FUNGI AFFECTING WHEAT 



The Bunt or Stinking Smut 



TiUetia feet ens 



This is the most destnictiye smnt affecting wheat. 

 It differs from the loose smuts in that the individiial 

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

 ing to Professor Arthur, wheat plants injured by this dis- 

 ease •• thrive about as nsiial. the head fills and the chaff 

 is distended, as if with normallT 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 mannre had 

 forced them to extra growth. The gTowth 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 uj) the leaves. The characteristics 

 now become rather more evident. The affected heads 

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

 time after the 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 open 

 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-history of this fungus does not differ essen- 

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

 cussed (pp. 18r-193). 



194 



