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GULF COAST RESEARCH A EDUCATION CENTER
UNIVERSITY OF FIRID&/IFAS
5007 60th Street East
Bradenton, FL 34203
GCREC Bradenton Research Report BRA1989-14
OCT 25 1989 I
Sve ty of Florida
Fusariun Wilt (Race 3) of 'Sunny' Tanato in Florida
Peat-Vermiculite Mix with Lime and Micrcnutrients Varied
S. S. Woltz and J. P. Jones1
Considerable research has been conducted at the GCREC on Fusarium wilt of tanato
as affected by soil fertility (1) but little has been done with "artificial
media" which are important in transplant production for Florida. Also, most of
the emphasis has been on lime, phosphates and nitrogen source as controlling
factors (2). The research reported herein was conducted to determine if a camaon
artificial medium would be conducive to disease development and if varied levels
of a camnercial micronutrient source would affect disease severity in combination
with lime variables with the artificial medium.
Materials and Methods
A mixture of 1:1 by volume Florida sedge peat:horticultural vermiculite was
amended with the following:
Table 1. Pounds per cubic yard mixed in media. (1:1 Fla. peat: Vermiculite)*
Treatment No. Perk** CaCO3
1 0.6 1.7
2 1.7 1.7
3 5.0 1.7
4 0.6 5.0
5 1.7 5.0
6 5.0 5.0
7 0.6 15.0
8 1.7 15.0
9 5.0 15.0
*Also, 6 Ibs of 14-14-14 Osmocote and 1.7 lbs of MgS04-7 H20 were
**Canposition of Perk micronutrient amendment, percent: Magnesium 5.0; manganese,
2.0; Copper, 0.5; Zinc, 1.0; Iron, 9.0; Boron, 0.02 and Molybdenum, 0.003.
1Professor of Plant Physiology and Professor of Plant Pathology, respectively.
Four 9-day old 'Sunny' tomato seedlings were set in each of quadruplicate, 6-
inch pots arranged in a randomized block design on June 22, 1989. Inocula were
produced in a liquid Fusarium medium in flasks grown with constant shaking.
After plants were established, inoculations were made June 28 followed by root-
wounding June 30; a second inoculation was made July 10 followed by root-wounding
July 11. Twenty-six million microspores in 150 ml water were applied to each
pot at the first inoculation and 91 million spores in 150 ml water at the second
inoculation. The terminal growing point of plants was removed July 11 to avoid
excess plant growth.
Disease ratings were made July 19. New axillary shoot elongation of the
uppermost shoot was measured July 21. Plants were harvested and weighed July
25, 7 weeks after seeding. Stem chips of all plants were cultured on potato
dextrose agar after harvest. Chips were taken from the bottom, middle and top
of the stems.
A second planting of tomato was made in the pots following the removal of the
first planting. Two 12-day old seedlings each of Bonnie Best and Sunny were
set in each pot August 1. Wilt ratings were made August 8.
Results and Discussion
Ratings of the severity of Fusarium wilt (Table 2) show that greater disease is
associated with the low level of lime while the plants at the intermediate and
high levels are successively less severely diseased. Minor elements did not
alter the severity of disease in terms of the severity rating. New shoot
elongation and plant top fresh weights had similar indications, namely, that the
low level of lime was more conducive to disease than the intermediate and high
levels. Micronutrients were not significantly effective. The elongation and
yield data are not compared with an uninoculated control but observation of the
plants indicated that Fusarium wilt was the primary factor affecting the plants.
Disease was especially pronounced at the low lime level.
Numbers of stem chips having Fusarium colonization on potato-dextrose agar plates
did not differ significantly probably because of the very heavy inoculation
procedure employed. Media pH was significantly affected by the liming procedure.
Whatever the cause of the liming amelioration of wilt is, it is consistent, even
with the artificial media used in this experiment. The results indicate that
this artificial medium does not greatly retard disease development. Artificial
media are available relatively free of pathogens for transplant production but
they are susceptible to the effects of contamination with root pathogens.
Lacking a complex microflora which soils have, artificial media may be more
seriously affected by pathogen contamination. Direct comparisons among soils
and media would establish the answer to a question of the relative Fusarium wilt
suppressing capacities of various soils and artificial media.
