ANNOSUS ROOT AND BUTT ROT
Fomes annosus fruiting bodies on stump.
Annosus root and butt rot is caused by the fungus Fomes annosus. This pathogen is common throughout coniferous stands of the North Temperate Zone. Hardwoods may be attacked, but damage is usually of minor consequence. In the South, the disease is most serious in pine plantations on sandy soils with low organic matter. All species of southern pine are susceptible. Slash and loblolly plantations are often severely affected.
The disease gains entry into plantations by spore infection of freshly cut stumps during thinnings. The fungus then spreads from the infected stumps to residual trees by growth along the roots to points of root contact. Residual trees usually begin to die within a few years after thinning. The sporophores or fruiting bodies are generally found at ground line or in the root crotch. Pines in initial stages of the disease usually exhibit sparsely foliated crowns; however, white pine with full crown may have extensive butt and root decay. Occasionally trees may die rapidly with a sudden red discoloration of a nearly full crown. Diseased trees are often found in groups or circular pockets in the stand. The indication of F. annosus decay may include the pink to violet stain of incipient decay, the narrow elongated white pockets and scattered black flecks in the wood of the early decay stages, and the yellow stringy rot of the late stages of decay.
Infection center in pulpwood size pine stand.
Control includes avoidance of planting on soils of low organic matter and elimination of thinning. Stump infection following thinning or harvest may be prevented using various methods.
BROWN CUBICAL BUTT ROT
Polyporus schweinitzii is a common cause of root and butt rot of conifers throughout North America. The primary hosts of the fungus are Douglas fir, spruce, and pine. All southern pines are susceptible to attack by P. schweinitzii. Common names of the rot are: red-brown butt rot and brown cubical butt rot.