376 



FUNGOUS DISEASES OF PLANTS 



Where the disease is very abundant it would be practicable, on 

 plats to be employed for seed, to weed out smutted plants prior to 

 final maturity. The most recent recommendation with respect to 

 seed treatment is to soak five hours in cold water, and then ten 

 minutes in water at 54 C. 



IV. SMUT OF CORN 

 Ustilago Zea (Beckm.) Ung. 



Arthur, J. C, and Stuart, W. Corn Smut. Ind. Agl. Exp. Sta. Ann. Rept. 



12: 84-135. 1900. 

 Hitchcock, A. S., and Norton, J. B. S. Corn Smut. Kan. Agl. Exp. Sta. 



Built. 62: 169-212. pis. 1-10. 1896. 

 Knowles, E. L. A Study of the Abnormal Structures Induced by Ustilago 



Zeae-mays. Journ. Myc. 5: 14-18. pis. 2-7. 1889. 



The common smut of corn (Zea mays) 

 occurs in all regions where maize is grown. 

 It is productive of considerable losses at 

 times, and it is probable that in many corn- 

 growing sections the yearly loss will aver- 

 age as high as 5 per cent. It may vary, 

 however, from o to about 25 per cent. 



Habitat relations. This fungus some- 

 times causes enormous enlargements of 

 various parts of the host, occurring in 

 staminate and pistillate flowers, on the 

 stalk, especially at the nodes, and also in 

 the leaves. The abnormalities or swellings 

 are usually prominent and often attain the 

 size of several inches in diameter. Very 

 careful experiments throughout a long 

 period of time have made it clear that 

 infection takes place through any young 

 and growing tissue, but that the plant is 

 not affected, as a rule, until a foot or 

 more in height. The spores retain their 

 vitality in the soil for some time, and the 

 sporidia may, by a sprouting process, be propagated and dissem- 

 inated through manure or compost spread upon the land. The 



Fig. 191. Ustilago Zeje: 

 Smut of Corn 



