Diseases of the Potato. 313 



until the period of active growth is passed, or until the plants have 

 become weakened by some mechanical agency. 



The first step towards checking the trouble, therefore, is to main- 

 tain the plants in as vigorous condition as possible. Proper ferti- 

 lization, abundant cultivation, and close attention to the welfare of 

 the plants become matters of prime importance. The selection of 

 suitable land in favorable localities, and its thorough preparation 

 will also prove of material benefit. This disease is an excellent 

 example of the theory that disease in plants is not the prime cause 

 of injury, but rather only an indication or symptom of weakness 

 which existed before the injurious organism could gain an entrance, 

 and which in fact must exist before such an entrance can be 

 effected. The idea, however, does not apply so aptly to all cases of 

 the disease. 



The mechanical injuries to potato vines are mostly brought about 

 by insects, and chief among these is the flea-beetle. The methods 

 of treating this pest will be found on page 323. 



The bulk of the injury done by the early blight has been ascribed 

 to a fungus {Macrosporium. Solani) which unduly hastens the 

 destruction of plants that are already on the down-hill side of life. 

 The fungus is widespread and is undoubtedly responsible for much 

 of the injury done to potato crops. 



During the summer of 1895 the writer endeavored to control the 

 early blight by means of thorough application of the Bordeaux 

 mixture. Four plots were selected for the work, I and II being 

 upon the University farm where Professor Roberts kindly allowed 

 me the use of certain portions of the potato field, and materially 

 assisted in carrying on the work ; plots III and lY were upon the 

 farm of H. E. McNair, Dansville, N. Y. By distributing the plots 

 in this manner it was hoped that more accurate and convincing 

 results might be obtained. 



Plot I. — The land selected for the experiment was divided into 

 four sections, each covering an area of a little more than three 

 square rods. Burbank potatoes were planted May 16 in rows 3^ 

 feet apart, the pieces being put in at intervals of 14 inches. At 

 this rate it was estimated that about 10 bushels of seed would be 

 used per acre. 



Notes taken July 5 show that the plants were growing vigorously, 

 and were scarcely troubled by flea-beetle. The first application 

 was made at this time, the four sections receiving the following 



