Lateral buds on grapevine canes are composite buds, each being comprised of a central bud and two to three additional axillary buds. In this study, the occurrence rates of necrotic buds were determined early in winter for the central and axillary ones, respectively, in the 1-year-old canes of 9 Japanese leading cultivars, and the relation between the rates and the shoot emerging from lateral buds was examined in the next spring.
1. Necrosis tended to occur in the central buds of lateral buds locating at relatively low position on canes. When the lateral buds at the limited position under the 12th node were compared, 'Campbell Early' showed the highest percentage of the necrotic central buds (58.3 %), followed by a group of 'Kyoho', 'Pione' and 'Steuben' (42.8-27.5 %), and further by 'Muscat Bailey A' (12.1 %). Other cultivars such as 'Super Hamburgh', 'Koshu', 'Neo Muscat' and 'Delaware' showed very low percentages (4.8-3.0%). Significant differences were detected among the percentages of these 4 groups.
2. In the axillary buds of the same limited position, 'Super Hamburgh' showed the highest necrotic percentage (15.0%), and the percentages of all other cultivars were lower than 5%. Thus, in general, the necrotic percentges in the axillary buds were extremely lower than those in the central ones.
3. As for shoot length, shoot thickness and bud size, significant differences were detected among some groups of the cultivars, but none of these parameters had significant relationship with the occurrence of necrosis in the central buds.
4. The rates of shoot emerging from lateral buds on fruitng canes were significantly different among some groups of the cultivars, and 'Delaware' showed the highest rate (93.5%) and 'Pione' did the lowest (60.5%).No significant relation, however, was detected between the shoot emerging and the occurrence of necrosis in the central buds. The probable reasons for it are estimated as follows ; 1. As mentioned above, the necrotic percentages in the axillary buds were extremely low even in the cultivars whose necrotic percentages in the central buds were high. 2. Some of the cultivars such as 'Neo Muscat' and 'Koshu' whose necrotic percentages in the central buds were very low，exhibited bad shoot emerging from the lateral buds locating at proximal position of frulting cane due to the phenomenon of strong apical dominance.