How to Manage Pests
UC Pest Management Guidelines
Selecting The Field
In this Guideline:
management is cheaper and easier on land that is well suited for a particular
crop. Lettuce planted in fields infested with lettuce pests or fields with poor
nutrient balance will suffer yield loss. Choose fields for lettuce 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
such as root knot nematode, green peach aphid, loopers, or problematic weeds.
Avoid fields that are heavily infested with weeds such as common groundsel,
prickly lettuce, and sowthistle that are hard to control with herbicides
labeled for lettuce.
fields for lettuce, check the soil and available water for the following:
- Nutrient levels. Check for excessive salt, sodium, boron, and other mineral
- Soil pH. Lettuce grows best at pH 6.0–6.5.
- Herbicide residues. Residues may inhibit seedling growth.
Perform soil herbicide bioassay.
- Soil type. Lettuce can grow in a variety of well-drained soils,
however, it does best on fertile, high organic matter soils with good
water-holding capacities. Heavy clay soils require very careful water
management, and root development may be problematic in fields with shallow
hardpans, compacted layers, or high water tables. Sandier soils usually have
higher root knot nematode populations than loamier soils. Avoid fields with
major variations in soil type that make herbicide difficult because rates must
be adjusted for soil type.
- Irrigation water. If the quality of the irrigation water is unknown, test
for pH, salinity, and specific ion toxicities.
- Root knot nematodes. Test for nematodes in desert areas before planting
lettuce if they have been a problem in a previous crop.
- Verticillium dahliae. Assay soil for microsclerotia if Verticillium wilt has
been a problem in a previous crop.
Also check field
information. Determine past lettuce
varieties that have been planted, including their planting and harvest dates
and yields. See if the field has supported successful production.
- Cropping history. Identify previous crops that are known hosts of lettuce
- Surrounding crops and areas. Check for cultivated crops
that harbor weeds, invertebrates, and diseases problematic to lettuce.
- Rotational crops. Consider planting a rotation crop to keep difficult to
control pests and weeds from building up.
UC IPM Pest Management Guidelines: Lettuce
UC ANR Publication 3450
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