CONTROL OF POSTHARVEST FRUIT ROT OF STRAWBERRIES BY FIELD SPRAYS

Abstract

The fungi causing postharvest fruit rot in strawberries vary with the weather during flowering and picking, with the cultivar and, increasingly, with the development of resistant strains. Consistent control is thus not possible with field sprays of the available fungicides. Carbendazim gave the best control of Botrytis. Captan and benomyl tended to be second best. All fungicides tested except thiabendazole, the least effective, gave almost comparable control. Captan reduced rot due to Rhizopus by 50% or more in 1970 and 1971, but was not effective in 1975. Captan gave the best control of Penicillium and was the only fungicide that controlled Alternaria. In general, considering all years of this trial, captan tended to be best for total postharvest rot control. Penicillium caused more than 50% of the postharvest rot in two picks in 1969 but only 4% in 1970 and less than 1% from 1971 to 1975. The cv. British Sovereign was more susceptible to Penicillium than cv. Agassiz. Rhizopus, which increased with high temperatures, was practically absent in 1969, 1972, 1973 and 1974, but was a major contributor of rot in 1970, 1971 and 1975. Powdery mildew was low most years but accounted for 25% of the rot in 1974.