Experiments in 1952 for Control of the Citrus Red Mite

Abstract

In 1952 experiments for control of the citrus red mite (Paratetranychus citri [McG.]) were continued in a grove of Temple orange trees at Fort Pierce, Fla. The trees were arranged in 10 blocks with 9 treatments randomized in single-tree plots in each block. The trees had been used in 1949 and 1950 (Spencer and Norman, 1951) and in 1951 (Norman and Spencer, 1952) for earlier experiments. On February 9, 1952, all trees were sprayed by the owner 2 with a mixture containing 2/3 pound of 40-percent dinitro-ocyclohexylphenol (DN Dry Mix No. 1), 3 pounds each of zinc carbonate and manganese oxide, 10 pounds of wettable sulfur, and 16 pounds of urea (Nugreen) per 100 gallons. The dinitro-ocyclohexylphenol was for the control of the citrus red mite. At postbloom spray time, March 31, a mixture containing 2 pounds of basic copper sulfate, 1 pound of 15-percent wettable parathion, and 10 pounds of wettable sulfur per 100 gallons was applied by the owner to all the trees. On May 28 a prespray estimate of infestations was made. One unhatched egg or crawling stage was enough to classify a leaf as being infested. On this basis citrus red mite infestations of 20 percent or less require no control. Infestations on leaves and fruits ranged from 76 to 88 percent, but the differences between treatments were not significant, an indication that the 1951 treatments had no influence on the present infestation, and that the dinitro compound applied in February controlled the red mites only until mid-May. The parathion used in the March postbloom spray, together with the basic copper sulfate, may have had a great deal to do with the reappearance of the red mites in heavy infestation during May. Apparently, winter applications of the dinitro compound cannot be depended upon to control red mites through the year on trees that receive copper, zinc, manganese, and/or parathion in winter or in postbloom applications. A summer miticide should be added to the sulfur rust mite spray in June or July for year-around control.