foliage may droop, curl lengthwise, wilt, and begin to fall. Leaves drop from the tree in the middle of summer, however less susceptible trees may retain leaves longer and resemble seasonal autumn foliage. Highly susceptible species will exhibit rapid crown dieback, while less susceptible species may only lose a few scattered branches. Live oaks may survive several years with progressive dieback, but often die within six months. Following defoliation, fungal fruiting bodies develop from mycelium under the bark of the tree. The mats grow to 10 – 20 cm in size, elliptical in shape, and grey in color with white margins that darken with age. These mats are not found on live oaks and rarely on white oaks. Trees capable of producing mats are called potential spore-producing trees (PSPT). Brown streaks in the sapwood is also observed in the oak wilt disease. However, this symptom is not always associated with the disease. The oak wilt fungus can spread from diseased trees to healthy trees in several ways. The disease can spread long distances (overland) by airborne spores in open wounds caused by wind damage, pruning, or other mechanical damage. Alternatively, under ideal conditions (temperature, moisture content, wood pH) spore mats form under the bark of the dead tree. Spore mats develop in the spring or fall for 2–3 weeks. The center of spore mats produce chains of barrel shaped spores, called endoconidia. Conidia are asexual spores dispersed by air, rain, and insects. If compatible mating types are present, these mats will also produce sexual spores called ascospores in fruiting structures called perithecia. Ascospores are spread by water and insects. These spore mats (or pressure pads) increase in size, eventually breaking through the bark and releasing a fruity odor that attracts wildlife, including sap beetles, bark beetles, other insects, birds and animals, such as squirrels. Insect vectors transmit the disease in spring to early summer in the Mid-West and late Winter in Texas. Insect transmission is the primary way new infection foci originate. The fungus can spread short distances through naturally occurring root grafts. Root grafts form when two or more underground roots merge from adjacent trees. Typically, roots from the same, or similar species, can form root grafts as their cambia are pressed together and combine. Fungal spores in the xylem travel to nearby trees through these root grafts and can rapidly kill many trees simultaneously. This transmission method accounts