EXPERIMENT STxVTION REPORTS. 2G3 



net! worked with three strams of the Phonia apiicohi known to cause this 

 (Hsease and finds in them <!;reat differences in virulence. The detailed re- 

 port on the causes of loss in virulence in connection with growth in pure 

 cultiu'c, in soil cultures and under various growth conditions can not be 

 outlined here. The finding, however, that the organism changes its 

 growth in soil away from the host plant, suggests very forcibly that by 

 the operation of this pi'inciple ''sick" soil becomes safe after some years of 

 crop rotation. Work along this line is l)eing continued. 



CEREAL DISEASE INVESTIGATIONS. 







Work on cereal disease was done under my direction by Mr. H. H. Mc- 

 Kinney whose work in this regard was most carefully done. Following the 

 outline of work given in the previous report in which the "Dry Method" 

 for cereal treatments was tested and found safe so far as laboratory tests 

 would show, the treatment was recommended for use with all cereals. 



The treatment which the farmers in Kent county had first tried and 

 found safe, when recommended in general throughout the State was used 

 by some farmers carelessly with the result that grave injury to stand re- 

 sulted. 



The facts in the case during the fall of 1917 were these: Farmers had 

 used the seed treatment for oats and had good success in control of smut. 

 No injury to stand resulted in spite of wide variations in the hands of 

 many farmers in seed treatment methods. This hardiness of oats tended 

 to make farmers careless in their treatment of wheat the following plant- 

 ing season. Coupled with this the weather of 1917, was exceptionally 

 rainy so that the planting of a given lot of seed extended in most cases 

 over a period of a week to a month. Under such conditions many reports 

 of loss came to the department. It was not sufficient for us to show dis- 

 obedience of the very plainly given directions. It devolved upon the 

 Experiment Station to discover the why's of formaldehyde injury. 



This work which was done by Mr. McKinney and myself showed first 

 of all that our knowledge of formaldehyde action was extremely limited. 

 We had a rule for treatment but no principle treating on the method of 

 action of the gas. We discovered that the prevailing notion that formalde- 

 hyde is a gas tending to escape readily is erroneous, and that on the con- 

 trary the formaldehyde as applied to grain by the wet method is extremelj^ 

 slow to air, since the formaldehyde polj'merizes so readily. Furthermore, 

 it was found that formaldehyde has a remarkable affinity for water, and 

 that it cannot be driven out of water by boiling, even. These and other 

 significant facts governing the use of formaldehyde developed in the 

 course of our investigations. A complete account of work to date has 

 been prepared for publication in the Twentieth Report of the Michigan 

 Academy of Science. The results important for use by farmers have 

 been given briefly in a popular bulletin. 



It is gratifying to note that as a result of the work on the technical 

 side, tfce formaldehyde injury question, our county agents, and through 

 them the farmers of the State have been thoroughly informed of the 

 dangers from careless treatment and as a result of this emphasis in follow- 

 ing directions carefully not a single case of injury to stand came to the at- 

 tention of the section last year. While here and there some fai-mer 

 used formaldehyde carelessly, the great majority' of the fields treated were 

 protected from smut without injury to stand. 



