1. Field of the Invention
The field of the invention relates to the regulation of the growth of aquatic weeds in canals, rivers, ponds, lakes and impoundments.
2. Description of the Prior Art
The problems of controlling or regulating the growth of organisms in aqueous systems are series and growing in severity. Submerged aquatic weeds, for example, cause major problems in water distribution and irrigation systems. The growth of such weeds in irrigation canals greatly reduces the conductivity and capacity of such systems with resulting substantial economic loss. Large sums are spent in the mechanical and other methods of removal of weed growths from irrigation canals, especially in the western parts of the United States. Because of the great difficulties involved in the mechanical removal of weeds and other undesired forms of aquatic life from irrigation canals, ponds, lakes, impoundments, etc., it has been proposed to utilize chemical control. Accordingly, various types of chemicals have been added to such bodies of water.
However, with the growing emphasis on conservation, current efforts are directed toward regulating the growth, that is limiting or inhibiting the amount of growth accomplished by the naturally occurring submerged or floating aquatic weeds, without killing those weeds. This approach is being taken in order to continue to provide the natural environment for fish and other forms of marine life. A further reason is to avoid the masses of dead and rotting aquatic weeds which result when said weeds are killed by means of an aquatic herbicide, since the decomposition of the weeds decreases the amount of available oxygen present in the water. Such decaying matter, when it occurs in reservoirs and/or streams from which drinking water for cities is obtained, makes purification of the water much more difficult. Such decaying vegetation also gives off an unpleasant odor when it collects in a body of water. Thus, a control of the amount of growth rather than a destruction of the submerged aquatic weeds serves to overcome both pollution of the water and pollution of the air.
In the prior art, Krumkalns et al., U.S. Pat. No. 3,655,359 Apr. 11, 1972), teach and claim the use of substituted 3-pyridylmethanes for eliminating germinating weed grasses and broadleaf weeds selectively from crop plants such as corn, cotton, and soybeans, and their close relatives in the plant kingdom. I have found many of the compounds appearing in this reference useful for the regulation of the growth of aquatic weeds and they come within the scope of the compounds used in the present invention. There is no teaching in the reference that the compounds disclosed therein would act to control the growth of submerged or floating aquatic weeds.
Also in the prior art, Krumkalns et al., U.S. Pat. No. 3,744,988 (July 10, 1973), teach and claim the use of substituted 3-pyridylmethanes in a method for inhibiting sucker growth to tobacco plants. This patent is a division of U.S. Pat. No. 3,655,359, supra, and includes in its disclosure many of the same compounds disclosed in that patent. There is no teaching in the reference that the compounds disclosed therein would act to control the growth of submerged or floating aquatic weeds.
Van Heyningen, U.S. Pat. No. 3,396,224 (Aug. 6, 1968), teaches and claims a method of controlling fungi pathogenic to plants by contacting the fungus-susceptible plant with a fungicidal amount of a 3-pyridylmethane derivative, mainly a 3-pyridinemethanol. I have found many of the compounds disclosed in this reference active as aquatic plant growth regulators, and they are included within the scope of the instant application. There is no teaching in this reference that the compounds disclosed would be active as aquatic growth regulators of submerged or floating aquatic weeds.
Van Heyningen et al., U.S. Pat. No. 3,397,273 (Aug. 13, 1968), teach and claim a method for protecting plants from attack by phytopathogenic fungi by treating the plants with a fungicidally-effective amount of a 3-pyridylmethane. Some of the compounds disclosed by this reference have now been found by me to be active as aquatic growth regulators, and their use for that purpose is disclosed and claimed in the instant application. This reference makes no suggestion that the therein disclosed compounds would be active as growth regulators of submerged or floating aquatic weeds.
Krumkalns, U.S. Pat. No. 3,335,148 (Aug. 8, 1967), discloses and claims the 9-(3-pyridyl) derivative of fluorene, 9-fluorenol, xanthene, 9-xanthenol, and the corresponding nonphytotoxic acid addition salts thereof. The compounds are alleged to posses antifungal and antibacterial activities. I have now found some of the compounds to be active as aquatic growth regulators, and such compounds are included for that use in the instant application. There is no teaching or suggestion in this reference that the compounds would be active as growth regulators of submerged or floating aquatic weeds.
Yet another reference, Krumkalns, U.S. Pat. No. 3,361,753 (Jan. 2, 1968), is directed to 9-(3-pyridyl)-thioxanthene and thioxanthol derivatives, active as plant antifungal agents and as antibacterial agents. There is no teaching that the compounds of this reference would be active as regulators of the growth of submerged or floating aquatic weeds.
Another reference is German Pat. No. 1,935,292, also identified by Derwent No. 04548S, which patent teaches and claims a means for controlling plant growth, that is restraining growth and influencing the habits of higher plants, influencing blossom and fruit formation, checking the growth of grass, and the like, using triarymethylimidazoles, -pyrazoles, and -triazoles, or their salts. One of the aryl groups is taught as pyridyl. The reference does not include use on aquatic weeds or plants.
Yet another reference is British Patent No. 1,274,578, also identified by Derwent No. 23143S. This reference teaches plant growth regulators containing N-benzylimidazoles, wherein one of the substituents is a pyridyl group. These compounds are alleged to be plant growth regulators capable of inhibiting or accelerating growth, flowering, and fruiting, according to the amount applied. Certain of the compounds are also alleged to be plant fungicides and bactericides.