The influence of the substrate on strawberry disease and pest resistance was assessed in 2003 when plants of strawberry cv. Alsanta were grown in parallel amended with a mineral fertiliser and in a mix of peat and compost, produced by a controlled microbial process. Disease incidence of Botrytis cinerea was strongly suppressed in the organic fruits (9,4% of diseased fruits versus 35,6% in the current culture). Powdery mildew (Sphaerotheca maculans) damages were enormously higher in the conventional than in the organic culture. Also, under a natural infestation with spider mites (tetranychus urticae) and strawberry aphids (Chaetosiphon fragefolii), the density of both pests became an epidemic on the conventionally grown plants whereas in the neighbouring compost culture their number was negligible. Resistance builds up in the organic plants seemed to be persistent during the whole four-month period of the experiment.
Influence of a composted nutritional substrate on diseases and pests in strawberry