Density dynamics of Gliocladium roseum in relation to biological control of Botrytis cinerea in red raspberry

Abstract Density patterns of colony-forming units (CFU) of the biocontrol agent Gliocladium roseum were investigated in raspberry cv. Boyne and cv. Redwing after spore suspensions (107 conidia/mL) were applied 2 h before dusk in field plots. Estimated density of G. roseum on leaves of both cultivars was 2 x 103 to 5 x 103 CFU/cm2 at 1 h after inoculation. During the next 2 days density of the agent progressively decreased, but at 3–10 days after inoculation it fluctuated around 10–102 CFU/cm2 leaf in ‘Boyne’ and after or 3–12 days, it fluctuated near 103 CFU/cm2 leaf in ‘Redwing’. Density of G. roseum on flowers was 1 x 104 to 5 x 104 CFU/flower at 1 h after inoculation and declined rapidly in ‘Boyne’ and slowly in ‘Redwing’. At 3–10 and 3–12 days, respectively, the density fluctuated around 70 CFU/flower in ‘Boyne’ and 800–2300 CFU/flower in ‘Redwing’. Germination of G. roseum, observed on stamens of ‘Boyne’, was sparse (<4–10%) in the field. However, germination potential, estimated in stamens of flower...