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Show 42 Utah Academy of Sciences, Arts and Letters fate. In 1945 no records of severity of the disease symptoms of each tree for the previous year were available, but all trees treated were in the general area showing disease symptoms. During 1945 and 1946 observations were made on the trees at monthly inter vals. In these surveys each tree was rated according to the sever ity of the disease with "0" indicating an absence of disease symp toms, "1" a trace of leaf markings, and extending to a "5" which indicates severe necrosis and a breakdown of the leaves. A record of soil treatment and tree injections made in 1945 and ratings of disease symptoms of the treated trees are shown in Table 1. These data show that there was no definite recovery from the disease by trees given any of the soil treatments made in 1945. Trees injected with manganese sulfate showed marked recovery. Questionable indications of improvement from the copper sulfate treatments were noted, but the tree injected with iron phosphate was definitely worse. The treatments made in 1946 and the tree disease rating are presented in Table 2. As in 1945, there was definite improve ment in the trees treated with manganese and benefits were similar whether the treatments were made in the soil or by tree injections. It is anticipated that observations on the condition of treated trees during subsequent years will indicate whether it is preferable to treat affected fruit trees by mangenese treatments in the soil or by injection. The copper treatments in each case resulted in a slight decrease in disease symptoms. In no case, however, was there com plete recovery from copper treatment. Trees injected with iron. phosphate showed no benefit in one case and were worse in other instances. The leaves were obtained from several trees by picking about fifty per tree! selected from the fifth and sixth leaves up the branches from the terminal ends. Results of analyses of leaf samples obtained in 1945 are shown in Table 3. The data show that only the leaves from trees injected with manganese sulfate were appreciably different in composition from the leaves from untreated trees. Leaves from the manganese treated tree were rela tively higher in manganese, calcium, and iron than leaves from other trees. . Additional leaf samples were obtained in July of 1946 from apricot trees showing definite symptoms of the disease and from nearly normal trees. In each case soil samples were taken from under each tree sampled for leaves. Leaf samples were also ob tained from normal and diseased trees in a nearby peach orchard. The leaf samples were thoroughly washed, dried, ground, and analyzed. The soil samples were taken to the laboratory and analyzed for exchangeable and readily reducible manganese while still fresh and undried, according to the technique proposed by Sherman, McHargue, and Hodgkiss.' Results of these determina- |
