The Balsam Twig Aphid (Mindarus abietinus) is an important pest on a variety of trees. Overwintered Balsam Twig Aphid eggs typically hatch in spring and the first adults may be seen soon after. There is typically many generations per year. Insecticide treatments targeting stem mothers are typically the best way to control Balsam Twig Aphid populations for the entire growing season. Balsam Twig Aphid 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. Eggs hatch at 60 GDD (F) after the Jan. 1st biofix. Stem mothers are present at approximately 100 GDD (F). These adults can be targeted for traps or insecticide treatment.

Source:

Fondren, K. and D.G. McCullough. 2002. Biology and management of balsam twig aphid. MSU Extension bulletin E-2813. 4 p.