The Effect of Compost Extract on the Yield of Strawberries and the Severity ofBotrytis cinerea

The effect of compost extracts on strawberry yields and in the suppression of grey mould, Botrytis cinerea, in strawberries was studied over a period of two growing seasons on an organic, market garden farm in the southern interior of British Columbia. Composts were prepared both anaerobically and aerobically as well as at a 8:1 and 4:1 water to compost dilution in order to determine if preparation method and concentration changed any suppressive effect. Anaerobically prepared compost extract had little effect on strawberry yields yet reduced the severity (0.38 ± 0.16%) of Botrytis cinerea compared to water sprays (1.02 ± 0.36). Aerobically prepared extracts improved yields (1.70 ± 0.08 t/ha) over the control (1.36 ± 0.11 t/ha) and water spray (1.37 ± 0.09) treatments and also reduced disease severity. Dilute extract reduced the incidence of the disease to a greater extent than all other treatments.