Last week, Ginger Grier and I started an insecticide drench timing for phylloxera. This is an insect pest that invades pecan trees at bud break. The insect is very small and must be treated before the distinguishing wart symptoms appear on the leaves. This site has stuggled with the control of phylloxera for a long time which makes it a valuable site to test.
One way to treat phylloxera is to include an insecticide with your first spray. However, the timing is difficult. Another route is to drench insecticide in the ground to be taken up by the tree. This can be done through irrigation, a sprayer tank, or mixing in a bucket.
We know the insecticide will translocate through the trees and be present in the stems at bud break; however, we do not know optimal timing of drench applications. In this study, we are applying imidacloprid as a soil drench in December, January, February and March. Thanks so Jake Ford and Keith Rucker who were very helpful getting us product on short notice. We will also test another insecticide that is waiting on label also for phylloxera.
UGA Extension Entomologist Dr. Will Hudson is attempting this study in Athens, so we will have information for both areas of the state. Phylloxera do not cause as much economical damage on the leaves as they do on the stems. Stem phylloxera is more of an issue if it is present. To see more on phylloxera, visit my post on Pecan Leaf Phylloxera.