No. 4.] FUNGOUS DISEASES. 103 



potutoes, — not all of them, of course, for in that case 3'ou 

 will know no more regarding the efficacy of spraying at 

 the close of the season than at its beginning. You must 

 have a basis of comparison, and that basis must be a portion 

 of your own field which you leave unspra\'ed. Make the 

 test a thorough one, even if it costs a little more to do so ; 

 note carefully every item of expense connected with the ex- 

 periment ; compare the product ; note the exact compara- 

 tive yield ; keep a record of the cash received for every peck 

 of potatoes from that field. To the keeping of such an ac- 

 count spraying lends itself more easily and accurately than 

 any other farm operation ; and within three months after the 

 close of the season you will know to a dollar the net result 

 of spraying potatoes on your land and in that particular sea- 

 son ; and you will have learned in one year more than any 

 human being could teach you in ten. 



With this advice I must close, only urging you, in conclu- 

 sion, to bear in mind the main features of what I have told 

 you regarding the fungous diseases of plants : that they are 

 not mysterious agents of destruction, with no attributable 

 origin, but are plants of definite and known habits, which 

 prey upon their higher relatives ; that, like weeds, they 

 propagate and spread if not destroyed ; that by cleanliness 

 and care the damage which they do can be lessened ; and, 

 finally, that by the intelligent use of fungicides they can in 

 many cases be practically controlled, to the great advantage 

 of the farmers' pocket-book. Accept with hesitation the 

 suggestions of others, but, if they commend themselves to 

 your own judgment, test them for yourselves, and spare no 

 pains to make the test a conclusive one from a business 

 stand-point. 



Mr. B. P. Ware (of Marblehead). We have had one 

 of the most instructive and practical lectures on this sub- 

 ject that I have ever listened to. I would like to draw 

 attention to the wonderful intelligence that appears from 

 that little black spot, the onion smut. I have unfortunately 

 had a good deal of experience with onion smut, and can 

 testify that these spores will remain year after year in the 

 soil, and when onions are grown again they will appear. 



