188 DISEASES OF ECONOMIC PLANTS 



trance through slight imperfections of the skin at the navel 

 end and make rotten areas under the skin. 



All diseased fruit should be collected and burned or 

 buried deeply. 



Scab {Cladosporium elegans Penz.). — The scab has been 



Fig. 81. — Scab of the sour orange. After Hume. 



known for twenty years, and occurs on the sour citrus fruits 

 such as the pomelo, kumquat, and sour orange, though its 

 presence on the last is of little importance. 



The disease attacks the young leaves, twigs, and fruit, 

 and causes them to produce conspicuous, warty, corky 



