42 N. J. Agricultural Experiment Stations Bulletin 356 



mained in the midribs of the leaves at all times. The amount 

 of starch remaining in the leaves was found to be in direct propor- 

 tion to the severity of the yellows, or little peach, or the completeness 

 of the girdling or winter injury. The leaves from trees affected with 

 yellows showed a greater starch content in the early morning than the 

 leaves from girdled trees with a corresponding rate of growth. The 

 cause of the prematuring of the fruit on the yellows trees and girdled 

 trees is apparently due to the interference with the processes of 

 translocation of the food supply. No explanation has been obtained 

 of the contradictory behavior of little-peach trees. In this disease, 

 starch accumulations are found, but the fruit is delayed in ripening 

 instead of ripening prematurely. The peaches on some branches of a 

 yellows tree frequently premature considerably in advance of those on 

 other branches, and if prematuring is in proportion to the severity 

 of the check to growth, this should be indicated in starch tests. Ex- 

 aminations of carefully selected leaves and twigs demonstrated this 

 point very clearly. The more advanced the disease in any one branch, 

 the greater the starch residue found in the leaves in early morning. 



The tips of branches of diseased trees commonly appear quite 

 normal and make a more free growth than those in the center of the 

 tree. Tests made in the early morning showed much less starch in 

 the growing tips than in the older parts of the twigs. 

 Studies With Healthy Trees 



If early maturity of the fruit of healthy trees depends upon a slow 

 rate of growth and the early storage of starch in the fruit and twigs, 

 then we would expect to find a larger amount of starch in the leaves 

 of slow-growing trees in early morning than in those of rapidly 

 growing trees. 



As previously noted, the fertilizer experiments at Vineland includ- 

 ed plots without nitrogen applications and plots with considerable 

 amounts of nitrate of soda or stable manure. The plots without ni- 

 trogen matured their fruit considerably in advance of those that re- 

 ceived nitrogen in some form, as noted previously. This is to be ex- 

 pected, as the latter plots were making a more active growth. Leaves 

 of healthy trees from various plots were tested for starch in the 

 early morning. The results of examinations indicated that the amount 

 of starch found decreased with the vigor and rapidity of growth. 

 In other words, the leaves from the trees in the no-nitrogen plots 

 contained the most starch, while those from the trees receiving the 



