JAMAICA. 



BULLETIN 



OF THE 



BOTANICAL DEPARTMENT. 







Vol.Y 



Mew Series 



NOVEMBER, 1899 



Part XX 



DISEASES OF THE VINE. 



Diseases of the Vine may be conveniently classed into : — 



(1) Those directly traceable to the action of parasitic fungi. * 



(2) Those directly traceable to the action of injurious insects. 



(3) Those for which neither fungi nor insects offer a sufficient 

 explanation. 



The first and second class of diseases we propose on this occasion 

 to pass over. 



The unexplained diseases of the Vine are important enough to merit 

 special notice, as tbey have been the subject of many investigations. 

 As a general conclusion of the perusal of some of the more important 

 results obtained, we are led to regard most of the unexplained diseases as 

 "physiological," that is, they are due to defects in cultivation, to ad- 

 verse climatic or other conditions, and to the use of unsuitable varieties 

 of the Vine. Fungi or insects may appear along with diseases of this 

 kind, but they come later and only because the plants are already 

 weakly. One might even go further, and say that most of the fungus- 

 diseases of the Vine are really started by defects in cultivation ; the 

 Vines are weakened, the fungi come and complete the mischief. 



The methods employed to produce a large supply of fruit of high 

 quality may easily result in conditions favourable to the development of 

 disease. 



Shanking. 



"Shanking" is a trouble which accompanies Grape-growing all 

 over the world. The Grapes as they approach maturity fall off the 

 bunch, breaking away where the stalk joins the fruit ; or they may 

 simply shrivel up and remain attached. The Grapes to go first are 

 those towards the lower end of a buuch, or those on the shoulders. The 

 number may vary from one to many, and the trouble may be apparent 

 all over the Vine or only on parts of it. The foliage is at the same 



* See Bulletin, 1897, page 37. 



