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Occurrence of metalaxyl‐resistant isolates of Pseudoperonospora cubensis in Israel: a 5‐year survey 1
Author(s) -
SAMOUCHA Y.,
COHEN Y.
Publication year - 1985
Publication title -
eppo bulletin
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.327
H-Index - 36
eISSN - 1365-2338
pISSN - 0250-8052
DOI - 10.1111/j.1365-2338.1985.tb00249.x
Subject(s) - metalaxyl , pseudoperonospora cubensis , downy mildew , fungicide , biology , horticulture
The occurrence of metalaxyl‐resistant isolates of Pseudoperonospora cubensis , the causal agent of downy mildew in cucurbits, was surveyed during 1980–1984 subsequent to their first appearance in December 1979. Metalaxyl use was abandoned in mid‐1981 and resistant isolates diminished in late 1981. Metalaxyl use was renewed in 1982 and a gradual increase in frequency of resistant (R) strains was detected. In 1983, 31 out of 40, and in 1984, 43 out of 47 isolates tested were highly resistant to the fungicide with 65 and 91% of them, respectively, collected from plastic houses or fields not treated with metalaxyl. The survey indicates a rapid build‐up of R strains of the fungus and the need for alternative chemicals for combating downy mildew in cucurbits.