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.

Friday, August 12, 2011

Bollworm Pressure Remains Extremely High Across the Coastal Plains of Alabama and Georgia

Bollworm pressure has been extremely high across the coastal plains of Alabama and Georgia for the past two weeks or so. Untreated sentinel plots of conventional cotton in southwest Georgia, southeast and southwest Alabama have been stripped of all fruit during this period. Bollworm moths were still active on August 10th at Headland, Alabama. We are relatively certain most of this population has been the bollworm species because sentinel plantings of tobacco in this same area have had few tobacco budworms present to date. As far as I know, no economic levels of escapes have occurred on varieties with Bt technology.

Aphids Reoccurring in Central Alabama Fields

Aphids have reoccurred in some central Alabama fields in the past week. Their infestation pattern on the plant is distinctly different from that of the aphids that normally occur in June and July. These August aphids are occurring down midways in the canopy while the terminals of the plants are aphid free.

Soybean Loopers in Southwest Georgia

Soybean loopers were discovered in cotton in Seminole county, southwest Georgia, last week. There were only about 2-4 per foot of row which is below treatment levels. However, since this is a little early for loopers to appear, they will have to be watched for in coming weeks.

Fleahoppers and Silver Leaf Whiteflies Reported in Southwest Alabama

After two uneventful weeks with little cotton insect news, several points have been learned this week. Consultants from the Mobile area of SW Alabama voiced that the cotton fleahopper has been their most persistent insect this season. This area also has another fleahopper species in the mix, that being the garden fleahopper. Fleahoppers are not difficult to control but populations can rebound very quickly within 5-7 days. Also in this same area, silver leaf whiteflies (SLWF) are infesting a few cotton fields that are planted adjacent to melon fields. Controls were needed for this insect.