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 slightly. 

 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- 



Jg^ ters are lost. Fruit, after it 



^f^\ ^^ is picked, may also succumb 



^[\ ^^ytw to attack, and peaches that 



T^BflH^B were apparentl}^ sound at pick- 



^S^^^^K^B^ ing may be seriously damaged 



UjH^^^^^^^^V when they reach market. Thus 



^^^^^^^^^^^Hf the loss falls upon grower, 



^^^^Hj^^H^ dealer, and consumer. The 



^^^Hppj^^ decay is so rapid that infection 



■■ 1 to-day may mean a totally un- 



FiG. 55. — Mummy peach showing 

 Sclerotinia ascophores. After 

 Scott. 



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 famihar 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 mth frost effects. From 

 the flower the rot may spread to adjacent twigs, through 



