Canadian Forest Service Publications
Evaluation of potential biocontrol agents for Rubus spp. in reforestation areas. 1995. Oleskevich, C.; Shamoun, S.F.; Punja, Z.K. Canadian Journal of Plant Pathology 17(4): 361.
Issued by: Pacific Forestry Centre
Catalog ID: 4258
Rubus spp., including Rubus spectabilis, R. parviflorus, and R. idaeus, become rapidly established in recently harvested forest lands and often outcompete seedlings in reforestation efforts. Potential fungal biocontrol agents were isolated from diseased Rubus leaves collected in coastal British Columbia during the summer of 1993. Several virulent candidate organisms, including a Phomopsis sp., Colletotrichum dematium, and Fusarium avenaceum, have been selected from preliminary pathogenicity tests. Initial tests with Phomopsis sp. on detached Rubus leaves have shown that inoculum consisting of conidia (107 spores/mL) suspended in 15% canola oil caused more extensive foliar lesions than other formulations or mycelia alone. C. dematium and F. avenaceum also induced foliar lesions with a similar inoculum dose, although mycelia alone were shown to cause disease symptoms as well. Phomopsis sp. produced conidia on barley grains and in modified Richard's (V8) liquid medium at 108 spores/g and 107 spores/mL respectively. Cell-free extracts from C. dematium and F. avenaceum, derived from sonication of colonized grain substrates, induced lesion formation within 48 h on detached leaves. The influence of cell-free extracts and of spore inoculum combined with surfactants, wounding, dew, and low doses of glyphosate on disease development in Rubus plants are currently under investigation.