Xylella fastidiosa

BACTERIAL LEAF SCORCH ON RED OAK

Description Leaves begin turning yellow at their margins and tips. The yellowing moves inward between the veins and a reddish-brown band occurs between the yellow and green areas. The outer areas turn brown and dry but do not drop off before autumn. Individual branches become affected and the disease spreads to other branches in the following growing seasons. This causes a slow decline and eventually the death of the tree.

Xylella fastidiosa is the bacterial pathogen the survives, travels through and reproduces in the xylem, reducing water transport and probably producing toxins. Xylem feeding insects such as leafhoppers and spittlebugs are believed to transmit the disease from tree to tree (Greenwood). Host Plants Red, pin and scarlet oaks are the shade trees mostly affected, though other oaks, red maples, sycamores, elms, and mulberries have been affected also. The bacterium is known to cause many other diseases in a wide variety of other hosts. Control Water stress plays an important role in this pathogen, causing the tree to suffer further in drought conditions. Avoid planting a new susceptible tree near a source of reflective heat.