42 FUNGOID DISEASES 



Preventive Measures. — 



1. Copper solutions, p. 28. 



2. Hot water treatment, p. 29. 



3. Formaldehyde treatment, p. 32. This is the 

 best of all. 



(K) Barley Smiits^ — (i) Naked or loose smut 

 {Ustilago nuda) = U. Hordei {^rd) ; (2) covered 

 smut ( Ustilago Jensenii ( Rostr .)) . 



(i) Naked Smut. — Of the two this is the more 

 common in Great Britain. The spores are dis- 

 persed before harvest. Infection takes place 

 through the flowers, the mycelium entering- the 

 ovary, where the grains become infected. The 

 diseased grain produces a plant in whose growing 

 point the fungus progresses, destroying the ear 

 when formed. 



Prevention. — Treatment, to be effective, must de^ 

 stroy the fungus within the grains without injuring 

 the vitality of the latter, this is possible with the 

 modified hot-water treatment of Jensen. (See fur- 

 ther note under wheat smut.) 



(2) Covered Snint. — Here the bulk of the spores 

 is not distributed before harvest. The ear may re- 

 main within the upper part of the sheath practically 

 intact, except that instead of the healthy grain, smut 

 spores are formed and surrounded by the fertile 

 glumes. Infection takes place at the seedling stage 

 from spores adhering to the grain, hence treatment 

 of the grain with fungicides is effective. 



Prevention. — Treat the grain prior to sowing 



