This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Introduced. Annual. Propagates by seeds.
Time of bloom: June to July.
Seed-time: July to August.
Range: All parts of the country, but most abundant and troublesome in the grain-growing sections of the Canadian provinces and in the United States from Minnesota to Oregon and California.
Habitat: All soils; fields of cereal grains, flax, and the large-seeded grasses.
Sowing Wild Oats is proverbially a bad thing to do, but the wide distribution of this weed is almost entirely due to the practice of allowing it to enter the soil with its betters. Once there, it is not an easy task to get it out again. It has a number of bad traits which render it particularly obnoxious in grain fields: it thrives best under the field conditions best suited to the growth of cereals; its seeds ripen irregularly, but usually before those of the grain with which it grows, and drop easily from the stalk as soon as ripe; the seeds have long vitality, and one fouling of the ground will last for several seasons. The plant adapts itself to the widest differences of soil and climate, from Dakota flax fields to southern California wheat fields. The stiff and twisted awns are frequently injurious to animals that eat them, causing serious irritation in mouth, nostrils, and digestive tract; also, the hard skins and thick hulls of the seeds sometimes permit of their passing unharmed through the intestines to be sown with the droppings. (Fig. 21.)
Wild Oats look much like the cultivated grain, the culms growing in tufts, two to four feet tall, with long, smooth, green leaves about a half-inch wide, and loose, open seed-panicles six to ten inches long, the spikelets pendulous, the glumes nearly equal, slightly ridged, smooth and pointed. But the lemmas or hulls that enclose the seed are, in the cultivated plant, smooth and thin; those of the Wild Oat are larger, much thicker, covered with stiff, brown hairs, and have a ring of rigid, brown hairs at base; they bear a stiff awn about an inch long, which is both twisted and bent; the awns of the cultivated oat are much shorter and not so stiff. These crooked and bristly awns are able to cling to the wool of sheep and to the insides of grain-sacks, which helps the seeds to find new homes; when dampened they relax, and twist again when dry, so boring easily into the soil. Wild Oats will germinate and the young plant force its way to air and sunlight, even when buried four or five inches deep in the ground.
Sow clean seed. No matter what its cost, it cannot be so expensive as the fouling of a whole grain crop, sometimes to such a degree as to suffer a dockage in the market of one to fifteen pounds to the bushel. And it is to be remembered that the soil on which such a crop grew is also damaged and below grade while the weed is its tenant. If a field is newly infested and the plants are not too numerous to make the job impracticable, hand-pulling and burning, before the hardening of the seed, is not too great a price to pay for its complete and prompt extermination. But if left until harvest, stubbles should immediately be plowed, very shallow, so as to induce germination of seeds in the soil, the growth being either grazed off or plowed under for humus. In the spring, plow more deeply and put in a hoed crop. Or a crop of sowed corn or rape may be grown and used for soiling or pasturage. Or, if such crops as winter wheat or rye are to be grown, summer-fallow the land, harrowing it well about every week or ten days until time to sow the rye or the wheat. Leave cultivated oats out of the rotation of crops until the wild plants are entirely destroyed. When Wild Oats show themselves in a hay field, no stress of weather nor pressure of other work should be allowed to interfere with the cutting of the crop before the Wild Oats are out of the "dough stage" of the seeds. The plant makes excellent hay when cut green.
Fig. 21. - Wild Oats (Avena fatua). X 1/4.