Forest Insect & Disease Management INCIDENCE OF CANKER ON SUGAR ON THE ARGONNE EXPERIMENTAL FOREST RHINELANDER, WISCONSIN, 1978 By Kathryn Robbins and Leon LaMadeleine Pathologists, St. Paul Field Office

INTRO DU CTI ON

The Argonne Experimental Forest near Rhinelander, Wisconsin, consists of 6,500 acres (2,600 hectares} of timberland, one-third of which is the northern hardwood type. USDA Forest Service personnel are conducting research at the forest in hardwood regeneration. Part of this research is evaluating the effectiveness of several cutting methods on the establish­ ment of sugar maple reproduction ( Marsh.} (Metzer and Tubbs 1971}. - Recently, numerous cankers, possibly due to Eutypella parasitica Davidson and Lorenz, have been noticed on sugar maple reproduction in one of the shelterwood-cut areas. Shelterwood cutting looks very promising for establishing sugar maple reproduction, but concern has developed that this method of regenerating may favor infection by~- parasitica. Eutypella cankers occur throughout the northern range of sugar maple from Minnesota to Maine (Kessler and Hadfield 1972}. Infection rates generally range from 2 to 28 percent of sugar maple stems in a stand (Kliejunas and Kuntz 1974}. The may infect young trees through small dead branches, branch stubs, sunscald, frost cracks, or logging wounds. The perennial canker caused by this fungus is usually found in the lower 12 feet of the stem, which is the most valuable portion of mature trees. Cankers may kill trees less than 3 inches in diameter, while cankers in older trees increase the risk of wind breakage and provide entrance points for decay fungi.

OBJECTIVE The objective of this survey was to determine whether there were significant differences in the incidence of Eutypella canker on sugar maple regenerated by different cutting methods.

July 1979 USDA FOREST SERVICE NORTHEASTERN AREA, STATE & PRIVATE FORESTRY BROOMALL, PENNSYLVANIA 19008