234 AGRICULTURAL EXPERIMENT STATION. [Jan. 



and badly attacked by the leaf-fungus, both those which had 

 and those which had not been treated with permangate, were 

 received from Mr. Philbrick. These were divided, as is the 

 custom with violet growers, so as to leave a good portion 

 of root to each, and set in good soil on one of the station 

 plats. As they made new leaves no signs of the fungus 

 were seen, and it was determined not to spray them at all 

 unless the appearance of the fungus should demand it. 

 Unfortunately for our study of the disease, the fungus did 

 not appear during the summer, except on a very few leaves, 

 and no test of the efficacy of s})raying as a preventive 

 of its spread was possible. Mr. Philbrick's experience was 

 difierent. He sprayed a part of his plants with the ammo- 

 niacal carbonate of copper until about the middle of August, 

 when a few days of warm, damp Aveather occurred, and the 

 disease spread rapidly and fatally. As he could see no 

 difference In the degree to which sprayed and unsprayed 

 plants suffered, he gave up the treatment in disgust, and 

 lost nearly all his plants. If it l)e true that the leaf- 

 spot fungus is the cause of this very destructive disease, 

 from which many violet growers near Boston suffer, — and 

 all the facts now at hand point to this as the correct conclu- 

 sion, — there is no apparent reason why thorough and 

 persistent spraying with one of the copper preparations 

 should not prove very efficient in holding it in check. And 

 Mr. E. O. Orpet of South Lancaster informs me that he 

 has had excellent success with this treatment. The failure 

 above quoted was probably due to some error in carrying 

 out the treatment. So far as I have been able to learn the 

 details, the intervals between the applications were apparently 

 so long as to leave the plants unprotected for a time in each 

 interval. One of these periods of exposure coming in 

 weather favorable to the spread of the fungus would be 

 quite sufficient to account for the result ; for, as has been so 

 often said, a ])lant once infcctc^d is lost. The secret of 

 imnumity lies in conq)U3te i)rotection of the })lants against 

 infection. A word more may not be out of })lace here. It 

 is a common })ractice of growers of violets to keep them 

 in activity during the entire year, forcing the vegetative 

 growth during the summer and fall, and forcing the blossoms 



