414 



CERTAIN INSECT AND FUNGOUS DISEASES. 



It has been suggested by good authority that much of 

 the trouble called peach-yellows may be caused by root- 

 lice. If this is true, and it appears to us very likely, we 

 would here have the explanation of the effectiveness of 

 potash applications. Plant - lice, root-lice, and many 

 other insect pests cannot stand contact with solutions 

 of potash salts. But whether the mischief is due to 

 animal life or to any other cause, we evidently have in 

 this supposed yellows a diseased condition which is cur- 

 able by the simple application of potash salts. As this 

 disease is easily confounded with the true yellows, it is of 

 great importance that peach-growers become acquainted 

 with the exact nature of both, and note especially what 

 differences there may be between 

 the external symptoms of each. 



The curable, supposed yellows, 

 so far as we found it, always ap- 

 peared on soil of rather sandy 

 character, and seemed to affect 

 every part of the peach trees uni- 

 formly and at once. This is not 

 generally the case with the true 

 yellows. The fruit of trees also 

 seems to be differently affected 

 by the two diseases, but all their 

 other symptoms are so nearly 

 alike as to cause little wonder 

 that the one is often mistaken for 

 the other. Further investigation 

 of this phase of the yellows ques- 

 tion is needed. 



Another dis- 

 ease of the peach 

 resembling t h e 

 yellows in many 

 respects, yet 

 probably distinct 

 from it, is the 

 peach-roset te . 

 This disease runs 

 i t s course in a 

 much shorter 



time than does the true yellows ; usually 

 the whole tree is diseased from the start, 

 and is often destroyed within six months 

 from the time the disease first attacks it. 

 The Department of Agriculture, Divis- 

 ion of Vegetable Pathology, gives the 

 following as the more noticeable symp- 

 toms of the rosette; "Commonly the 

 disease appears first in the unfolding 



shoot-axes, i. e., in early spring when sehdling Peach Tree Diseased 

 the buds first open. In healthy trees with Yellows. 



only a small proportion of the winter-buds develop into 

 branches. The rest die or remain dormant. In this 

 disease a large number of the winter-buds grow into 

 shoot-axes and also a very considerable number of dor- 

 mant buds on the older and larger branches. The 

 shoot-axes push only one to three inches and lose the 



ability to develop and ripen wood, and to form dormant 

 buds. The buds on such shoots grow as soon as they 

 are formed, developing into diminutive soft branches, 

 which frequently branch again but never attain any 

 good degree of size, vigor, or maturity. The leaves on 

 these dwarfed, branching shoot-axes are multiplied cor- 



Healthy Peach Shoot. 



respondingly, and the result is compact tufts or rosettes 

 containing 200 to 400 diminutive leaves, and many ad- 

 ditional green stipules which are frequently misshapen 

 and abnormal. The older and larger leaves near the 

 base of the shoot frequently reach a length of several 

 inches and are characterized by a very pronounced in- 



