62 THE BOOK OF ALFALFA 



DANGERS OF INOCULATION BY SOIL TRANSFER 



Touching upon the dangers possibly resulting from 

 inoculation by soil transfer a bulletin from the United 

 States Department of Agriculture has this to suggest : 



"Satisfactory inoculations have been obtained by trans- 

 ferring soil from old fields on which the legume has 

 been grown, but experience has shown that there are 

 dangers incident to such methods of soil transfer which 

 it is wise to avoid. 



"The source of supply of such soil should be definitely 

 known, and in no case should soil be used from fields 

 which have previously borne any crop affected with a 

 fungous disease, a bacterial disease, or with nematodes. 

 Where a rotation of crops is practiced, it is often difficult 

 to make sure of this factor, so that the method of soil 

 transfer is, under average circumstances, open to sus- 

 picion, if not to positive objection. Numerous animal 

 and plant parasite live in the soil for years, and are 

 already established in so many localities that it is mani- 

 festly unwise to ship soil indiscriminately from one por- 

 tion of the country to another. 



" The bacterial diseases of the tomato, potato, and Ggg 

 plant, and the club-root, brown rot, and wilt disease of 

 the cabbage, all more or less widely distributed, are read- 

 ily transmitted in the soil ; while in the South and West 

 there are the wilt diseases of cotton, melons, sweet pota- 

 toes, cowpeas, and flax, and various nematoid and root- 

 rot diseases which might easily become a serious menace 

 over areas much larger than they now occupy if delib- 

 erately spread by the careless use of soil for inoculation 

 purposes. There are several insects and fungous 



