Effects of boron on the “Ebi” disease of grapevines. (II)

Abstract

Effects of soil application and foliage spray on grapevines suffering from “Ebi” disease (boron deficiency) were studied for three years. The results were as follows. 1. Experiment on Koshu-sanjaku variety (own-rooted, fourteen years old, sandy loam soil): Boric acid was applied at the rate of five pounds per tan (about 1/4 acre) and was mixed with the surface soil to the depth of 10 cm on March, 1952. The treatment improved setting of berries and increased average weight of cluster, and this effects were yet significant three or more years after the application. 2. Experiments on Delaware variety (vineyard A, own-rooted 30 years old, clay soil: vineyard B, own-rooted 12 years old, clay soil: vineyard C, own-rooted 20 years old, clay soil): Soil applications of boric acid at the rate of five and ten pounds per tan on March or April were effective to increase average weight of clusters for more than two years. Foliage sprays of 0.3 and 0.5%, boric acid were also increased the cluster weight and yields. 0.5% spray was more effective than 0.3% spray. 3. Experiments on Koshu variety (grafted, 35 years old): Effects of soil application at the rate of ten pounds per tan and foliage spray of 0.5 solution of boric acid were tested. Both treatments were effective to reduce the abnormal growth of the vines and to improve the setting of berries. 4. Boron content in the leaves of the treated Delaware and Koshu-sanjaku varieties was about two times as much as the untreated one. 5. Penetration rate of boron applied to the soil was determined by chemical analysis. Boron reached 60cm depth faster in the sandy soil than in the clay soil. The more the quantity of the boric acid applied, the more the available boron in the soil.