THE POTATO . 175 



in certain areas, the tissues of which die, producing 

 the characteristic brown spots. While in full 

 growth and while the tissues of the host are supply- 

 ing an abundance of food, there are few, if any, 

 reproductive bodies (spores) produced. When the 

 leaves become partially exhausted and dry, spore 

 reproduction takes place freely and the character- 

 istic several-celled spores, formed in chains, occur 

 abundantly. 



"Since the early blight has only recently 

 attracted attention in this state, it is not generally 

 known to our growers. It may, however, be 

 readily recognized and easily distinguished from 

 the late blight and the other potato diseases. 

 Early blight begins to show itself about the time 

 that the blossoms appear, which, with us, is usually 

 in July. More rarely it attacks plants scarcely six 

 inches high. The first indications are relatively 

 small grayish brown spots, which, as they become 

 larger, are marked with faint concentric circles, 

 giving a target-like appearance to them. The 

 spots may increase in size until several of them 

 run together and form large patches of dead tissue. 

 In the course of a few days these spots become 

 brown and withered, while the rest of the leaf 

 takes on a yellowish, sickly color, though the 

 stems may remain green. Sometimes the disease 

 progresses quite slowly and the vitality of the 

 plant is only gradually reduced. In any case, 

 however, the tubers either stop growing entirely 

 or remain so small as to make them of little 

 value. The death of the vines in this way is 

 often mistaken for early ripening and it then 

 occasions a surprise to find that no tubers of value 

 are present. 



"Any injury to the foliage, such as insect bites 



