12 



This shows that although the scab on the treated plots was not 

 wholly prevented, it was greatly reduced. The seed which was 

 xevy badly scabbed was not washed previous to treating it, and 

 possibly the solution of corrosive sublimate did not penetrate to 

 all parts of the scabby patches. 



It would not be advisable, of course, to plant scabby seed even 

 with this treatment, if clean seed could readily be obtained ; but 

 it is difficult to obtain seed in regard to which one can be cer- 

 tain that it is not more or less contaminated, for small patches 

 of scab are easily overlooked. Tubers absolutely free from 

 scab themselves, if selected from a biu in which there are a few 

 scabby ones, would be liable to carry germs iu the dirt adhering 

 to them. In using such seed it would doubtless be beneficial to 

 wash thoroughly in water aloue, but better iu the corrosive 

 sublimate solution. The relation of fertilizers and conditions of 

 soil to the development of scab has not yet been definitely made 

 out, aside from the fact that they are not the direct cause of it. 

 It seems likely that certain conditions of soil, existing naturally 

 or produced by the use of certain fertilizers, are especially favora- 

 ble to the growth of the scab plant w^hen its germs happen to 

 be present on the seed or in the soil. 



The cost of treating the seed for an acre ought not to exceed 

 $1.50 for both labor and materials. In the above experiment 

 thei'e was a gain of thirty bushels of marketable potatoes per 

 acre on the treated plots. 



As corrosive sublimate is a powerful poison, it should not be 

 used carelessly. 



BORDEAUX MIXTURE 



The Bordeaux mixture is coming to be recognized as the 

 most efficient among the many fungicides which have been tried 

 during the past few years. 



The ingredients of it are copper sulphate, which is commonly 

 known as l)lue vitriol, or blue stone, lime and water. A large 

 number of formulas, differing in the proportion of these ingre- 

 dients, have been published. 



