Some Physiological Effects of Insecticides on Citrus Fruits and Leaves

Abstract

Studies were made to detn. the effects of certain insecticides, primarily petroleum oil, parathion, and DDT, on juice quality in freshly picked oranges and on dry matter in Valencia and navel orange leaves. A few tests were made on grapefruit juice. Oil sprays caused a significant reduction in the concn. of total soluble solids in the juice of oranges and grapefruits and, in the majority of tests, in the dry matter of navel and Valencia orange leaves. Parathion and DDT caused very little if any reduction in the concn. of total soluble solids in the juice of oranges. The effects of the insecticides on the total acids in the juice, and hence on the ratio of solids to acids, were variable, but in about 60% of the tests the acids were at least slightly higher in fruits sprayed with parathion or with DDT than in those sprayed with oil. The ascorbic acid content of the juice of the DDT-treated fruit was noticeably higher than that of the oil-sprayed fruit.