Another disease of oaks, Ceratocystis fagacaerum, or oak wilt, causes mortality in patches of oaks, and especially red oaks, and was recently described as a potential threat to southern and western oak forests (Wilson 2001). The disease moves slowly from year to year through root-to-root transmission from and to oak, chestnut, chinkapin, and tanoak. The spread of the disease is greatly accelerated by the harvest and transport of oak firewood and by pruning of oaks in urban areas that increases susceptibility to insect transmission. The disease is reported to be endemic across Texas and much of the Midwest and Northeast, and is at epidemic levels in central Texas (Figure 76), where damage through 2000 is conservatively estimated at $102 million. Though not yet known to have reached the southern coastal states other than Texas, the potential for spread into these areas is high. As of FY 2000, only 4.6 percent of USFS Cooperative Pest Suppression Funds were dedicated to oak wilt (Wilson 2001).

Figure 76
Distribution of Oak Wilt Incidence by County in the United States
as of December 1999.

Source: Wilson 2001