THE POTATO 317 



Spraying with Bordeaux mixture increases the yield of potatoes 

 through stimulation, and is profitable, except in case of very highly fer- 

 tilized soil, even when no blight prevails. The early blight which is 

 prevalent in the southern tier of our Northern states is not well controlled 

 by spraying, but in cooler latitudes where the late blight prevails spraying 

 should never be omitted. Directions for making the Bordeaux mixture and 

 applying it are furnished by the experiment stations. The only point to be 

 emphasized here is that the spraying should be thoroughly done, insuring a 

 perfect coating of the plants, and that is possible only by use of strong pres- 

 sure and two nozzles to the row when the plants have reached some size. 



Insect Pests. — For white grubs and wire-worms, which may render a 

 potato crop unmarketable, there is no remedy. There is no soil treatment 

 that will kill these pests. The grower should know the life history of these 

 insects and plan his rotation as far as possible for their control. Examina- 

 tion will show whether a soil is infested or not at planting time, and pota- 

 toes should not be planted where serious injury is sure to come. 



The potato beetle is easily controlled by use of arsenical poisons and 

 these should be on the plants when the larvae of the potato beetle are hatch- 

 ing. Two pounds of Paris green or four pounds of arsenate of lead in fifty 

 gallons of Bordeaux will prevent injury by this insect. 



The flea-beetle does great injury not only by impairing the vitality of 

 the plant, but by opening the way for disease attacks. Control is very 

 difficult. The Bordeaux mixture repels for twenty-four to forty-eight 

 hours and to that extent is a help. 



Harvesting the Crop. — An early crop of potatoes when dug for market 

 in hot weather must have careful handling. All cut and bruised tubers 

 should be discarded. If there is reason for not marketing promptly, the 

 crop is safer in the ground than out of it, although excessive wet weather 

 may cause rot. Later varieties, dug usually in the fall when nights are 

 cool, will bear placing in large bulk. 



The best diggers elevate the soil of the row with the tubers and, having 

 sifted the soil back, drop the tubers on top of the fresh surface. Such 

 diggers are relatively expensive and small growers use low-priced diggers 

 that do fairly good work. When good seed is planted in highly fertilized soil 

 the percentage of seconds may be so small that little grading is required, 

 but it never pays to send to market any tubers below merchantable grade. 



REFERENCES 



"The Potato." Fraser. 



"Potatoes for Profit." Van Ornam. 



"The Potato." Grubb and Gilford. 



"Potatoes: How to Grow and Show Them." Pink. 



South Dakota Expt. Station Bulletin 155. "Selection of Seed Potatoes." 



Farmers' Bulletins, U. S. Dept. of Agriculture: 



365. "Farm Management in Northern Potato Sections." 

 386. "Potato Culture on Irrigated Farms of the West." 

 407. "The Potato as a Truck Crop." 

 533. "Good Seed Potatoes and How to Produce Them." 



