68 BOARD OF AGKICULTUEE. [Pub. Doc. 



Touching the question of resistant varieties of potatoes, 

 resisting blight, I want to say a word. For the last eight 

 or nine years perhaps, we have had at Amherst, grown 

 under my direction, a good many varieties of potatoes, 

 grown on a small seale, for the purpose of testing their 

 value. Several years we have had as many as eighty sorts, 

 and Ave have observed them elosely, and we have not found 

 a very wide degree of difference in respect to variety when 

 this early blight takes hold of them. AVe find a difference 

 in the date when the foliage of different varieties is affected, 

 but when grown side by side it is not long before they are 

 all gone, and I do not think there is very wide difference in 

 the amount of damage. There are possibly a few excep- 

 tions. We have found a few varieties which were peculiarly 

 susceptible to injury. I should say our experience would 

 prove that there are no varieties which are able to resist it 

 altogether. 



On the question of seab and the persistence of the spores 

 or fungus in the ground where you have once had a seabby 

 crop, we have made an observation this year which is of in- 

 terest ; although I would not have you conclude, after hear- 

 ing it, that it would be perfectly safe for you to go ahead 

 and plant potatoes in ground where you have recently had a 

 seabby crop. 



There is on our ground a piece of land notorious for seabby 

 potatoes. Some eight or nine years ago Dr. Goessmann used 

 it again and again in experiments, for the purpose of trying 

 to discover some method for preventing seal). This was 

 when Dr. Humphrey, whom some of you may remember, 

 was at the college, and the experiments were carried out by 

 Dr. Goessmann and Dr. Humphrey together. Later, some- 

 thing like five or six years ago, I should say, speaking from 

 memory, I had the same piece of land used in this experi- 

 ment, testing the theory which has just been advanced by 

 the State of New Jersey, — that sulphur prevents scab, even 

 in ground where potatoes were ordinarily scabby. We used 

 sulphur without any apparent effect. The potatoes were 

 all scabby, almost all of them, whether we used sulphur 

 or not, and we could not see that there was any particular 



