Position of Bud: Tip vs. Middle vs. 

 Base of a Shoot 



In 1989, 60 three-year-old Marshall Mcln- 

 tosh/M.26 were grouped into 10 blocks (replica- 

 tions) of six trees each. One bud in the tip, 

 middle, and base of one-year-old and two-year- 

 old portions of the central leader were marked 

 with paint in March. The marked buds on three 

 of the six trees in each replication were notched 

 three weeks before full bloom. Buds on the 

 remaining three trees were not notched and 

 served as controls. Growth measurements were 

 made after leaf drop in November. 



When buds were not notched, the most 

 shoots grew from those buds on the upper third 

 of one- or two-year-old growth, and very few 

 shoots developed from buds on the lower third 

 (Figure 4). Presumably, this relationship was 

 due to greater apical dominance imposed by the 

 shoot tip upon buds located on the lower portion 

 of a year's growth. If a bud was notched, it 

 appeared to make no difference where the bud 

 was located. Shoots grew equally well from 



notched buds at the tip, middle, or base of a 

 year's growth. 



Wood Age 



The trees used in the previous experiment 

 were used to determine the effect of wood age on 

 the response to notching. The percent of notched 

 buds that developed into shoots was not influ- 

 enced by wood age (Figure 5). Notching was 

 equally effective on both one- and two-year-old 

 wood; however, a word of caution is in order. 

 Because one-year-old shoots are relatively small 

 in diameter, they can be broken during the 

 notching process unless extreme care is exer- 

 cised. 



Bud Size 



In 1990, 80 four-year-old Marshall Mcln- 

 tosh/M.26 were selected and grouped into eight 

 blocks (replications) of 10 trees each. One bud 

 that was less than 4 mm in diameter, one that 

 was between 4 and 5 mm, and one that was over 

 5 mm in diameter were selected in March on the 



two-year-old portion 

 of the central leader. 

 Buds on five trees per 

 replication were 

 notched on April 20. 

 Buds on the remain- 

 ing five trees were not 

 notched and served as 

 controls. Growth 

 measurements were 

 taken as described 

 previously. 



Size is an indica- 

 tion of bud vigor and 

 potential for vegeta- 

 tive growth. In this 

 experiment, small 

 buds that were not 

 notched did not pro- 

 duce shoots. Some 

 medium sized buds 

 produced shoots, and 

 large buds generated 

 the largest number of 

 shoots (Figure 6). 



12 



Fruit Notes, Winter, 1992 



