How to Manage Pests
UC Pest Management Guidelines
(Reviewed 1/07, updated 1/07)
Tomatoes planted in fields infested with
tomato pests or fields with poor nutrient balance will suffer yield loss. Choose
fields for tomato planting carefully, taking into account the field's cropping
history. Also take into account pest problems that may originate in adjacent
crops or fallow ground. Do these areas harbor pests of tomato such as root knot
nematode, potato tuberworm, or problematic weeds? Many weed problems can be reduced
by not planting tomatoes in fields that are severely infested with difficult
weeds such as nightshades,
field bindweed, nutsedge, and parasitic dodder.
If this is unavoidable,
treat weed infestations before planting (see SPECIAL WEED PROBLEMS).
Use the information below when selecting
fields for tomato planting. Well-chosen fields can result in fewer pest
Assay soil and water
- Nutrient levels. Check for excessive salt and boron, and
other mineral imbalances.
- Soil pH. Tomatoes grow best at pH 6.0 to 7.5.
- Herbicide residues. Residues may inhibit seedling growth. Perform soil
- Identify soil type. Tomatoes can grow in a variety of soil types,
however, heavy clay soils require very careful water management and are
generally less desirable. If possible, choose a field with deep, uniform loamy
soil. Sandier soils usually have higher root knot nematode populations than
soils that are more loamy. Avoid fields with large sandy streaks. Major
variations in soil type within a field make application of herbicides difficult
because rates must be adjusted for soil type.
- Check irrigation water. If the quality of the irrigation water is unknown,
assay for pH, salinity, and specific ion toxicities.
- Root knot nematodes. Assay for nematodes before planting
tomatoes if they have been a problem in a previous crop.
information. Determine past tomato varieties that have been
planted including their planting
and harvest dates and yields. See if the field has supported successful
history. Identify previous crops that are known hosts of
crops and areas. Check for cultivated crops such alfalfa, cotton, or
safflower that harbor lygus, which damages tomato fruit. Check alfalfa for
armyworms, cutworms, darkling beetles, whiteflies, and tomato pinworm. If
pinworm is found, get rid of solanaceous weeds that may harbor them.
Check previous crop. Determine if pest problems such as garden
symphylans, pinworms, potato tuberworm, nematodes, Fusarium or Verticillium
wilt, dodder or other weeds, that might
carry over to a new tomato crop were present in the previous crop(s).
UC IPM Pest Management Guidelines:
UC ANR Publication
R. M. Davis, Plant Pathology, UC Davis
T. K. Hartz, Plant Sciences, UC Davis
W. T. Lanini, Weed Science/Plant Sciences, UC Davis
E. M. Miyao, UC Cooperative Extension, Yolo County
C. J. Rivara, Calif. Tomato Res. Institute
F. G. Zalom, Entomology, UC Davis
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