14 PEACH YELLOWS. 



from the premature and abnormal development of ordinary winter buds. 

 These begin to grow as soon as they are formed in the leaf axils, and 

 the feeble shoots to which they give rise develop buds which also ger- 

 minate the same season, and so on (plates v and vi). The winter buds 

 upon healthy-looking terminal branches and stem and limb shoots 

 may also unfold prematurely into diseased growths. This may take 

 place at any time from early spring to late autumn. It is very com- 

 mon in September, October, and November, and is one of the strik- 

 ing characteristics of this disease (plate n, from a photograph made 

 at Amherst, Massachusetts, December 4; see also plates in and iv, 

 made from photographs taken in Maryland in the autumn of 1890). 

 Plate ii represents a shoot taken from the trunk near the earth. Plate 

 in represents one healthy shoot and three diseased shoots taken from 

 the base of main limbs. The spring foliage remains on the healthy shoot 

 (Fig. 2) and its winter buds are dormant. On the contrary, nearly all of 

 the spring foliage has fallen from the diseased shoots (Fig. 1), and many 

 of the winter buds, terminal and axillary, have germinated. Plates iv 

 and vi represent the same appearances in terminal branches. The pre- 

 maturity extends also to the blossoms, which generally come out earlier 

 than on healthy trees, and appear sometimes even in autumn (plate 

 IV, made from a photograph taken October 15, 1890). My attention 

 was first drawn to this symptom in the spring of 1890, but extensive 

 observations were then impossible. In the autumn of 1890, and again 

 in the spring of 1891, about 0,000 trees were examined with special 

 reference to the effect of yellows upon the blossoms. All of these trees 

 are in Maryland and Delaware, and all were healthy in the autumn of 

 1890. About 500 of them were found diseased in whole or in part in 

 the spring of 1891, having developed yellows between fall and spring. 

 The most characteristic symptom was the general pushing of leaf buds 

 one to two weeks in advance of the proper time. This was peculiarly 

 striking by contrast whenever the trees developed symptoms on one or 

 two limbs only. On many of these trees some of the blossoms also 

 came out very early, and were destroyed by frosts, but in general, the 

 disease could be detected in these trees before the blossoms opened. 



In this climate under normal conditions winter buds of the peach do 

 not germinate until after a considerable period of rest. They never un- 

 fold in the autumn, and it is difficult to induce them to do so even in 

 winter. This period of rest may be shortened somewhat by mild winters 

 and early springs, or by artificial means, e. </., June budding, but it is 

 not abrogated in nature, so far as I know, except under the influence of 

 this peculiar disease, and the one described in Part II. 



When the winter buds become affected in spring, the growths to 

 which they give rise are occasionally more extensive but are somewhat 

 variable, their appearance depending, of course, to a great extent, upon 

 the length of the iuternodes and the amount of branching. Different 

 forms of these terminal spring and summer growths are shown in plates 



