AU598867B2 - Method for controlling plant diseases and microorganisms in the presence of plants - Google Patents

Description

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PCT WORLD INTELLECTUAL PROPERTY ORGANIZATION INTERNATIOA International BureauN

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INTERNATIONAL APPLICATION S E E ENCOOPERATION TREATY (PCT) (51) International Patent Classification 4 (1 International Publication Number: WO 88/ 02987 A01N 43/50, 25/30, 25/00 Al (43) International Publication Date: 5 May 1988 (05.05.88) (21) International Application Number: PCT/US87/02257 (81) Designated States: AT (European patent), AU, BE (European patent), CH (European patent), DE (Euro- (22) International Filing Date: 8 September 1987 (08.09.87) pean patent), DK, FR (European patent), GB (European patent), IT (European patent), JP, LU (European patent), NL (European patent), NO, RO, SE (31) Priority Application Number: 925,321 (European patent), SU.

(32) Priority Date: 31 October 1986 (31.10.86) Published (33) Priority Country: US With international search report.

With amended claims.

(71) Applicant: GREAT LAKES CHEMICAL CORPORA- TION [US/US]; Highway 52 P.O. Box 2200, West Lafayette, IN 47906 oJ.P. 2 3 JN 188 (72) Inventor: SMITH, Roger, E. Highway 52 P.O.

Box 2200, West Lafayette, IN 47906 (US).

(74) Agents: Roedel, John, K. et al.; Senniger, Powers, Lea- AUSTRALAN vitt Roedel, 611 Olive Street, Suite 2050, St. Louis, MO 63101 2 5 MAY 1988 PATENT OFFICE (54) Title: METHOD FOR CONTROLLING PLANT DISEASES AND MICROORGANISMS IN THE PRESENCE OF PLANTS (57) Abstract Novel method for controlling the growth of microorganisms on, in or near plants. More particularly, in one embodiment, growth of microorganisms is controlled on a surface that is in such proximity to a higher order plant that contacting such surface with a stream of water may cause liquid water from the stream to be deflected and contact the higher order plant or the growth medium in which it is rooted. In this embodiment, an N-halohydantoin is incorporated in water to produce treated water having an N-halohydantoin concentration sufficient to inhibit the growth of microorganisms in the water or on a substrate to which the treated water is applied. Then the surface is contacted with the treated water, thereby inhibiting the growth of microorganisms on the surface, without harming the higher order plant by contact with the N-halohydantoin contained in any of the treated water that may contact the plant or the growth medium in which said plant is rooted. In other embodiments, plants, fruit, vegetables, seeds, plant bulbs, or the medium in which plants, seeds or bulbs are implanted may be treated with N-halohydantoin to control plant disease or unwanted microorganisms without harming the plants, fruit, seeds or plant bulbs.

r WO 88/02987 PCT/US87/02257 1 METHOD FOR CONTROLLING PLANT DISEASES AND MICROORGANISMS IN THE PRESENCE OF PLANTS Background of the Invention This invention relates to plant diseases and deleterious microorganisms found in environments adapted for the growth of higher order plants, and more particularly to control and inhibition of plant diseases and deleterious microorganisms found in such environments.

In environments adapted for the growth of plants of higher biological development or complexity than microorganisms such as bacteria, yeast, algae or simple fungus, that is, in environments adapted for the growth of higher order plants, development of such microorganisms on practically any moist surface has been a longstanding and intractable problem.

Greenhouses contain a myriad of water sources, including irrigation water, irrigation water run-off, V spilled water, cleaning water, condensation, atomized water drifting from a humidifier or evaporative cooler and extraneous sprayed water as might result from a water hose. Since almost all surfaces in a greenhouse tend to become moist from these sources, nearly any surface in a greenhouse may serve as a site for microorganism growth.

Thus, in conventional greenhouses, microorganisms inevitably colonize and grow not only on the plants themselves, but also on all other surfaces such as walls, ceilings, floors, flower pots, flats, irrigation mats, irrigation equipment and evaporative cooling pads.

Similarly, in outdoor nurseries, crop fields, and any other environment, such as lawns or golf courses, WO 88/02987 PCT/US87/02257 2 adapted for the growth of higher order plants,,microorganisms tend to develop on irrigation or sprinkling equipment, soil and the plants themselves, and containers and planters.

