Susceptibility of silver birch pruning wounds to infection by white-rot fungus (Chondrostereum purpureum), a potential bioherbicide

Abstract

We artificially inoculated pruning wounds of silver birch (Betula pendula Roth) to study seasonal variation in their vulnerability to infection by the fungal decomposer Chondrostereum purpureum (Pers. ex Fr.) Pouzar. This information is critical to the assessment of incidental infection risks in areas where C. purpureum may be used as a bioherbicide. On seven monthly occasions between April and October 2005, 30 birch trees were pruned to yield a total of 210 experimental trees. On each occasion, 10 trees were inoculated immediately with C. purpureum mycelium, 10 were inoculated with blank inoculum and 10 were only pruned. In the summer of 2007, a survey of 129 experimental trees showed that pruning wounds were most susceptible to infection during May. Treatment with C. purpureum at other times during the growing season also increased the extent of discoloration or decay but the effect was considerably less.

A PCR-Based Method for the Rapid Detection ofChondrostereum purpureumin Apple

“…Furthermore, to observe wood necrotic symptoms the plant has to be destroyed. In addition, wood staining is not always caused by C. purpureum and it may also be produced by defense mechanisms of the plant or other pathogens (Vartiamäki et al 2009). Isolation and incubation is the traditional diagnosis method for wood pathogens.…”

“…Pouzar is an important wound pathogen that causes silverleaf disease in more than 230 woody species, including major fruit crops such as peach, plum, cherry, blueberry, apple, and also ornamental and forest crops (Bus et al 1996;Ogawa et al 2000;Setliff 2002;Spiers and Brewster 1997;Spiers and Hopcroft 1988). This basidiomycete fungus disseminates through airborne spores from different inoculum sources such as infected fruit orchards, windblown trees, logged areas, woodpiles, and pruned branches (De Jong et al 1990;Vartiamäki et al 2009), reaches wounded wood, like grafts and pruning cuts, and causes infection. Basidiospores germinate and mate with compatible hyphae forming heterokaryotic mycelia that grow deeper into the wood, producing the enzyme that causes the disease foliar symptoms.…”

Role and function of Chondrostereum purpureum in biocontrol of trees

“…Considering the biocontrol use of C. purpureum, the first problem might be the infection of nontarget trees due to the increased production of basidiospores. This possibility was studied in North America by Wall (1991) and in Europe by de Jong et al (1990a, b) and Vartiamäki et al (2009b). All these studies suggested that the risk is small, and even the assumption of considerably increased spore load compared to natural levels may be incorrect (de Jong et al 1996).…”

Short communication. A review on the efficacy tests and risk analyses conducted on Chondrostereum purpureum, a potential biocontrol agent, in Finland

“…Vartiamäki et al (2009b) tested this risk by pruning and inoculating birches in one month intervals from spring to autumn, and showed that pruning causes highest risk for C. purpureum infection in early spring. However, the infection in neighboring trees in control plots was very low throughout the experiment.…”