FUNGI AFFECTING WHEAT 



The Bunt or 5tinkin:g Smut 



Tilletia foeteiis 



This is the most destructive smut affecting wheat. 

 It differs from the loose smuts in that the indiyidual 

 kernels are affected, instead of the whole head. Accord- 

 ing to Professor Arthur, wheat j^lants injured by this dis- 

 ease *^ thrive about as usual, the head fills and the chaff 

 is distended, as if with normally plump grain. A close 

 observer will notice, however, that already before wheat 

 heads out the diseased plants have a darker green color 

 and somewhat more luxuriant appearance. When the 

 grain is only six inches high or so, this difference in 

 appearance is quite striking, the affected plants being 

 darker green and taller, as if droppings of manure had 

 forced them to extra growth. The growth does not con- 

 tinue so long, however, as in the healthy plants, so that 

 they do not usually become so tall, and are premature in 

 heading and ripening up the leaves. The characteristics 

 now become rather more evident. The affected heads 

 retain a bluish-green, or greenish- lead color, for some 

 time after tlie sound ones begin to ripen, and then take 

 on a bleached appearance, in strong contrast to the yel- 

 low of the sound heads ; the heads being much lighter 

 stand more erect, and the chaff and beard are more ojoen 

 and spreading (Fig. 81)." If the injured kernels are 

 broken open they are found to contain a solid mass of 

 black powder — the spores of the fungus. 



The life-historv of this funsrus does not differ essen- 

 tially from that of the loose smut of oats already dis- 

 cussed (pp. 187-193). 



194 



