3S6 Journal of Agricultural Research voi. xvni. no. 7 



These symptoms are typical of seedling infections from the scab organ- 

 ism. The seedlings from the wheat of both varieties treated by the dry- 

 heat method were free from any indication of disease (PI, 49, B, at right). 



FIELD SOWINGS AND RESULTS 



Field sowings were made of all the seed lots of the barley, wheat, rye, 

 and oats treated in experiments 3 and 4, as listed in Table IV. The 

 sowings were made in an isolated place on the university farm at Madison, 

 Wis. Seed from each lot was sown in from one to five rows, each 150 

 feet long and about 1 2 inches apart. Care was taken throughout to avoid 

 contamination of seed from any source. In order to prevent secondary 

 infections from other fields no similar grains, not even the control seed- 

 lings, were grown within about ^ mile of this plot. The control seedings 

 of a complete parallel series of untreated seed lots were grown in another 

 field of similar soil type, elevation, and exposure. The plants, both 

 from the treated and untreated seed lots, developed normally; and good 

 stands resulted except from the Preston and Kubanka wheats. These 

 stands were thin. 



While the results with regard to disease on plants from the dry-heat- 

 treated seeds were in certain respects disappointing, yet in others they 

 were rather encouraging, and in still others they were very satisfactory, 

 as shown by the following brief account. 



Bacterial blight of barley. — The bacterial blight of barley (Bac- 

 terium translucens, J. J. R.) was controlled perfectly by the dry-heat 

 treatment as used, not even the slightest trace of this disease being 

 noted in the plot from the treated seed, though the seed was known to 

 be heavily infected. The corresponding plot from untreated seed, on 

 the other hand, showed abundant infections with the disease. 



The perfect control of the bacterial disease of barley is highly signifi- 

 cant. The results were very definite and striking — perfect control in 

 the treated plots and abundant disease in the untreated plots. Fur- 

 thermore, there are indications that this bacterial organism of barley is 

 more resistant in the seed than is that of bacterial disease of wheat 

 known as "blackchaff." The above results would indicate the very 

 strong likelihood that this dry-heat treatment will prove highly efficient 

 in controlling the "blackchaff" of wheat. The data given above show 

 definitely that wheat of good quality will stand the treatment. 



Bacterial blight of oats. — The perfect control of the bacterial 

 blight of oats (Pseudomonas avenae) was equally definite. It was the 

 more striking because this disease was general throughout southern 

 Wisconsin during the season of the experiment (191 8). In fact, while 

 numerous fields were examined, the only field of oats noted where this 

 bacterial disease could not be found was the plot sown from dry-heat- 

 treated seed. The untreated plot showed abundant infection with the 



