Early evaluation of orange peel blotches caused by spray oils

A simple quantitative test was developed to examine the tendency of spray oils to cause peel injuries to oranges. It was based on the correlation between the appearance of certain peel discolorations a short time after oil treatment, and subsequent oil blotches. In a trial carried out in a ‘Shamouti’ orange grove, fruitbearing branches were treated with various concentrations and compositions of spray oils. Spots which appeared on the immature fruits several days after application were found to give a fair forecast of the subsequent occurrence and intensity of oil blotches on the mature rind. This early spotting appeared spontaneously (aslight-colored spots) but could also be developed artificially by ethylene degreening (green spots).