426 OHIO EXPERIMENT STATION: BULLETIN 214 
season by the late, adventitious growth. The sources of disease are diseased 
trees or affected nursery stock, more often the former. The remedy is to remove 
and to burn the yellows trees, root and branch, on the spot where found. Drag- 
ging diseased branches may spread yellows and all such trees are a menace. 
To leave an open hole over winter and replant the next year is a safe practice. 
(See Bulletins 72 and 92 for fuller discussion). 
Fig. 77. Peach Yellows, winter buds of diseased tree unfolding 
in autumn. (After Smith, Farmers’ Bul. 17, U. S. Dept. Agric.) 
Recent investigations of this disease show that it is due to an enzyme which 
converts the leaf chloryphyll into a diseased form, causing yellows conditions. 
It is doubtless this enzyme which is transmitted, as in the case of tobacco, by 
actual contact. These discoveries have changed in no way our method of hand- 
ling the disease. (See enzymatic diseases in introduction). 
Rosette of peach is a disease of the southern states which appears to be 
similar in cause and transmission to peach yellows. 
