Central Leader vs. Scaffold Branches Notching vs. No Notching 



In 1987, 14 Spurcort/M.7 trees were paired 

 into seven blocks (replications). One bud was 

 marked with white paint at the tip, another in 

 the middle, and another at the base of one-year- 

 old wood on the central leader. Buds were 

 selected and marked in the same way on each of 

 four scaffold branches on each tree . Three weeks 

 before full bloom all marked buds on one tree per 

 replication were notched. Marked buds on the 

 remaining tree in each replication were not 

 notched and served as the control. Growth 

 measurements were taken as described previ- 

 ously. 



The central leader is upright and generally 

 is the most vigorous portion of a tree. Scaffold 

 branches are frequently less vigorous because 

 they are positioned lower in the tree and they 

 originate on the central axis of a tree at an angle 

 of 45° or greater. Probably because of this 

 difference in vigor, un-notched buds of the cen- 

 tral leader tended to produce shoots more 

 readily than those of scaffold branches. Notch- 

 ing dramatically enhanced the shoot develop- 

 ment in both locations (Figure 7). 



100 



co 



a> 



o 



c 



CM 



AJ 



CO 



o 

 o 



Central leader 



Branch type 



Figure 7. The effects of notching on the central leader vs. scaffold 

 branches. Data represent the percent of marked buds. This 

 experiment was conducted in 1987 on Spurcort/M.7. 



The overall effectiveness of notching for 

 stimulating shoot growth from buds was as- 

 sessed by pooling data collected in several ex- 

 periments performed during four years. Only 

 data taken from notching done at the proper 

 time and on the appropriate buds were included. 



Notching increased the chance of a bud 

 growing into a lateral shoot by about 600% 

 (Figure 8). This success rate can realistically be 

 expected, since it was derived from information 

 collected over several years, on different types of 

 trees, on different cultivars, and under a wide 

 range of growing conditions. 



Conclusions 



We believe that notching is the most effec- 

 tive technique available to stimulate shoot de- 

 velopment on apple trees. The reasons for this 

 conclusion are as follows: 



1. It is rapid. A bud can be notched with a 

 hacksaw blade in less than five seconds. 



2. Buds can be stimulated to grow in areas 

 where they are wanted. 



3. Growth, fruit set, and 

 flower bud formation 

 are not adversely af- 

 fected on other por- 

 tions of the tree. 



4. Shoots that are 

 stimulated to grow 

 with notching fre- 

 quently are longer 

 than those induced 

 by other means. 



Shoots that develop 

 from notched buds fre- 

 quently have a sharper 

 crotch angle than shoots 

 that develop from buds 

 that were not notched. 

 Angles can be improved 

 by using clothes pins or 

 weights; however, unless 

 angles are much below 

 50° from vertical, this 

 detrimental aspect of 



Scaffold 



14 



Fruit Notes, Winter, 1992 



