The Scientific American cyclopedia of formulas : partly based upon the twenty-eighth edition of Scientific American cyclopedia of receipts, notes and queries 15,000 formulas / edited by Albert A. Hopkins.
- Albert A. Hopkins
- Date:
- 1910
Licence: Public Domain Mark
Credit: The Scientific American cyclopedia of formulas : partly based upon the twenty-eighth edition of Scientific American cyclopedia of receipts, notes and queries 15,000 formulas / edited by Albert A. Hopkins. Source: Wellcome Collection.
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![(Weeds) (Weeds) become abundant and widely distributed, their extermination is regarded as almost impossible, but they may be brought un¬ der subjection to an extent that will render them comparatively harmless. A new species, if taken in time, may be completely eradicated. Annuals.—An annual reproduces itself from the seeds only, dying root and branch each year. The seeds of many an¬ nuals retain their vitality for several years, and are likely to germinate at ir¬ regular intervals, even though no fresh seed is introduced. Preventing the production of seed will reduce the quantity of weeds and prevent spreading. In cultivated fields burn over the land to destroy as many as possible of the seeds on the surface. Plow shallow so as not to bury the remaining seeds too deeply. The succeeding cultivation, not deeper than the plowing, will induce the germination of seeds in this layer of soil and kill the seedlings as they appear. The land may then be plowed deeper and the cultivation repeated until the weed seeds are pretty thoroughly cleared out to as great a depth as the plow ever reaches. Barren summer fallowing is often prac¬ ticed to clear out weedy land by the method just described ; but usually corn, potatoes, cotton, cabbages or beets may better be grown, giving a profitable re¬ turn for the extra cultivation. The best results can be obtained, of course, with crops that allow cultivation during the greater part of the season, and that do not shade the soil too much, as the direct rays of the sun heating the surface of the soil aid materially in the germination of many seeds. Good results have been ob¬ tained by spraying with 2 to 4 per cent, solutions of copper sulphate to destroy charlock or wild mustard in growing grain, but the application of chemicals cannot be recommended for killing annual plants where cultivation is possible. As annual weeds usually thrive best in soil that has been broken but is not oc¬ cupied, it is evident that broken land should not be permitted to remain idle. A little grass seed raked in on bare hillsides will often keep down annual weeds and will at the same time prevent washing. Mowing the roadside two or three times during the summer will sub¬ due the dog fennel and ragweed. Mow¬ ing the stubble about two weeks after harvest in grain fields that have been seeded to grass or clover will check the annual weeds and at the same time pro¬ duce a mulch that is very beneficial to the seeding during the August drought. Biennials.—The best methods for kill¬ ing the roots or root-stocks vary consider¬ ably according to the soil, climate, char¬ acter of the different weeds and the size of the patch or the quantity to be killed. In general, however, the following prin¬ ciples apply : 1. —The roots, root-stocks, bulbs, etc., may be dug up and removed, a remedy that can be practically applied only in small areas. 2. —Salt, coal oil or strong acid applied so as to come in contact with the freshly cut roots or root-stocks destroys them for some distance from the point of contact. Crude sulphuric acid is probably the most effective of comparatively inexpensive ma¬ terials that can be used for this purpose, but its strong corrosive properties render it dangerous to handle. Carbolic acid is less corrosive and nearly as effective. Ar- senite of soda, a dangerous poison, is sometimes effective, applied as a spray on the growing weeds. 3. —Roots may be starved to death by preventing any development of green leaves or other parts above ground. This may be effected by building straw stacks over small patches, by persistent, thor¬ ough cultivation in fields, by the use of the hoe or spud in waste places and by salting the plants and turning on sheep in permanent pastures. 4. —The plants may usually be smoth¬ ered by dense sod-forming grasses or by a crop like hemp, buckwheat, clover, cow- peas or millet that will exclude the light. 5. —Most roots are readily destroyed by exposing them to the direct action of the sun during the summer drought, or to the direct action of the frost in winter. In this way plowing, for example, be¬ comes effective. 6. —Any cultivation which merely breaks up the root-stocks and leaves them in the ground, especially during wet weather, aids in their distribution and multiplication, and is worse than useless, unless the cultivation is continued so as to prevent any growth above ground. Plowing and fitting corn ground in April and May, and cultivating at intervals until the last of June, then leaving the land uncultivated during the remainder of the season, is one of the best methods that could be pursued to encourage the growth of couch grass, Johnson grass and many other perennial weeds. Special Weeds Attracting Attention. Bracted Plantain.—This weed is so low and inconspicuous and its leaves are so much like those of grass that it is not [56]](https://iiif.wellcomecollection.org/image/b31361523_0070.jp2/full/800%2C/0/default.jpg)
