The Pecan Nut Casebearer (Acrobasis nuxvorella) is an important pest on pecan trees. Overwintered Pecan Nut Casebearer eggs typically hatch in spring when they can be targeted by traps or insecticide treatments. The Pecan Nut Casebearer Growing Degree Day Model, developed by researchers at Oklahoma State University, and available on the Pest Prophet app, is a tool growers can use to predict egg hatching.

Initiating the Biofix

To properly use the model, the biofix must first be set. This is the date that will serve as the starting point for growing degree day accumulation. For this type of model, once 50% budbreak is observed, the biofix should be set to 10 days before this date. March 1st may be used, alternatively, but using budbreak will improve accuracy of the model.

Growing Degree Day Accumulation and Treatment

After the biofix is set, growing degree day accumulation can begin, using a lower threshold of 38F. This can be done using daily high and low temperatures, or using hourly temperature data using the Pest Prophet app. Larvae emergence, pupation, adult emergence, egg laying, egg hath and nut casing entry can all be tracked using the model. Nut clusters should first be inspect at 1740 GDD(F) after the biofix date, which coincides with peak adult moth emergence.

Source:

Harris, M. K., J. A.Jackman, and D. R.Ring. 1988. Sound management vital to minimize impact of pecan nut casebearer. Pecan South. 22: 4–6.