Lesser cornstalk borer (LCB) is one of the most damaging and difficult to control pests in peanut. This insect is very fresh on the minds of many growers after a season of widespread heavy infestations in 2014. LCB is a sporadic pest in much of GA, and while outbreak populations in back to back years would not be common, they are possible. Scouting is the only way to know for certain if LCB is present in a field. The presence of LCB moths is a very good indication of an active infestation and of continued pest pressure. We need to be diligent in our efforts to monitor fields for this and other pests, and we do not need to make blanket insecticide applications if no pests are present.
There have been numerous reports of LCB in peanut from several areas of the state in 2015. The single best management tactic for lessers is water. Lesser cornstalk borers thrive in hot, dry conditions, and they generally do very poorly in fields that receive adequate moisture. We do sometimes see LCB at damaging levels in irrigated fields, but that is not the norm. Helping growers decide what to do in the event that lesser cornstalk borers become established in a field is tricky at best. The only product currently recommended for controlling LCB in peanut is granular chlorpyrifos (Lorsban). Unfortunately, this material requires irrigation/rainfall to be activated, and it can flare secondary pests like two spotted spider mites. Additionally, the equipment needed to apply granular chlorpyrifos is often difficult or impossible to find.
The weather in the coming weeks will probably be the key factor in determining if 2015 will be a bad LCB year. For now, we should continue to monitor fields and make our management decisions based on accurate scouting information.
