The White Pine Aphid (Cinara strobi) is an important pest on a white pines, and a variety of other hosts. White Pine Aphid nymphs and adults from overwintered eggs typically emerge in spring when they can be targeted by traps or insecticide treatments. The White Pine Aphid Growing Degree Day Model, developed by researchers, and available on the Pest Prophet app, is a tool growers can use to predict nymph and adult emergence, as well as second generation adult emergence.

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 the biofix date should be set to March 1st for the Northern Hemisphere.

Growing Degree Day Accumulation and Treatment

After the biofix is set, growing degree day accumulation can begin, using a lower threshold of 50F. Calculating growing degree days can be done using daily high and low temperatures, or using hourly temperature data using the Pest Prophet app. Nymph emergence occurs between 7-121 GDD (F) and adult emergence occurs between 121-246 GDD(F). Second generation adults emerge between 1912-2271 GDD (F). These adults can be targeted for treatment.

Source:

Growing Degree Day Information. Nathan W. Siegert, Deborah G. McCullough and Jeffrey A. Andresen. Michigan State University, 2 October 2015. Web. 25 February 2016.

Using Growing Degree-Days for Insect Pest Management. Thomas Kowalsick and Scott Clark. Cornell Cooperative Extension in Suffolk County, March 2012. Web. 25 February 2016.