New York Agricultural Experiment Station. 919 



effect of thoroughness it is necessary to do the work on farms where 

 all conditions, except the spraying, are such as the average farmer 

 would meet. 

 Work at Rush Accordingly arrangements were made by which 

 the Station secured the right to spray one-fiftieth 

 of an acre in each of many potato fields near Rush. The Station 

 employed a man (a Cornell student, during his summer vacation) 

 to measure the required area in each field and to spray the vines 

 thoroughly every two weeks. As already stated, no bordeaux 

 spraying was done by the owner in 47 of the 66 fields selected ; while 

 in the other 19 fields the Station spraying was in addition to from 

 one to eight treatments by the owner. The Station work was done 

 with a knapsack sprayer, thoroughly and repeatedly, so that five 

 applications were made on late-planted fields and six on those planted 

 earlier. 



■p ,. The season was a very poor one for testing 



any spray treatment, as dry weather restricted 

 growth and prevented development of fungus diseases, while a frost 

 on the night of Sept. 14, when the sprayed vines were still green 

 and vigorous, cut the season short two or three weeks. Very little 

 early blight appeared and no late blight, so that the greatest factors 

 in spray benefit were absent; yet by a somewhat better control of 

 " bugs " in a few instances, some repression of tip-burn and by 

 the little-understood stimulus of the copper sulphate on potato 

 plants, spraying resulted in increased yields in 41 out of 47 unsprayed 

 fields and in 15 out of 19 of those sprayed more or less frequently 

 and thoroughly by their owners. The average net gain, as measured 

 by the difference between the actual weighed yield of the sprayed 

 row and of an equal length of check row beside it, was at the rate 

 of 17| bushels per acre where no spraying was done by the owner 

 and 15 bushels where the owner sprayed and the gain came from 

 the added applications or more thorough work in the Station spraying. 

 T s<;n of These tests confirm the belief gained from 



.« , . x previous potato spraying experiments, that this 

 operation is seldom performed at a loss and is 

 generally very profitable. Certainly conditions would rarely be as 

 unfavorable for showing benefit from spraying as in these cases, 

 yet in probably more than one-third of the fields there was a finan- 

 cial profit from the spraying, no gain or very slight loss in another 

 third of the fields, and a small loss on most of the remaining fields. 

 This applies with almost equal force to sprayed and unsprayed 

 fields. 



The work also enforces the necessity for careful, thorough and 

 repeated applications if the greatest benefit is to be secured; for 

 there was apparently, in this dry season, little gain from much of 

 the spraying done by the growers themselves. 



