Control of thrips is a must for a good cotton stand to blossom into a good crop. After several years of testing and a season or two in the field, growers are seeing solid thrips control. It comes from a seed treatment insecticide that appears comparable to proven in-furrow and planter-box applied products.
Cruiser, a Syngenta-manufactured seed treatment released for corn and soybeans in the late 1990s, was labeled for cotton in 2001. It has some cotton producers taking a more diversified route to fighting thrips. They like the safety aspects, as well as the convenience of not having to handle insecticides used in planter hopper boxes or tank-fed applications.
“We used Cruiser for the first time last year, and we had good success with it,” says Terry White, who grows cotton and wheat near El Dorado, OK. “In the past, we used over-the-top sprays of Orthene during over-the-top Roundup broadcast sprays between plant emergence and fifth true leaf. Since there was a lot of thrips pressure in 2003, we still had to come back with an Orthene application on the treated seed.”
But by looking at the three-bale crop he harvested last October, any insect pressure had been headed off at the pass. “I ordered my seed with the treatment, along with Roundup Ready- and Bt-stacked genes, in mid-winter of 2003,” says White. “It was convenient for me to have thrips control already added to the seed.”
Scott Stewart, University of Tennessee entomologist in Jackson, tested Cruiser; Temik, the granular product from Bayer CropScience; and Gaucho, a seed treatment from Gustafson for more than five years. “All three had comparable performance in thrips control,” he says.
“Because of the performance of Cruiser and other treatments, we're seeing seed treatments taking an increasingly larger slice of the market,” says Stewart. “Growers like the convenience of not having to handle insecticides, which can clog up in hopper boxes or cause other problems. There is also less potential for exposure to farm chemicals.”
Miles Karner is an Oklahoma State University extension entomologist in Altus who says the rotation of different classes of insecticide can help thwart resistance.
Also, control of thrips is likely more critical for early planted cotton.
“The ability of the cotton plant to resist or tolerate thrips injury is directly related to growing conditions,” says Karner. “Cooler temperatures retard cotton growth and development, allowing thrips to inflict greater damage. So the greatest returns on money invested for seed treatments or at-planting applications normally occur in cotton planted in April and early May.”
Regardless of which insecticide is used, scouting plants is essential. “Growers can determine if the treatment is performing and if additional over-the-top sprays are needed to keep thrips numbers below economic thresholds of two to three thrips per plant,” says Karner. “Growers should maintain weekly scouting for thrips until plants reach the fourth to fifth leaf stage.”
There are several other insecticides used for thrips control. Foliar products, commonly used in cotton, are acephate, the ingredient in Orthene, and Bidrin, from Amvac Chemical Corporation.
Stewart advises growers to determine which insecticides have provided the best treatment for thrips in their growing areas. “Some areas have different species of thrips and may require different types of treatments,” he says.