CEREAL PESTS WEEDS 



469 



The best time to spray is while the weeds and crop are 

 still seedlings, and only 2 or 3 inches high, before the 

 weeds even form flower buds. At that stage the weeds 

 will be killed outright. If sprayed later, they are likely 

 to produce more or less seed. Spraying should be done 

 on a cloudy or " muggy " day, when rain is not expected 

 for eighteen hours. If spraying is done on a hot, dry 

 day, the spray will dry off too quickly. The wheat crop 



FIG. 147. A weed-spraying outfit in North Dakota. 



may be sprayed at any time before heading, but the 

 younger it is the less harm is done. Barley will not stand 

 as severe treatment as wheat. 



614. Spraying in North Dakota. Bolley (1908) re- 

 ports considerable work in spraying to kill weeds at the 

 North Dakota Experiment Station, and states that the 

 following weeds may be eradicated or largely subdued 

 thereby : false flax, wormseed mustard, tumbling mus- 

 tard, wild mustard, shepherd's purse, pepper-grass, ball 

 mustard, cockle, chickweed, dandelion, Canada thistle, 

 bindweed, plantain, rough pigweed, kinghead, red river 

 weed, ragweed, and cockle bur. The following other 



