New threats from spider mites add to the importance of early insect control if cotton is expected to make a good stand, then progress with vigor during the “First 40 Days.”

Recognizing the importance of insect control and other production factors in cotton's initial month and a half of growth, the “First 40 Days” project was started in 2005 by some 60 cotton agronomists, entomologists, plant physiologists, plant pathologists and other cotton experts. They've spent the past two years identifying the Best Management Practices (BMPs) for that crucial first chapter of a cotton plant's life.

Tom Barber, Extension cotton specialist at Mississippi State University (MSU), points out that thrips and sometimes aphids have long been major early pests for growers, adding that good control has usually been provided through either insecticide-treated seed or in-furrow insecticide applications at planting.

But spider mites are showing up in many southern cotton fields. Barber and others say mites can be an “induced pest,” due to increased early use of broad-spectrum insecticides, particularly in reduced-tillage fields. Some believe problems with mites can be lowered where an in-furrow insecticide such as Temik is used.

Angus Catchot, MSU Extension entomologist, notes that an in-furrow application of Temik can reduce spider mite numbers, but under heavy pressure foliar applications of an acaricide may still be necessary to control high populations.

Research has also shown that an additional sidedress application of Temik either following an in-furrow application or even behind a seed treatment can lower mite numbers as well. He notes that the ease of application at planting and safety concerns have seen many growers switch to treated seed for early insect control. “Whether you're using a seed treatment or an in-furrow insecticide, the goal is to cut early season insect stress on the plant,” says Catchot.

“Things that happen early are generally magnified later in the season, so it's critical to get the crop off to a good start to maximize the chances of an early uniform crop later,” he says.

Barber and Catchot were among those who helped develop the First 40 Days BMP recommendations, which were discussed as part of the 2007 Beltwide Cotton Conference in New Orleans, LA, in January. Here are some of the insect control guidelines outlined by the group:

  • Evaluate systemic inputs based upon the range of pests controlled, including nematodes, mites and thrips. Ideally, the at-planting systemic pest control input would control thrips, fleahoppers and other arthropod pests throughout the first 40 days.

  • Avoid “convenience application” programs with “automatic” oversprays for thrips and plant bug control. These can create pest problems, including cotton aphids and mites as the season progresses. Avoid insecticides co-applied with glyphosate as a convenience.

  • Growers are encouraged to avoid unnecessary applications when thrip, fleahopper and tarnished plant bug numbers and damage ratings are below thresholds. Eliminate host plants and breeding sites with preplant weed control and seedbed preparation, as well as weed management around field perimeters.

  • Keep seedbeds free of all green plant tissue for at least three weeks prior to planting. Recognize the residual limitations of insecticides.

  • Scout and treat as needed, according to Extension threshold guidelines.

  • The length of control of various at-planting insecticides ranges from a low of 14 days after planting with certain seed treatments up to five weeks after planting with an in-furrow granular.

For further information, go to www.cottonexperts.com.