The Peachtree Borer (Synanthedon exitiosa) is an important pest on a variety of trees. Overwintered Peachtree Borer larvae typically emerge in spring and the first adults may be seen soon after. The Peachtree Borer Growing Degree Day Model, developed by researchers, and available on the Pest Prophet app, is a tool growers can use to predict the onset and peak of adult trap catches using field-specific temperature data.

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 January 1st is the standard biofix to start accumulation (for the Northern Hemisphere). This can be used to predict when adults will emerge and pheromone traps can be used.

After adults are observed and confirmed, the biofix can be adjusted in order to improve accuracy of the model for predicting later life stages.

Growing Degree Day Accumulation and Treatment

After the biofix is set, growing degree day accumulation can begin, using a lower threshold of 10C and an upper threshold of 31C. This can be done using daily high and low temperatures, or using hourly temperature data using the Pest Prophet app. Adults typically emerge at 800 GDD (C) after the Jan. 1st biofix. These adults can be targeted for traps. Peak adult trap catch will occur at approximately 400 GDD(C) following first trap catch.

Source:

Johnson, D. T., and R. L. Mayes. 1983. Studies of larval development and adult flight of the peachtree borer, Synanthedon exitiosa (Say) in Arkansas. J. Georgia Entomol. Soc. 19: 216-223.