Insect pressures could also deplete yields
WESLACO – All indications are that cotton growers in the Lower Rio Grande Valley this year will produce one of the area’s smallest crops on record, according to experts at the Texas A&M AgriLife Research and Extension Center at Weslaco.
Abundant cotton modules like those seen here last year in Harlingen, may be harder to find this year thanks to a devastating drought. (AgriLife Communications photo by Rod Santa Ana)
“To begin with, our estimations are that growers have planted only 80,000 acres of cotton,” said Danielle Sekula, a Texas A&M AgriLife Extension Service cotton integrated pest management entomologist.
That compares with an average of 150,000 acres planted each of the last three years, and an average of 220,000 acres of cotton planted between 2004 and 2006, she said.
This year could rival 2009 when only 60,000 acres were planted, 77 percent of which were lost to drought, according to the U.S. Department of Agriculture.
“The lower acreage years, like this year, are mostly due to drought,” Sekula said. “But this year we also have a lack of irrigation water in reserves as well as higher market prices for alternative crops that growers switched to, like corn and grain sorghum.”
While mature cotton plants prefer hot, dry weather, those same conditions are not conducive to healthy growth in its early stages, Sekula said.
“Plant growth has been very slow due to a lack of soil moisture and the cool nights we’ve been having,” she said. “Slow plant growth gives insects more time to do damage to a cotton plant during its first 45 days out of the ground, which is its most vulnerable and critical stage. ”
In Willacy County, home to a majority dryland cotton fields, plants never emerged from seed in some fields, Sekula said.
“Even in water districts in other counties where some water is still available, irrigated fields are also showing slow growth, even after preplant irrigation. Some growers are already on their second irrigation, and there’s still slow growth.”
Conditions are such that growers who manage to make a crop this year will be fighting off high insect pressures, according to Dr. Raul Villanueva, an AgriLife Extension entomologist in Weslaco.
“The light rains we’ve had the last few days have not been a big help at all,” he said. “They didn’t even start to put a dent in the drought, nor did they help reduce insect populations.”
By knocking insects to the ground where they drown, rain is an important and natural form of reducing pest populations, Villanueva said.
“A lack of rain, a lack of irrigation water and a mild winter that failed to kill off insect populations all point toward heavy insect pressures that will simply move from winter vegetables to cotton and other row crops this year,” he said.
Spider mites, thrips and aphids are just a few of the pests that are already showing higher populations than normal, Villanueva said.
“Whiteflies, for example, were high in the winter potato fields,” he said. “Thrips hit cabbage and cilantro fields pretty hard, to the point some fields were abandoned. They seem to move from onions to cabbage to cotton. With few alternative host plants, a lot of these sap-sucking insects will naturally migrate to our summer crops.”
Villanueva said spider mites, which reduce cotton yields and in high numbers can cause defoliation, are showing a trend of expanded longevity.
“We’re in the third year of a three-year study of tracking spider mites in an area along the Gulf Coast roughly from the Rio Grande to just north of Corpus Christi, in Sinton,” he said. “What we’re seeing is that as recently as 2011 they were observed in high populations only early in the cotton season. But last year, likely due to the drought, we saw that they were present throughout the cotton growing season.”
Controlling spider mites is an expensive proposition for growers because miticides cost roughly two to three times more than other insecticides, Villanueva said.
“If insecticides are misused or overused,” he said, “they can kill the natural enemies of spider mites which, especially in a drought, could cause spider mites to become abundant.”
The only silver lining to a drought that weather experts say shows no sign of abating, Sekula said, is the hope of controlling boll weevils, long a nemesis of South Texas cotton growers.
“With cotton acreage as low as it is, the boll weevil eradication program should be able to depress populations with much greater ease this year,” she said. “That’s the only good thing we can see to this devastating drought.”
