Fusiform Rust of Southern Yellow Pines

Pest Alert, USDA Forest Service, Forestry Bulletin, SA-FB/P 13 October 1979.

Fusiform rust is the single most damaging disease of pines in the southeastern United States. Caused by a fungus, Cronartium quercum (Berk.) Miyabe ex Shirai f. sp. fusiforme, which requires oaks to complete its life cycle, this disease is most destructive in planted pine stands.

Species Affected – Loblolly, slash, pitch, and pond pines are most susceptible to infection by the rust fungus. Water, willow, bluejack, blackjack, southern red, and turkey oaks are favored alternate hosts.

Symptoms – This disease is characterized by tapered, spindle-shaped swellings (galls) on the branches or stem of the host tree. In the spring, when fruiting, these galls are bright orange. Commonly, old galls on the main stem develop into open-faced cankers.

Damage – On small stems, death is the usual result of this disease. On bigger stems, where cankers do not girdle the bole, structural weakening is the expected damage. Wind breakage often occurs at the galls. In all cases there will be degrade due to the galls. Heavily infected young stands may require replanting or complete regeneration.

Report Damage To:
USDA Forest Service, SA, S&PF
1720 Peachtree ST., NW, Room 710
Atlanta, Georgia 30367.

Multiple infections on a single tree. Bright orange color is spore mass of infectious fungus.

Branch cankers normally kill the branch on which they occur. Cankers which occur within 6" of the main stem eventually affect the stem.

Typical breakage of the main stem where canker has weakened the tree.

Loblolly pine top kill of seedling caused by fusiform rust gall on main stem.

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University of Georgia The Bugwood Network USDA Forest Service Georgia Forestry Commission

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