Armillaria melleaand Decline of Red Spruce

Abstract

found on dead and severely declining Carey, A. C., Miller, E. A., Geballe, G. T., Wargo, P. M., Smith, W. H., and Siccama, T. G. 1984. trees within a plot, it was not found on Armillaria mellea and decline of red spruce. Plant Disease 68: 794-795. mildly declining or healthy trees in the same plot. Therefore, at the two upperRoots of 288 red spruce trees (Picea rubens) in mixed hardwood, transitional, and montane boreal elevation transects, if A. me/lea was not forest in New England and New York were excavated and examined for colonization by Armillaria esention any of th r eldea or mellea. The fungus was associated with declining and dead spruce in all locations. The percentage of roots colonized by the fungus increased with increasing severity of decline symptoms but severely declining trees in a plot, no decreased with increasing elevation. In high-elevation boreal forests, where the decline has been mildly declining or healthy trees were documented to be most intense, 75% of the recently dead and severely declining trees were not excavated. colonized by A. mellea. Although A. mellea is involved in red spruce decline, it is not the major For trees that were excavated, all main cause of the current regional episode of spruce decline and mortality, lateral roots were uncovered to at least 1 m from the bole. After noting the presence of rhizomorphs of A. me/lea on root Red spruce (Picea rubens Sarg.), a York, and Vermont on the basis of surfaces, the roots and root collar were long-lived (300+ yr old), shade-tolerant previous documentation of decline of red debarked to detect mycelial fans. The forest tree (7), has declined in basal area spruce (9). Study sites in order of total number of roots number of roots and density within part of its native range sampling were Styles Peak, Peru, VT; with rhizomorphs, and number of roots in the northeastern United States Camel's Hump, Huntington, VT; Mt. with mycelial fansdwere recorded. (6,9,16). Decline intensity is positively Mansfield, Stowe, VT; Mt. Washington, Soil samples were collected from the correlated with elevation and is most Gorham, NH; Mt. Cushman-Hubbard forest floor and A2 horizon at each