390 Journal of Agricultural Research voi. xix. no.s 



Actual soaking in water throughout the presoak period does not appear 

 to be so favorable for wheat-seed treatment as the procedure of soaking 

 lo minutes in water and merely keeping moist for 6 hours. 



For use in farm practice this method does not involve any radical 

 change in present procedure other than to keep the seeds moist for a 

 definite time before treating. In controlling the blackchaff disease of 

 wheat, seeds should first be screened to remove shriveled grain. Then 

 the seeds in sacks or bags, in quantities of not more than ^ bushel each, 

 can be soaked early in the morning in water for lo minutes, drained, 

 and set away in the bags while moist. Six hours later, at about noon, 

 the seeds should be thoroughly soaked for lo minutes in a formalin 

 solution of I pound to 40 or 50 gallons of water, drained, and left in the 

 bags for 6 hours. In the evening the seeds should be spread out to dry 

 overnight and are ready for planting the next morning. 



The use of formaldehyde vapor recently proposed by Thomas {10) for 

 seed treatment, while eminently suitable for the disinfection of small 

 seed lots which are not to be planted immediately, is open to the serious 

 objection of lack of penetration throughout the seed mass and is not so 

 well adapted as the presoak method for the treatment of seeds in large 

 masses in farm practice. His experiments indicate that the vapor, 

 while efficient on surface seeds, does not reach seeds at a depth of K inch, 

 so that these remain as badly contaminated as untreated controls. In 

 the presoak method, every seed is surrounded by a film of the disinfectant 

 acting on the pathogens which previously have been brought into a vege- 

 tative condition by the long exposure to moisture at room temperature. 



The presoak method used with copper sulphate, if efficient for con- 

 trolling the cereal smuts, ^ would be particularly adapted for the grain 

 sections of the Northwest. Extensive soil infection in this area renders 

 the use of copper sulphate preferable to formalin because of its residual 

 germicidal effect; and, as here shown, copper-sulphate injury may be 

 prevented by a 6-hour presoak. 



The general application of the presoak method, extremely simple in 

 itself, to the formalin and copper-sulphate treatments of the cereal 

 diseases amenable to control by seed disinfection should, if the results 

 here recorded are confirmed for other diseases by subsequent careful 



1 A paper by Heald {2), first brought to the writer's attention in Nov. 14, 1919, when these experiments 

 were completed and the manuscript was prepared for the press, shows some interesting data on a somewhat 

 similar method used for treatment of barley smut. Heald soaked barley seeds in water 4 hours, covered 

 them 8 hours longer, then treated them with formalin i to 288 for 10 minutes and then kept them covered 

 2 hours. No statement as to the manner of arrivins at the use of this procedure is made. His figures indi- 

 cate for this treatment ( i) less injury to germination than for any other formalin treatment which he used, 

 (2) effective control of barley smut — 0.93 per cent smut in a plot treated in this manner and 0.73 per cent 

 in a somewhat sim.ilarly treated copper-sulphate plot compared to an average of 33 02 per cent smut in 

 three untreated plats. This corroborates for barley smut the work reported on blackchaff with the presoak 

 method. Heald does not appear to have followed up his work, which was clearly a rule of thumb, nor did 

 he recommend this particular method for general use with other methods. He made no allowance for loss 

 in number of seeds per bushel through swelling, otherwise he must have obtained results which would 

 have indicated to him clearly the importance of the method, since he must then have obtained larger yields 

 than by any other method which he used. Moreover, my method differs from Heald 's in that it gives 

 only a short plunge'n water rather than a long one, and this is an important difference. 



