Spider Mites Defoliating Mid-South Cotton

Tough western pest is worse than in many years say cotton watchers. Michael Danna

Published on: Jul 27, 2005

Cotton fields across the Mid-South and surrounding states are being defoliated, but not on purpose. This time it’s spider mites in numbers not seen in many years.

The mites, tiny white specks smaller than grains of sand, are sucking cotton leaves dry. If fact, hundreds of thousands of acres across the Southern Cotton Belt are being infested and the impact on yields could be significant.

"Leaves develop the photosenthates that we need to fill out bolls," explains Ralph Bagwell, cotton specialist at the LSU AgCenter’s Macon Ridge Research Station. "When you begin to lose leaves you begin to see a fairly significant impact on yields."

In Louisiana alone Bagwell estimates some 70,000 to 80,000 acres have been hit by spider mites. He says he’s not sure why the mites have struck harder than normal this year. "It’s something in the environment," he says.

MITE DAMAGE--Rough, reddish penetrations and discolored leaves are evidence of spider mite damage. Photo by Chase Danna

One thing is clear, however, farmers need to recognize the signs of spider mites and begin a control regime immediately. The mites nest on the underside of the leaf and within days a smooth green cotton leaf can be brown and curled.

Bagwell says farmers in Louisiana and across the Cotton Belt haven’t had positive results with more traditional miticides. Newer products like Denim, Zeal, Zepher and Abba are being used by farmers with better results when used at the highest-labeled rate.

"But depending on the product, the costs of those applications could range from $19 to $45 per acre," Bagwell says. "Unfortunately this is a very, very expensive pest to control. The control measures for this type of pest are cotton (that’s) valued out at four to five bales (per acre) and not cotton that’s valued at one-and-a-half to two bales."

Traditionally a western pest, it’s been nearly 20 years since Louisiana has seen spider mite infestations at current levels.

Bagwell says the tiny creatures damage the cell structure of the cotton leaf, causing them to turn brown. The plant then drops the leaf.

"These populations started off at seedling stage and have been a problem in some areas of since," Bagwell continued. "Alabama, Mississippi, Tennessee and Arkansas also have been experiencing these problems. This points to something in the environment that has been conducive to spider mite population development. This is a western-type pest and unfortunately we don’t have a lot of knowledge about it."

MITE INSPECTION--LSU AgCenter cotton specialist Ralph Bagwell, says some growers, like Mike Emfinger, Indian Lake, La., right, have sprayed three times to control spider mites this season. Photo by Chase Danna

In Madison Parish cotton grower Mike Emfinger found spider mites in heavy concentrations in parts of his 740 acres of cotton. He says his treatment costs have exceeded budgetary expectations this growing season, but added he had little choice but to begin spraying for the pests.

Within days of discovering the pest, swaths of his cotton plants turned brown and dropped leaves. He says he’s already sprayed twice and was preparing to spray some fields a third time.

"I’m having a real tough time controlling them," Emfinger says. "Usually we have small spots of them, but right now they’re really bad. I’ve got one field that if left untreated I suspect the entire field would be defoliated inside of a week."