Recent Studies ox Peach Yellows and Little Peach 45 



Storage in Leaves at the Time of Fall from Trees 



The fact that there was not a complete transfer of the starch from 

 the leaves of diseased trees indicated that considerable quantities of 

 starch might be lost at the time of leaf-fall. Starch tests, therefore, 

 were made as the leaves were falling from the trees, and very large 

 quantities of starch were found in such leaves as compared with 

 leaves from healthy trees. This was true of leaves that were quite- 

 yellow, as well as of those that still retained some green color. This 

 was especially true of leaves falling from yellows trees, but somewhat 

 similar results were noted in the case of girdled trees and those which 

 were making slow growth. 



When Is Reserve, or Stored Starch Exhausted? 



Having observed the storage of starch in the branches and roots 

 during the growing season, the studies were carried further in an at- 

 tempt to determine when the reserve starch supply would become 

 exhausted and whether the varying amounts as stored by trees under 

 varying conditions of growth would result in any marked differences 

 of growth the following spring. Tests were made at various dates, 

 namely, April 15, May 8, May 25 and June 1, 1914. It was not 

 until May 25 that the roots of the young trees set in 1912 became 

 practically clear of starch. More mature but healthy trees in orchard 

 no. 2, set in 1908, still showed a little starch in the roots, and the 

 slow growing trees on the "no nitrogen" plots in orchard no. 1 

 showed a trifle more. Several yellow trees, including plot 19, tree 25, 

 showed still more starch in the roots. 



On June 1, 1914, another examination was made of the roots of 

 the same trees and all were found to be practically free of starch 

 except those that were diseased. At this time, the green peaches 

 measured 24 to 1 inch in length. The yellows and little-peach trees 

 which showed a very large starch content in the fall appeared to 

 retain it late in the spring. The trees with unusually large starch 

 content, whether diseased or girdled, made bud and leaf growth more 

 promptly in the spring than those which contained the smaller quan- 

 tities of starch. In other words, early and rapid leaf development 

 was in proportion to starch content. 



It has been noted previously that trees checked in growth and 

 yellows trees bloom earlier and make leaf growth earlier than rapidly 

 growing normal trees, but soon slow down and grow more slowly 

 than normal trees. The early spurt in growth is apparently correlated 



