HEAD FORMATION IN APPLE TREES 



153 



It is doubtful if much significance can he attached to the diflferences appear- 

 ing in this table. The central leader trees, not headed, again appear to be 

 somewhat larger than any of the other groups. These trees are in each case 

 at the south end of a series and as has been stated the soil is in general better 



Table 4.. — Average Trunk Diameters. 



Globular headed 

 Globular not headed 

 Not pruned 

 Modified leader 

 Central leader headed 

 Central leader not headed 



mm. 

 82 + 

 82 ± 

 82 + 

 88 + 

 82 + 



1924 



mm. 



129 ± 



126 ± 

 124 ± 

 131 + 



127 + 



130 + 



Tompkins King 



1921 



mm. 



66 + 

 70 ± 

 78 + 

 65 ± 

 70 ± 

 68 + 



mm. 



113 ± 



114 + 



124 + 

 109 + 

 111 ± 

 111 + 



Average of 

 all Varieties 



74.2 

 76.7 

 78.8 

 77.2 

 77.5 

 80.1 



116.0 

 118.8 

 119.3 

 119.0 

 116.6 

 123.0 



towards the south end of the orchard. It is probably safe to conclude that the 

 rather light pruning given these trees has not dwarfed them significantly ex- 

 cept in the two groups where heading back has been practiced. 



During the summer of 1922 the trunk diameter at a fixed point of the Mc- 

 intosh and Northern Spy trees was taken at approximately two-week intervals 

 from May 2 to August 16 and also September 14 and October 9. The results 

 are shown in Figs. 1 and 2. These indicate that trunk growth continued at 

 a fairly steady rate from May 15 to about September 1. Before and after 

 these dates it was slower. The type of pruning seems to have had little effect, 

 except that growth was a little slower in the case of the headed trees, espe- 

 cially late in the season. 



The rainfall for June was excessive, while July and August had more sun- 

 shine than usual with a moderate rainfall. Possibly these conditions influenced 

 the rather slow growth during the latter half of June and the increased growth 

 during July and early August. Mcintosh grew more rapidly than Spy during 

 August which is in harmony with observations of the writer on nursery trees, 

 where Mcintosh grows more in late summer than most other varieties. 



Measurements of shoot growth were made during 1922 on the Baldwin and 

 Mcintosh. Ten shoots on each tree were tagged and measured at weekly in- 

 tervals from May 26 to July 14 with additional measurements on July 31, Aug- 

 ust 19 and October 12. The averages for the headed and not headed trees are 

 shown in Fig. 3. This shows the later growth of the Mcintosh. It also shows 



