130 POTATOES AND POTATO CULTURE 



tion after the plants have become well established causes untold 

 injury to the roots feeding in the top soil. 



The amount of hand hoeing necessary will depend upon the 

 thoroughness of the above operations and the amount of grass 

 and weed seeds in the soil. If the weeding and cultivating has 

 been faithfully done, the only necessary hand work should be in 

 the removal of the scattering weeds along the row. 



Diseases. 



The principal diseases are the early and late blight and scab. 



The early blight usually appears from the middle to the latter 

 part of July, during hot, dry weather, and causes a premature 

 dropping of the foliage, but is unattended by rot. 



The late blight usually appears in August, and spreads very 

 rapidly during warm, moist weather. Its attacks are sudden 

 and destructive, and are usually accompanied by rotting of the 

 tubers. 



The above diseases may be prevented by thoroughly spraying 

 with Bordeaux mixture. The first spraying application should 

 be made when the vines are 8 to 12 inches high, which with the 

 late varieties will be about July 15th. The number and fre- 

 quency of later sprayings will depend largely upon the weather. 

 Usually four to five times will be sufiicient, unless washed off 

 by heavy rains, the object being to keep the vines covered with 

 the mixture at all times after the first spraying. To destroy 

 the potato beetle, J to i pound of paris green should be added 

 to each 50 gallons of mixture. To prevent the scab, avoid con- 

 taminated land and seed, also excess of fresh stable manure. 

 Seed that is affected, and smooth tubers that have been selected 

 from aftected stock, should be treated with formalin or corrosive 

 sublimate solutions before planting. 



A preparation known on the market as Bug Death has been 

 widely recommended as a fungicide and insecticide, but after 

 giving it several trials we have been unable to obtain results 

 that would warrant its general use as either. More extensive 

 trials are contemplated during the coming season. 



Acknowledgment. Figures 4, 5, 6, 7, and 8 are from photo- 

 graphs loaned us by Burton A. Corbett, B. S., of Colebrook, 

 N. H., a seed potato specialist, and are good representations of 

 the respective varieties. 



