14 



/ 



desired height but before growth begins, 

 effective if made after start of growth. 



The treatment is not 



Last summer, we compared the NAA tree training technique on 

 Marshall Mcintosh, Macoun, and Redspur Delicious with removal of 

 buds 2, 3, and 4 immediately after planting (disbudding) or removal 

 of shoots competing with the central leader in mid-June. The 

 Marshall Mcintosh and Redspur Delicious were headed at 36 and 30 

 inches, and the Macouns at 30 inch height. All treatments were 

 replicated at least 16 times. 



The NAA treatment was a complete disaster in the 3 orchards. 

 The first bud below the heading cut, which was supposed to develop 

 into the leader, was with only one exception either severely stunted 

 or killed. When the bud selected for the central leader died, no 

 strong leader developed from the NAA-treated area. 



Crotch angles were affected only on the Redspur Delicious 

 (Table 1) . The trees receiving the NAA treatment and those on 

 which the competing shoots were removed in mid-June, had wider 

 crotch angles than the disbudded trees for each heading height. 



Table 1. Effect of NAA application, removal of competing shoots 

 in mid- June, and disbudding on crotch angles. 



Treatment and 

 heading height 



NAA, 36 in 

 NAA, 30 in 

 Shoots removed, 36 

 Shoots removed, 30 

 Disbudding, 36 in 

 Disbudding, 30 in 



m 

 in 



Mean separation in columns by Duncan's multiple range test, 5% 

 level. 



We do not know why the results with NAA were so unfavorable 

 although we believe the concentration was too high. However, it 

 is obvious that Massachusetts growers should not use NAA for tree 

 training until further experimentation shows the procedure to be 

 reliable. 



Even if the NAA tree-training technique is proven to be reli- 

 able, it has at least 3 obvious drawbacks. Spring is an extremely 

 busy season and chances are great that the NAA will not be applied, 

 Secondly, the treatment must be applied before growth starts. And 

 lastly, frequently a better choice of a leader can be made in mid- 

 June and this job can be combined with limb spreading with clothes 



