92 PROTECTION OF PLANTS, 1915-16 



OLD AND NEW METHODS IN WEED CONTROL 



P. L Bryce, Macdonald College 



What is a weed? This is a question that cannot be perfectly answered. 

 We all know some weeds, and most of us presume that they are always 

 weeds. Whether that be so or not, need not concern us; it is quite sufficient 

 if a plant be growing to the injury of the crop in which it is found, then it 

 is a weed. 



Losses due to Weeds. 



Weeds are not only useless, but may be definitely injurious to man 

 and beast. Some act as specific poisons, such as the poison hemlock. Some 

 of the most poisonous plants in our range include purple cockle, poison ivy, 

 water hemlock, the nightshades and ragwort {Senecio jacohea). These 

 should be known to all stockmen, in particular the ragwort which produces 

 fatal disorders in cattle. The roots of water hemlock are deadly to cattle 

 if eaten in quantity. Purple cockle darkens and poisons flour, as the seed is 

 next to impossible to separate from wheat. While not poisonous, thorny 

 or barbed plants injure live stock. Among these hurtful plants, squirrel 

 or skunk-tail grass has bristly awns which pierce the gums and cause inflam- 

 mations. Russian thistle causes trouble in wheat fields in the West, by 

 injuring the legs of horses drawing binders etc. 



Losses in yield are a much more serious result of weeds. They seem 

 to have harmful effects on the crop. It may be that this effect is due to 

 substances given off from the weeds, and poisonous to crops. Such actual 

 loss to the crop was estimated in Minnesota to mount up to 40 bushels 

 per acre. Where 60 bushels should have been harvested, only 20 bushels 

 were threshed out. The general result of the presence of weeds is the 

 crowding out of the crop, while weeds shade it and keep the leaves from 

 evaporating enough water to make the proper amount of food. In dry sea- 

 sons, the weeds use up too much of the available moisture. The U. S. 

 Department of Agriculture has estimated the loss due to weeds in crops and 

 meadows at SI. 00 per acre. 



Another injury from weeds is increased harvesting cost. Weedy hay 

 takes longer to cure. W'eedy grain uses more binder twine and extra work 

 is required of the horses to cut the grain. "Russian thistle, bindweed, 

 and Canada thistle are usually a source of great annoyance at harvest 



