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Copyright 2005, Board of Trustees, University
' 3n" HUME LIBRARY
NOV 12 1971
..S. Univ. of Florida
AGRICULTURAL RESEARCH & E
Gulf Coast Station Mimeo Report GCS71-6 September, 1971
SOIL PREPARATION FOR TOMATOES ON OLD SAND LAND
A. J. Overman, J. P. Jones and C. M. Geraldson
The Old Land Problem:
Old land is a term used to describe agricultural fields cultivated for several
seasons. Production problems develop in such fields with time, particularly when
one crop is planted for several successive seasons. Problems associated with
reduction of tomato yields in old land are:
1. Selection and increase of crop-specific nematodes and soil insects.
2. Spread and development of soil-borne disease-causing fungi and bacteria.
3. Increase in weed populations.
4. High salt accumulations.
5. Depletion of organic matter.
6. Soil compaction.
Growers avoid many of these problems by migrating to newly cleared land periodically.
Since desirable new land is becoming difficult to obtain and increasingly expensive
to prepare or lease, a procedure for managing old sand land for tomato production
has been developed through several years of field research at the Agricultural
Research and Education Center, Bradenton (formerly Gulf Coast Experiment Station).
Each of the steps in the operation (outlined,for your convenience in the field, on
the last page of this report) is of major importance in proper preparation for
tomato production on old sand land in peninsular Florida.
In Florida, soil-borne plant pathogens (fungi, bacteria, and nematodes)
frequently cause extensive damage to vegetables being grown on old land. Some
growers practice crop rotation and summer fallowing to combat these problems,
whereas others migrate periodically to newly cleared virgin land. However, certain
pathogens, such as the tomato wilt Fusarium, can survive in the soil for a number
of years without a host plant and others, like the Verticillium wilt organism, not
only survive in the soil for a number of years, but also grow on a large number of
different plants. When these types of organisms become established in an area,
crop rotation and summer fallowing are ineffective.
How To Use Old Land:
As an alternative to annual or biennial migration to virgin land, the farmer
can now utilize his old location by adapting a coordinated crop management
procedure. Properly coordinated management should start with choice of the tomato
variety to be grown. Varieties which are resistant to one or more of the soil-
borne pathogens are available. Since the disease complex may include several
species of nematodes and damping-off as well as wilt organisms, good practices can
materially improve yields of resistant as well as non-resistant varieties. It is
of little value to control some, but not all, of these pathogens. Money invested
for nematode control is wasted if the crop is destroyed by Fusarium wilt or vice
versa. Therefore, a wide-spectrum soil fumigant is recommended for use prior to
For maximum control an effective fumigant must be chosen and applied at the
recommended rate to land that has been properly prepared for treatment. Extreme
care must be exercised during the crop season to avoid or minimize recontamination
by disease organisms.
Fumigants vary in their effectiveness against soil pests. Consequently, it is
incumbent on the grower to recognize and evaluate the relative importance of
diseases, nematodes, and weeds. Then the proper fumigant must be chosen and
applied properly at the rate, time, and in the manner prescribed on the label. In
the following table fumigants available for use in tomato production are compared
in regard to their efficacy in multiple pest control.
Vegetable Pathogens Controlled in Sandy Soil by Various Fumigants
Rate Pyth- S. Nema-
Fumigants gal/A. Fus. Vert. ium rolfsii todes Phoma
Chloropicrin 30 X X X
Chloropicrin + D-D 30 + 25 X X X X
Chloropicrin + EDB 30 + 6 X X X X
D-D 25 X
EDB 6 X
Vorlex 35 X X X X X
Vorlex-201 35 X X X X X X
All of these fumigants are liquids and should be injected into the soil no shallower
than 5 inches and no deeper than 8 inches. The streams should be 8 inches apart
for Vorlex, Vorlex-201 and chloropicrin, whereas the EDB and D-D streams may be 12
inches apart. The County Agricultural Agent may be contacted to help evaluate the
pest problem and to select the proper fumigant.
The soil to be fumigated should be of seed bed tilth (friable and moist) so
that the fumigant vapors will move evenly through it. All plant debris should be
well rotted at treatment time since fungi, bacteria, and nematodes remaining in
undecomposed plant tissue are not destroyed by the fumigant. All soil conditioners
and fertilizers should be applied prior to bedding and fumigation so that the
finished bed will be disturbed as little as possible after fumigant application.
Soil moisture sufficient to permit seed germination should be maintained for 2
weeks prior to fumigation. Adequate soil moisture at the time of bedding and
treating is a "must" in order to prevent premature loss of fumigant vapors. Beds
should be dressed and compacted simultaneously with treatment to help maintain soil
moisture and to contain the fumigant vapors. A bed press is highly recommended
when fumigants are used so that crevices, through which vapors may escape
prematurely, will be eliminated.
Use of Mulches:
Mulches available to cover fumigated soils are: black or translucent poly-
ethylene film of various thicknesses and laminates of Kraft paper and polyethylene
film. In addition to improving the benefits derived from fumigation, mulches
prevent leaching of nutrients from covered beds, prevent recontamination of treated
soil, confine root development to the treated soil volume, protect roots from
mechanical damage, retain soil moisture, prevent bed erosion, and reduce fruit rots
in ground culture. Both plastic and paper mulch provide weed control, but differ
in that nutgrass will emerge through the plastic film, but not through the present
paper mulches. Ideally, applying the chemical, pressing, fertilizing, and mulching
should be done simultaneously. Growers who do not have facilities to perform these
operations with one pass of the tractor through the field, should make every effort
to follow each step with as little delay as possible.
