Necrosis of the Grape Vine. 



331 



The relation of this disease to these 

 " physiological diseases," however, as yet 

 remains a matter of investigation, so that 

 none of these names could be applied with 

 any degree of certainty, Anthracnose is 

 untenable since that disease has distinctive 

 and entirely different characters. Side 

 Arm is not a good name to apply since 

 it more frequently happens that the whole 

 vine is attacked. Black Knot by common 

 consent is reserved for the Knot in plums 

 and cherries and is entirely different. 



None of these names seems tenable since 

 they are either grossly incorrect or when 

 descriptive do not express the whole truth 

 and are unaccompanied by name of fungus 

 so that identity is uncertain. It therefore 

 seems that Necrosis (L., Gr. nekrosis, a 

 killing, nekros, corpse) would be a more 

 suitable name. 



ETIOLOGY 



Nature of the causal parasite. 



This disease is caused by a fungus {Fiisi- 

 coccum viticolum n. sp.).^ It is a vege- 



* Descriptions of various fungi known to occur on 

 species of Vitis have been carefully exam- 

 ined but no species seem to have been de- 

 scribed to which this might correspond. 

 While it is quite possible that a so-called 

 perfect stage may eventually be found, 

 none is known at the present time. For 

 that reason, the fungus must be placed in 

 some one of the imperfect " form genera." 

 Fusicocctim has been chosen in preference 

 to Dothiorella because of the presence 

 of numerous paraphyses. Some of the de- 

 scribed species of Fusicocctim have para- 

 physes while none of the Dothiorellae are 

 described as having paraphyses. 



Fusicoccuiii znticolum, Reddick, n. sp. 

 Stromatibus rotundis ovoideisve ; sparsis vel 

 confluentibus vel dense gregariis ; tectis, 

 dein_ erumpentibus; nigris ; carbonaceis ; 

 spurie plurilocellatis (1-6) ; ostiolo non 

 prominente perforato-punctatis ; sporulis 



Photo Sept. 8, 1908 



Fig. ^T.— Isabella. Excrescences 

 on two-year-old renewals, 

 Keuka Lake 



