MICROBIOLOGICAL QUALITY OF ORGANIC STRAWBERRY FRUIT

The effect of different irrigation methods, mulches and alternative preparations for grey mould control in organic strawberry production was investigated in Jokioinen, Mikkeli and Ruukki, Finland. In the irrigation trial, grey mould infection of fruit was studied from petals and receptacles from early to late flowering. Rainy periods during the flowering season could be seen in the Botrytis cinerea infection of flowers, but on fruit, dry harvest periods kept visible infection low. As a whole, microbial contamination of fruit was more affected by weather conditions than irrigation practice. Organic mulches of green mass, buckwheat husks, straw, birch woodchips, pine woodchips and flax fibre mat were compared with black plastic. Only green mass increased fungal infections on fruit and shortened shelf-life. Biological sprays Trichoderma (Binab^® TF-WP) and Gliocladium (Prestop), compost and garlic extracts as well as seaweed and silicon solution used for grey mould control did not affect fruit quality. In marketable fruit, fungi such as Cladosporium, Acremonium, Penicillium, Trichoderma, Fusarium, Mucor and Alternaria species were abundant while Hainesia lythri and Zythia fragariae (Gnomonia comari ) were uncommon. Infection of Escherichia coli in fruit was investigated on VRB plates, but E. coli was not detected in the fruit.