l8o MAINE AGRICULTURAL LXPPERIMLNT STATION. I909. 



of these recommendations suggested is to lay particular stress 

 upon the clause "or later if necessary." In ordinary years the 

 tops are killed by frost early in September and there is enough 

 spray still adhering to them to furnish adequate protection till 

 this takes place or the crop is dug. This year the tops were 

 partially killed late in August but much of them were untouched 

 till digging time. As a result of inefficient spraying, combined 

 with excessive washing of rain, these were slowly dying of 

 blight all through September and showering millions of spores 

 onto the water-soaked soil, which resulted in an abnormal 

 amount of tuber infection. Hence, the tops should be protected 

 by spray up to the day they are killed by frost or the crop is 

 dug, particularly in rainy seasons. As far as late blight is con- 

 cerned some of the earlier sprayings might be dispensed with, 

 but these early sprayings are necessary as protection against 

 the early blight and ravages of the flea-beetle. 



SPRAYING IS effective;. 



Spraying must be looked upon as a form of insurance but 

 records covering a series of years show that it is the most 

 profitable kind of insurance. Long continued experiments at 

 the New York and Vermont Experiment Stations show that 

 spraying is seldom conducted at a loss, after allowing for time 

 and materials, and frequently it is the means of saving a large 

 per cent of the crop. Records of yields of sprayed and 

 unsprayed plots side by side covering a period of 17 years show 

 an average increase of 113 bushels per acre or 68 per cent as 

 a result of spraying. The greatest increase in any one year 

 was 224 bushels and the least was 32 bushels per acre.* The 

 writer upon Commissioner Oilman's farm in Foxcroft in 1907 

 secured an increase over unsprayed plots of 231 bushels of 

 sound tubers per acre from 6 double sprayings, 162 bushels 

 from 6 single sprayings, and 186 bushels from 3 double spray- 

 ings plus one single spraying. He also secured from 6 double 

 sprayings on the John Watson farm at Houlton 420 bushels of 

 sound tubers on a measured acre with no decay following in 

 storage, while fields in this vicinity either unsprayed or less 

 thoroughly protected were showing from 25 to 75 per cent of 



Jones, L. R. and Giddings, N. J., Vt. Exp. Sta. Rep. 20, p. 339 (1908). 



