Control of the Fruit Tree Leaf Roller with Lubricating Oil Emulsion

Abstract

From 1922 to 1924, the Fruit Tree Leaf Roller, Archips argyrospila, increased in abundance in the western Illinois orchards, and for the first time became a serious pest of apples in this section. In 1924, this insect destroyed up to 50% of the entire crop in some of the largest orchards. During the winter of 1924-25, experimental work was carried on to test the effect of different oils and oil emulsions on the eggs of this insect. The result of these experiments showed a very high kill of eggs by the use of 8% boiled lubricating oil emulsion, and by some of the commercial oils. Some of the largest orchards were sprayed with this strength of oil emulsion during the dormant period, and a nearly complete clean-up of leaf roller obtained. The damage was reduced in 1925 to a point where only 2% or less of the apples showed feeding by the leaf roller larvae. The eggs of the leaf roller were fully as abundant in these orchards in the winter of 1924-25, as was the case in the winter of 1923-24. Data on the hatch of eggs from untreated check plots showed a very high per cent of hatch. No bad effects from spraying with the percentage of lubricating oil emulsion was noted during the summer of 1925, and trees thus sprayed bore heavy crops of fruit during this season.