104 



Report on Botany. 



of New York early in June and attaining its full growth 

 by the end of July. Usually a tree that is attacked in this 

 manner is affected worse and worse every year until it is 

 finally killed, and where one tree of a group is affected, the 

 malady usually spreads to them all in process of time." 



According to our own observations the death of the 

 branch above the excrescence is not always produced by 

 the first attack. In such cases the malady extends upwards 

 as well as downwards. The time of the first appearance 

 of the excrescence is in late autumn, although the external 

 development of the fungus is not manifest until the fol- 

 lowing May. We have never found it on peach trees. 



Let us now see what is written concerning the origin of 

 black knot. Schweinitz, the botanist who wrote the ori- 

 ginal description of Sphceria morbosa, the fungus that develops 

 itself on the excrescence, seems to have been in some doubt 

 concerning the origin of the tumor. In his description he 

 uses these words : " Hcec massa num sit effectus ictuum 

 Cynipis nescimus, videmus tamen hie illic exesum foramen, 

 forte e prof undo progresses." At a later day, in writing 

 upon this same subject in his Synopsis of North American 

 Fungi, he says : "Paucis annis post, fere omnes destructi 

 sunt, combinato furore hujus fungi et Cynipis." And again 

 he says : "Et in his omnibus Cynipis fungusque incepiunt 

 scevire." Thus he constantly associates the insect which 

 he calls Cynips with the fungus, without definitely assign- 

 ing the honor or dishonor of the mischief to either. "We 

 find the following in Harris's Treatise on Injurious Insects. 

 " The plum, still more than the cherry tree, is subject to 

 a disease of the small limbs, that shows itself in the form of 

 large irregular warts of a black color. Professor Peck 

 referred this disease, as well as that of the cherry tree, to 

 the agency of insects. Dr. Burnet rejected the idea of the 

 insect origin of this disease, which he considered as a kind 

 of fungus. * * * But whether caused by vitiated sap 



