May 18, 2021

A phenology model for pear psylla was recently developed by Dr. Vince Jones. This model predicts the relative number of pear psylla from each life stage occurring as degree days are accumulated. Below is a graph showing the psylla degree day model and the status of psylla development on May 6th 2021. Degree days were averaged among weather stations in Medford, OR, Hood River, OR, Wapato, WA and Cashmere, WA; the difference from the coolest to hottest location was approximately 110 DD.

Click the graph for the full article.