The use of metalaxyl to control Phytophthora syringae rot of apple fruits

Abstract

SUMMARYIn an orchard in Kent, metalaxyl applied to the soil at 0.5 or 1.5 kg/ha on 20 July and to fruit as a 0.03 per cent spray on 3 September 1979 controlled rotting of Cox's Orange Pippin apples by Phytophthora syringae. There was also a residual effect of similar treatments applied in the previous year. Dipping fruits in 0.03 per cent metalaxyl controlled infections which had been developing on zoospore‐inoculated apples for five days at 10°C but not when the incubation period was longer. In post‐harvest dip treatments, the ability of metalaxyl at 0.01 per cent to control the spread of rotting by contact with apples inoculated with P. syringae was not affected if it was mixed with 0.05 per cent benomyl.