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 age 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. 
