HEAD FORMATION IN APPLE TREES 



155 



no^ae JUoei Ju.i«3 Jixieir J-»Tei5I,oeio Xvlr6 J„1,H J^VJi Augie 



Figure 3. Average Shoot Growth (in centimeters), 1922. 



that tlie lieaded trees started off somewhat slower than those not headed, but 

 that they continued growing much later in the season. The shoots not headed 

 liad in most cases formed terminal buds by the middle of June, while the head- 

 ed shoots continued growth for a month or more after that time. This is in 

 harmony with common observations on this point. 



Effect of Heading on Bud Development 



In May, 1922, observations were made on the development of the lateral buds 

 on the shoot growth of 1919 and 1920; that is, on the two- and three-year-old 

 wood. A comparison of the performance of the buds on the headed and not 

 headed trees is shown in Table 5. On the wood of 1919 the average total num- 

 ber of lateral buds was not materially reduced by heading, though they were 

 reduced from 39.6 to 32.3 per cent on the wood of 1920. 



The second column of Table 5 shows the percentage of buds remaining dor- 

 mant at the time the count was made. On the 1919 wood the percentage of 

 dormant buds was somewhat larger on the headed branches; but on the 1920 

 wood it was considerably less. This may have been due to seasonal differences, 

 or to thinning out shoots in pruning. The differences in blossoming spurs are 

 striking on the younger wood. Less than 1 per cent of the buds had developed 

 into fruit buds on the headed branches, and on the older wood the percentage 

 was much less than on the branches not headed. The number of non-blossom- 

 ing spurs was larger on the headed branches of the older wood but somewhat 

 less on the two-year-old wood. On the 1920 wood, nearly one-half of the buds 

 on headed branches developed into leafy shoots; but on the older wood, only 

 12.9 per cent so developed. Probably many shoots had been pruned off in the 



