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DISEASES OF ECONOMIC PLANTS 



recognize it easily. It first appears as small, circular, brown, 

 decayed spots. These rapidly enlarge until they embrace 

 the whole fruit, which at the same time shrinks shghtly. 

 As the decay advances, small tufts of brown threads appear 

 near the centers of the original spots, and spread rapidly 

 until the whole fruit is covered with them. 



If the fruit hangs in clusters, adjacent fruits begin to 

 decay at the points of contact, and the disease spreads from 



fruit to fruit until whole clus- 

 ters are lost. Fruit, after it 

 is picked, may also succumb 

 to attack, and peaches that 

 were apparently sound at pick- 

 ing may be seriously damaged 

 when they reach market. Thus 

 the loss falls upon grower, 

 dealer, and consumer. The 

 decay is so rapid that infection 

 to-day may mean a totally un- 

 salable peach two days hence. 

 Peaches diseased on the tree 

 may fall to the ground, or 

 remain on the tree, where they shrivel and hang over winter, 

 to constitute the " mummy " peaches so familiar in infected 

 orchards. 



Upon the blossom the disease is first evident as a slight 

 brownish discoloration which spreads rapidly, causing the 

 flower to wither and eventually fall off as a rotten mass, 

 carrying contagion to everything in its path. This damage 

 to the flower is often confounded with frost effects. From 

 the flower the rot may spread to adjacent twigs, through 



Fig. 55. — Mummy peach showing 

 Sclerotinia ascophores. After 

 Scott. 



