10 



BULLETIN 1410, U. S. DEPARTMENT OF AGRICULTURE 



to reduce greatly, if not to eliminate entirely, the common types of 

 plant parasites as causal agencies. 



Fig. 8. — Comparison of the growth of tomato plants : A, In soil affected with brown 

 root rot, sterilized ; B, in unsterilized soil of the same kind 



Kotation plat experiments indicate, contrary to expectation, that 

 the more common apparently nonhost plants are much more likely 

 to develop or retain the brown root-rot condition in the soil than the 

 typical host plants. The data on this subject will be presented later. 



