Comparative Effects of Oil Spray and Hydrocyanic Acid Fumigation on the Composition of Orange Fruits1

Abstract

The spraying of citrus trees with light-medium oils in concs. of l/4-13/4% caused a reduction in the total soluble solids and in reducing and total sugars of the fruit juice. Oil sprays with and without the toxicants were equally effective in reducing the soluble constituents in the fruit. Although oil spray tends to reduce the titratable acidity, the results were not so decisive as in the case of the soluble constituents. Since orange juice is highly buffered, the small change in titratable acidity of the juice was not sufficient to produce an effective change in pH of the mature fruit. Only slight differences occurred in the composition of the juice of fruits from plots that had been sprayed with 3/4-13/4% oil. The data show that although the groves of these expts. were widely separated and differed greatly as to environmental conditions and soil types, the change effected by the spray in chem. composition of the fruit was practically the same. The time of the year at which the oil was applied was found to be relatively unimportant. The fumigation of citrus trees with HCN either in the fall or in the winter had no marked effect on the chem. composition of the mature fruit.