DISEASES. 195 



of weeds will often lie dormant in the ground. Still, with 

 all these possible drawbacks, I have little doubt that the 

 above remedy will, as a general rule, if applied according 

 to directions, be found effectual." 



The foregoing is interesting as giving the conclusions 

 of an entomologist who had investigated the subject, and 

 arrived at the same result that had been reached by a 

 botanist many years before. Schweinitz, in 1832, published 

 the correct history of the Black-knot in the Transactions 

 of the American Philosophical Society. In the American 

 Agriculturist, April, 1863, p. 113, Mr. C. F. Austin con- 

 firmed Schweinitz's observations, and gave a popular ac- 

 count of the botany of this fungus, with figures. It may 

 be considered as fully established that the knot is of vege- 

 table origin ; and whenever insects or larvas are found in 

 it, it is only because they find a diseased portion of the 

 tree suited to their necessities. 



ROT AND MILDEW upon the grape both destroy our 

 crops, and render the vines unhealthy. Would that I 

 were able to give the reader some encouragement as to its 

 cause and prevention, or cure ; but some of our oldest and 

 most experienced vine-planters have come to the con- 

 clusion, as to treatment, that " the more they find out, 

 the more they don't know." It is now generally conceded 

 that it is caused by a fungus growth. That on the leaves 

 is probably the Oidium Tuckeri, and it is generally sup- 

 posed that the mildew and rot of the berries is owing to 

 the same cause. The microscope clearly indicates its fun- 

 goid character. As to the causes, it must be admitted 

 that the weather favors or prevents its access, and that 

 so far it is a proximate cause, but that the spores are the 



