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Continued Work on Stink Bug Management in Cotton
| Name | Tommy Walker | | Situation | Data shows stink bugs have been ranked the 3rd most important pest across the cotton belt during 2003-2006, behind only the worm complex and plant bugs. Our insect pest situation in the southeast has shifted from a budworm/bollworm driven system to a piercing-sucking bug driven system due largely to the widespread acceptance of B.t. cottons that reduce or
eliminate the need to spray insecticides for caterpillar control. I
estimate 90% of the cotton in the greater Hampton County area was first sprayed in 2005 for stink bugs rather than caterpillars. Greater acceptance of dual gene ( BollgardII, Widestrike, VIP, BollgardIII) cottons will further reduce the need to spray for caterpillars and will therefore solidify the status of bugs as our primary pests of cotton. Bugs are more difficult to scout for than caterpillars and established thresholds, while serviceable, are still much debated. Our cotton community has largely accepted the Jeremy Green 20% internal boll wall threshold, but many observers (including Dr. Green) acknowledge the need to exercise judgment regarding planting date, variety, weather patterns and insect pressure. Numerous tests in the southeast show 100-200 pounds of lint yield lost using the 20% threshold compared to more aggressive spraying (such as weekly). Pre-determined spray schedules such as the 3-5-7 ( automatic sprays at 3, 5, and 7 weeks after 1st bloom) program are widely discussed as an option to scouting. "Dynamic" thresholds recognize the importance of weeks 3-6 of bloom relative to earlier and later bloom weeks and adjust the spray threshold downward to 10% during those weeks. We have clearly recognized and addressed this shift in species importance, but we still need to validate and refine our insect management recommendations in a climate that will continue to change during the next several decades. We need to capture that 100+ pounds of lint yield that we sometimes "leave on the table" with our existing threshold. | | Response | Extension, in cooperation with Edisto REC and entomologists at NC State, UGA and Auburn, installed and monitored a large plot cotton stink bug threshold test on the Ashley Bush farm in lower Hampton County in 2006. Plots were sprayed, monitored season long and carried to harvest.
Seedcotton was picked up by Dr. Phillip Roberts, UGA Cotton Entomologist, and ginned at Tifton to determine gin turnout. Lint cotton samples were forwarded to Dr. Pat O'Leary at the National Cotton Council in Memphis for mill quality tests. | | Impact | Our 20% internal boll wall threshold is widely accepted in our cotton community (growers, consultants, ag dealers, basic industry reps). I believe this threshold or a similar modification of it is applied to 100% of our cotton acres in the Lowcountry. Visible and openly discussed on-farm evaluation of this threshold further instills confidence that our cotton insect management recommendations are sound AND that we are looking for ways to refine and improve them. Clemson data suggests this threshold protects growers from economic losses in most situations.
However, further refinements may be needed in high yield and/or heavy pressure situations. The "dynamic" threshold looked good in the 2006 data in NC, SC, GA, and AL. Multi-state tests also show the importance of weeks 3-6 of bloom, so our growers will be encouraged to use our existing 20% threshold as a guide and be aggressive (maybe lower to 10%) during these important weeks of bloom. Continued work on this threshold is merited. |
Last update6/26/2007
This website is maintained by Lisa Terry.
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