DISEASES OF CEREALS AND GRASSES 59 



bore the conldia ; these are the perithecia contain 

 They remain 



ing asci. 



attached to the leaves 

 until the spring, when 

 they liberate the asco- 

 spores, which on ger- 

 mination again produce 

 the disease. But even 

 failing these perithecia, 

 the fungus may be found 

 on the wheat plant in 

 winter, where it un- 

 doubtedly can remain 

 until the spring. 



Preventive Measu res . 

 — Unfortunately very 

 little can be done. 



1. Small areas may be dusted with llowers of 

 sulphur, but this is too costly and impracticable for 

 field crops. 



2. Spring sowing is said to be an advantage. 

 VII. Discoloration Due to Funci. 



{a) Broivning of Wheat Leaves. — This browning 

 of the leaves is of somewhat frequent occurrence 

 on the Continent. 



Symptoms. — Appears in spring on winter sown 

 wheat : the leaves turning somewhat yellow at first, 

 and later more to the brown, while hnally they dry 

 up. On the brown surface small black spots may be 



Fig. 16. — Portion of the hyphai ; 

 (H) of Erysiphc ^raniinis bear- 

 ing the oval conidia (C) in chains. 

 (Highly magnified.) 



