Oak Leaf Roller And Springtime Defoliation Of Live Oak Trees in Austin, TX

LIFE CYCLE

The adult moth of the Oak Leaf Roller is about 1/2 inch long, with wings that have brown and dark brown markings. This species undergoes one generation per year. In May the moths lay their eggs on twig tips and leaf buds, and the eggs remain there for about ten months and begin to hatch in mid March. Once they hatch, the caterpillars feed on tender new spring growth of the trees from Mid-March until late April. They are creamy white to greenish and have a dark black or brown head. Trees that are heavily infested will be defoliated by mid to late April, when the fully grown worms form the pupae stage on the tips of twigs, and on other adjacent plants. At about the first of May, moths begin to emerge from their cocoon and begin laying eggs on the twigs of Live Oaks, Hackberry, Pecan and Walnut trees. These eggs will remain dormant until the following March, thus completing the cycle.

CONTROL

In residential situations trees may need protection from caterpillar outbreaks. Valuable landscape trees with a history of leaf roller infestation should be watched carefully from Late March to mid April. If heavy leaf feeding damage is observed, the tree should be sprayed with either a carbaryl product, or an insecticide containing Bacillus thuringiensis var. kurstaki. To minimize stress and to restore tree vigor, Oaks or other trees that have been severely defoliated in the past should be fed with a balanced fertilizer and watered regularly. Choose a fertilizer that has equal parts of the three major elements and apply it at a rate of one pound of nitrogen (N) per diameter inch at waist height. This pesticide application is best left to a professional.