Growth of microorganisms often is deleterious to the operation of an irrigation system as well as to the higher order plants themselves. Growth of slime bacteria has a propensity to foul the system and clog irrigation equipment, reducing its efficiency. Likewise, development of yeast, fungus and algae causes spoiling of plants, and the fruits and seeds of plants, and otherwise harms higher order plants. Development of pathogenic microorganisms such as Verticillium, Pythium, Fusarium, and Pseudomonas in or on plants also causes various plant diseases. Furthermore, microorganism development in living plants may accelerate rotting or spoiling of the plants after harvesting, or even accelerate rotting or spoiling of fruits or seeds harvested from the plants. Moreover, development of microorganisms in a greenhouse can cover the greenhouse with an unappealing slime which rubs off on workers who brush against a coated greenhouse surface, blocks light transmission through the glass walls of the greenhouse, fouls the greenhouse, makes the greenhouse floors slippery, provide a breeding ground for fungus gnats and other pests, and potentially poses health hazards.

Previous attempts to inhibit microorganism development in plant environments either have failed or have been self-defeating because ordinary biocides or disinfectants, such as bleach or various quaternary ammonium compounds, that have been employed to kill or inhibit microorganisms, also are toxic to the higher order plants in the environment. Thus, ordinarily the cleaning of 1 WO 88/02987 PCT/US87/02257 3 greenhouse surfaces has entailed tedious, labor intensive careful scrubbing of the surfaces to avoid accidentally contacting a plant with the biocide, or time consuming removal of all the higher order plants from the greenhouse before washing down the surfaces with a hose. Moreover, it seems clear that because such biocides are phytotoxic, they cannot be considered for direct plant treatment either in the irrigation water to keep clean the surfaces contacted by the water, or in irrigation water or otherwise in order to treat the plants themselves. On the other hand, however, while some biocides may have low enough phytotoxic characteristics to use directly on plants, many have been associated with health hazards to humans that eat the plants or harvested parts thereof.

In addition to the health hazards from the toxicity of the oxidizing biocides used in the prior art for treating microorganism development around plants, such biocides also usually involve other health hazards from some other characteristic, such as the explosiveness of chlorine gas tanks. Other problems with many of the conventional chlorine biocides include instability of the biocide in the presence of organic matter, effectiveness of the biocide only in a narrow pH range, and the formation of Schloramines in the presence of ammonia, thereby producing residual compounds which undesireably persist in the environment. Further, the additives typically employed in irrigation systems for control of certain microorganisms, or for other purposes such as fertilization, tend to be compositions of high water solubility and so require employment of expensive pumps and other mechanical parts to regulate the concentration of the additives, to maintain an appropriate concentration and to avoid a phytotoxic overdose.

WO 88/02987 PCT/US87/02257 I4 As disclosed in Paterson U.S. patent 3,412,021 and Macchiarolo U.S. patent 4,297,224, l-bromo-3is known as an oxidizing biocide for use in water treatment in certain environments, such as swimming pools and cooling towers in which higher order plants are not a concern. Patent and other technical literature discloses a number of uses for this and other N-halohydantoin compounds based on the biocidal properties of these compounds.

Summary of the Invention Among the several objects of the invention, itherefore, may be noted the provision of a method for controlling unwanted microorganisms located on, in or near higher order plants without harming the higher order plants; the provision of a method for cleaning greenhouses and surfaces therein with biocide treated water that does not harm higher order plants; the provision of a method for treating higher order plants for inhibition of unwanted microorganisms without harming the higher order plants; the provision of a method for treating higher order plants for controlling disease to the plants without harming the plants; the provision of a method for treating higher order plants for inhibition of unwanted microorganisms and control of disease without harm to the plants and without the need for extra pumps to apply the treatment; the provision of a method for treating harvested plants, fruits, vegetables, and seeds for inhibition of rotting or spoiling by treating growing plants; the provision of a method for irrigating plants whereby development of unwanted microorganisms is inhibited; the provision of a method for treating soil, growth media or aggregate, or hydroponic solutions for inhibiting unwanted microorganisms without WO 88/02987 PCT/US87/02257 harming the plants; the provision of a method for treating an evaporative cooler or humidifier whereby development of unwanted microorganisms is inhibited; and the provision of a method for treating an evaporative cooler or humidifier whereby development *of unwanted microorganisms is inhibited, and plants contacted by atomized water emitted from the evaporative cooler or humidifier are unharmed.

