292 



FIELD CROP PRODUCTION 



be controlled, alfalfa seed is an important crop. The 

 yield of seed is also influenced by the rate of seeding, the 

 best yield being obtained when the crop is seeded thinly, 

 either in rows or broadcast. The crop is harvested when 

 most of the seed pods have turned brown. It may be 

 cut either with a self -rake or a buncher ; and if a machine 



Fig. 104. — Farmers examining alfalfa test plots at the Ohio station. 



for hulling it is available, the seeds may be thrashed out 

 immediately, or it may be stacked after curing for some 

 time in the bunches so as to prevent heating in the stack. 

 The yield varies from 2 to 5 bushels per acre, which at 

 present prices makes it a profitable crop. 



296. Insects and diseases. — While many insects feed on 

 alfalfa, seldom are they numerous enough to cause serious loss. 

 Sometimes in the West, however, the grasshoppers become so 

 numerous as to cause serious injury to the crop. They may be 

 controlled to some extent by disking the field early in the spring 

 to destroy the egg sacs, and later in the season by the use of a 

 " hopperdozer." 



The most common fungous diseases of alfalfa are the leaf spot, 

 leaf rust, and root rot. The root rot is commonly found in the 

 South, where it also attacks the cotton plant and as the spores 



