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If you are watering at the mouth just thinking about your 1999 tomato crop, plan ahead, beginning now, to prevent diseases and disorders that affect tomatoes.
The following five steps will help you grow better tomatoes this year.
Choose wilt-resistant varieties
Varieties resistant to Fusarium wilt and Vermicelli wilt are available for home Gardens and are
the only feasible method of reducing losses to these diseases. Whether buying seed or transplants,
ask for wilt-resistant varieties specifically. You will find the letters "VFN" on the plant tag or
seedling packet; often VFN is part of the variety name. When purchasing seedlings, inspect the
plants and choose only green, vigorous-looking seedlings. Avoid wilted plants and those with
yellow leaves or brown spots on the leaves.
Till the Garden and fertilize properly
Plant tomatoes in well-tilled, properly-fertilized soil; plants will be less prone to early blight and
Septoria infection. Tomatoes will grow in many different soil types, but a deep, loamy, well-drained soil is ideal. They grow best in a slightly acid soil, pH 6.2 to 6.8.
Tilling the soil in the fall to a depth of 4 to 8 inches is best to bury and hasten decomposition of
plant residue. The soil should be tilled again in spring prior to transplanting. If soil fertility is low,
apply 2 or 3 pounds of a complete fertilizer for each 100 square feet of Garden area. Examples are
5-10-10, 6-12-12, 8-16-16. Excess nitrogen promotes heavy foliate, reduces fruit yield and
increases the chance for blossom-end rot. Nitrogen deficiency predisposes plants to early blight
and Septoria leaf spot.
If soil fertility is adequate before transplanting, an application of 5-10-10 or 6-12-12 (2-3 pounds
for each 100 square feet) three weeks after transplanting will keep plants vigorous throughout the
season. Apply monthly thereafter.
Ensure adequate and even watering
Water stress usually is accompanied by blossom end rot and can make plants more susceptible to
early blight and Septoria leaf spot infection. Tomatoes require about one inch of water a week.
The water should be added gradually and allowed to soak into the soil. Do not allow soil to
become so hard and dry that plants wilt. Avoid fluctuations of too much and then too little water.
A mulch of grass clippings can prevent a certain amount of evaporation and will also reduce weed
growth. (Avoid clippings from a lawn recently treated with herbicide.)
Apply fungicides as needed
Fungicide applications may be necessary to protect fruit and foliage from anthracnose, early
blight, and Septoria leaf spot. This is especially true for Gardens with a history of disease
problems. Expect best results when fungicides are mixed in water and applied with a pressure
sprayer. Compared to dusting the plants, the pressure sprayer allows much better coverage or
distribution of the fungicide on the plant. Better protection will result in less disease!
Proper use of fungicides means: (a) using fungicides at rates stated on the label, and (b) providing
good coverage to the plant. Before purchasing a fungicide, check the label to be sure that it will
control these tomato diseases and that it is safe to use on tomatoes. All fungicides are required by
law to include such information on their labels. Providing good coverage over the entire season
means that fungicide applications must be repeated. The sprays should begin when plants
approach 10 to 12 inches tall and should be continued at 7 to 14-day intervals throughout the
season, especially if disease has been severe in recent years. Obtaining good coverage throughout
the season with an effective fungicide is the bottom line in controlling anthracnose, early blight
and Septoria leaf spot.
Clean up the Garden at season's end
Removing dead tomato plants from the Garden in the fall is actually the first step in producing
health tomatoes for the next season. Plants that are not removed provide a winter haven for all
sorts of tomato pathogens. Dead plants can be composted or simply discarded. Some residue can
be expected to remain in the Garden. Tilling the soil to a depth of 4-8 inches will bury this residue
and hasten its decomposition. This cleanup should be routine with all Garden vegetables. Weeds
also should be destroyed because they can harbor tomato pathogens until spring.
For more information on Gardening, contact your
local Colorado State University Extension office.
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