Soil microorganisms are effective (2) at retarding disease-production by Fusarium
and other pathogens by competition for a limited nutrient supply and by
antagonism by way of antibiotics and certain metabolites produced by the
antagonists (2). Higher pH's favor bacteria and actincmycetes while lower pH's
favor fungi, in general.
Fusarium wilt developed very quickly in a large number of the second planting
tomato seedlings. Results in Table 2 show that lime at both the medium and high
rates of application significantly reduced disease. Separate data for the two
cultivars are emitted since the reactions in this experiment were
indistinguishable. Perk at varied rates did not significantly alter disease
In summary, it was shown that the mix of 1:1 Florida sedge peat:horticultural
vermiculite was prone to disease production when inoculated with Fusarium race
3 microspores. Lime (powdered calcium carbonate) was effective, even with a
short reaction period in the mix containing acid peat; significant reduction in
race 3 Fusarium wilt was obtained for two plantings of tomato seedlings using
a very severe inoculation procedure. Micronutrients did not significantly affect
disease in this experiment, however, there is ample evidence (1,2) to indicate
that the Fusarium pathogen reacts to low-level micronutrient supply with reduced
virulence. It would be expected that the low level of Perk micronutrient mix
under the conditions of this experiment was not limiting to the Fusarium because
of adequate supplies from peat, vermiculite and well water used for irrigation.
The capable technical assistance of Patricia Cox and Russell Owens is gratefully
1. Jones, J. P. and S. S. Woltz. 1981. Fusarium-incited diseases of tomato
and potato and their control In: Nelson, P. E., T. A. Tousson and R. J.
Cook. Fusarium Diseases, Biology and Taxonomy. Penn State Univ. Press,
University Park. pp. 157-168.
2. Woltz, S. S. and J. P. Jones. 1981. Nutritional requirements of Fusarium
cxysporum: Basis for a disease control system In: Nelson, P. E., T. A.
Tousson and R. J. Cook. Fusarium Diseases, Biology and Taxonomy. Penn
State Univ. Press, University Park. pp. 340-349.
Table 2. Fusarium wilt (Race 3) and plant growth data for greenhouse grown 'Sunny' tomato plants
greenhouse on a 1:1 by volume mix of Florida sedge peat: vermiculite.
grown in the
Perk CaCo~ Fresh Wt. Total No.
lbs./ lbs. Wilt New Shoot of Plants Chips with Fusarium Wilt Ratingz Mdia
cu.yd. cu.yd. Rating Length, anY g/pot Bottoman Middle Top 2nd planting pHx
0.6 1.7 1.75 73 93 16 16 14 3.94 6.16
1.7 1.7 2.58 48 85 16 16 16 3.75 5.97
5.0 1.7 2.33 56 94 16 16 15 3.75 5.87
0.6 5.0 1.38 83 121 16 16 12 2.31 6.35
1.7 5.0 0.75 112 133 16 15 10 1.56 6.41
5.0 5.0 2.00 72 83 16 15 15 0.38 6.45
0.6 15.0 0.38 101 112 16 14 11 1.56 7.00
1.7 15.0 1.25 77 110 16 14 14 0.68 6.98
5.0 15.0 0.20 124 142 15 14 16 2.00 7.01
LSD, 5% level 1.20 27 32 2.26 0.21
0.6 1.17aw 86a 109a 2.60a 6.50a
1.7 1.52a 79a 109a 2.00a 6.45a
5.0 1.50a 84a 106a 2.04a 6.44a
1.7 2.21a 59b 90b 3.81a 6.00c
5.0 1.38b 89a 112a 1.42b 6.40b
15.0 0.61c 101a 122a 1.42b 7.00a
ZFusarium wilt disease rating scale:
0 = none, 1 = very slight, 2 = slight, 3 = medium, 4 = severe, 5 = very severe, 6 =
YLength of new growth of uppermost shoot after removal of growing point, as indication of disease.
xSampled 8-1-89 at end of experiment. pH at start for 3 CaCO3 levels: 1.7 lbs = 5.6; 5.0 lbs = 6.5; and 15.0 lbs = 7.5.
Values in same column followed by different letters are significantly different at the 5% level.