THE GKAPE ASTTHRAON'OSE 



89 



When one of these spores falls upon a green leaf, stem or 

 fruit where there is a particle of water, it sends out a 

 germinating tube, which penetrates the skin or cuticle. 

 On the inside it begins the production of mycelium 

 which grows near the surface, and finally produces, in 

 certain spots, quantities of spores. These masses of 

 spores gradually push the skin outward, as shown in a, 

 and finally rupture it and escape, as seen in #. They 

 are then blown and washed about, and such of them as 

 alight on the green parts of other vines when conditions 

 are favorable for germination, start the fungus again. 





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FIG. 44. AXTHKACNOSE. 

 , l>, Vertical -section of grape showing development of spores; <, spores. Magnified. 



The light colored and white varieties of grapes are 

 the ones most affected by anthracnose. A bunch of 

 Elviras injured by this disease is represented in Fig. 43. 



Treatment. This is a difficult disease to prevent. 

 The treatment usually recommended is to cut out all 

 injured canes during winter, and early in spring, before 

 the buds start, to spray the vines thoroughly with a 

 strong copperas (iron sulphate) solution. Mr. E. P. 

 Powell has reported successful results from a solution of 

 ten pounds of copperas to a barrel of water. In case 

 the disease appears, a powder composed of equal parts 



