362 MANUAL OF FRUIT DISEASES 
satisfactory program of eradication. There is no objection to 
more frequent inspections, but a single annual inspection, if 
carefully done, should prove sufficient. It is necessary to 
destroy these knots, otherwise the spores contained therein are 
likely to be liberated and start the trouble again. This method 
of control has not given the satisfaction that it should, the 
difficulty apparently lying in the carelessness of the inspector 
and the failure of the neighbor to cooperate. It is obvious that 
if but a few knots are overlooked, the fungus may still operate 
successfully. And the growers of a given region must make the 
plan one of joint-action; one individual cannot exterminate 
the fungus in a locality. If the existing laws were enforced, the 
extent of injury from this disease would be greatly diminished. 
The reward for any such eradication measures will be reaped in 
accordance with the vigilance of the local orchardists. 
As a measure purely supplemental to the one just outlined the 
trees should be sprayed with bordeaux mixture, the number of 
applications depending upon the severity of the case in hand. 
In cases of a threatening nature the sprayings should begin late 
in March; five or six subsequent applications at intervals of 
two or three weeks should be made. 
REFERENCES 
Farlow, W. G. The black knot. Bussey Inst. Bul. 1876 : 440-453. 
1876. 
Beach, 8. A. Black knot of plum and cherry. New York (Geneva) 
Agr. Exp. Sta. Bul. 40: 25-34. 1892. 
Hesler, Lex R. Diseases of the plum. Black knot. Jn The Fruit 
Industry in New York State. New York Agr. Dept. Bul. 79: 
1190-1192. 1916. 
Humphrey, J. E. The black knot of the plum. Massachusetts 
(Hatch) Agr. Exp. Sta. Rept. 1892: 27-30. 1893. 
Humphrey, J. E. The black knot of the plum. Massachusetts 
(Hatch) Agr. Exp. Sta. Rept. 8: 200-210. 1891. 
Halsted, B. D, Destroy the black knot of plum and cherry trees. 
An appeal. New Jersey Agr. Exp. Sta. Bul. 78: 3-14. 1891. 
