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Many growers have begun planting cotton and peanuts, and some growers are much further along. There are choices and decisions made at planting, either with seed treatments or at-plant treatments, that can affect early season protection of the crop from nematodes, diseases, and insects.

One main issue for nearly all earlier planted fields of cotton and peanuts is the presence of thrips and the plant injury from their feeding. The pressure has been high in fields, and many early planted fields have needed supplemental foliar insecticide sprays. It is important to scout these young crops to determine the need for supplemental insect control. The thrips pressure, the grower’s injury/risk threshold, and field conditions should be used to make a treatment decision.

According to Dr. Phillip Roberts, “The decision to use a foliar insecticide to supplement at-plant insecticides for thrips control should be based on scouting. Scout thrips by randomly pulling a seedling and “slapping” the seedling against a piece of paper or box to dislodge the thrips. There will likely be sand and other debris on the paper. Thrips will begin to move within a few seconds and will cling to the paper whereas sand and other debris will slide when you tilt the paper. Count the number of thrips per plant after each sample. Be observant for immature thrips when making counts. Immature thrips are wingless and crème colored (Figure 1).”

Figure 1. Immature thrips are crème colored and wingless (bottom). Adults are brownish with wings (top). Image by Jack T. Reed, Mississippi State University, Bugwood.org

“Adult thrips are usually brownish or almost black in appearance and have wings (depends on species, tobacco thrips is the most common thrips species infesting cotton and adults will be dark brown or black). Do this on several plants and determine the average number of thrips per plant. The threshold for thrips is 2-3 thrips per cotton plant with immatures present. The presence of numerous immature thrips suggests that the at-plant insecticide is no longer providing acceptable control (i.e. thrips eggs laid on the plant, eggs hatched, and immature thrips are surviving). Foliar insecticide options include the systemic insecticides Orthene, Bidrin, and dimethoate. Note that these products are systemic. Pyrethroids will not provide acceptable control thrips in cotton.
Economic damage from thrips rarely occurs once seedlings reach the 4-leaf stage and are growing rapidly. It is important that we make thrips decisions
early in the plant’s development. Seedlings become more tolerant to thrips feeding in terms of yield potential with every true leaf it puts on. 1-leaf cotton is much more susceptible to yield loss than 3-leaf cotton.”

If we can be of assistance in the field or with questions, please contact us at the Worth County Extension Office.