A waiting period between treatment and planting is necessary to permit the
fumigant vapors to dissipate and to prevent crop damage. The length of the
waiting period depends on the weather, the fumigant used, and the method of
planting. The average waiting period is 2 weeks. This may be increased to 3 or 4
weeks if the temperature is low or if heavy rains seal the beds and prevent vapor
loss. Seeded crops are less likely to be injured by residual fumigant vapors than
are transplants. If no mulch is used, the beds may be aerated 2-3 days before
planting by forming a small furrow in which the plants will eventually be set.
When a mulch is used, plant holes may be cut 1 week after fumigation.
Soil fumigation procedures do not eliminate indefinitely all soil pests from
the field. Rather, the aim is to permit good growth of the crop for as long as is
economically feasible. For example, single stream in-the-row applications of a
liquid fumigant will ordinarily protect the plant root systems for about 8 weeks.
This method is profitable for short term crops but not for a long term crop such
as vine-ripened tomatoes. For longer protection a greater volume of disinfested
soil is needed. This is accomplished by injecting the fumigant at 3 or more points
in the bed width. In all cases the rate of material applied per stream remains the
same. For the control of systemic diseases, such as the Fusarium and Verticillium
wilts of tomato, the roots should be confined to the fumigated area; for, if one
root penetrates into a contaminated area, that root may be invaded and the entire
plant then becomes diseased. In the case of a non-systemic root-rotting disease,
the errant root, which becomes infected, is merely rotted off and the rest of the
root system and plant remains healthy. The plastic or paper mulches help to
confine the root system to the fumigated area in sandy soil.
When a mulch is used, the fertilizer amendments are applied in bands on the
surface of the bed prior to mulching. A constant water table is maintained with
this system. The plant roots tend to move laterally to the fertilizer bands and
the high water table limits the downward root growth. Consequently, the roots are
effectively limited to the fumigated soil volume and greater control of systemic
diseases is obtained. Moreover, covering the fumigated bed area with a mulch
immediately after fumigation averts recontamination. Without a mulch, higher
fumigant rates and a much larger volume of fumigated soil is required for control
of the systemic diseases during the entire crop season.
Often crops grown without a mulch and infected late in the season by root-
rotting fungi or nematodes can be greatly improved by careful attention to moisture
and fertility. Fertilizer should be placed where the restricted root system can
absorb it and a constant water table should be maintained to prevent moisture from
SOIL PREPARATION FOR TOMATOES ON OLD SAND LAND
PRELIMINARY DECISIONS TO BE IIADE:
1. PLANTING SITE:
a. Determine potential production problems based on cropping history.
b. Obtain cooperation of your County Extension Director in evaluating site.
2. TOMATO VARIETY:
a. Consider growth habit of candidate varieties.
b. Consider disease resistance of candidate varieties.
3. PLANT SOURCE:
a. Cell-pack transplants improve stand survival.
b. Use only disease-free transplants.
4. SOIL FUMIGANT (See Table on page 2):
a. Factors to be considered:
1) disease pressure expected in the field.
2) "green-wrap" vs. "vine-ripe" culture.
5. MULCH (See page 3):
a. To improve fumigant action. e. To control weeds on the beds.
b. To retain soil moisture. f. To protect roots from mechanical damage.
c. To restrict leaching of fertilizers. g. To reduce fruit rots in ground culture.
d. To prevent bed erosion. h. To prevent recontamination.
1. SOIL MOISTURE:
a. Maintain seedbed moisture during preparation of the field.
1) encourage rotting of crop debris.
2) encourage hatching of nematode and insect eggs, germination of weed seeds,
and spores of disease organisms.
a. Rotovate, disk or plow the field repeatedly for at least 1 month before planting.
1) destroy previous crop debris.
2) destroy weeds.
3) clean fallow to starve out soil pests.
3. SOIL AMENDMENTS:
a. Mix 500 lbs/A dolomite broadcast during cultivation and 500 lbs/A superphosphate
+ 20 lbs/A FN503 fritted trace elements in the beds.
1) liming materials and phosphates must be thoroughly mixed in the plow layer.
4. SOIL FUMIGATION:
a. Apply a soil fumigant in prepared beds or as the beds are being constructed.
1) 3 streams 6 inches below the final bed surface.
2) distance between streams varies with chemical (8-12 inches).
3) compact the treated bed immediately with a press, eliminate chisel crevice.
5. FERTILIZATION: (Immediately)
a. Place 1500-2000 lbs/A 18-0-25-2 in 2 narrow bands on outer edge of bed surface.
b. Broadcast 300 Ibs/A 6-10-10 between the bands.
6. MULCH: (Immediately)
a. Seal mulch over fumigated and fertilized bed.
b. 7 days after fumigation cut the plant holes in mulch.
c. 14 days after fumigation set tomato transplants.
Overman, Jones, Geraldson