Report on Botany. 



193 



Some attention has been given for some time past, by one 

 of jour committee, to the investigation of the cause and 

 nature of the so-called black knot, that terrible pest of the 

 plum trees and cherry trees of our country. Various and 

 conflicting opinions have been entertained respecting its 

 character, but all agree in pronouncing it a very injurious 

 and even fatal visitant to the trees it affects, and all who 

 have proposed any remedy, so far as we are aware, have 

 recommended the most thorough use of the knife. 



It is a noticeable fact that most of the authors who have 

 written upon this subject wrote as entomologists, not as 

 botanists, and any errors they may have fallen into should 

 therefore be looked upon with leniency. One author even 

 apologizes to the botanists for " stealing their thunder," as 

 he expresses it, pleading as his excuse that he had at first 

 mistaken the black knot for an insect gall. We think the 

 botanists scarcely deserve any apology since they have so 

 persistently neglected to investigate a matter of so much 

 importance. 



What is black knot ? To this question Dr. Fitch, entomo- 

 logist of the New York State Agricultural Society, answers: 

 " it is a large irregular black wart-like excrescence which 

 grows upon the limbs of plum and cherry trees causing 

 the death of all the branch above it and extending down 

 the limb farther and farther every year till the whole branch 

 is destroyed, other limbs at the same time becoming affected 

 in the same manner, and also the limbs of other trees in 

 the vicinity. If it is neglected, it in a few years kills the 

 tree." 



The late lamented B. D. Walsh, entomologist of the State 

 of Illinois, thus defines it : " It is a black, puffy, irregular 

 swelling on the twigs and smaller limbs of plum and cherry 

 trees, and in one instance that came under my observation, 

 of peach trees, making its first appearance in the latitude 



Trans. vii.~\ 25 



