Chondrostereum purpureum as a biological control agent in forest vegetation management. III. Infection survey of a national field trial

A nationally coordinated field trial was established in the summer of 1995 to assess the utility of Chondrostereum purpureum (Pers. ex Fr.) Pouzar as a biocontrol agent for several weedy deciduous species. In this study, C. p urpureum infection of cut stumps was surveyed 4 months following applicatio ns of the biocontrol agent in New Brunswick and Ontario field trials. The u se of diagnostic molecular genetic markers to detect and identify C. purpur eum was compared with morphological identification methods. Samples of trem bling aspen (Populus tremuloides Michx.) and red maple (Acer rubrum L.) fro m the New Brunswick trials confirmed infection with the biocontrol isolates of C. purpureum, and no cross contamination of treatment applications was detected. Analyses of recovered fungal samples from aspen and speckled alde r (Alnus rugosa (Du Roi) Spreng.) in Ontario also confirmed the success of biocontrol infection. The percentage of C. purpureum infected stumps differ ed between hosts in the Ontario trials. An average of 84% of speckled alder stems and 54% of aspen stems were estimated to have been infected by the a pplied isolates of C. purpureum. Given a sufficient number of samples, this methodology can provide an early indication of successful stump infection by C. purpureum, a prerequisite for effective weed biocontrol.