Pathogenicity of Verticicladiella penicillata (Grosm.) Kendrick to Northern Idaho Conifers
Roots of Pinus contorta, P. ponderosa, Pseudotsuga menziesii, Larix occidentalis, and Abies grandis, ranging 5.8 to 30.5 cm dbh, were inoculated with Verticicladiella penicillata previously isolated from black stain in roots of P. ponderosa. Roots of all species became infected although the characteristic black stain was not observed in P. contorta and P. ponderosa and appeared infrequently in A. grandis. No trees were killed as a result of infection within the 160-day test period indicating weak pathogenicity under study conditions. Hyphae of V. penicillata were concentrated in tracheids of all species tested and moved from tracheid to tracheid via hyphal branching through bordered pit pairs. Occasional hyphal fragments were observed in ray parenchyma. There was resin occlusion of all xylem elements, particularly ray cells. No direct lysing of tracheid walls was found. Additional variation in the morphology of V. penicillata was found. Forest Sci. 27:103-110.
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