Minnesota Plant Diseases. 



295 



Stinking smut of wheat [Tilletia tritici (Bjerk.) IVint.]. This 

 is a common smut-fungus of wheats and is well known to be 

 very destructive. The fungus gains entrance to the plant, when 

 the latter is still a seedling, and keeps pace with the growth of 

 its host, until flowering time. The mycelium then invades the 

 ovaries and replaces the contents of the latter with fungus 

 threads. These threads form an oily or greasy mass which is 

 later transformed into the smut powder. The smut spores are 

 blackish in color and have, in bulk, a very disagreeable odor, 

 which gives rise to the common name of the disease. The smut- 

 ted ovaries do not open until harvested. Smutted heads are 

 usually erect and can be detected in the field at harvest time. 

 The presence on smutted grains in quantity amongst the healthy 

 is a very serious damage as it unfits the crop for use as flour, 

 unless the smut is cleaned out by a special process. When 

 smutted grains are fed to animals the results are sometimes seri- 

 ous. Corn smut, and other smuts of grasses are known to have 

 injurious effects upon animals. Horses, cattle, sheep and swine 

 may be affected. Not much is known about the specific results 

 of poisoning from each kind of smut, so that confusion as to 

 symptoms exists. "As a result one generally finds a continuous 

 movement of the jaws, and a flow of saliva, also lameness, stag- 

 gering and falling." (Tubeuf and Smith, p. 306.) 



The stinking smut of wheat differs in its development very 

 radically from the smuts of the group to which the loose smut 

 of oats belongs. When the spore of the latter germinates a fine 

 tube is produced which is divided into a row of cells, each of 

 which buds off tiny, oval or spherical spores from, the side of 

 tube. In the stinking smut of wheat, the tube of the germinating 

 smut spore is not divided into cells but forms its spores from the 

 end of the undivided tube. These secondary spores may fuse to- 

 gether in twos and from the fused cell, a third crop of spores may 

 be formed. Any of these secondary or tertiary spores are capable 

 of growing out into a fine tube ; when it comes into contact with 

 a wheat seedling this tube penetrates into the tissues of the stem 

 and so begins its parasitic life. The life of such a smut can 

 therefore be divided into two stages; first, the parasitic stage, 

 beginning with penetration of the infection tube and ending 

 with the formation of the smut spore powder; and second, the 



