Wednesday, August 24, 2011

Weather and Insects Affect Late Season Cotton, Soybean and Peanuts

The greatest impact on cotton during the past two weeks has been the lack of rainfall. Drought and intense heat has resulted in the shed of all fruit less than 10 day old bolls from the terminals of plants. This will tend to shorten additional boll production by 2 to 3 weeks and will likely reduce the “top crop” by 200 or so pounds of lint in many fields. Rainfall in the next 7 days would still help fill top bolls that are not mature.

As the result of the above conditions, the insect control season, especially stink bugs, is about over. A few southern green stink bugs can be found in late maturing fields or “swag” areas that remain green in more mature cotton fields. Thresholds for these would be 30-50% internal boll damage on 10-12 day old bolls. A few fields would still profit from stink bug controls.

Tobacco budworms have been extremely low all season but field observations and pheromone traps indicate an increase in the past week or two. Also, bollworm moths are abundant this week in the southern counties of the state.

Soybean Insects- Soybean loopers are at economic levels of 5 or more per row foot in some Gulf Coast area soybeans. Chemical choices (in no particular order) are: Intrepid, Steward, Belt, Tracer and Besiege (Coragen and Karate). Dimilin will give good suppression and long residual. On cotton, the same can be said for Diamond.

Peanut Insects- Scouts reported a mixture of foliage feeding worms in peanuts in Monroe County (S.W. Alabama) about 10 days ago. Many of these were controlled or either they have cycled out by now. This mixture was dominated by bollworm and fall armyworm (grass strain) species. Also in the mix were a few green cloverworms, loopers, and granulate cutworms. Pyrethroids gave nice control of this mix.