256 



thoroughly wet and warm the grain. Allow it to drain a 

 moment, and then transfer it to the hot water. Let it re- 

 main in the hot water for ten minutes, agitating freely, then 

 remove and spread the grain to dry. The success of the 

 treatment will depend entirely on keeping the hot water as 

 nearly as possible at 133 degrees. If the temperature rises 

 above 135 degrees, it may injure the seed, and if it falls 

 below 130 degrees, some of the smut spores will not be 

 killed. The wet seed should be spread out two or 

 three inches deep, and be shoveled over frequently until 

 quite dry. This is not necessary if it is to be sown imme- 

 diately by hand. 



An important consideration in favor of these two treat- 

 ments of seed oats, is that the seed germinates quicker, 

 and the yield is considerably increased aside from the gain 

 in preventing smut. The copper sulphate treatment re- 

 tards germination and does not increase the yield. 



Oat Rust. — This disease is produced by Puccinia coro- 

 nata,^' quite a different fungus from those causing smut. 

 The mycelium in this case also consists of colorless threads 

 buried within the oat tissues, but instead of extending 

 throughout the plant as with the smut, they are confined to 

 rather small areas beneath the spots covered by the reddish 

 or rust-colored powder from which the disease takes its 

 name. This reddish powder consists of the spores of the 

 fungus. Under the microscope they are seen to be three 

 or four times as large as the smut spores. They 

 are oval in shape, and of a light yellow color. They ger- 

 minate quickly under proper conditions of heat and 

 moisture, and their germ tubes are able to penetrate the 

 oat leaves, where they soon develop new spots of rust. 

 The disease is thus enabled to spread very rapidly when 

 weather conditions are favorable. This disease does not 

 attack the grain itself, as does the smut. If only a little is 

 present, the injury is slight, but when abundant, it de- 



*Puccinia graminis and P. rubigo-vera also occur on oats, but the 

 above remarks will apply equally well to these species. 



