PEACH YELLOWS AND PEACH ROSETTE. 167 



the grower, seriously impairing the subsequent demand for healthy fruit 1 . 

 In many cases the red-spotted, prematurely-ripened fruits are the first 

 indications of disease, or at least the first symptoms striking enough to 

 attract general attention. They are very often borne exclusively upon 

 one or two limbs of otherwise healthy-looking trees. These limbs are 

 not different in appearance from the rest of the tree. They bear vigorous 

 shoots and full-grown, smooth, dark-green foliage; often, also, green half- 

 grown fruits, which afterward ripen in a normal manner. There is no 

 indication of disease except in the fruit, which, in color and size, contrasts 

 strikingly with the fine green foliage and the normal immature fruit. 

 Occasionally, in places, the foliage already begins to look yellowish green 

 while weak, pale sprouts begin to push through the bark. Sometimes 

 branches bearing good foliage are covered from base to tip with these 

 feeble shoots. They grow vertically through the bark on the upper sur- 

 face. Later, in summer or autumn, or the following spring, such branches 

 begin to show marked indications of disease. The spring foliage is yel- 

 lowish or reddish green, dwarfed, rolled, and curled; and the shoot-axes 

 are stunted. Commonly, especially in moist seasons, many - feeble, 

 branched sprouts are developed on the trunk and the base of the main 

 limbs. Again, stem and limb shoots will grow normally and very vig- 

 orously for several feet and then all at one branch repeatedly near the 

 extremity in a very feeble and peculiar way. Many of these growths are 

 due to the excessive and abnormal development of obscure buds hidden in 

 the deeper layers of the bark or developed from the cambium. Why they 

 should germinate in such numbers, and often in midsummer or autumn, 

 when the tree has passed its period of active growth, remains to be 

 explained. The appearance suggests a profound disturbance of the dis- 

 tributive metabolism of the plant, followed by an equally profound dis- 

 turbance of the function of assimilation. The branched character of 

 many of the growths results from the premature and abnormal develop- 

 ment 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 germinate the same season, and so on. The win- 

 ter 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 common 

 in September, October and November, and is one of the striking charac- 

 teristics of this disease. Plate II represents a shoot taken from the trunk 

 near the earth. Plate III 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 and many of the winter buds, terminal and axillary, have germina- 

 ted. Plates IV and VI represent the same appearances in terminal 

 branches. The prematurity extends also to the blossoms, which generally 

 come out earlier than on healthy trees, and appear sometimes even in 

 autumn. 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 6,000 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 



