Cotton insect losses lowest on record

U.S. cotton insect losses in 2001 were the lowest on record, according to Mississippi State University Extension Entomologist Michael R. Williams.

“This marks the first year that average insect losses across the entire Cotton Belt have been below 5 percent,” said Williams at the recent Beltwide Cotton Conference in Atlanta. “The average losses over the years usually is about 7.5 percent, and it's probably driven mostly by weather conditions.”

Overall cotton insect losses averaged about 4.65 percent in 2001, he adds. “Insect pressure throughout the United States was light in 2001, with only seven states reporting losses of more than 5 percent. North Carolina was the top loser to insects this past year with losses of 10.3 percent, while Kansas and New Mexico reported losses of less than 1 percent,” says Williams.

The hiliothine complex, including bollworms and budworms, was the most destructive pest of U.S. cotton in 2001, he says. These pests infested about 66 percent of the U.S. crop, causing the loss of 357,201 bales.

“Since the advent of transgenic Bt cotton in 1995, bollworms have become the predominant species of heliothine pests. Once more, in 2001, bollworms were the predominant species, making up 74 percent of the population.

“Bt cotton acreage increased from just less than two million acres in 1996 to almost six million in 2001. North Carolina — at 3.78 percent — and Mississippi — at 3.32 percent — reported the heaviest losses for the Cotton Belt. In general, heliothines caused more damage east of the Mississippi River in 2001.”

Plant bugs infested about 57 percent of U.S. cotton fields in 2001, reports Williams. The Southern states — Alabama, Louisiana, Georgia and Tennessee — and the Western states — California and Arizona — reported the highest losses to plant bugs. These pests, he says, combined to reduce yields by 0.97 percent for a loss of 279,376 bales of cotton.

The third most damaging insect pest in 2001 was stink bugs, notes the entomologist. “They reduced yields by 0.88 percent across the United States. These insects are increasing in importance as an insect pest of cotton. The complex infested more than six million acres of cotton in 2001.

The following states were the biggest losers to stink bugs this past year: North Carolina at 5.53 percent, Alabama at 3.09 percent, Florida at 2.97 percent, Louisiana at 1.49 percent, Georgia at 1.34 percent and Tennessee at 1.34 percent.

Each year, says Williams, thrips infest more acres of U.S. cotton than any other insect pest. “Thrips infested 97 percent of the U.S. acreage in 2001 and cost U.S. farmers $5.84 per acre in management costs. Thrips contributed to the loss of 235,085 bales of U.S. cotton in 2001.”

South Carolina at 1.72 percent and Alabama at 1.71 percent reported the heaviest losses from thrips in 2001. Three states — California, Georgia and Kansas — reported no losses from early season thrips. Only California reported that no cotton acres were infested by thrips, says Williams.

Aphids were the fifth damaging pest of U.S. cotton this past year. Aphids infested 61 percent of U.S. cotton fields, while yield losses were only 0.28 percent.

“This pest continues to be a concern because of the potential for rapid reproduction and resistance. South Carolina at 1.03 percent, California at 0.9 percent and Florida at 0.8 percent reported the heaviest losses to aphids in 2001. Five states — Georgia, Kansas, New Mexico, North Carolina and Virginia — reported no losses to aphids. Only Kansas reported that no acres were infested by aphids.”

The boll weevil ranked seventh among cotton pests in 2001, and this is the lowest ranking since boll weevil losses have been reported. Less than 20 percent of the U.S. crop was infested with boll weevils this past year, says Willliams.

“This pest reduced U.S. cotton yields by 0.099 percent. Seven states — Arkansas, Missouri, New Mexico, North Carolina, Oklahoma, Tennessee and Texas — reported acres infested by boll weevils. Only five states — Arkansas, Missouri, New Mexico, Tennessee and Texas — lost bales to the boll weevil. Those losses amounted to 28,414 bales of cotton. Boll weevil eradication costs for U.S. cotton was $10.51 per acre in 2001.

Saltmarsh caterpillars were persistent, low-level pests of more than two million acres of cotton in 2001, says Williams. “All of the other pests reduced yields by less than 0.1 percent, and only spider mites and bandedwinged whitefiles infested more than 20 percent of the crop.

Cabbage loopers, cotton leaf perforators, cotton flea-hoppers and European corn borers caused only a trace or no losses in U.S. cotton.

This past year, says Williams, reflects how management technologies were more responsive to the needs of cotton production. “As the boll weevil fades from the scene via eradication efforts, other pests are arising. Research, development and management are rising to the challenge being presented by these new pest species.”

The average cost of insect management in 2001 was $53.68 per acre, he says. The average of costs plus losses was $80.99 per acre.

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