THE RUSSIAN THISTLE. 13 



"Like all noxious weeds, the Russian thistle may be kept out much 

 more easily than it can be eradicated when once established. In regions 

 not yet infested all avenues of introduction should be watched so that 

 it may be discovered and killed before it can obtain a footing. 



' * It may be expected along all lines of railroads, especially those hav- 

 ing direct traffic with infested regions. It is by way of the railroads that 

 the seeds most often enter new territory, being dropped from stock or 

 grain cars at stock yards, elevators, and sidings. The plants usually 

 appear first close along the tracks by the ends of the ties, where the 

 seeds falling from the cars find conditions favorable to growth in the 

 unoccupied soil, kept stirred by repairs on the tracks and the ballast. 



1 1 The seeds have been introduced in some cases in baled hay and grain 

 at fair grounds, race tracks, lumber camps, and railroad construction 

 camps. They have also been carried in shelled corn, wheat, oats, millet, 

 flax, alfalfa, and grass seed. They are supposed to have been brought 

 to some localities in Idaho in sheep's wool. While the seed has no 

 hooks, barbs, or gum to cause it to stick like cocklebur or clammy 

 cuphea, its small size and light weight enable it to retain a place for 

 some time in a fleece. 



"Another means of introduction and rapid distribution, and one that 

 threatens to be most troublesome, is running water. During the past 

 three years the thistle has spread with remarkable rapidity over irri- 

 gated lands in Colorado and Idaho. Robust plants are produced on 

 the banks of the irrigating canals and ditches. The seeds from these 

 are carried long distances by the water and deposited in the fields. In 

 some cases quarter-sections of irrigated land have been practically 

 covered with the Russian thistle in a single season. The plants have 

 also spread along river banks, especially during freshets. 



"These sources of introduction should be carefully guarded, and 

 every Russian thistle seen should be destroyed before it has produced 

 seed. If any escape notice until the seeds are mature they should be cut 

 and burned before they begin to roll. One Russian thistle destroyed 

 this year is likely to obviate the necessity of destroying from 1,000 to 

 100,000 next year." 



"Efforts have been made to check the progress of tumbleweeds or, 

 at least, of the Russian thistle, by building fences. Thase efforts have 

 been successful only in a very small degree, as the weeds pile up and are 

 blown over the tops of the fences, and also the detached seeds are blown 

 through. In any case the only safe and thoroughly effective method 

 is to destroy the weeds before the seeds reach maturity." (Yearbook, 

 1896.) 



