The effect of sprays on the fauna of apple trees I. The influence of winter wash, captan, and lime-sulphur on the interaction of populations of Panonychus ulmi . Blepharidopterus angulatus

Muir, R.C.

J Appl Ecol 2(1): 31-41

1965


Accession: 025763634

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Abstract
The influence of routine sprays of 0.1% dinitroortho-cresol + 3.0% petroleum oil, lime-sulphur and captan on populations of Panonychus ulmi and its principal predator, Belpharidopterus angulatus was studied in a 5 ac. orchard from 1953 to 1959. Peak numbers of Panonychus ulmi occurred in 1956 and 1958 followed by peak numbers of Belpharidopterus angulatus in 1957 and 1959 which drastically reduced the mite population. Populations of Panonychus ulmi were numerically inversely proportional to the numbers of Blepharidopterus angulatus which generally highest on plots treated with captan and lowest where winter wash plus lime-sulphur was used. It was concluded that under certain orchard management conditions a fluctuating equilibrium existed between populations of Panonychus ulmi and Blepharidopterus angulatus which could easily be disturbed by spray programmes which were only mildly toxic to the predator.