46 N. J. Agricultural Experiment Stations Bulletin 356 



with the larger amount of foodstuffs which these trees store up and to 

 the advanced condition of their buds. In all normal trees reserve food 

 stored up the previous fall is apparently exhausted by the time the 

 peaches reach about }i to 1 inch in length. The time varies somewhat 

 according to the rate of growth of the trees, requiring a longer period 

 for the slow growing trees. In a normal season in the vicinity of 

 Vineland the reserve food supply of normal peach trees would be 

 assimilated by June 1 to 5. This is the period of the "June drop." 

 Statements are rather frequently made that the bulk of the "June 

 drop" is due to lack of pollination. Our studies indicate that peach 

 blooms that fail to pollinate commonly fall from the twigs within 

 10 to 14 days after petal fall. The curculio and various other insects 

 and diseases may cause a heavy drop of fruit in June, but in many 

 cases the June drop is a normal thinning by the tree itself at the 

 time when the reserve food has been wholly utilized. 



It can readily be seen why young fruits forming upon slow grow- 

 ing trees have a large amount of food available for their support. 

 Therefore, when the set of fruit is not in too great quantity, the 

 young fruits on the slow growing trees soon become extra large. 



Trees with yellows start growth early and appear quite green in 

 very early spring, but later become yellow in color. Starch tests 

 of the new foliage from yellows trees, however, showed that the 

 transfer of starch was inhibited even at the beginning of growth in 

 early spring, although only to a slight degree as compared with a 

 later period. 



Effect of Nitrogen Applications Upon Healthy and Diseased 



Trees 



The application of available nitrogen to peach trees during the 

 growing season commonly promotes the development of leaves and 

 branches, causing a freer and larger growth. This tends to delay 

 the storage of starch and fruit-bud formation, and directly affects 

 the time of blooming and growth the following spring. 



It has been observed frequently that severe winter pruning will 

 cause a yellows tree to appear much more healthy, perhaps almost 

 normal in some cases. The tree may become normally green, make 

 considerable growth and behave like a normal tree. Any stimulant 

 which would cause the tree to make a rapid growth would tend to 

 obscure the checked or girdled appearance caused by the yellows. 

 The transfer of starch would take place more readily and the appear- 

 ance of the tree would change accordingly. 



