PLUM DISEASES 357 



nineteenth century. It is not possible to state accurately just 

 where the disease originated, but the first records show that 

 many years ago black-knot was particularly abundant along 

 the northern half of the Atlantic seaboard. The evidence at 

 hand indicates that the disease may have first affected cultivated 

 forms of the plum and cherry in Massachusetts about 1800. 

 It may be pointed out, however, that this portion of the East 

 was first most thickly settled and consequently it was there first 

 noticed. The disease was confined to the eastern United States 

 until about 1879, when the pathogene spread westward, appear- 

 ing in the vicinity of Cincinnati, Ohio. This invasion of the 

 western states has continued uninterruptedly, and now the 

 disease is found across the northern United States to the Pacific 

 Coast. It occurs less commonly in large portions of the South- 

 west and Central West. 



The disease is one of the most common of stone-fruit tree 

 troubles in America. It is as destructive as it is common. It 

 is of great economic importance because of its wide geographical 

 range and on account of its prevalence for the past century. 

 The loss in dollars incurred during this long period would be 

 difficult to determine. But it is interesting to note that the 

 destructive nature of black-knot caused plums to be so scarce 

 in New England in the autumn of 1875 that $2.50 was paid 

 for a peck of Damsons in the city of Boston. At one time 

 the raising of cherries was almost abandoned in the State* of 

 Maine on account of black-knot. The disease has been equally 

 destructive in New York. In one plum orchard which, in 



1884, netted $8000, thousands of trees were rooted out in 



1885, and from the remaining ones the sum of but $250 was 

 realized. Numerous similar cases might be cited, not only for 

 New York, but for many other states within the geographical 

 range of the disease. Destruction in any degree is a direct 

 result of the death of affected twigs, limbs, and occasionally 

 the trunk. 



