A new and as yet unidentified insect is causing heavy damage to Lower Rio Grande Valley cotton fields already battered by an extended drought, according to a Texas AgriLife Extension Service cotton expert.
“We know this new pest is what’s commonly called a bean thrips of the genus Caliothrips,” said LeeRoy Rock, a cotton integrated pest management specialist in Weslaco. “What we don’t know yet is its species, but we’re working on it.”
Rock has sent out a special alert advisory to area growers on his electronic mailing list warning them to be on the lookout for the pest.
"It’s a small, sucking insect found on cotton plant leaves,” Rock said. “It relieves the plant of its nutrients and water which causes defoliation and eventually boll loss as well.”
The insect was first detected June 23 in a dryland cotton field west of Lyford and has since been found in a few other fields, Rock said.
For now, he’s recommending growers manage these populations with the same products used to control other thrips found in cotton.
“These insects are easy to miss,” Rock said. “You have to look closely. And the damage they cause resembles the damage caused by spider mites except for one little detail: Spider mites cause leaves to curl downward; this new bean thrips causes them to curl upward.”
He said area U.S. Department of Agriculture personnel, including Drs. Scott Armstrong and John Adamczyk, have sent insect samples to laboratories and universities outside the state for identification.
In an area where in recent years growers routinely planted upwards of 200,000 acres of cotton, only 60,000 acres were planted this year, Rock said.
“Low market prices, the drought, and rising input prices have decreased the number of acres planted,” Rock said. “Many growers planted sorghum instead.”
Of the 60,000 acres, only 20,000 acres were planted in irrigated fields, leaving the majority of the crop at the mercy of a relentless heat, high winds and below-average rainfall.
But even irrigated crops are showing signs of stress, according to John Norman, a cotton consultant who along with a colleague, Webb Wallace, first detected the new insect late last month.
Until now, the only good news to report about this year’s crop was the lack of widespread insect damage, likely due to the reduced acreage planted and a good ratio of beneficial insects to damaging insects, according to Rock.
“We’ll have more information soon on this new insect,” he said, “but for now growers are advised to keep a close eye on their crop and if they see infestation, treat this new thrips as they would any of the other thrips that affect cotton, including soybean and Western thrips.”