HEMIBASIDIOMYCETES , 75 



III. LOOSE SMUT OF WHEAT 

 Ustilago Tritici (Pers.) Jens. 



Brefeld, O., u. Falk, R. Unters. 13 : /. c. (Die Bluteninfektion bei den 



Brandpilzen). 

 Freeman, E. M., and Johnson, E. C. The Loose Smuts of Barley and 



Wheat. Bur. Plant Ind., U. S. Dept. Agl. Built. 152: 1-43. pis 1-6 



1909. 

 Swingle, W. T. The Grain Smuts, /. c. (see Ustilago Avena). 



The above species, producing the well-known loose smut of 

 wheat, is almost as widely distributed as the organism producing 

 the loose smut- of oats. The general appearance of the affected 

 plant at the time of flowering is much the same as in the case of 

 oats, and in many respects the life histories of the two species are 

 similar. This species is found upon practically all varieties of wheat 

 and under all climatic conditions. Morphologically, this fungus is 

 scarcely to be distinguished from the oats smut, and this is true 

 whether one considers the form of the spores or the characters 

 made evident upon germination ; but the absolute failure of cross 

 inoculations indicates that the two forms are distinct. According 

 to recent investigations, moreover, it would appear that this species 

 may also gain entrance to the host plant at the time of flowering. It 

 is stated that the infection tube penetrates the stigma and style, and 

 by that means enters the developing seed. In the developing seed 

 it retains its vitality and grows up through the plant when the seed 

 germinates. This mode of infection is said to be the most com- 

 mon ; therefore, according to these results, treatment of the seed 

 wheat for loose smut might seem to be useless ; nevertheless, from 

 experiments which have been made in this country, it would seem 

 that a modified method of Jensen's hot water treatment is partially 

 effective against this fungus. It appears at present possible to assign 

 a cause for this latter fact. It does not seem to be due to a greater 

 number of infections through seedling stages than is now assumed, 

 and is presumably due to the killing of the fungus within the tissues 

 by the hot water method. 



Control. In view of the recent studies upon blossom infection, 

 it would seem that the only reliable means of prevention would 

 consist in the hot water treatment together with seed selection. 

 It would be necessary to select seed from a field free of smut. 



