44 SPRAYING CROPS 



seasons. In 1891, a single application, made August 

 20, was sufficient on a piece of late potatoes, while 

 in 1892 three applications were necessary. In general, 

 we should plan for making three applications on all 

 except very early or very late potatoes. These three 

 applications will require from 200 to 500 gallons of 

 the mixture on the average 400 gallons used (in 

 Vermont) as follows: 100 gallons per acre the last 

 of July, 150 gallons per acre the middle of August, 150 

 gallons per acre the last of August. This estimate is 

 for a field planted about May 15 to May 20, and 

 which will yield 200 bushels per acre. In our work it 

 has taken (for three applications) about 2 gallons of 

 mixture per bushel of yield. On early potatoes a 

 fourth application may sometimes be necessary to keep 

 off the early blight, the first application being made 

 the first week in July; in this case it will take about 

 2J/2 gallons per bushel of yield. The mixture costs 

 us about % cent per gallon, as follows : 



5 pounds blue vitriol at 7 cents ..................... $o 35 



5 pounds lime at ^ cent ............................. 



Total cost of 50 gallons weak mixture .......... $o 



"As most potato growers have to pay a little 

 more than this for blue vitriol, one cent per gallon is 

 about the average cost. The cost of applying also 

 varies much, depending upon luxuriance of growth 

 of plants, and upon apparatus used. In our work, 

 with a barrel pump, three men and one horse have 

 sprayed an acre well in two hours, when water was 

 convenient, or at the rate of five acres per day, making 

 the expense of labor about $i per acre. Others with 

 similar apparatus have said they could cover ten 

 acres a day." 



