TIME OF SOWING 



265 



probably of about two weeks, which requires a total of ten weeks 

 from the sowing date to the appearance of the plants in the 

 resistant stage. Early sowing, furthermore, reflects its advantages 

 upon reduced grain infestation, since it tends to the early exsertion 



Fig. 73. Graph showing correlation between dates of sowing of barley 

 and degrees of subsequent infestation -by gout-fly. (After Frew.) 



of the panicles. Since the majority of the second swarm of flies 

 appear about mid-July, the risk of heavy grain attack is often 

 obviated, since by that time the grain should be half-way towards 

 maturity and therefore approaching its resistant stage {vide also 

 Cunliffe, 1929). 



