Plant husbandry – Process
Patent
1984-11-16
1988-02-23
Schofer, Joseph L.
Plant husbandry
Process
47DIG10, 405 36, 405128, 405263, A01B 7900, B09B 100
Patent
active
047261447
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to the field of agriculture. More specifically, the invention pertains to the fumigation of soils, enclosed spaces, and agricultural commodities.
BACKGROUND ART
Among the more economically serious plant parasites are nematodes, which are roundworms, comprising as many as 10,000 species, of which at least 150 are known to adversely affect plant life. Plant parasitic nematodes have been known since about the year 1750. Most of the nematodes which cause crop damage do so by feeding on plant roots, and therefore are found primarily in the upper few inches of soil in the roots or in close proximity to the roots. Nematode feeding causes hypertrophy or gall formation, and the evidence of heavy infestation is plant stunting, pale foliage, wilting, and even plant death in extreme cases.
Virtually all of the world's crops and ornamental plants can be attacked by parasitic nematodes. Important destructive nematode species include the root knot nematodes which are hosted by tomatoes, alfalfa, cotton, corn, potatoes, citrus and many other crops, the golden nematode of potatoes, the sugar beet cyst nematode and the citrus nematode. These, and few other species, are described in "The Soil Pest Complex", Agricultural and Food Chemistry, Vol. 3, pages 202-205 (1955). Also described therein is a further complication resulting from nematode infestation, namely a lowered resistance to the effects of plant attack by bacteria and pathogenic soil fungi.
Except for small volumes of soil which can be sterilized, it has not been found possible to eliminate nematodes. Parasite populations can, however, be kept at levels which economically permit agricultural operations by soil fumigation, crop rotation using non-hosting plant varieties, and (to a much lesser extent) the development of plants which are resistant to infestation. In many instances, control of nematodes is achieved only by combinations of these techniques, and most control programs have proven quite costly.
Another serious problem in agriculture is the attack of plants by pathogenic microorganisms, particularly fungi. Such pathogens are normally controlled by fumigation, prior to crop planting, using broad spectrum biocides, many of which are no longer regarded as environmentally safe. Certain narrow spectrum fungicides are available, but are extremely expensive and lose effectiveness against successive generations of fungi, due to genetic adaptability.
The process of soil fumigation requires the movement of gaseous chemicals through the soil which is treated, and the readily apparent necessity for a sufficient concentration of gas at a given temperature and pressure condition to be lethal to the pest which would be controlled. Volatility of the chemical agent is critical to successful fumigation, since a very volatile substance will disperse too readily and not develop an effective concentration except for locations very close to the point of introduction to the soil. Substances having a very low volatility are also undesirable, since they will not disperse in the soil, and will be effective only at locations near the point of introduction.
Since fumigants typically are effective against a pest only during specific phases in the life cycle of the pest, some measures must be taken to ensure that the fumigant is present during the proper phases. This requirement normally has been met by either applying highly persistent chemicals, applying large enough doses of the chemicals so that the normal decomposition, leaching, volatilization, and other processes will have a lesser effect upon pesticide concentration in the treated environment, or, for highly volatile chemicals, enclosing the treated area (such as by covering soils) for sufficient time to achieve control of the pest. Unfortunately, most of the persistent chemicals are now environmentally undesirable and the noted application methods are sometimes prohibitivel expensive.
Carbon disulfide is the first reported soil fumigant, used in Europe during the 1870's to control the su
REFERENCES:
patent: 1042501 (1912-10-01), Thompson
patent: 1044452 (1912-11-01), Holland
patent: 2046128 (1936-06-01), Mequiston
patent: 2836532 (1958-05-01), Seifter
patent: 3837304 (1974-09-01), Carroll
patent: 4476113 (1984-10-01), Young et al.
C. R. Acad. Sc. Paris, t276, (12 Mar. 1973), pp. 951-954.
Green, II James A.
Young Donald C.
Kulkosky Peter F.
Larid Michael H.
Sandford D.
Schofer Joseph L.
Union Oil Company of California
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