382 



Journal of Agricultural Research 



Vol. XIX, No. 8 



RESULTS OF PRESOAK TREATMENTS ON NATURALLY INFECTED WINTER WHEAT PLANTED 

 IN THE WHEAT FIELDS OF IOWA AND KANSAS 



The first extensive field trial of this method was made in 191 9 at 

 three places in the middle western wheat belt — Ames, Iowa, and Hays 

 and Abilene, Kans.,* where Kharkoff and Kanred from infected fields, 

 screened and unscreened, was treated and drilled in after two to nine 

 days' drying. The treatments used were (i) presoak copper-sulphate 

 treatment, in which seeds were soaked 10 minutes in water, covered 6 

 hours, soaked K hour in copper sulphate i to 80, limed, dried, and 

 planted; (2) presoak formalin treatment, in which the seeds were soaked 

 10 minutes in water, covered 6 hours, soaked 10 minutes in formaUn 

 I to 320, covered 6 hours, dried, and planted. Notes on the amount of 

 infection on the seedlings were first made four to seven weeks after 

 planting, since infection at this time would represent mostly primary 

 infections due to diseased seed, before general dissemination from infec- 

 tion centers could set in. The results are summarized in Table X. 



Table X. — Preliminary results of presoak treatments of infected winter wheat in the 



Middle West, igiQ 



o A very susceptible variety. 

 * Part of main field. 



e One diseased plant was found; but, judged by its advanced stage of growth, it was a volunteer and was 

 therefore not from the treated seeds. 



The seedlings at the time of observation bore two to five leaves, with 

 infection visible on the first leaf of diseased plants verified by micro- 

 scopic examination. In untreated areas, from 7.8 to 11. 5 per cent infec- 

 tion was present; in treated areas, from o to 0.6 per cent, as shown in 



' The author is indebted to Dr. I. E. Melhus, at Ames, and to Mr. Swanson, at Hays, for cooperation and 

 assistance at these localities. 



