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Shrinking Louisiana cotton acres still need insect control

How many acres of cotton will be planted in 2008 in Louisiana is anybody's guess at this point. But no matter how many are planted, farmers can save money by using best management practices for insect control.

“Plus or minus 5 percent of last year's 320,000 acres is a wild guess,” said Ralph Bagwell, LSU AgCenter entomologist, who spoke at a cotton grower meeting in Caddo Parish in early February. “This is the most volatile I've ever seen cotton acreage as long as I've been working cotton.”

Cotton acreage has gone down as farmers turn to other crops such as corn and soybeans that deliver higher prices.

To reduce the cost of raising cotton, Bagwell strongly suggests the following practices. “There is no magic bullet for plant bug control, but the more of these practices that are adopted, the less severe plant bug damage will be,” he said.

  • Concentrate cotton acreage into contiguous blocks to reduce cotton borders with other crops and noncrop areas. Many plants serve as hosts for plant bugs. Plant bug populations will often build to high levels on these hosts and then move into cotton as the host matures. Reducing the amount of borders between cotton and alternate plant bug hosts will help to reduce the number of insecticide applications required for plant bug control.

  • Plant early-maturity varieties to help reduce the time cotton is exposed to plant bugs. This also will reduce the number of insecticide applications required for plant bug control.

  • Avoid planting within 50 feet of trees or any other obstacle that may reduce insecticide coverage. Such impediments limit the ability of application equipment to reach some areas with an insecticide.

  • Use aircraft equipped with GPS guidance systems and flow-rate controls. Aircraft ground speed can vary as much as 20 percent to 25 percent during an application. A flow-rate controller varies the aircraft's output flow rates so the applied insecticide rates are similar regardless of ground speed. “Most pilots have gone to it,” Bagwell said.

  • Use flat fan or twin jet nozzles at 50-60 psi for ground applications. Spray pressure at 50-60 psi will help reduce droplet size. Small droplets increase insecticide efficacy by increasing plant coverage.

  • Base mid- and late-season treatments on sampling, usually with a black dropcloth. “A black dropcloth is better than white to spot the insect nymphs,” Bagwell said.

    Some consultants and pest managers are reluctant to use dropcloths because of the perceived time and effort required for sampling, but acceptance is increasing, Bagwell said. Many agricultural consultants base their control recommendations on visual observations, but methods of visual scouting are not standardized and vary considerably among individuals, he said.

  • Don't expect 100 percent control for an insecticide application. Insects are mobile. No insecticide provides acceptable residual activity in excess of 48 hours — most less than 12 hours, Bagwell said.

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