Biological pest control saves money COTTON pests put a large dent in producers' pocketbooks each year either by damaging precious lint and reducing yield, or through application of costly insecticides.

Researchers at Texas A&M's Agricultural Research and Extension Center at Vernon are taking a new look at biological control of these costly pests.

"We've been investigating the potential of relay intercropping to enhance biological control of cotton pests for several years," said Jeff Slosser, Texas Agricultural Experiment Station entomologist. "In relay intercropping, we plant two or more different crops that provide good habitat for beneficial insects that prey on cotton pests.

"These crops provide a winter and spring home for beneficial insects that will later move into our summer cotton and help reduce populations of cotton pests. The relay crops are planted in adjacent strips to make it easier for beneficial insects to move from one habitat to another."

Slosser and other researchers typically plant vetch in early fall to provide winter habitat for beneficial insects such as lady beetles, big-eyed bugs, minute pirate bugs, ground beetles, spiders and earwigs. A mid-winter planting of canola, followed by a spring grain sorghum planting provide a home for these beneficials in spring and early summer.

"Based on our past results, we believe relay intercropping shows more promise for controlling cotton aphids than other pests such as bollworms. This year, we planted cotton adjacent to our relay crops, and cotton isolated from our relay crops," Slosser said. "We also planted cotton into spring-planted wheat terminated with Roundup herbicide, as a third test.

"Then we monitored and sampled beneficial insect populations in all three experiments.

"The next step was sampling for early-season cotton pests such as thrips and fleahoppers, and mid- to late-season pests such as bollworms, aphids and whiteflies. We found more thrips in cotton planted adjacent to our relay crops, but fewer fleahoppers. The cotton's proximity to, or isolation from, relay crops made little difference in bollworm numbers."

Initially, there were fewer aphids in cotton planted next to relay crops than in isolated cotton. But aphid populations in cotton planted next to relay crops did increase about two weeks after aphid populations peaked in isolated cotton. On the other hand, whitefly numbers in cotton planted next to relay crops remained lower than in isolated cotton, the entomologist said.

"This suggests relay intercropping can help suppress aphids, to some degree. We also noticed more predaceous ground beetles and taller plants with more blooms (potential fruit) per foot of row in cotton planted into killed wheat," Slosser said. "Our preliminary conclusion is planting cotton into a killed-wheat relay crop can help increase the number of beneficial predator insects.

"It can also help boost yield, but it is only practical when the cotton crop is irrigated."

Slosser shared his research results with more than 130 producers at a recemt field day hosted by the Texas A&M University Agricultural Research and Extension Center at Vernon.