161 



The time at which a grass sort is in condition to cut is olten a matter of 

 great practical importance. This is especially the case when it is to be grown 

 with clover as both crops should be in the best condition for cutting at the 

 same time. While considerable difference in time of ripening between 

 certain lines of Timothy has been noted, yet the greatest difference has been 

 found to exist in the case of Orchard grass. 



In regard to resistance against rust the differences between different 

 lines in the case of most grasses, are exceedingly striking. The most common 

 rust in Orchard grass is said to be " rust-spot" (Uromyces dactylidis Orth). 

 When at Svalof, the writer was struck by the fact that certain lines of the 

 above grass seemed quite resistant against this disease, while others, im- 

 mediately adjoining, were very badly attacked. According to Witte the 

 relationship between resistant and susceptible lines in the successive years 

 of their existence is quite uninterrupted. In the following table it is also 

 shown that susceptibility to this disease is apparently an hereditary character, 

 thus (82, p. 60) : 



Attitude of the successive progeny of different lines of Orchard Grass toward rust. 



