INTRODUCTORY 9 



as a whole, from weeds growing upon cultivated land. In various 

 ways they lower the yield, depreciate the quality and value of 

 crops, and add to the cost of production. 



1. Weeds rob the soil of plant food and of moisture, thus 

 increasing the effects of drought by taking up water from the 

 soil and wasting it by evaporation. 



2. Weeds crowd out more useful plants, being hardier 

 and, as a rule, more prolific. 



3. Weeds are a source of expense. From the time farmers 

 begin to prepare their land for a crop, these enemies increase 

 the cost of every operation of plowing, harrowing, seeding 

 cultivating, cutting, binding, carrying and threshing, as well 

 as in cleaning, freighting and marketing the produce. Direct 

 losses are the larger consumption of binder twine necessary when 

 weedy crops are harvested, the extra wear and tear on machinery 

 due to coarse-growing weeds, and the depreciation in the market 

 value of the crop because of the presence of weeds in hay or of 

 weed seeds in grain. 



4. The eradication of the worst weeds is costly in labour, 

 time and machinery, and frequently prevents a farmer from 

 following the best crop rotation, or even compels him to grow 

 crops which are less advantageous. 



5. Many weeds are conspicuous and all are unsightly on 

 farm lands. They thus, in a varying degree, according to their 

 several natures, depreciate the value of land. 



6. Some weeds are harmful to stock, being poisonous, as 

 Water Hemlock; others are injurious to their products, as 

 burs in wool, or Wild Garlic and Stinkweed, which taint milk. 

 The horny or barbed seeds of some grasses, as Porcupine Grass 

 and Skunk-tail Grass in the Northwest, cause irritation or pain- 

 ful wounds by penetrating the flesh, particularly the mouth 

 parts. 



7. Weeds attract injurious insects and harbour fungus 

 diseases-. Weedy stubbles or summer-fallows are breeding 



