116 



INTERNATIONAL CONGRESS OF VITICULTURE 

 Methods of Control. 



Spraying with ordinary fungicides during the growing season only does 

 not prove effective in preventing the disease. The treatment of dormant 

 plants with a mixture of iron sulphate and sulphuric acid has been success- 

 fully applied in Europe. This, however, is a very unpleasant mixture to 

 prepare and use on account of the corrosive action of sulphuric acid. As a 

 result of experiments conducted by Dr. Hawkinsi2 under our direction in 



Fig. 3. Treated vine. 



Michigan on Champion grape vines, very seriously affected with anthracnose, 

 it was found that a treatment less troublesome to apply than the sulphuric 

 acid mixture was entirely successful. In connection with any treatment by 

 spraying it is of course necessary to eradicate and destroy as much of the 

 disease as possible. All the diseased wood should be pruned out and burned; 

 then spray the dormant vines thoroughly with concentrated lime-sulphur 

 solution, 1 to 9, after which thorough treatment with four or five applications 

 of 4-3-50 Bordeaux mixture has been found to reduce the injury from this 

 disease to the minimum. Figure 3 shows treated and figure 4 untreated 

 vines. The first spraying with Bordeaux mixture should be done when the 



i2Hawkins, L. A. Experiments in the Control of Grape Anthracnose. 

 Circ. 105, Bureau of Plant Industry. Feb., 1913, pp. 1-8. 



