3 3.3m 43.3n 83.3
Saturn 70.t 70.0- 96.7b 100o.o
727-63/ 16.7m 16.7m 63.3n 96.70
713-1-Bk4 6.7m 3.3m 53.3n 80.0n
1/ Five replications.
Six adjacent plants for each replicate
in a randomized complete block design.
2/ Compare subscript letters vertically for variety effects.
Compare superscript letters horizontally for time of planting
effects. Means followed by the same letter do not differ
significantly at the 5% level (Duncan's multiple range test).
3/ Pedigree CAB 54-112-Il-Bk-Bk-5 (obtained from J. P. Crill).
4/ Pedigree CAB 54-10-2-1-1-Bk-Bk-l-Bk (obtained from D. S. Burgis).