Briefly, therefore, the present invention is directed to a novel method for controlling the growth of microorganisms on a surface that is in such proximity to a higher order plant that contacting such surface with a stream of water may cause liquid water from the stream to be deflected and contact the higher order plant or the growth medium in which it is rooted. Also controls microorganisms in the root zone within the growth media. The method comprises incorporating an N-halohydantoin in water to produce treated water having an N-halohydantoin concentration sufficient to inhibit the growth of microorganisms in the water or on a substrate to which the treated water is applied, and contacting the surface with the treated water, thereby inhibiting the growth of microorganisms on the surface. In the method, the higher order plant remains unharmed by the N-halohydantoin contained in any of the treated water that that may contact the plant or the growth medium in which the plant is rooted.

The present invention is also directed to a novel method for controlling growth of unwanted microorganisms on a surface whereby a higher order plant is not harmed, the surface being located in an environment for the growth of a higher order plant. The method comprises incorporating N-halohydantoin in water to produce treated water having a concentration of N-halohydantoin sufficient to inhibit WO 88/02987 PCT/US87/02257 6 growth of microorganisms, and contacting a surface with the treated water for controlling microorganisms thereon, the higher order plant being contacted with the treated water in connection with contacting the surface with the treated water.

The present invention is further directed to a novel method for irrigating plants wherein growth of unwanted microorganisms on or in the plants is controlled without harming the plants. The method comprises incorporating N-halohydantoin in water to produce treated water having a concentration of N-halohydantoin sufficient to I inhibit growth of microorganisms, and irrigating plants with the treated water. The present invention is also directed to such irrigation methods in which growth of unwanted microorganisms in or on irrigation equipment and materials is controlled, and to such methods in which plant disease is controlled without harming the plants.

The present invention is further directed to a novel method for controlling growth of disease or unwanted microorganisms in a plant or a plant rhizosphere without harming the plant. The method comprises applying an N-halohydantoin to a growth medium in which the plant is rooted. The N-halohydantoin is dissolved in and conveyed to the rhizosphere by precipitation or irrigation water received by the growth medium. The invention is also directed to such method wherein the N-halohydantoin is applied to a growth medium in which a seed or bulb for the plant are implanted.

The present invention is also drawn to a novel method for controlling disease or growth of unwanted micro- organisms in or on a plant without harming the plant. The WO 88/02987 PCT/US87/02257 7 method comprises contacting the plant with an N-halohydantoin, preferably by dissolving N-halohydantoin in water to produce a disinfectant solution having a concentration of N-halohydantoin sufficient to inhibit growth of microorganisms, and applying the disinfectant solution to said plant. Alternatively, a seed or bulb for the plants may be treated with N-halohydantoin.

The present invention is also drawn to a novel method for treating harvested plants whereby growth of unwanted microorganisms in or on the harvested plants is controlled without harming the plants. In the method, harvested plants are contacted with an N-halohydantoin.

Preferably, N-halohydantoin is dissolved in water to produce a disinfectant solution having a concentration of N-halohydantoin sufficient to inhibit growth of microorganisms. Then, the harvested plants are contacted with the disinfectant solution, whereby rotting or spoiling of the harvested plants is inhibited.

The present invention is further drawn to a novel method for production of harvested plants, fruit or seeds, or controlling disease in the plants, fruits, seeds, or vegetables, whereby growth of unwanted microorganisms in or on the vegetables, plants, fruit or seeds is controlled without harm to the vegetables, plants, fruit or seeds. In the method, growing plants are contacted with an N-halohydantoin and then the plants, or fruit or seeds from the plant are harvested. Preferably, the method comprises several steps. First, N-halohydantoin is dissolved in water to produce a disinfectant solution having a concentration of N-halohydantoin sufficient to inhibit growth of microorganisms. Then, growing plants are contacted with the disinfectant solution. Finally, the growing plants, or W O 8 8 0 2 8 P C U 8 7 0 2 WO 88/02987 PCT/US87/02257 8 their fruit or seeds are harvested and rotting or spoiling of the harvested plants is inhibited.

Descriotion of the Preferred Embodiment In accordance with the present invention, it has been discovered that N-halohydantoins, their metabolites and residuals, can be used for effective control of microorganisms in a plant environment without risk of injury to higher order plants. More particularly it has ben found that aqueous solutions of N-halohydantoins may be formulated in a wide easily attainable range of concentrations that are high enough to kill various unwanted microorganisms such as slime bacteria, yeast, fungus and algae, yet low enough not to harm higher order plants, whether contact of the plant with the solution is intentional or incidental. Regulation of the concentration of N-halohydantoin is simplified by the relatively low solubility of these compounds in water, and the fact that the highest concentration of N-halohydantoin that is obtained under ordinary conditions is too low to result in phytotoxicity.

