The Zimmerman Pine Moth (Dioryctria zimmermani) is an important pest on pine. Overwintered Zimmerman Pine Moth larvae typically emerge in spring and the first adults may be seen soon after. There can be 2 generations in a year, depending on the weather. Insecticide treatments targeting 1st or 2nd generation larvae are typically the best way to control Zimmerman Pine Moth populations for the entire growing season. Zimmerman Pine Moth Growing Degree Day Model, developed by researchers at Michigan State University, and available on the Pest Prophet app, is a tool growers can use to predict egg hatch based on 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 50F. This can be done using daily high and low temperatures, or using hourly temperature data using the Pest Prophet app. Larvae typically emerge at 25 GDD (F) after the Jan. 1st biofix. These larvae can be targeted for insecticide treatment. Adults emerge at approximately 1675 GDD(F) following larvae emergence.

Source:

Eliason, E.A. and D.G. McCullough. 1997. Survival and fecundity of three insects reared on four varieties of Scotch pine Christmas trees. Journal of Economic Entomology 90:1598-1608.