2018 ASHS Annual Conference

Codling Moth (Cydia pomonella) is a serious pest of apple throughout the world and has been found wherever apples are grown. Control is generally achieved by setting out pheromone traps at first bloom, then tracking degree days after first catch. Pesticide sprays are applied around 250-300 degree-days. In Utah, setting a codling moth biofix from pheromone traps has become problematic due to inconsistent spring weather conditions, and higher use of mating disruption. In addition, an online decision-aid tool (Utah TRAPs) which includes 91 locations is offered to growers. Currently the biofix dates for each location must all be entered manually; automating this system would save time and resources.

Research by Jones et al. (2013) found that site-specific codling moth emergence (in degree days) is predictable using a formula based on latitude alone, or in combination with elevation for sites > 400 m in elevation. The study hypothesized that errors in setting the biofix with the formula timing were low, as it represented only a small percentage of the degree-day accumulations needed for predicting subsequent flight and egg hatch. This project objective is to introduce the “formula biofix” to Utah apple growers by demonstrating a low error rate in predicting codling moth phenology between the formula- and trap catch-based methods.

Through season-long trapping and determination of first larval entry into fruit for 1st and 2nd generations, we found that predictions for egg hatch and subsequent moth flight using the two biofix options varied by 0 to 3 days in 2016, and by 1 to 7 days in 2017. Our target was a variance of ≤ 5 days. The formula-based biofix (with a March 1 start date) meets our goal for most locations in most years, and performs as well as the trap-catch biofix.

The final phase of the project will be to continue with grower outreach, and in gauging grower confidence in switching to the formula biofix option.

Jones, V. P., R. Hilton, J. F. Brunner, W. J. Bentley, D. G. Alston, B. Barrett, R. A. Van Steenwyk, L. A. Hull, J. F. Walgenbach, W. W. Coates, and T. J. Smith. 2013. Predicting the emergence of the codling moth, Cydia pomonella (Lepidoptera: Tortricidae), on a degree-day scale in North America. Pest Management Science DOI 10.1002/ps.3519 (www.wileyonlinelibrary.com)