igoy.] DISEASES OF THE POTATO. 219 



present types. There is a demand for a machine that will do 

 good work on large fields and do the work quickly, and at the 

 same time do it thoroughly. 



Now I planned some experiments this year with reference 

 to the potato blight, but the experiments were very unsatis- 

 factory because there was less of the blight and less of the rot 

 than in any of the four years. My experiments, this year, 

 therefore, do not show what I wanted to bring out, because of 

 the lack of cause of the rot in the tubers. 



I am studying potatoes from two points of view, — first, 

 to find out everything I can in regard to the fungus without 

 any reference whatever whether it is of practical or impractical 

 importance, and, secondly, to see if there are any modifications 

 that I can make in our method of treatment of fungus disease. 

 I have found out a good deal about the fungus, but there are 

 some points that may have escaped me, as others have worked 

 on them and have not discovered them. 



Now as to the practical part of the thing, the spraying, I 

 am testing different ways and different kinds of spray. So 

 far, it has all practically come down to this point, that you 

 must do your spraying thoroughly and at the proper time. If 

 that is done, you may expect an increase of a moderate amount 

 such as we had this season. It is more difficult, or rather per- 

 haps I should say that it has been my experience, that it is 

 more difficult to prevent the rot of the tubers than it is the 

 blight of the vines. The rotting of the tubers, as I understand 

 it, from my experience, comes about by the spore of the blight 

 being washed on to the tuber, and under favorable conditions 

 of moisture, producing the rot in the tubers. Therefore, if 

 you can keep the blight off the vines, there is no danger of rot 

 to the tubers. Still, differing conditions sometimes alter cases. 

 Where the vines rot suddenly, the rot will sometimes reach the 

 tubers below. I think that may be due to the fact that the 

 blight has only been there for a short period of time and then 

 a rain has come on, or some other reason has arisen which has 

 carried the rot down to the tubers. We all know that seasons 

 differ very much as to the amount of rot which is produced, 

 but some seasons where the blight on the vines has not been 

 so serious the rot on the tubers has been much greater. I 

 think when that is the case that they have had this a long time, 

 and that it has fallen down from the leaves. This year we had 



