206 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



pines, were successful in reducing the disease to a negligible mini- 

 iniini or even entirely excluding it on small controlled areas. 



Tlu> I'esults of (his i-esear h are being prepared foi" ]inblic;itl<>n. the 

 lirst j)aper in the series ha\ ing been issued. 



CEREAL SMUT INVESTIGATIONS. 



These investigations were conducted in cooperation with the agri- 

 cultural experiment stations of the States mentioned in the text. 



UUNT. OR STINKING .SMUT, OF WIIKAT. 



W/)eat varieties resistant to hunt. — An extensive series of wheat 

 varieties w'as sown in .smut nurseries located at Pullman, Wash., and 

 Moro, Oreg. All the seed was inoculated with spores of Tilletia 

 trltic?', the common species in that section of the country. Practically 

 all the wheat varieties under experiment proved susceptible, a few 

 showing 100 per cent of infection. On the other hand, a few varie- 

 ties — notably Florence, Wardoo, Kanred, Kharkov, and AVhite 

 Odessa — showed a high degree of resistance. Numerous selections 

 of different varieties belonging to the Crimean or hard winter wheats 

 also shoAved low i)ercentages of infection. The prospect of develop- 

 ing resistant varieties is very promising. 



Seed hijuvTj resulting from treatment against hunt. — Experiments 

 in controlling bunt by various methods of seed treatment were under- 

 taken at field stations in Xew York, Virginia, Texas, Kansas, Mon- 

 tana, Washington, Oregon, and California. The usual treatments 

 with copper sulphate and foi'maldehyde were xQvy effective, result- 

 ing in the control of bunt and increased yields from the treated seed 

 compared with untreated checks. Treatment by the dry formalde- 

 hyde method, however, has not been satisfactory, due partly to 

 resulting seed injury and partly to failure to control bunt. 



In the semiarid West severe injury to the vitality of seed wheat 

 frequently follows treatment against smut. This injury has been 

 investigated and the cause determined. The principal factor is 

 found to be the cracking or chi])ping of the seed coats of the ker- 

 nels in thrashing. Under dry-land conditions the seed coats are 

 much more brittle than under humid conditions, Avhich accounts for 

 the occurrence of this injury in the West. When wheat seed Avith 

 mechanically injured seed coats is treated with copper sulphate this 

 chemical may kill the embryo by penetrating through the broken 

 seed coat. Such injury may be prevented in part by dipping the 

 treated seed in a lime solution to neutralize the copper sulphate 

 remaining on or in the seeds. 



The commonly used formaldehyde treatment also has resulted in 

 severe injury to wheat seed in the West. This injury is found to be 

 due to the drying of the kernels after treatment rather than to the 

 treatment itself. Under certain conditions of drying, the formalde- 

 hyde present on the seeds is precipitated as paraformaldelwde. 

 AVhen the seed is sown, the paraformaldehyde passes back into solu- 

 tion and causes the injur3\ If treated seed is thoroughly rinsed in 

 ■water, no injury occurs. 



LOOSE SMUT OF WHEAT. 



Further progress has been made in the development of central 

 treating stations w^here the farmer may bring his seed wheat for 



