Encoelia pruinosaonPopulus tremuloidesin Minnesota: occurrence, pathogenicity, and comparison with Colorado isolates

摘要

The occurrence ofEncoelia pruinosa(Ell. amp; Everh.) Torkelson amp; Eckblad in Minnesota and its pathogenicity on nativePopulus tremuloidesMichx. were investigated. Isolates from Minnesota were also compared with those from Colorado. The fungus appears to be widely distributed in Minnesota, where apothecia were collected from trembling aspen in eight counties. The optimum temperature for mycelial growth of all isolates was 22 deg;C. Minnesota isolates ofE.pruinosaproduced limited sooty-bark cankers on aspen from Minnesota in field inoculations within 2 years. Elongation of cankers in the 3rd year was observed only on the larger diameter inoculated trees. Colonization of recently cut aspen stem sections by Colorado and Minnesota isolates after 2 months was greatest for Colorado isolates. Sections of aspen from Colorado were more readily colonized byE.pruinosathan sections from aspen in Minnesota. It is hypothesized that Colorado isolates ofE.pruinosaare more virulent than Minnesota isolates and that Minnesota native aspen is more resistant to colonization byE.purinosathan Colorado native aspen.