194 FORAGE PLANTS AND THEIR CULTURE 



The yield of seed to the acre in Europe is given by Pinck- 

 ert as 880 pounds; by Walker, as 88 to 132 pounds; 

 by Michalowski as the average of 4 years, 328 pounds; 

 by Jung, 880 pounds, when grown on a large scale ; and 

 by Werner as 724 to 880 pounds. 



Tall oat-grass is frequently infested with a smut (Usti- 

 lago perennans) which destroys the attacked seeds. 



207. Seed. The seed of tall oat-grass weighs 10 to 16 

 pounds per bushel. It loses viability quite rapidly after 

 the first year, and by the fourth year is practically 

 worthless. In common with other grass seeds for which 

 there is small demand in America, seed is quite likely to be 

 old or else mixed with old seeds. 



The percentage of impurities in tall oat-grass seed is 

 rather large, on the average 20 per cent, but the other 

 seeds are commonly those of other grasses which occur 

 in fields, such as orchard-grass and meadow fescue, but 

 there is often considerable cockle (Agrostemma githago) 

 present. One pound contains about 150,000 (138,000 to 

 159,000) seeds. 



208. Mixtures. Tall oat-grass should rarely be sown 

 alone unless for the purpose of seed production. Among 

 the reasons for growing it in mixtures are its bunch habit, 

 its relative lack of palatability, the cost of the seed and 

 the fact that it is primarily a top grass. It must not, 

 however, be sown in mixtures containing much Italian 

 rye-grass or other grasses which grow more rapidly and 

 thus injure the tall oat seedlings by shading ; nor should 

 it be sown with grasses that mature distinctly earlier 

 or later, as tall oat-grass should be cut when in bloom. 

 It is early and blooms about 10 days sooner than red 

 clover. European authorities recommend that only 10- 

 20 per cent of tall oat-grass should be used in mixtures, 



