12 MINNESOTA WEEDS 



enables them to be carried long distances by the wind. The Canada 

 thistle, bull thistle, milkweed, and many other weeds have such seeds. 

 Then again, in some plants like the Russian thistle, tumbling mustard, 

 and tumbling pigweed, the entire plant breaks away about the time 

 the seeds are mature and tumbles over the ground scattering its seeds 

 in this manner. 



Many weed seeds are carried long distances in streams of running 

 water. This is noticeable in low lands when a stream overflows its 

 banks. Along the stream after the overflow many weeds spring up 

 which were never seen there before. Threshing machines and other 

 machinery going from one farm to another or from one part of a farm 

 to another often scatter seeds. 



Some of the perennial weeds,, like quack grass and the Canada 

 thistle, which have underground stems or running roots, are spread 

 by machinery and horses. They scatter parts of the underground 

 stem or root. A small portion of this stem is capable of producing 

 a new plant, and the greatest care should be exercised to see that 

 none of them are scattered on uninfested lands. 



Many weeds, like the burdocks, have barbed fruits or seeds 

 which cling to the fur of animals and to the clothing of man, and are 

 thus carried from one place to another. 



A bad weed often gets a strong foothold in a community because 

 its habits are not known. Whenever a new weed appears on the 

 farm, it should be carefully studied and the person finding it should 

 at once become acquainted with it. Such weeds, if not kncwn, 

 should be sent to the Experiment Station for determination. 



Thus it can be seen that weeds may be scattered in many differ- 

 ent ways. In order to keep down the spread of weeds the following 

 rules should be followed: 



Sow only pure seed. 



Use well-rotted manure. 



Keep weeds from seeding. 



Be careful not to spread seeds or the underground stems of 

 perennial weeds. 



Learn to know all bad weeds and their seeds. 



Practice clean cultivation and crop rotation. 



LEARN TO KNOW THE WEEDS 



Farmers should study weeds, learn how they grow, when they 

 mature seed, whether they come from the seeds or from roots each 

 year, in what soil they thrive best, and many similar features of weeds. 

 Then the question of eradication would be more easily solved. A 

 weed is most commonly known when it is in flower or in fruit. Very 



