326 



INJURIOUS INSECTS AND FUNGI. 



[Dec. 189.5. 



those not infected. They are of a dull lead colour, and tlie line 

 or furrow on the underside is often indistinct ; upon pressing the 

 grains they crush easily, and it is seen that they are full of the 

 olive -coloured stinking spores, like the finest dust, of the fungus. 

 Mr. Worthington Smith Ccilculates that one grain of wheat can 

 contain 4,000,000 spores. These bunted grains spread infection 

 throughout the bulk of the grain in which they happen to be, 

 through the spores escaping from them and falling upon the 

 grains in their vicinity. Not only is the yield often lessened 

 materially by bunt, but the flour made from wheat containing 

 bunted grains is, and remains, tainted by the foetid odour given 

 off by its spores. This unpleasant smell, which is like that of 

 bad fish, is characteristic of this fungus. It is so powerful that 

 a very small per centage of infected wheat will communicate a 

 most unpleasant flavour to flour made from it. Dealers, there- 

 fore, decline to buy wheat in which bunt appears, as it is not 

 fit for flour. In some bunted grains of wheat kept for eight 

 years, the fishy smell was still very strong. 



This fungus causes much harm to wheat in most continental 

 countries, and in America. 



Life History, 



Bunt — Tilletia tritici — is one of the UstilaginecB, The fungus 

 is propagated by means of spores, as shown in the Figure, drawn 

 by Mr. Worthington Smith, which are for the most part globular,, 

 and olive brown. When wheat is sown with the spores upon it 

 either in the line, or furrow, on the underside of the grain or among 

 the downy hairs at its extremity, or upon its cuticle, these spores 

 throw out the wreaths of sporidia shown at D., between some 

 of which, according to Kuhn, there is congregation, or fusion. 

 Conidia (E.) are developed and germinate, throwing out delicate 

 threads, which enter the wheat plant at the root knots or joints 

 (WuTzelknoten) directly it has commenced growing, as has been 

 observed by Kuhn, who has made many interesting experiments, 

 in this direction. Mycelium is formed from the conidia, which 

 grows with the plant and finally sends its hyphse, or branching 

 filaments, into the ear, stems, and forming grains, whose substance 

 is entirely absorbed, and the husks filled with countlSss spores. 



Kuhn says that in his experiments he found that infection 

 with too many spores of the fungus caused the mycelium to be 

 produced so abundantly that the wheat plants were destroyed. 

 He also found that spring wheat is more attacked by this fungus 

 than winter wheat. This fungus preserves vitality for a long- 

 time. Spores from the bunted grain, kept in a dry place for 

 eight years germinated in 24 hours, wlien placed in water on a 

 slide in a temperature of 60° Fahr. 



Methods of Prevention, -..^.j 



It is obvious that no remedial measures can be adopted for this 

 attack. There are, however, means whereby the spread of the 



