1892.] PUBLIC DOCUMENT — No. 33. 247 



of all smutted parts as soon as they appear. It should hardly 

 be necessary to call attention to the fact that to throw them 

 into the compost heap is not to destroy them, but is often 

 the surest means of perpetuating and disseminating the 

 disease. 



Fig. 5 shows a portion of a " tassel" of corn attacked by 

 smut. 



The leaf-smut of rye (Fig. 4) forms its black masses on 

 the leaves and stems of rye, which are often considerably 

 distorted by it. It does not, therefore, cause a direct loss 

 of grain, but indirectly reduces the crop by weakening the 

 plants which are attacked. 



The same is true of the onion smut, which forms its 

 pustules on both leaves and bulbs, and commonly kills its 

 host. If the attack is not too severe, however, the plant may 

 recover, though greatly weakened and never producing a 

 strong bulb. It appears that only the young seedlings are 

 susceptible to attack. This smut is propagated by means of 

 the soil, and its spores may retain their vitality in the earth 

 for several years. Treatment must consist in sowing with 

 the onion seed some fungicidal substance which shall prevent 

 the development of the smut spores in its vicinity, and the 

 consequent infection of the seeding onions. The substance 

 which gives most promise in this line at present is flowers 

 of sulphur, although its protective effect is not all that can 

 be desired. When a field becomes badly infected it should 

 be used for some other crop, and the onion crop transferred 

 to fresh ground for several years, at least. 



For the assistance of any who may not feel certain as to 

 the identify of the diseases here discussed, a plate is appended 

 showing the characteristic appearance of the various smuts 

 here mentioned, except that of onions. This plate was made 

 from a photograph taken directly from specimens of diseased 

 plants, and shows the effects of the various fungi on their 

 respective host plants very clearly. With its help one should 

 be able to identify the diseases represented without doubt. 



