PEACH YELLOWS AND PEACH ROSETTE. 191 



Since one case in point is as good as many, I have been at some pains to 

 learn the history of this tree. This tree is 36 years old It is one of a 

 number of accidental seedlings which came up from stones thrown out in 

 the fall of 1854. It then stood back of an old shop. This was afterward 

 removed and other changes made so that for quite a good many years the 

 tree has stood in sod ground, in the lawn, somewhat isolated from other 

 peach trees. It was budded by Mr. Harris himself in the fall of 1855, 

 and has been under his observation and care ever since, with exception 

 only of a few years when he did not reside on this farm. The variety is 

 Crawford's Early. The tree has been hardy and productive. Its last crop 

 was in 1888, since when, in common with other trees in that region and 

 owing solely to unfavorable seasons, it has borne no fruit. The tree is 

 about twenty-five feet high and has a good top; the trunk is nearly a foot 

 in diameter and still quite well preserved. I have seen this tree each year 

 since 1887, and always it seemed to me good for another ten years. This 

 tree was budded from a neighboring tree when there was no yellows in 

 the vicinity. Some years 'after, perhaps ten, the disease appeared and 

 gradually destroyed many younger trees upon the same farm, one of the 

 badly affected orchards being within a stone's throw of this tree. The 

 disease has increased from that time to this, and has been very destructive 

 for the last five or six years in all that region. This old tree, however, 

 kept on the even tenor of its vigor until the summer of 1890. Then for 

 the first time it developed unmistakable symptoms of yellows on one small 

 limb. Next year, undoubtedly, the disease will be manifest on other limbs 

 if it does not involve the whole tree.* 



Admitting the contagious nature of yellows, and this, I think, can be 

 doubted no longer, I am at a loss to explain the appearance of the disease 

 in middle-age and old trees except by infection from without. If such be 

 the case, then, of course, every tree which becomes affected is a fresh 

 source of danger, and ought to be removed and destroyed as soon as 

 possible. 



V. CONCLUSIONS. 



m 



The intelligent reader will draw his own conclusions. It is not out of 

 place, however, for me to present my view of the case. This is as follows: 



Facts Established. 



(i) The disease is contagious. It seems to me] that Experiments 1, 2, 

 and 5 settle this point beyond dispute. 



(2) It may be conveyed by seemingly healthy buds when these are 

 taken from diseased trees. This is proved by Experiments 2 and 5. 



(3) Only a very small amount of infective material is necessary, pro- 

 vided it be in the forms of living cells, which can be induced to unite 

 with the actively growing tissues of the tree. 



(4) The disease has a longer period of incubation than we have been 

 accustomed to suppose. (See Experiment 2, especially Table I, columns 

 5 and 6. See also the Excisions, especially B 16, 18; E 3; G 3, 4, 5, 6, 12, 

 19; and the note under G 3.) 



( 5 ) The death of the entire tree occurs, ordinarily, only after a very 

 considerable period, i. e., several years. 



♦Examined July 21, 1891. The disesased limb and the adjoining healthy one have been removed and the 

 remainder of the tree shows no symptoms. The tree bears green peaches. 



