Peach Yellows. 401 



is the recognized authority upon the disease, now declares that 

 "it is almost certainly not a bacterial disease. ' ' Dr. Smith 

 thinks that the disease is ' ' nearest allied to that phenomenon in 

 plants known as variegation." It has been long known that most 

 variegation is an abnormal state or condition and that it can 

 sometimes be communicated to normal plants by means of bud- 

 ding ; but it is difficult to conceive of any means by which such 

 condition can become contagious without the presence of germs. 



But there is every reason to expect that when the cause of the 

 yellows shall have been discovered, the treatment will remain the 

 same as now, — extermination of the affected trees. This seems to 

 follow, from the fact that when the first symptoms of yellows are 

 discovered upon any branch, the entire tree is diseased. Numer- 

 ous critical experiments have been made to determine this fact, by 

 cutting off the diseased limb. In every case the remainder of the 

 tree has shown yellows, usually the following year, but sometimes 

 not until the second year. And these results are exactly in line 

 with the experience of all peach growers who have had to deal 

 with yellows. It will also be necessary to exercise the same 

 caution in the choice of buds for propagation , for it is known that 

 a bud from a yellows tree — even from that part of a tree not yet 

 visibly affected — will make a yellows tree and will communicate 

 the disease to the stock. Premature yellows peaches rarely have 

 good seeds, but the pits from the apparently healthy portions of 

 diseased trees may be expected to convey the disease to the off- 

 spring. 



So far as known, peach yellows, like pear blight and plum 

 knot, is a purely American disease, and has not been introduced 

 into other countries. It is generally distributed in peach sections 

 east of the Mississippi river and north of North Carolina and Ten- 

 nessee. It first attracted attention about a hundred years ago in 

 the neighborhood of Philadelphia, whence it appears to have 

 spread throughout the country. It was probably introduced into 

 the peach region of southwestern Michigan — where it appeared 

 nearly thirty years ago — by diseased eastern stock. As near as I 

 can learn, it appeared in Niagara county, New York, about 

 twenty years ago. The disease seems to prefer the peach, but it is 

 known to attack the nectarine, almond, apricot and Japanese plums. 



