POTATO DISEASES "IN 1907. 297 



those which were dusted. As near as could be judged 30 per 

 •cent to 50 per cent of the foliage on the wet sprayed portion was 

 alive and practically none on the dusted portion when the freeze 

 •came. 



Relative Efficiency of Light and Heavy Spraying : 

 Frequency of Spraying. 



While the losses from early blight are not so marked as from 

 late blight, and often pass unnoticed, careful observations show 

 that, especially in dry years, this fungus does much damage 

 even on what are generally considered well-sprayed fields. The 

 examination of a large number of fields in Aroostook County 

 in the late summer of 1906 indicated that early blight, was not 

 controlled to any great extent by the methods of spraying com- 

 monly practiced there. Since in the experience of the writer a 

 moderate number of thorough, heavy sprayings gave ample pro- 

 tection against this fungus,* it seemed best to test the matter 

 on a large scale in two different parts of the State. The places 

 selected were Houlton, Aroostook County, near the eastern bor- 

 der, and Foxcroft, Piscataquis County, near the center of the 

 State. The former on the John Watson farm and the latter 

 on Commissioner Gilman's farm, being a continuation on the 

 south of the field described under the dusting experiment. 



On account of the nature of the season very little early blight 

 developed, but the results secured furnish some interesting data 

 with reference to how often and how thoroughly we should 

 spray for late blight. 



Plots were selected on each field as nearly as possible to an 

 acre in size. Plot 1 to be double sprayed 6 times (twice on the 

 same date going in opposite directions on the row). Plot 2 

 to be double sprayed 3 times and Plot .3 to be single sprayed 

 6 times. In practice this going over the ground twice for the 

 double spraying would be avoided by doubling the number of 

 nozzles to the row, so arranged that half pointed slightly to 

 the front and half to the rear, taking care that the cones of the 

 spray are so adjusted and directed as to cover the entire width 

 ■of the foliage on the row. Thus the labor for the 6 double 

 applications would be no more than for 6 single. If the extra 



Vt. Sta. Rep. 18, p. 275 (1905). 



