"Besides looking on the underside of cotyledons and true leaves, be sure to examine the terminal bud,” Goodson advised. “Both adults and immature thrips feed and lounge there and are easily overlooked unless you carefully inspect this region. Also, don't forget to count and record the numbers of dislodged thrips running around on the inside of the baggie.

"Crop demographics play a large role in thrips pressure. Wheat is widely known as an early season habitat for thrips. However, alfalfa is another thrips nursery that can produce large numbers of the insects. With each cutting, thrips migrate from the field in search of a food source. Cotton fields in close proximity to alfalfa meadows may experience a huge influx of thrips overnight that might rival the exodus from nearby wheat fields.”

Goodson said the amount of spring rainfall the area has received may mean a lot of other alternate hosts have provided considerable habitat for thrips to build populations.

 "Finding adult thrips in protected fields is normal and is expected as long as the thrips migration continues,” he said. “Remember, thrips blown in from adjacent fields may not feed immediately and feeding is required for the insect to pick up a lethal dose of a systemic insecticide. Historically, Temik (aldicarb) has been a product of choice; however, with the loss of this product in 2011, farmers have come to rely more on seed treatments such as Gaucho (imidacloprid) or Cruiser (thiamethoxam) for early control. Other seed treatment products containing these products are also being sold," he said.

 Over-the-top sprays can be used in fields planted to glyphosate-tolerant (Roundup Ready Flex and GlyTol) varieties. Tank mixing an insecticide with glyphosate is cost effective, Goodson said.  Acephate (Orthene) has been a standard foliar thrips treatment for many years. Application rates can be found in the Cotton Comments, a periodical online production of the OSU Southwest Research and Extension Center staff. 

For a table showing these products and expected length of control, inspect the May 15, 2012 edition of Cotton Comments located at www.ntokcotton.org. To receive Cotton Comments in your email, contact jerry.goodson@okstate.edu.