Eastern and western gall rusts

From Bugwoodwiki

U.S. Department of Agriculture, Forest Service. 1979. A guide to common insects and diseases of forest trees in the northeastern United States. Northeast. Area State and Private Forestry, Forest Insect and Disease Management., Broomall, PA. p. 123, illus.(USDA Forest Service, Northeast Area State and Private Forestry Publication. NA-FR-4)

Eastern gall rust (Cronartium quercuum) and western gall rust (Endocronartium harknessii) are fungi that cause the formation of round galls on the branches and stems of hard pines. Eastern gall rust requires oak as an alternate host, while western gall rust requires no alternate host. The diseases commonly attack jack, Scots, and shortleaf pines in the northeastern United States.

Eastern gall rust is found throughout the eastern United States.Western gall rust is found in both western and eastern United States. The only certain way to distinguish eastern from western gall rust is through laboratory culturing. These gall rusts are important primarily in the Lake States. The diseases can kill small trees and losses may be severe in nurseries, young forest stands, and Christmas tree plantations. In older stands, trees with trunk infections may develop decay and can be broken off easily by wind.

Infection on pines begins in the current year's shoot. A year later, a round swelling develops at the point of infection; it enlarges annually, and may eventually attain a diameter of 6 inches or larger. In the spring about 4 years after infection, the surface of the gall cracks, revealing large blister-like structures. Orange aeciospores are released from the gall for several years.

Infections on oak leaves (eastern gall rust) begin as dark brown spots. Uredia and later telia eventually develop on the undersides of the leaves. Telia mature by early or mid-summer.