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FS ShieldForest Health Protection, Southern Region

PITCH CANKER,

caused by Fusarium moniliforme var. subglutinans

Importance. - Pitch canker can damage many pine species, including all of the commercially important southern pines. In forest stands, only plantations of slash, and occasionally loblolly pine, are seriously affected. While mortality can result from abundant cankering, losses from growth suppression are more common.

Identifying the Fungus. - Pinkish fruiting bodies (sporodochia) containing fungus spores are produced on cankered shoots in the needle scars and on the outer surface of bark. Microscopic features of the sporebearing structures aid in identification.

Identifying the Injury. - Infected trees exhibit shoot dieback of the current year's growth, and abundant resin flow from the affected area. The wood beneath cankers is resin-soaked. The main terminal and upper laterals are most often affected.


Shoot dieback caused by pitch canker fungus

Shoot dieback caused by pitch canker fungus. (Click for detail. JPG 51K)


Resin soaked branch

Resin soaked branch. (Click for detail. JPG 51K)


Biology. - Fungus spores are airborne and spread in the summer during windy, wet periods. The spores infect wounds. The eastern pine weevil, which breeds in dying trees and feeds on the phloem of young branches, can transmit the disease. Spores are abundant in the litter beneath diseased stands, and fruiting bodies persist for months on diseased shoots.

Control. - No specific control procedures are available for pitch canker. Forest practices which maintain stand vigor-for example, thinning-may minimize disease hazard. Salvage harvesting of heavily.diseased stands is recommended. Genetic resistance to the disease exists and should be included in future pest management strategies.