Unexpectedly, not only is a saturated solution of N-halohydantoin harmless to plants but, astonishingly, actually seems to stimulate plant growth. It has further been found that solid state N-halohydantoins are not harmful to higher order plants, and that these biocides may thus be applied in either solid or solution form in plant environments, or indeed to the plants thermselves, without risk of injury to plant systems or tissue.

Moreover, since ingestion of reasonable amounts of N-halohydantoins is not believed to pose health dangers to humans from toxicity, ingestion of plants or parts thereof treated with N-halohydantoin is believed to present 7 WO 88/02987 PCT/US87/02257 9 no serious or appreciable health risk. Further, since N-halohydantoins are neither flammable nor typically stored in pressurized containers, they do not present dangers from explosions. The N-halohydantoins of this invention also show greater stability in the presence of organic matter and effectiveness over a wider pH range than shown by typical chlorine disinfectants of the prior art. Further, the N-halohydantoins of this invention do not tend to form chloramines in the presence of ammonia, and so are not believed to form residual compounds which undesirably persist remain in the environment.

Due to the surprising selective toxicity of aqueous N-halohydantoin compositions, the compositions can be employed in many biocidal applications wherein the composition does or may contact desired higher order plants.

Accordingly, greenhouse surfaces susceptible to microorganism development may be cleaned with a solution of N-halohydantoin without undue'concern as to whether any of the solution incidentally contacts the higher order plants growing in the greenhouse. Moreover, N-halohydantoin can be incorporated into irrigation water to control the growth of microorganisms in the water, on the irrigation equipment and on surfaces contacted by the water without harming the plants to be irrigated.

It has also been found that because of the selec- V tive phytotoxicity characteristic, N-halohydantoin can be incorporated into irrigation water or otherwise applied directly to plants or to the growth medium in which plants are rooted to treat the plants, to control microorganism development in, on and around the plants and to control certain plant diseases, without harming the plants. Also surprisingly, it has been discovered that treating growing WO 88/02987 PCT/US87/02257 plants with N-halohydantoin and then harvesting the plants, or their fruit or seeds, results in harvested plants, fruit or seeds that do not rot or spoil as early as do harvested untreated plants, or fruit or seeds from untreated plants.

It further has been 'found that the benefit of delayed rotting or spoiling also can be achieved by applying N-halohydantoin composition directly to the harvested plants, fruit and seeds.

In addition, it has been found that the relatively low water solubility of N-halohydantoins avoids the formation of a highly concentrated phytotoxic solution.

However, the concentration necessary for inhibiting microorganism development is so low that the low solubility of N-halohydantoin does not present a significant obstacle to production of a solution effective in killing microorganisms. In fact, even solutions of low N-halohydantoin concentration have been found to be dramatically effective in killing microorganisms. Therefore, N-halohydantoin practically self-regulates for the appropriate concentration range, and it is essentially unnecessary to provide expensive pumps and other mechanical parts for introduction of N-halohydantoin into a water system, or to introduce the biocide in a meticulously regulated manner to carefully control the N-halohydantoin concentration therein.

It also has been found that incorporating N-halohydantoin in a circulating water system, such as an evaporative cooler or humidifier, located in a greenhouse or otherwise located in close proximity to desired plants or other organisms, keeps the system substantially free of unwanted microorganisms but does not harm the desired plants or other organisms in the environment. Moreover, Lt is believed that the atomized treated water propelled from WO 88/02987 PCT/US87/02257 11 the cooler or humidifier and contacting surfaces and plants and other organisms in the environment improves the sanitation of the environment.

Preferably, the N-halohydantoin of this invention is an N,N'-dihalohydantoin compound, more preferably a 1,3-dihalohydantoin corresponding to the formula: R =0

R

0/ X2 where R1 and R 2 are independently selected from among hydrogen and alkyl, and X1 and X 2 are independently selected from among fluorine, chlorine, bromine, and iodine. Where R 1 and/or R 2 are alkyl, they may for example, comprise methyl, ethyl, n-propyl, isopropyl, n-butyl, or n-pentyl. Generally, it is preferred that the constituents comprising R 1 and/or R 2 contain not more than about 5 carbon atoms. Preferred N-halohydantoins are N-halogenated dialkylhydantoins, especially N-halogenated dimethylhydantoins. Particularly preferred N-halohydantoins include 1,3-dibromo-5,5-dimethylhydantoin, 1-bromo- 3-chloro-5,5-dimethylhydantoin, and 1,3-dichloro-5,5dimethylhydantoin, and other hydantoin derivatives.

