DISEASES OP CULTIVATED PLANTS 617 



of rice having satisfactory resistance to blast. Proper care ought to 

 maintain the excellence of such varieties. (La. E. S. B. 105.) 



Black Smut of Rice. The interior of an affected grain is filled 

 with a dry black powder which is enclosed for a time in the grayish 

 outer membrane or cuticle. Often there is a slight enlargement of 

 the grain, and the glumes are separated a little so that a portion of 

 the affected kernel is exposed to view; but sometimes the grain is 

 not enlarged. When ripe, the thin dry enclosing membrane is 

 readily broken, and the black powder scattered, leaving the glumes 

 empty except for the remnant of the membrane. Some of the pow- 

 der adheres to the outside of the glumes, giving them a black color, 

 and it is by this appearance that affected grains are most readily 

 detected in the field, they being otherwise rather inconspicuous. 

 But frequently the glumes of sound grains are black, either from 

 spores of black smut reaching them from nearby affected grains, or 

 from the growth on them of the dark mycelium of another and 

 saprophytic fungus. The presence of the black powder filling the 

 seed is the distinctive indication of black smut. (La E. S. B. 105.) 



Treatment of Smutted Rice. Until we have succeeded in ger- 

 minating the spores of rice smut, and have learned how infection of 

 rice plants takes place it will be impossible to say definitely just what 

 fungicide or treatment will be most effective as a remedy. What 

 seems to be the mycelium of this fungus has been found by the 

 botanist in the tissues of rice culmus. Rice grains are affected in a 

 manner similar to that in which wheat is affected by the stinking 

 smut. Spores are found adhering to the husks of the seed. The 

 smut appears to be closely related to stinking wheat smut. The 

 spores in the seeds may not be the ones through which infection of 

 rice seedlings takes place. This infection may result from spores 

 remaining in the soil. It seems probable, however, that the smutty 

 grains, and the spores on the seeds are instrumental in infection. In 

 this case these spores should be destroyed. There are effective reme- 

 dies for stinking wheat smut, and it seems probable that the remedies 

 for wheat smut will be found useful here. 



We have shown that the potassium sulphide treatment may be 

 safely employed ; indeed, that it has a tonic effect upon the seedlings. 

 Likewise, that copper sulphate (y% per cent, solution) is safe though 

 not as desirable as the potassium treatment, and that the seed may 

 be scalded three seconds with advantage, and soaked 24 hours in a 

 % per cent, solution of formalin without material injury, while J /4 

 per cent, solution has been found by others sufficient in the treat- 

 ment of stinking wheat smut. Without positive evidence, we be- 

 lieve that any of these treatments would destroy the spores of rice 

 smut. This we hope to find out. That the reader may try them 

 we give several treatments which have been found effective in the 

 treatment of the above mentioned wheat smut. 



Before giving the several fungicidal treatments I wish to call 

 particular attention to the method of separating smutted and other 

 light rice grains from the good and heavier seeds. Not only may a 

 large number of smut spores be destroyed in this way, but the proc- 



