EXPERIMENT STATION BULLETINS. 353 



If potatoes are planted by hand, a good implement with which to open the 

 furrows is a wing shovel plow. Such a plow makes the furrows narrow at the 

 bottom and the seed pieces can be planted in a straight line. The furrows 

 should be opened just before the seed is dropped and should be covered at 

 once, so as to keep the soil cool and moist and to prevent the seed pieces from 

 being exposed to the sun and wind. The seed may be covered with a hoe or 

 with a shovel plow. 



CULTIVATION 



Shortly after the field is planted it should be gone over with a spike-tooth 

 harrow or a drag, lengthwise of the rows. This operation should be repeated 

 several times before the plants get well above the ground, so that weeds and 

 grass will be killed and a soil mulch maintained. 



When the plants are large enough so that the rows can be easily seen, a cul- 

 tivator should be used. The first cultivation should be deep and quite close 

 to the plants. Frequent cultivations must be given to keep down weeds and 

 grass and to provide a soil mulch. Each subsequent cultivation should be 

 shallower and farther away from the plants than the one preceding it. By 

 the time the plants are eight to twelve inches high, their roots extend well 

 into the middle of the rows, and deep cultivation will cut many of the roots 

 and reduce the yield. Cultivation should ordinarily cease after the plants 

 are in full bloom and the tubers have set. 



The riding or sulky cultivators are often preferred over the one-horse 

 walking cultivators since they can be regulated to work at a uniform depth, 

 and generally do less damage to the potato roots than the walking type of 

 cultivator. 



On light soil that is comparatively free from thistles, etc., narrow or peg- 

 teeth are generally used. On heavier soils and on those in which there are 

 serious weeds, wider teeth should be used. 



On soils that are well drained, level cultivation is usually preferable to 

 ridging or hilling the potatoes. The ridging method is used to some extent 

 in the Upper Peninsula where there is ample rainfall, but in sections where 

 drought is of common occurance soil that is ridged dries out more quickly 

 than soil that is kept level, with the result that the yield is often greatly 

 reduced. 



SPRAYING 



The green leaves of the potato plant are largely responsible for the develop- 

 ment of the tubers, for it is in the green leaves that starch and other elaborate 

 food substances that go into the making of the tubers are made. In a large 

 measure, the yield of potatoes is limited by the amount of healthy green leaf 

 area that the plant possesses. If insects or fungous diseases destroy even a 

 small portion of the green leaves, the yield of potatoes will be materially 

 reduced. 



The green leaf area can be saved from the ravages of insects and diseases 

 that attack the foliage by spraying the plants thoroughly with arsenicals, 

 bordeaux mixture, etc. 



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