Conservation Federation of Missouri!

White oak leaves damaged by jumping oak galls (Photo: S. Madison)

 Problem: Leaves on entire crowns of white oak trees turn brown in late Spring. In some cases, whole hillsides appear brown. Individual leaves turn brown starting at the margins, and sometimes curl up and turn black.
Tree Species: White oak (Quercus alba) primarily, and some other white oak group species.
Description: Leaves may be damaged by multiple causes, but the main cause in May 2010 appears to be high populations of a jumping oak gall wasp (Neuroterus sp.)  These very tiny, stingless wasps cause pinhead-size galls (abnormal plant growths) to form on the undersides of leaves. Each round, button-like gall contains one wasp larva. Most galls drop from leaves in early summer. Brown pockmarks remain where galls had been attached. Brown, scorch-like areas appear on leaves where many galls are present. In more severe cases, leaves turn black, curl up and drop early from trees.