In this invention, N-halohydantoin is incorporated in wate: to produce an oxidizing biocide composition.

The concentration of N-halohydantoin in the composition as it is applied to inhibit microorganism development or to control plant disease should be at least about one part per million, and preferably at least about 5 ppm, to be effective against microorganisms and related diseases. However, WO 88/02987 PCT/US87/02257 12 the concentration of N-halohydantoin in the composition as the composition contacts desired higher order plants should not exceed the point at which the composition becomes phytotoxic. Nevertheless, it has been found that the concentration of N-halohydantoin, due to its low solubility, under ordinary conditions, does not exceed about 1500 ppm, at which concentration not only has phytotoxicity not been observed, but the growth of higher order plants seems to be stimulated. Thus, a biocide of N-halohydantoin concentration between about 1 and about 1500 ppm has been found effective to kill unwanted microorganisms, yet harmless to higher order plants.

The N-halohydantoin may be incorporated into a water system at any point in the system although, of course, for a non-recirculating system the biocidal activity resulting from the N-halohydantoin only occurs downstream of the point of incorporation. Moreover, as noted, due to the self-regulatory nature of the N-halohydantoin dissolution, special pumps and other mechanical parts for metering the N-halohydantoin are unnecessary, and so the incorporation of the N-halohydantion in water can be an essentially passive operation.

Thus, for example, solid N-halohydantoin, preferably in particulate form, can be placed in a mesh bag and suspended in a stream of water or in a well of a water circulating system. Water contacting the N-halohydantoin in the bag dissolves some of the N-h _ohydantoin. For a stream the relationship between flow rate and effective area of contact between water and solid biocide should be such that the downstream N-halohydantoin concentration is at least 1 ppm. As noted, due to the relatively low water solubility of N-halohydantoins, the concentration of WO 88/02987 PCT/US87/02257 13 N-halohydantoin under ordinary conditions remains less than about 1500 ppm. Ordinarily, the concentration remains between 2 ppm and 10 ppm. Preferrably the concentration is between about 5 ppm and about 10 ppm. Accordingly, by this essentially passive mechanism, the treated water contains a concentration of N-halohydantoin sufficient to control development of microorganisms and plant disease without harming higher order plants.

On the other hand, if so desired, N-halohydantoLn may be introduced into the water by means of an inexpensive standard halogenator or brominator. If a brominator is used, either the entire water stream is directed through the brominator, or a side stream is diverted, passed through the brominator and reunited with the main stream.

Likewise, for applications of N-halohydantoin by hose, a brominator may be connected to the hose line or N-halohydantoin may be placed in a hose attachment such as those originally intended for application of detergents and cleaning compounds.

There are several applications for the water so treated with N-halohydantoin. For example, the treated water can be applied to an irrigation system to clean the irrigation equipment and other surfaces, to clean or to treat the plants and the fruit and seeds they bear, to treat by foliar application the plants and the fruit and seeds the plants bear, to clean a greenhouse without harming plants therein and to treat and to clean evaporative coolers or humidifiers often found in a greenhouse.

In a greenhouse, plants are often watered by means of a capillary mat irrigation system. In a capillary mat irrigation system, irrigation water typically is WO 88/02987 PCT/US87/02257 14 delivered through a conduit to a water absorbent sheet of material, such as polypropylene felt. By means of the natural absorbency of the material, the water is transported through the material to the growth medium of potted plants sitting on the absorbent material.

N-halohydantoin may be introduced into a greenhouse irrigation system by directing the stream of water to be used for irrigation through a brominator containing N-halohydantoin. The biocidal activity of the treated water not only tends to prevent development of unwanted microorganisms that otherwise proliferate in the water and on the irrigation equipment, but also prevents the development of microorganisms that otherwise grow and coat the [j irrigation mat and the pots holding the plants. Thus, by including N-halohydantoin in the system, clogging of the irrigation equipment and coating of the irrigation mat are avoided, and the efficiency degradation normally encounk tered with the irrigation system is suppressed. Also extends the useful life of the equipment. Further, such treatment of the irrigation water also inhibits development of microorganisms on the floor and other surfaces in the greenhouse often contacted by irrigation water run-off.

