124 DISEASES OF CROPS. 



Prevention. — The drainage of the land lessens tlie 

 attacks of this pest. 



Cure. — ^Top-dressing the land with iron sulphate de- 

 stroys this fungoid growth. 



The Bunt of Wheat {Tilletia tritici, Tilletia caries) 

 is a fungoid disease which confines itself to the grains 

 within the ears. Infested grains are of a darker green 

 colour, besides being shorter and wider than healthy- 

 ones. The interior of an infested grain consists of an 

 exceedingly large number of brownish-black spores pos- 

 sessing a putrescent fishy odour. These dark-coloured 

 spores are globular and slightly spinulose. They either 

 give rise to a short mycelium (pro-mycelium) which bears 

 eight or ten elongated sporidia ; or go on branching and 

 rebranching. Each mature sporidium throws out a lateral 

 process, which unites with a similar process of the nearest 

 sporidium (i.e., two sporidia coalesce or conjugate). After 

 conjugation, they become detached from the pro-mycelium, 

 and either germinate, producing secondary sporidia, or 

 produce mycelial hyphse. The secondary sporidia are also 

 capable of germinating, and either give rise to tertiary 

 sporidia, or they may produce a ramifying mycelium 

 bearing a large number of sporidia of the first and second 

 order. The secondary and tertiary spores also germinate, 

 and give rise to short hyphae which bear the first or true 

 bunt spores. 



As the bunt spores of this fungus hibernate in seed 

 wheat, the wheat plants become affected from the begin- 

 ning. These spores germinate, and ultimately give rise 

 to the various sporidia and mycelia (already described) 

 " on and in the ground." The last-formed mycelia (from 

 the secondary and tertiary sporidia) find their way into 

 the host-plants through the fii'st-formed stomata. When 



