Epidemiology of colletotrichum acutatum, cause of anthracnose on highbush blueberry, in British Columbia

Blueberry anthracnose reduces yield and post-harvest quality of blueberries in British Columbia. Isolates recovered from diseased fruit during 2002-2004 were identified as Colletotrichum acutatum using colony morphology, growth rate, and PCR. Leaf-wetness and temperature data indicated that plants exposed to prevailing environmental field conditions and natural inoculum in 2001-2003 required 10 hr of leaf wetness at 1 1•‹C for successful fruit infection. Three peaks of infection occurred; at blossoming, mature green berry stage, and ripening. Artificially inoculated plants in 2004 were found to be susceptible throughout the season, indicating that inoculum availability and weather conditions primarily affected disease. The pathogen overwintered mostly in flower buds and infection in May-July of the preceding season resulted in the greatest inoculum recovery. Two fungal biocontrol agents, Gliocladium catenulatum and Trichoderma harzianum, reduced anthracnose by up to 45% when applied thrice in 2003- 2004. Infection requirements and related epidemiological data support effective management of this disease.