V>. L] MODERN POTATO CULTURE. 59 



A few days after planting, the field should be harrowed 

 with a fine-toothed harrow. This is the bej>iiniino- of the 

 soil mulch which it is important to keep over the land 

 during the growing season so as to conserve the moisture. 

 Furthermore, this first harrowing will kill the weeds which 

 are beginning to germinate. It sometimes is practicable to 

 harrow a second time before the potatoes are up. After the 

 potatoes are through the ground the horse weeder can be 

 used once to advantage. A tine-toothed cultivator should 

 be used between the rows throughout the growing season, 

 until the vines practically cover the ground. This can 

 ordinarily be used to advantage as frequently as once in ten 

 days, and should always be used after a rain of sufficient 

 amount to compact the surface soil. It will, of course, be 

 necessary to narrow^ up the cultivator as the vines begin to 

 spread. 



The fighting of insect and fungous enemies is as important 

 as any other part of potato culture. The application of an 

 arsenical poison is the only reliable inexpensive method for 

 fighting the insect pests, and Bordeaux mixture is the only 

 sure preventive of the blight. As soon as the potatoes are 

 three or four inches in height the} r should be sprayed with 

 Bordeaux mixture and Paris green (formula 3), or Bor- 

 deaux mixture and lead arsenate (formula 3a), repeated 

 as often as the plants make five or six inches of addi- 

 tional growth. When the danger of the Colorado beetle is 

 passed, Bordeaux mixture alone (formula 2) can be used. 

 The spraying should be continued as long as the potatoes 

 continue to make rapid growth. To ward oft' the blights it 

 is necessary that each leaf be protected so far as practicable 

 with a coating of copper. 



Spraying is the most effective method of applying insecti- 

 cides and fungicides. To obtain the best results the material 

 must be forced through a proper nozzle so as to make a very 

 fine mist. On small fields a force pump, a hose, nozzle and 

 a barrel for holding the spraying mixture, and a wagon for 

 carrying the above, would constitute the necessary spraying 

 outfit. This form of an outfit can be used not only for 

 spraying potatoes but also used on fruit trees. In large 



