452 FORAGE PLANTS AND THEIR CULTURE 



tures. The seed retains its viability well for 5 years and 

 then quickly deteriorates. The legal weight of a bushel is 

 60 pounds, but a bushel may weigh as high as 68 pounds, 

 or as low as 52 pounds. 



Large seed is preferable to small seed of the same variety. 

 In two-year trials at the Ontario Agricultural College the 

 yield from the large seed averaged 26.2 bushels of peas 

 and 1.14 tons of straw to an acre, while the small seed 

 yielded 22.6 bushels of peas and 1.04 tons of straw. 



544. Pea-weeyil (Laria pisorum or Bruchus pisorum). 

 - The most serious enemy of the pea, especially when 

 grown for seed-production, is the pea-weevil. This insect 

 lays its eggs in the very young pea pods, and the larva 

 upon hatching burrows into the soft young seeds, only one 

 larva entering each seed. The larvae grow with the seed 

 and remain therein until they become adult beetles. Nor- 

 mally the beetles do not emerge until spring, in fact usually 

 being in the seed when planted ; but if the seed is stored 

 in a warm room, they emerge sooner. There is only one 

 generation a year, and the insects do not multiply in the 

 stored seeds. 



Seed may be rid of weevils in two ways ; namely, by 

 fumigating with carbon bisulfide, so as to destroy the 

 insects without injuring the seeds (Par. 625) ; or by keeping 

 the seeds over one season in tight bags or other receptacles 

 The beetles all emerge from the seeds and, being unable 

 to escape, perish. 



Where peas are grown each year, weevils tend to be- 

 come increasingly abundant, and finally make it impos- 

 sible to grow crops of satisfactory seed. If, however, their 

 planting is suspended for 2 to 3 years, the weevils are 

 nearly eradicated. The growing of peas for seed is prac- 

 tically limited to those regions where weevil injury is 



