Cotton in the field is as old as 3-4 leaf stage. This year’s crop has already been through a lot of turmoil from high winds and blowing sand to cold temperatures in the 40s.
Early season cotton insect pests include thrips, aphids and mites. Seed treatments are usually effective in controlling these pests but sometimes problems will still occur.
We have found several fields in Calhoun County with mite problems. Mites feed on the underside of the leaf. They feed by piercing plant cells with their mouthparts and sucking the liquid contents of the cells. Damaged leaves develop white or yellowish specks, called stipules.
When mites are found across a significant part of the field and leaf damage is found treatment may be required to prevent yield losses.
Mite control products are different from the insecticides we would normally use in early season cotton and tend to be more expensive.
Keep in mind that mites tend to colonize along field margins and spot treatment may be both economic and effective in controlling the pest.
Thrips are tiny insects 1/16 inch long and the width of a hair. They can be pests in young cotton until it reaches 5-6 leaves in size. The cooler weather we have been seeing will slow down plant growth and result in more potential yield loss from thrips.
Thrips damage plants by rasping the underside of leaves and feeding on the plant fluids. This feeding injury often causes the leaf to cup downward to the underside of the leaf in a kind of “drawstring” effect. Thrips injury often resembles wind damage which is common in most fields.
When scouting, look on the underside of the leaf with a hand lens and count the thrips. You may also use a white piece of paper or a cup to beat the plant on and count the thrips against the white surface.
Treat fields when the number of thrips per leaf exceed the number of true leaves on the plant. In good growing conditions including warm temperatures, the plants can tolerate more thrips per leaf without suffering damage.
Aphids may also be found feeding on young cotton plants and can be found on the underside of the leaf. Feeding injury caused by aphids generally causes the leaves to cup upwards. Aphids rarely achieve high enough numbers to cause yield losses early season.