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Sustainable control of Strawberry Powdery Mildew

Avice Hall: University of Hertfordshire

<div>The most serious disease of protected strawberries in the UK is strawberry powdery mildew caused by <em>Podospheara aphanis</em>. This disease can cause 20%- 80% yield loss, where 20% loss is worth £56.8 mp/a. At present the disease is controlled by spraying with fungicides up to 18 sprays a growing season).Most strawberries eaten in the UK are home grown but in addition to financial pressures, growers are under pressure to reduce fungicide sprays and residues. The aim of the work reported here was to devise an integrated control programme, to reduce the inoculum and achieve control with reduced use of fungicides. The programme operates throughout the growing season. Chasmothecia of <em>P.aphanis</em> survive on plants and initiate infection in the spring on plants grown for more than one season<em>. P.aphanis</em> also comes onto farms on plants brought in from propagators. Both inoculum sources are reduced by an early season fungicide spray. Regular use of a silicon nutrient once or twice a week in the fertigation tubes throughout the season reduces susceptibility to strawberry powdery mildew. The temperature and humidity necessary for <em>P.aphanis</em> germination, growth and spore production have been used to design a web based, real time, rule based prediction system which accumulates the hours of disease conducive conditions. All these measures used in an integrated management programme give good disease control with five fewer fungicide sprays a season.</div>