1956 Volume 25 Issue 1 Pages 35-48
1) Boron deficiency of grapevine (so called “Ebi” disease in Yamanashi Prefecture) has become epidemic recently in Yamanashi Prefecture. Many instances of the disease varying markedly in symptoms and severity were found in 1951. Then, details of symptoms, vine and edaphic con-ditions in relation to the occurence of the disease and controlling measures, were studied in the Horticultural Branch, Yamanashi Agricultural Experiment Station and on commercial vineyards from 1951 to 1954.
2) Typical symptoms of the disease were: (1) cap of resish brown color remaining on calyx at anthesis, (2) poor germinative power of pollens, (3) slight- or non-setting of berries, (4) setting of small seedless berries, (5) leaf mottling, and in severe case, leaf burn, short internodes, and die-back of canes.
Infestation of phylloxera and Rosellinia necatrix were frequently found on the roots of abnormal vines.
3) Results of the survey on the relation of soil moisture to the disease were not conclusive in
this study, but it was generally observed that the drought at the blooming period accelrated the incidence of the disease.
4) Large number of severely affected vineyards had been supplied with excess of lime or potassium or both without manure for several years.
5) Boron contents in the leaves decreased gradually from preblooming to post blooming time. In the deficient vines, it was low and a half as much as in the normal ones. It seemed that the critical level was 12_??_13 ppm on dry weight base in late July.
6) Calcium, potassium, and nitrogen contents in the abnormal leaves were generally lower than those in the normal ones. Ca:B ratio and K:B ratio in the abnormal leaves were two to three times as high as those in the normal ones.
7) Available boron content in the soils of de-ficient vineyards was about a half as low as that in the normal ones, and the critical level seemed to be 0.2_??_0.3 ppm.
8) There found no difference in pH value between the deficient and the normal vineyards.