22 



Diseases of Economic Plants 



and Australia, and may 

 be regarded as of world- 

 wide distribution. The 

 first account of it in 

 the United States was 

 made by Pamrael in 

 1891. Since then nu- 

 merous bulletins deal- 

 ing with it on various 

 hosts have been pub- 

 lished. It is quite in- 

 different to its hosts, 

 embracing especially 

 members of the pink, 

 crucifer, legume, po- 

 tato, and sunflower 

 families and in all about 

 fifty families of plants 

 including conifers and 

 ferns. Some 165 spe- 

 cies and varieties of 

 host plants are re- 

 corded. Among these, 

 the most important in 

 America are : potato, 

 beet, lettuce, bean, cel- 

 ery, carrot, cabbage, 

 eggplant, tomato, 

 sweet potato, cucum- 

 ber, watermelon, pump- 

 kin, squash, pea, corn, 

 radish, rhubarb, alfalfa, 

 clover, buckwheat, to- 

 bacco, cotton, aster, 

 carnation, violet, 

 cherry, raspberry, currant, pine. If conditions favora- 

 ble to its attack obtain, the fungus may well be ex- 



FiG. 5. 



Corticium on cabbage. 

 Peltier. 



After 



