94 



DISEASES OF CROPS. 



phate (of a grass-green colour) from the nearest maker, in 

 the crystalline form, and powder it themselves ; this would 

 prevent adulteration. (2) Lime has also been recom- 

 mended for eradicating moss, but its action is not so 

 certain as that of iron sulphate. 



The Coronated Mildew of Grasses {Puccinia 

 coronata, Pig. 37) is similar in its life-history to the 

 " mildew of corn " (wheat), which will be described later 

 in this chapter. Puccinia coronata produces numberless 

 oval-shaped spots on various grasses. The sori (Fig. 37 B 



Fig. 37. — CoBONATED MiLDEw {Puccinia coronata), 



A. Sori on grass (enlarged). 



B. Sori (enlarged). 



and a) are crowded together, and ultimately rupture the 

 epidermis of the host-plant. 



Prevention and Cure.~{l) The drainage of grass lands 

 has a tendency to lessen the ravages of this fungoid pest. 

 (2) Top-dressing pastures and meadows with ^-cwt. of 

 iron sulphate, mixed with five to ten times its weight of 

 sand or dry earth per acre, is a means of destroying the 

 mildew of grasses. 



The Grass-Culm-Smut {Ustilago hypodytes)he\ong3 

 to the Ustilaginece, an important group of fungi whose 

 mycelia usually spread throughout the tissues of the host- 



