The Tumbleweed That Threatened Washington's Wheat

At various times during the past three years we have called attention through the press to the damage threatened to the agricultural welfare of the state by the advent of the Russian thistle, and have emphasized as almost certain the prediction that the weed would be introduced along railway lines, from seeds or parts of the plant that had become lodged in the wheels, or on the brakebeams of the cars, as they passed through the infested regions of Dakota, Nebraska and other states. In 1895, and again in 1896, we made as careful a search as our time would permit along the railway lines, and especially about the freight yards of the larger towns, but found none of the weed. In 1897 a similar search, in which Mr. A. B. Leckenby assisted, resulted in finding the weed in seven different localities, namely: Spokane, Walla Walla, Pasco, Kennewick, a point 12 miles west of Badger, Yakima county, Toppenish and Sunnyside.

Other Points.—We had no opportunity to inspect along the Great Northern railway in 1897, but at our earnest solicitation orders were issued by this company to their employees to search for and destroy all Russian thistles that might be found along their right-of-way. In carrying out this order the thistle is said to have been discovered in small patches at several different places, but we were unable to secure data regarding the exact localities.

Description of the Russian Thistle. The plant now famous under the name "Russian thistle" is undoubtedly of Russian origin, having been accidentally introduced into South Dakota in flaxseed in 1873. It is not, however, a thistle, nor does it resemble one, except in its spines and noxious character. In its rolling habit it is like the common tumbleweed of the plains. Properly it is a vicious inland variety of the saltwort, a nearly harmless plant abounding on our Atlantic seacoast.

The seeds of the weed germinate in April, May and June, each sending up on a slender stalk two narrow green leaves about an inch long, somewhat similar in appearance to blades of grass. Between these seed leaves a short stem soon appears bearing slender, sharp-pointed leaves, presently with branches in their axils. Until dry weather begins the herbage is tender and juicy, and is eagerly eaten by sheep, cattle and horses. During this stage the growth is rather slow. With the advent of dry weather in July and August the moisture disappears from the leaves, and they wither and sometimes fall off. New shoots are rapidly formed, which at first are densely crowded with spine-pointed leaves less than half an inch long, but later elongate, so that the leaves become separated by intervals of one-sixteenth to one-half an inch. Each leaf is accompanied by bracts similar to the leaf itself, all spine-tipped and projecting almost at right angles to the stem. A single small, stemless flower grows in a cup-shaped depression formed by the bases of the two bracts. The outer parts, or perianth, of the flower are thin and paper-like in texture, usually bright rose-colored, and spreading, when fully open, about one-fourth of an inch. If the flower is taken out and carefully pulled to pieces a small pulpy, green, coiled body, appearing like a minute snail shell, will be found. This is the embryo or miniature plant. As the seed ripens its coat becomes of a dull gray color, and at maturity the whole seed is about one-sixteenth of an inch in diameter, irregular in form, and of about one-half the weight of a flax or clover seed.

During August and early September the plants become rigid throughout and increase rapidly in size, forming a dense bushy mass of spiny branches, often 2 or 3 feet in height and 4 to 6 feet in diameter. By the middle of September the exposed parts of the plants have usually changed color from dark green to crimson or rose-red. When the ground is frozen in November the entire plant, except the seed, dies.

The root, one-half inch or less in diameter, is now broken off at the surface of the ground by the force of the wind, and the plant is blown about as a tumbleweed, scattering seed wherever it goes. The seed remains inclosed in the paper-like perianth, and, together with this, is loosely held in its place by numerous twisted hairs, so that it is not readily shaken loose from the plant. A plant may therefore roll about all winter and still retain some of its seeds until the following spring. When the seed breaks loose from the plant the dry flower parts surrounding it act as a sail, so that it may be carried a long distance over the snow independently of the rolling plant. The seeds alone will not be borne through the air like thistle down except in a very high wind, and they will not in any case be blown very far over the bare ground.

A single plant of average size, 2 to 3 feet in diameter and weighing 2 to 3 pounds at maturity when dry, 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. At maturity the heaviest and strongest parts of the plant are the seed-bearing twigs. The inner branches receive little of the wear incident to tumbling about, and are only strong enough to hold the plant together.

Remedies. The Russian thistle is an annual plant, easy to kill at any time during its growth. It is only necessary to pull it up or cut it off at the surface of the ground to destroy it. This should always be done if possible before the seed ripens, which rarely occurs until August. If the weeds have already ripened their seeds, they should be burned, to prevent their scattering seed by rolling. In any case where the weeds were not destroyed until after the seed was ripe, such places will require careful watching the following season.

Injuriousness of the Weed. What damage the Russian thistle would do in this state if it became well established can only be estimated by comparing its behavior in other states. L. H. Dewey, Department of Agriculture, writes: "The history of the weed in the Dakotas indicates that while it is not often troublesome on well-kept farms, and is not generally injurious except during certain years which are favorable to its growth, it is likely to complete the destruction of the wheat crop during any year when the wheat is slow in starting. I have received comparatively few complaints in regard to the Russian thistle this season, but I attribute this largely to the fact that it has been a favorable year for wheat and an unfavorable year for the thistle. My observation of this plant in the vicinity of Scotland, South Dakota, where it has been growing for more than 20 years, confirms my opinion that the plant will not die out of itself when introduced into localities favorable to its growth, and furthermore, that when it becomes thoroughly established and widely distributed in any region it is practically impossible to exterminate it."

Can This Thistle Be Kept From Spreading in This State? Prof. Piper thinks it can. He believes that those already in the state can be destroyed.