Canadian Forest Service Publications
Assessment of endemic fungi as potential biological control agents of Rubus spectabilis in coastal British Columbia. 2003. Sumampong, G.; Shamoun, S.F.; Punja, Z.K. Canadian Journal of Plant Pathology 25(4): 436-437.
Issued by: Pacific Forestry Centre
Catalog ID: 23740
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Isolation of fungi pathogenic to Rubus spectabilis (Pursh.) (salmonberry), an invasive plant in forest regeneration sites, was initiated during August 2000. Naturally infected salmonberry foliage and stems showing disease symptoms such as necroses, shoot dieback, and stem blight were collected from Vancouver Island and coastal British Columbia locations. Diseased tissues were excised, surface sterilized, and cultured on malt extract or potato dextrose agar to obtain fungal isolates. For an in vitro pathogenicity test, detached salmonberry leaves were placed on moistened paper towels in germination trays and inoculated with mycelial plugs (1-cm diam.) taken from 7- to 10-day-old colonies. Inoculated leaves were covered with plastic wrap, incubated in a growth chamber (21 °C (day) : 18 °C (night) with a 12- h photoperiod), and assessed after 14 days. The experiment was repeated with four replicates per isolate, and control leaves were inoculated with sterile agar plugs. A visual assessment of leaf damage, using the area-addition method, showed that 76 out of the 281 isolates tested were pathogenic. Pathogenic fungi included species of Phomopsis, Botrytis, and Phoma. Three Phoma spp. were selected for further consideration as potential biological control agents based on their ability to induce >50% leaf-area damage after 14 days. Inoculation of intact plants was conducted under greenhouse conditions by spraying to runoff fungal mycelia grown in potato dextrose broth. Foliar and stem blight was observed as early as 3 days post inoculation, pro- 436 Can. J. Plant Pathol. Vol. 25, 2003 gressing to >50% and >75% of the total number of leaves infected after 7 and 14 days, respectively. The fungus was reisolated from diseased tissues.