RYE-' smut' 721 



more easily injured than that of the other cereals mentioned, 

 and a temperature not higher than 53° C. (or 126° F.) should 

 be employed when dealing with this grain. 



(c) i. Dissolve one pound of copper sulphate in five quarts 

 of boiling water in a wooden bucket or copper pan, and when 

 cool pour the solution over 4 bushels of grain spread on the 

 barn floor. Shovel the grain about in order that the solution 

 may wet all the grains ; then allow the whole to dry before 

 sowing. 



Or, ii. Dissolve half-a-pound of copper sulphate in ten 

 gallons of water and place the solution in a wooden vessel ; 

 soak the seed-corn in this for 12 to 16 hours, taking care that 

 the surface of the solution is at least three inches above the 

 grain in the vessel. Then remove the grain and spread it out 

 to dry for 24 hours before sowing. 



Both the above methods of ' pickling ' or ' dressing ' the seed- 

 corn leaves each grain covered with a thin film of copper 

 sulphate : and although the latter is incapable of killing the 

 chlamydospores themselves it protects the grain, for the pro- 

 mycelia and conidia produced by the spores are destroyed 

 when they come in contact with it. 



By sowing untreated and treated portions of the same sample 

 of grain side by side in the same soil, it may readily be 

 proved that 'pickling' with solutions of copper salts destroys 

 the germinating power of a considerable amount of the ' seed ' 

 grain, the proportion killed depending on the strength of the 

 solution, the time during which it acts and the nature of the 

 grain itself. 



If Brefeld's researches are correct, 'pickling,' which aims at 

 the destruction of spores on the outside of the grain, can be of 

 little use for diminishing smut in barley and wheat where the 

 fungus is in the seed itself and the young plants immune to 

 external attacks. In these two cereals seed grain must, as far as 

 possible, be obtained from healthy crops. 



2 z 



