⋅ BY DRS. SCOTT GRAHAM AND RON SMITH ⋅
Following are comments related to key pests and considerations for Integrated Pest Management in Alabama this year.
Key Pests
■ Grasshoppers. Grasshoppers tend to be worse in lighter, well-drained soils and following dry winters in reduced-tillage fields. Immatures begin hatching out in late March and continue until June. Stand loss occurs when grasshoppers feed on the mainstem of emerging seedlings. Preventative insecticide applications are a judgement call based on the risk a grower is willing to take.
■ Thrips. Getting cotton seedlings off to a good start is important for maximizing yields. Remember that what we see above ground is a good indication of the below ground root system. Use the Thrips Infestation Predictor Model https://products.climate.ncsu.edu/ag/cottontip/ to help gauge which planting dates are at the highest risk of infestation.
■ Tarnished Plant Bugs. Migrating adults in June may or may not reduce pinhead square retention below 80% to 85%. However, they are depositing 100-150 eggs per female that will hatch out in July to present post bloom control needs. Don’t give them a head start. When treating plant bugs after the second to third week of bloom, use tank-mixtures or chemistry that will also control stink bugs.
RONALD SMITH/AUBURN UNIVERSITY
■ Aphids. Aphids always crash from natural disease, sometimes a little later than desired. If controls are warranted, use a chemistry that will also suppress plant bugs.
■ Bollworms. For the first time since 2017, we experienced damaging levels of bollworms in two-gene (Bollgard 2) cotton. Keep an eye out between July 20 and August 10 if planting two-gene cotton. Bollworm control with foliar insecticides is better when applied to small worms.
■ Spider Mites. Mites are present in most fields season long. They reproduce and spread faster during hot, dry periods. If significant rain is imminent, wait to monitor populations after the rain to determine if an application is warranted.
■ Stink Bugs. Stink bugs are often the most damaging pest of Alabama cotton. One reason is time. Stink bugs damage bolls in the mid-to-late season, leaving little time for the plant to compensate. The most critical period for stink bug control is between the third and sixth weeks of bloom when most of our yield is being set. Sample quarter-sized (1” diameter) bolls and be prepared to treat if damage reaches 10% during peak bloom.
Be Informed
Cotton insect management is different from all other aspects of row-crop production. The situation changes from week to week and sometimes field to field. To stay up to date on the situation in Alabama, subscribe to the Pest Patrol Hotline https://www.syngenta-us.com/pest-patrol/alabama, Alabama Insects Blog https://alabama-insects.blogspot.com/, Alabama Crops Report rb.gy/h26lwt, and Cotton Shorts rb.gy/zwhpk1 Newsletters and the Alabama Crops Insect Report https://www.aces.edu/blog/topics/crop-production/alabama-crops-insect-report/.