140 K.EPOKT OF THE DEPARTMENT OF BoTANY OF THE 



Some persons thought they saw evidence that the single appli- 

 cation of Bordeaux for worms had lessened the amount of dam- 

 age from anthracnose. In the plantation of Mr. A. B. Clarke at 

 Milton, we observed that in one portion anthracnose was con- 

 siderably more severe than in an adjacent portion. Upon inquiry 

 as to the cause we were informed that one portion had lL>een 

 sprayed once with Bordeaux mixture while the other had not. 

 In this case there appeared to be a marked benefit from spray- 

 ing; but in general the Bordeaux applied for worms did not have 

 much effect on the anthracnose. Probably the application was 

 made too late. 



In the absence of experimental data we can only make sugges- 

 tions as to treatment. Bordeaux mixture will pr\)bably control 

 the disease, but the spraying must be commenced early. In view 

 of the fact that the anthracnose fungus inhabits the canes, the 

 first application should be made on the bare canes before the 

 leaves appear.^^ Special attention should be given to the new 

 wood because there is where the spores are most abundant. In 

 fact no spores have yet been found on the old wood. However, 

 the old wood should also be sprayed, because it is possible that 

 some spores do occur on it, and also because of the possible 

 effect on cane blight. How the fungus of cane blight gets into the 

 canes is not known, but there is good reason for believing that 

 thorough spraying of the canes will have a tendency to prevent 



"For the first treatment a strong solution of copperas (iron sulphate) 

 may be used instead of the Bordeaux. Make a saturated solution (that 

 is, add copperas to water until no more will dissolve) and apply while 

 the buds are swelling but before they break. By some, this treatment is 

 thought to be beneficial for grape anthracnose (See N. Y. Agr. Exp. Sta. 

 Bui. 86:79; and Bui. 170:410). particularly when about one per ci'ut. of 

 sulphuric acid is added to the copperas solution. But if tlie sulphuric 

 acid is added the mixture can not be applied with a spraying machine, 

 because it is so very corrosive. In that case it must be applied wiMi a 

 swab or whisk broom. The fungus of grape anthracnose is closely 

 related to tliat of currant anthracnose and there is some I'eason for 

 believing that any treatment which is successful for the one AAOuld be 

 successful for the other. Nevertheless we have i-ecommended Bordeaux 

 mixture for the first treatment for the following reasons: (1) Bordeaux 

 is likely to be equally effective; (2) The treatment is less complicated; 

 (3) There is no danger of injury to the plants or to the sprayer. 



