New York Agricultural Experiment Station. 503 



eousequentlj- the one to be recommended is as follows: Make 

 the first application when the plants are from 6 to 8 inches high 

 and repeat at intervals of about two weeks until five or six appli- 

 cations have been made. In rainy seasons it is necessary to spray 

 more frequently than in dry seasons. The Bordeaux mixture 

 should be plainly visible on the foliage all the time. Spray 

 thoroughly. 



Since blight (late blight) appears on Long Island perhaps not 

 oftener than one year in four on the average some have expressed 

 the opinion that it will not pay to spray every year to'prevent it. 

 They who hold such opinions overlook the fact that spraying pro- 

 tects the plants not only against the blight (late blight) but also 

 against the early blight which on Long Island is really the more 

 destructive of the two. It will pay Long Island potato growers 

 to spray if the late blight should never appear. 



This leads us to the consideration of the expense of spraying. 

 It is readily seen that the expense must vary with the price of 

 labor and the kind of machinery used. Supposing that a knap- 

 sack sprayer is used, that a man can spray two acres per day, that 

 the price of labor is |1.35 per day and that 90 gallons of mixture 

 are used per acre, Mr. Hunn* places the cost of four sprayings at 

 ^0.50 per acre or $1:62 for each spraying. Prof. Galloway, Chief 

 of the Division of Vegetable Physiology and Pathology, U. S. 

 Department of Agriculture, makes a lower estimate. He says,t 

 " With suitable apparatus and labor estimated at |1.50 per day, 

 potatoes may be sprayed six times for about $6 per acre. This 

 estimate is based upon experiments extending over several years 

 and includes the cost of chemicals as well as of labor." The dif- 

 ference between these two estimates is due chiefly to a difference 

 in the kind of apparatus used. The treatment with the knap- 

 sack spraj'er involves a greater expense per acre. However, all 

 agree that the expense is small as compared with the increased 

 value of the croj). 



♦Hunn. C. E., Bordeaux Mixture Used to Prevent Potato Blipht. Eleventh Ann. Rept., 

 N. Y. Agrl. Exp. Sta., 1893. p. 698. 



t Galloway, B T.. Some Destructive Potato Diseases : What They Are and How to Prevent 

 Them. U. S. Dept. of Agriculture, Farmers' Bulletin No. 15. p. 7. 



