Effects of boron on the“Ebi”disease of grape vines. (I)

Abstract

“Ebi”disease of grape vine is characterized by poor setting of berries, chlorotic condition of leaves and poor seed development in berries. Though this disease has been known on vineyards in Yamanashi Prefecture for many years, its causes have not been fully elucidated. Experiments were carried out in border to clarify the effect of boric acid sprays applied before blooming upon the own-rooted Kosyu sanjaku grapevines suffering from the“Ebi”disease.
The results were as follows;
1. Sprayings of 0.3% boric acid solution on the leaf, flower cluster, or both, a week and three weeks before blooming decreased abnomal flowers, improved setting of berries, and increased the average weight of fruit clusters more than double the untreated ones.
2. Germination of pollon grains was improved by the treatment.
3. Average number of seeds per berry and percentage of abnormal seed were increased by the treatment.
4. Development of vascular strands in peduncle (fruit stalk) was greatly promoted, but leaf mottling was not corrected, and growth of young canes had not been accelerated by the treatment.
5. In this experiment, significant correlation was not found between percentage of setting of berries and percentage of abnormal flowers, severity of leaf mottling, or length growth of young canes.
6. It seems that boric acid may be absorbed through the leaf surfaces and the flower cluster, and improved pollon activity, fertilization and meristematic activity of the flower stalks.