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Lesions may develop on secondary needles at any time, but they most commonly appear from May to October. Infected seedlings are seldom killed, but severe defoliation reduces vigor, which, in turn, may result in poor survival and growth following outplanting. It has also been reported on pines in plantations in nine additional States. Distributionīrown spot is found in nurseries in nine Southern States. The fungus also infects seedlings of slash, loblolly, and white pines in nurseries within or slightly beyond this area. Scirrhia acicola), is common on longleaf pine seedlings within the natural range of longleaf pine, that is, within the Coastal Plain from North Carolina to Texas. Hostsīrown spot needle blight, caused by the fungus Mycosphaerella dearnessii (syn. Photo by George Blakeslee, University of Florida. Brown Spot Needle Blight Longleaf pine seedling with advanced symptoms of brown spot needle blight. Prevention and control strategies for annosus root rot include stump treatment, timing of thinnings, prescribed burns, and the manipulation of planting density. Twelve inches (30 mm) or more of sand or sandy loam above a clay subsoil in a soil with good internal drainage is considered a high hazard site for tree mortality. Damage increases with the sand content of the soil. Mortality usually begins 2 to 3 years after thinning and often ceases 5 to 7 years later. The fungus grows through the remaining root system into nearby live trees via root grafts or contacts. BiologyĪnnosus root and butt rot probably enters the stand when fungal spores land on fresh cut stump surfaces. Infected roots exhibit resin or pitch-soaking, and stringy root decay. Trees in various stages of dying or death may suffer windthrow.

Damageĭamage from annosus root and butt rot may be scattered throughout a stand or in pockets of dead and dying pine trees called “infection centers.” Mortality is sometimes preceded by thinning and yellowing of the crown however, some trees simply turn red and die. In the southern United States, conks are most common from December through March. Conks, when fresh, are tan to brownish on the upper surface and white with tiny pores on the lower surface. IdentificationĬonks are often present in the litter at the base of dead or dying trees or tree stumps, or under root masses of windthrown trees.

All southern pines are susceptible, but loblolly and slash pine are most severely affected. Annosus Root Rot Courtesy USDA Forest Service, HostsĪnnosus root and butt rot is a commercially important disease of conifers.