400 EXPEBIMENTS WITH PLANTS 



others still iii the blotting-paper). Have a number of 

 uninfected plants as a control. If growing Corn is 

 available, (6) place a few drops in a young ear by 

 gently opening the end of the ear and forcing the 

 pipette down into the center. Results from {a) should 

 be apparent in about two weeks. If no result is 

 obtained, repeat the experiment. 



The yearly loss from Corn- smut in the United 

 States alone is estimated at over $2,000,000. The best 

 remedy is to go through the fields once or twice during 

 the growing season and again when the Corn is ripen- 

 ing, collecting all the smutted portions each time and 

 burning them. Formerly the seed was treated with 

 bluestone, but this is of no value, because the infection 

 occurs after germination. 



The Smuts of Grrain^ (i. e., the Black Smuts of 

 Wheat, Oats, Barley and Rye and the Stinking Smut 

 of Wheat) do not spread from plant to plant, like the 

 Corn- smut; infection takes place only when the spores 

 come in contact with the seed; for this reason the 

 attacks of these Smuts may be prevented by treating 

 the seeds with a germicide. For this purpose blue- 

 stone (copper sulphate or blue vitriol) is used at the 

 rate of a pound (or more) to a gallon: the seeds are 

 dipped into this long enough to get thoroughly wetted 

 (wheat for a few minutes, oats and barley, on ac- 



1 See an article by Swingle in the Year - Book of the United States Depart- 

 ment of Agriculture for 1894; for 1896 by Carleton, 



