Association of Verticicladiellaprocera and Leptographiumterrebrantis with insects in the Lake States

Abstract

Verticicladiellaprocera Kendrick was isolated from damage associated with Dendroctonusvalens Lec, Hylobiusradicis Buch., Hylobiusrhizophagus M.B.W., Hylobiuspales (Herbst), and Pachylobiuspicivorus (Germ.) on pines in Minnesota, Wisconsin, and Michigan. The fungus was also isolated from surface-sterilized adult D. valens, H. radicis, H. pales, and P. picivorus. Leptographiumterrebrantis Barras and Perry was isolated from the galleries of D. valens on trees stressed by fire, flooding, windthrow, and tissue attacked by H. radicis or H. rhizophagus. Verticicladiellaprocera was not pathogenic on white pine seedlings whereas L. terrebrantis killed 70% of seedlings inoculated. Verticicladiellaprocera appears to be weakly pathogenic and is associated with primary (H. radicis and H. rhizophagus) and secondary (P. picivorus, D. valens, H. pales) forest insects in the north central United States. Leptographiumterrebrantis was more virulent than V. procera and was associated with a secondary bark beetle which commonly attacks stressed trees.