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Abstract
Morphology, cultural characteristics, and pathogenicity of
Rhizosphaera kalkhoffii from spruce (
Picea spp.) showing premature needle loss in northern Minnesota and Wisconsin were investigated. Pycnidiospores from needles, conidia of the
Hormonema-like synanamorph, and pycnidiospores produced in culture were similar for Colorado blue, Engelmann, Norway, and white spruce collections and isolates. Pycnidiospores from black spruce needles were smaller than those from Colorado blue or white spruce (P < 0.05). colony diameters at 14 days were similar on four different spruce needle extract agars for isolates from colorado blue, engelmann, and white spruce. growth profiles of the fungus from colorado blue, engelmann, and white spruce on three agar media at five temperatures, and in three liquid media at three temperatures, were also similar to each other, with optimum growth occurring at either 20 or 25 c. needle cast symptoms and
R. kalkhoffii pycnidia developed within 12 mo on black, Colorado blue, Norway, and white spruce after inoculation with pycnidiospores of an isolate of the fungus from either Colorado blue or white spruce.
Citation
Juzwik, Jennifer. 1993. Morphology, cultural characteristics, and pathogenicity of
Rhizosphaera kalkhoffii on
Picea spp. in northern Minnesota and Wisconsin. Plant Disease 77(6):630-634
