GRAMINEOUS CROPS. 95 



plant. In this point the Ustilaginece differ from the 

 localized mycelium of most Uredinece. The grass-cnlm- 

 smut, which is sometimes common, " makes its appearance 

 at first beneath the sheaths of the leaves surrounding the 

 stems of grasses, and ultimately appears above and around 

 them as a purplish-black dust." The minute spores of this 

 fungus are of a brownish-black colour. 



Cure. — See the method for destroying Puccinia 

 coronata. 



The Smut Fungus {Ustilago carbo), which will be 

 fuUy described under " The Parasites of Oats," has been 

 found on the following grasses amongst others : Aira 

 ccespitosa (hair grass), Avena flavescens (yellow oat grass), 

 Avena elatior (false oat grass), Avena pubescens (downy 

 oat grass), Festuca pratensis (meadow fescue), Lolium 

 perenne (rye grass), Lolium temulentum (darnel grass), 

 Cynosurus cristatus (crested dogstail), Festuca elatior 

 (tall fescue), Festuca ovina (sheep's fescue), and Dactylis 

 glomerata (cocks-foot grass). 



The Grass Blight {Erysiphe graminis) is similar 

 in its life-history to the pea mildew (Erysiphe Martii) 

 already described. 



Prevention. — (1) Good cultivation, clean farming, and 

 a liberal use of artificial manures are means of preventing 

 the attacks of this fungus. Farmyard manure containing 

 mildewed straws and grasses should not be used for grass 

 lands. (2) Whenever possible bum all mildewed straws 

 and grasses, for these retain the perithecia of this destruc- 

 tive fungus. (3) A thorough drainage of meadows and 

 pastures lessens the risk of infection, not only of this 

 fungoid growth, but of others as well. 



Cure. — A top-dressing of iron sulphate (|-cwt. per acre) 

 is an effectual remedy. 



