CEREAL PESTS PARASITIC FUNGI 525 



shown the increase in smut that will occur in barley, in 

 2 years, without treatment. 



After any treatment the seed must not be allowed to 

 sprout or mold, and should not be exposed to a freezing 

 temperature while still swollen. In sowing allowance 

 must be made for the swelling of the seed by sowing more 

 to an acre. All sacks and bins must be kept thoroughly 

 disinfected. All new seed, after removal of weed seeds, 

 should be treated for smut. 



567. Smut in the soil. Even for bunt the treatments 

 above described are only of value where there is a smut- 

 free soil. In the Columbia Basin district, where much 

 of the harvesting is done with the header and combined 

 harvester-thrasher, or even where the self-binder is used, 

 it has been determined by actual count that as high as 

 34,800 smutted spikes to an acre have been left on the 

 field. These spikes, on being broken by the disk harrow 

 and other implements, are the direct means of distributing 

 myriads of viable smut spores in the soil, ready to infect 

 the new seed when germinated, without regard to seed 

 treatment. As these machines cut high, and the smutted 

 plants are short, it is easy to miss them in harvesting. To 

 clear the soil of these spores, crop rotation must be sub- 

 stituted for continuous cropping and summer fallow. 



568. Loose smut of wheat ( Ustilago tritici, Rostr.). - 

 One reason that progress in treatment for cereal smuts 

 has not been more rapid is that we have not been in pos- 

 session of the facts about their life histories. For many 

 years it was supposed that this smut and the naked smut 

 or barley were capable of infecting the host seedling or 

 were able to infect the blossoms in such a way as to result 

 at once in the formation of smutted ovaries. The thor- 

 ough researches of Brefeld and Hecke revealed the true 



