Black-Knot of Plums and Cherries. 653 



with certainty when the infections take place, nor when the knot 

 appears after infection has occurred. If this were known the 

 matter would be considerably simplified, and still better results 

 obtained. It would appear from the above that an orchard may 

 be kept practically free from the knot if the trees are sprayed at 

 the proper time. One or two treatments might be given before 

 the blo.ssoms open, and later applications probably need not be 

 made oftener than is required to co-'trol the leaf-blight and the rot- 

 ting of plums. If in addition to this the comparatively few knots 

 which will undoubtedly appear be removed as soon as discovered, 

 no grower need have much fear of this disease even though his 

 trees be considerably exposed to infection from neighboring trees 

 or thickets. The treatments which the above-'' experiment seems 

 to justif\' me in recommending are as follows : 



First. During the latter part of March or earl)- in April. 



Second. When the buds are beginning to swell. 



Third. During the latter part of May, or as soon as the new 

 knots begin to show their velvety coating. 



Fourth. About two weeks after the third. 



Fifth and Sixth. At intervals of two or three weeks after the 

 fourth, but these two will probably not always be necessary. 



The Bordeaux mixture may prove more valuable than other 

 fungicides even in making the first applications, as it adheres 

 better to the branches. It is probable that some of the above treat- 

 ments may in time be dispensed with. Much will depend upon 

 the season and upon the degree of infection to which the or- 

 chards are exposed. 



It is scarcely necessary to add tha". all thickets, hedges, and 

 useless trees which serve as breeding and distributing centers 

 should be destroyed at the first opportunity. The species of 

 Prunus mentioned on page 641 should be .served in the same man- 

 ner as useless cultivated plants, if the}^ aid in the propagation of 

 the fungus. In the end unceasing vigilance must bring its reward. 



*It is unfortunate that other experiments begun at the same time and 

 carried on in a manner similiar to the above have failed to give results from 

 the fact that no new knots formed upon either the sprayed or the unsprayed 

 portions. The plum orchard of Geo. T. Powell, Ghent, N. Y., has been 

 under treatment during two years, as well as other trees in the vicinitv of 

 Ithaca. AH have failed to develop new knots. But the work will be con- 

 inued and it is hoped to make other reports in the future. 



