152 THE BOOK OF WHEAT 



By 1894 it had crossed to the west side of the Missouri river, 

 and was spreading in Minnesota, Iowa and Nebraska. In 1895 

 the injuries which it caused extended from Michigan to Col- 

 orado, Idaho and California, but the greatest damage resulted 

 in the Dakotas and Nebraska. 



The Russian thistle is an annual with a dense, yet light 

 growth of circular or hemispherical form. The average plant 

 is 2 to 3 feet in diameter, weighs 2 to 3 pounds when matured 

 and dry, and is estimated to bear 20,000 to 30,000 seeds. Single 

 plants have been found 6 feet in diameter, weighing about 20 

 pounds when thoroughly dry, and estimated to bear 200,000 

 seeds. It is ideally fitted to be carried by the fall winds, which 

 easily break off or pull out its slender roots. A severe frost 

 kills the plant at any time, but it produces seeds abundantly 

 as far north as the Canadian boundary. 



In Russia no effectual method of exterminating the weed is 

 known. It is continually growing worse, and as a consequence 

 the cultivation of crops has been abandoned over large areas in 

 some of the provinces near the Caspian sea. Laws for its 

 eradication were. passed in South Dakota in 1890, in Iowa in 

 1893, and in Kansas, North Dakota, Minnesota and Wisconsin 

 in 1895. In 1892 and again in 1893, the department of agricul- 

 ture sent an assistant botanist to the Dakotas to work out the 

 whole life history of the plant, and the method of dealing with 

 it was established chiefly on the basis of the knowledge thus 

 obtained. It is claimed that if this had been done before 1885, 

 a saving would have been effected for the wheat growers of the 

 northwest' l ' sufficient to pay the cost of maintaining the whole 

 department of agriculture for many years to come. ' ' T Wetter 

 seasons, more intensive farming, the building of fences, and 

 the planting of trees reduced the Russian thistle to the 

 ranks of comparatively unimportant weeds in the Dakotas, but 

 in Nebraska stringent measures were necessary. Farmers co- 

 operated in the work, and the weed was t( hunted almost as 

 strenuously as game would be," so that for some years it has 

 not been an important factor in wheat growing in Nebraska. 



Darnel (Lolium temulentum L.) has its widest distribution in 

 Europe. It also occurs in the wheat fields of California, where 

 1 Yearbook U. S. Dept. Agr., 1897, pp. 95-96. 



