Wednesday, June 29, 2011

Tarnished Plant Bugs

High numbers of adult tarnished plant bugs have been reported by two consultants in the Talladega county area this week. In both cases the fieldmen found the plant bugs before square retention began dropping. Numbers as high as 21 adults per 100 row feet were recorded. This is far in excess of what I would consider threshold. Some might question if they should wait until square retention drops before applying controls. I would suggest for controls to be applied immediately since this generation of bugs will not only feed, causing square loss, in the next week—they will also deposit eggs in the plant tissue that will result in a July in-field generation.

A few growers have expressed concern about conserving beneficials but one advantage of having Bollgard II and WideStrike genetics is that you can react to plant bugs when they reach damaging levels. We do not have an insecticide that will kill tarnished plant bugs and conserve beneficials. Any chemical choice that is selective on beneficials would also be selective on plant bugs.

Monday, June 27, 2011

Tarnished Plant Bugs Threatening Cotton Yields

Tim Reed, Extension Entomologist

June 21, 2011

Control measures for tarnished plant bugs (TPB’s) in the oldest cotton fields in north Alabama began two weeks ago and initial applications continue to be applied to later planted fields. Consultants report TPB pressure to be higher than normal than at this time last year and there is concern that some fields, especially older fields may require two TPB treatments. The cooler, wetter weather we are having this week in parts of Alabama will be favorable to TPB’s. The longer TPB treatments are postponed the more eggs are deposited by adult TPB’s which result in higher numbers of immature TPB’s present in late June and July. One consultant reports that TPB’s can presently be collected in a sweep net at any time of the day in north Alabama cotton fields but they tend to be more abundant on field edges. Some cotton fields in Montgomery county this week are also suffering 20% (Bt cotton threshold) or better pin head square loss due primarily to TPB damage and there could be control measures initiated in this central Alabama county this week. TPB’s are a much more serious pest for conventional cotton producers than for Bt cotton growers since all available chemicals that control adult plant bugs also significantly reduce beneficial insects/spiders. This increases the chances of a severe tobacco budworm infestation in the last half of June. Conventional cotton growers have a difficult time deciding on whether or not to spray for adult plant bugs in mid-June when they know it will be expensive to “fight” worms. Dry weather makes the decision even more difficult. Mississippi entomologists are reporting higher than normal numbers of tobacco budworm moths being collected in pheromone traps and budworm moths are now depositing low numbers of eggs on cotton in Montgomery county. Another concern for all cotton producers is the fear of spider mite populations increasing after TPB applications. Spider mites tend to appear in the same areas each year. Thus far a few north Alabama cotton fields have been treated with bifenthrin to help slow spider mites. Serious spider mite problems will require more expensive chemistry and consultants hope disease will take out the spider mites before more costly chemicals are required.

Thursday, June 23, 2011

Tarnished Plant Bugs Reported in Central Alabama

Three fieldmen from central Alabama (Montgomery, Macon and Lee Coutnies) reported significant movement of adult tarnished plant bugs into cotton this week. Damage, in the form of pinhead square loss, was evident in all three locations. Square retention was below 70% in several fields. This square loss will likely become greater if controls are not applied since the plant bugs are relatively young and have several more days to do damage. Bidrin, Orthene (or generics), or Centric would provide the highest level of control. Pyrethroids would also provide an acceptable level of control. We need to set a high percent of early fruit in fields that have received moisture in the past few days.

Monday, June 13, 2011

Drought Conditions Continue

Despite a few scattered thunderstorms, the drought conditions continue to dominate the row crop situation in much of Alabama. We have cotton that ranges from about 13-15 nodes (planted mid April) to other fields lacking moisture for seed germination. The oldest cotton is about knee high with squares from nodes 6 through 13-15. At this point, potential plant bug damage does not appear to be high. Roadsides and field borders dried down before cotton was old enough to provide food and shade in most fields. Excessive heat during the past 30 days has likely reduced plant bug populations on wild hosts.

Thrips numbers have been low for several weeks following about 4 weeks of high pressure from late April to mid May. The most prominent insects of the past few weeks have been false chinch bugs and white margined burrower bugs.

Most fields are in the stage between being susceptible to thrips and being susceptible to plant bug injury.