Cotton farmers cannot let their guard down at anytime from the day cotton is planted until the crop is ready for harvest.
Insects can create problems throughout the entire cotton growing season, says David Kerns, Associate Professor and Extension Entomologist for Cotton at Lubbock, Texas.
“This potential can be minimized by proper management of both predators and destructive insects, and proper management requires timely scouting and corrective measures when needed.
“Over the past few weeks we’ve been seeing fairly high infestations of cotton fleahoppers, pests that can trigger significant yield reductions by causing small squares to shed,” said Kerns. “Fortunately, these insects can be controlled with various insecticides, including Orthene, but control should not be initiated until unacceptable square set is detected.”
Currently, certain areas in the High Plains also are experiencing unusually high Lygus infestations. These insects can also reduce yields significantly by feeding on cotton terminals, squares, and small bolls.
Lygus can be controlled with a number of insecticides, but Ammo and Carbine appear to be most widely used. “Ammo is more likely to result in aphid “flares” than Carbine but is less expensive,” Kerns said.
“Because of the Texas Boll Weevil Eradication Program, the boll weevil has been functionally eradicated in the High Plains, Trans Pecos, and Rolling Plains areas of Texas. However, the Texas Boll Weevil Eradication Program is continuing to monitor for boll weevils in these areas and if anything significant comes to light, we’ll know right away.”
Widespread use of Bt varieties has minimized problems with bollworms. “Thus far we have not had any reports of bollworm problems in the Bt varieties,” said Kerns. “However, under rare conditions, problems can arise, so Bt cotton should be scouted. And if the variety is not Bt cotton, probability of yield losses from bollworms is substantially higher.”
Aphids are becoming a widespread problem, particularly on lush plants that have received higher amounts of fertilizer and irrigation.
“Aphids secrete honeydew which causes stained, sticky, lower quality fiber, and create harvest, ginning, and spinning difficulties, all of which result in negative economic effects,” Kerns said.
“Controlling aphids with insecticides should not be necessary until infestations exceed 50 aphids per leaf. And sometimes unfavorable weather, predators, parasites, and pathogens hold populations below damaging levels.”
Pink bollworms are primarily late-season pests. The larvae prefer 15- to 20-day old bolls of upland varieties, and Pima bolls are susceptible to larvae damage until they are 35 to 40 days old. Bolls should be protected from pink bollworms for the first four to six weeks of the boll-setting period. “This protection requires continued scouting and perhaps treatments until mid-September or early October. But thanks to the adoption of Bt cotton varieties and the adherence of producers to planting and stalk-destruction guidelines, insecticides should seldom be necessary,” Kerns said.
Other insects that occasionally damage plants include grasshoppers, stink bugs, cabbage loopers, and spider mites. These can all be controlled with insecticides, or, in the case of cabbage loopers, Bt varieties.
Kerns recommends producers carefully read and adhere to instructions on pesticide container labels.
Additional information about cotton pest management is available in Extension publications E-6 and E-6A at website Lubbock.tamu.edu. Also during the summer this website has a weekly-updated sub-site, Focus on South Plains Agriculture.”