The current weather pattern (intense precipitation followed by hot dry days) is ideal for caterpillars. Caterpillar pressure continues to rise in peanuts – the average numbers have increased from 0.3 to 1 per foot of row. This is still below the economic threshold but the situation may change in the next two weeks.
A high population of velvetbean moths and caterpillars were observed in Headland along with a low population of soybean loopers in irrigated peanuts. Corn earworm activity also continues to rise – CEW moths are about 10x more active than tobacco budworms. Budworms have been detected at 40 to 50 percent locations with highest moth catches/activity recorded in Cullman and Lee counties.
Finally, watch for soybean loopers – they are on the move in south and western Alabama – moth activity has quadrupled in the past two weeks.
Caterpillar control is relatively easy in peanuts with a wide range of nonselective and selective materials available to producers. While synthetic pyrethroid insecticides can be very cheap and readily available in the form of generic formulations, I want to remind producers about some new insecticides that have better residual and less nontarget effects.
The new chemistries include insect growth regulators (novaluron = Diamond, IRAC Group 15), spinetoram (Radiant, IRAC Group 5), flubendiamide (Belt) and chlorantraniliprole (Prevathon, IRAC Group 28). Formulations containing Bacillus thuringiensis (Bt – Javelin, Xentari) are also effective and can be tank-mixed with other chemicals – but it requires more patience and some additional sprays due to short residual.
Incorporation of selective insecticides (e.g., flubendiamide, Bt) can be cost-effective in the long-run and also help conserve beneficial insect populations in the field.
Economic threshold for caterpillars = Four or more caterpillars per foot of row
Although threecornered alfalfa hoppers (TCAH, in picture) have not flared up in our research plots, there have been several reports of outbreaks from producer fields (lush green foliage in irrigated fields attracts TCAH). Damage to peanut leaf terminals is not as threatening as damage to the pegging branches which may cause yield loss. Don’t let the nymph and adult TCAH move into the peanut canopy and stop them from getting close to the plant base.
Choice of insecticides for TCAH control is narrower than caterpillar control, but this is not a hard insect to kill using synthetic pyrethroids like beta-cyfluthrin (Baythroid), lamda-cyhalothrin (Karate, Silencer), and bifenthrin (Brigade). I recommend one good application of any pyrethroid insecticide followed by repeat scouting – spray twice only if necessary to avoid spider mite outbreak in hot weather.
Beseige, an insecticide premix with lambda-cyhalothrin and chlorantraniliprole, can also be effective at the 6 oz or higher rate with broad-spectrum control of TCAH and caterpillars.
Economic threshold for TCAH = One adult per three foot of row 75 days to digging
Keep looking for burrower bugs directly in the peanut canopy (there are no pheromone traps for monitoring this pest).
Refer to the Alabama Peanut IPM publications for detailed scouting and pest management instructions.
For more details about insect pest control options, download the Alabama Peanut IPM Guide here.