98 THE NEW ONION CULTURE 



and its consequent transportation from one part of a 

 field to another or to different fields ; an agency by no 

 means unimportant. Thirdly, the smut spores may 

 be readily washed with surface earth from higher to 

 lower ground, as is a matter of common observation. 

 Fourthly, popular opinion to the contrary, the spores 

 being practically imponderable may be readily blown, 

 with other dust-like material, either about the same 

 field, or into adjoining fields. The reason that this 

 mode of dissemination is of less importance than some 

 others, lies probably in the fact that the spores being 

 formed and making their exit from the onion com- 

 paratively near to the ground, are readily washed into 

 it by rain, and have little opportunity for blowing 

 directly into the air, as is the case with corn smut, 

 for example. 



It may be mentioned here that the smut appears 

 to be very attractive to the "flea beetles," which swarm 

 over the ruptured parts of diseased seedlings and ap- 

 parently feed upon the spores, although they do not 

 seem to trouble the healthy onion leaf. That these 

 or other insects may serve to spread the smut, in a 

 way similar to that observed in some other fungi, is 

 not impossible. 



General Precautions — Attention should perhaps 

 be called here to a few general precautions which may 

 be of service against the Urocystis, the most important 

 of which have already been referred to in connection 

 with its dissemination by farm implements, etc. Such 

 implements should never be used on smutted ground 

 and then upon new ground, without thoroughly wash- 

 ing off all adhering earth. The same may be said in 

 regard to any means by which smutted earth may 

 be transported. 



All refuse of whatever kind that is left on the 

 field should be burned as soon as practicable, and 



