DISEASES OF WHEAT 151 



Those which choke the crop, preventing its growth; (2) those 

 which interfere with harvesting and curing; and (3) those 

 whose seeds injure the commercial value of the grain by min- 

 gling with it. Deterioration in the quality of the grain by the 

 third class is perhaps the greatest damage resulting from weeds. 



Kinds of Weeds: CHESS OR CHEAT (Bromus secalinus L.) This 

 is an annual grass that will not produce seed unless sown in the 

 fall, and consequently it is not found in spring wheat. It is 

 less vigorous than wheat, but more prolific, and also more re- 

 sistant against cold and insects. One pound of seed has been 

 known to multiply 99-fold in one generation, and one seed 

 3,000-fold. The ordinary observer cannot distinguish the young 

 chess plant from wheat. Chess injures flour and must be 

 cleaned from the wheat before grinding. Seed wheat properly 

 cleaned by a fanning mill is quite free from chess. If wheat 

 is treated for smut by stirring it in a solution, the chess seeds 

 will rise to the surface and can be skimmed off. A pound of 

 chess and a bushel of wheat have about the same number of 

 seeds. 



Russian Thistle or Cactus (Salsola kali tragus L.). This 

 weed is neither a thistle nor a cactus, but a saltwort, closely re- 

 lated to the tumbleweed, lamb's quarters, and pigweed. In 

 parts of Russia, where it has been known over 150 years, ex- 

 tending now to northern Russia and central Siberia, it is known 

 as Tartar or Hector weed. It was first introduced into the 

 United States in 1873 or 1874, being sown in South Dakota with 

 Russian flax seed. As the weed prefers a dry climate, it could 

 not have found a more congenial habitat. When the plants 

 were uprooted in the fall they rolled across the prairie with 

 the speed of the wind, scattering seeds at every bound, and 

 stopping only when they were worn to pieces, or when the wind 

 ceased, for in the early Dakotas there were few fences, forests, 

 or streams to stop their course. 



Thus they covered an advance of 5 or 10 miles in a season, 

 though stray plants went much farther. As a rapid traveler 

 thoroughly covering territory it surpassed any other weed 

 known in America, and very few cultivated plants intention- 

 ally distributed have such a record for rapidity. Within 20 

 years it infested a continuous area of about 35,000 square miles, 

 and caused at least $1,600,000 damage to wheat every year. 