As for the plants themselves, the cleaner water provided by this method is believed to deliver to the plants via the roots thereof fewer living microorganisms that could be deleterious to the plant. Moreover, the biocidal activity of the treated water delivered to the plant is believed to inhibit microorganism development in and on the plant, and so helps prevent or control certain plant diseases which could result from pathogenic microorganisms. Importantly, therefore, this method is believed to control diseases that otherwise spread quickly through w mnmmm----1 Il I I WO 88/02987 PCT/US87/02257 the plants in a greenhouse. Also prevents spread of disease by re-cycled greenhouse irrigation water. Yet, despite such biocidal activity of water treated with N-halohydantoin, the plant itself is not harmed by the treated water. Thus, irrigation water can be treated with N-halohydantoin for all these purposes, to avoid fouling and clogging of the equipment and other surfaces and to treat the irrigated plants, without endangering the plant.

Walls, ceilings and floors :n greenhouses, and even filters from evaporative coolers may be cleaned in accordance with this invention by hosing down the surfaces with treated water. The biocidally treated water kills the algae and other microorganisms that develop on the surfaces and cleans far more effectively than does untreated water, but treated water that splashes onto the plants in the greenhouses does not harm the plants as do other biocides such as bleach. Therefore very time consuming removal of plants from the greenhouse before cleaning is unnecessary.

For this application, the water can be treated by dissolving N-halohydantoin in a volume of water, by inserting N-halohydantoin in the water stream, or by directing the stream, or a side stream, through a brominator containing N-halohydantoin. The greenhouse may then be quickly and easily hosed down without serious danger of harming the plants hit by splashed water, deflected water, extraneous A atomized sprays of water, or even misdirected streams of water.

By the method of this invention, evaporative coolers or humidifiers, whether located in a greenhouse or another environment containing plants, animals, or other organisms also can be maintained substantially free of fouling microorganisms without harming plants or animals WO 88/02987 PCT/US87/02257 16 nearby. As with the other particular applications, N-halohydantoin can by incorporated at essentially any point in the system. Advantageously, N-halohydantoin can be placed in a mesh bag in the water collecting well of the circulating system. The self-regulating mechanism of N-halohydantoin discussed above tends to maintain the treated water at an appropriate concentration. In accordance with this method, the evaporative pad remains substantially free of unwanted microorganisms that otherwise accumulate, while equipment, plants or other organisms contacted by atomized treated water drifting from the cooler or humidifier not only are not harmed by the treated water, but may be disinfected by the treated water. Thus, an unhealthy environment can be converted to a healthful, somewhat antiseptic environment.

As with greenhouse plants, crops or plants in an outdoor nursery may be irrigated with treated water.

N-halohydantoin may be incorporated anywhere in the water j system as described above, and the plants irrigated with the treated water by any of several irrigation methods, such as spray irrigation, trickle or drip irrigation, mist or fog irrigation, sub-irrigation, ebb-and-flow irrigation, and hydroponics. Also as with the greenhouse irrigation methods, the treated water acts to control unwanted microorganisms from developing on the irrigation equipment, as well as in or on the plants and growth medium in which the plants are rooted. The treatment thereby helps prevent certain plant diseases arising from pathogenic microorganisms and control the outbreak and spread of such diseases.

In an alternative application of the method of the invention, solid N-halohydantoin may be placed on or in WO 88/02987 PCT/US87/02257 17 the ground near growing plants so that rain or irrigation water delivers the N-halohydantoin to the plant's roots or rhizosphere. Likewise, solid N-halohydantoin may be placed on or in the ground near implanted bulbs or seeds so that rain or irrigation water delivers the N-halohydantoin to the roots or rhizosphere of plants grown from the bulbs or seeds. Or, if desired, the bulbs or seeds themselves may be treated by applying powder or granular N-halohydantoin or a slurry or solution of N-halohydantoin directly to the bulbs or seeds before planting.

In still another alternative embodiment of the application of the method of this invention growing plants may be treated with the treated water or by foliar application of an N-halohydantoin powder, slurry or solution to inhibit the development of unwanted microorganisms and diseases on or in the fruit or seeds of the treated plants, and to delay rotting or spoiling of the plants, fruit or seeds even after harvesting. Significantly, the treatment process of this invention not only is harmless to the plants, but because ingestion of N-halohydantoins in ordinary doses is widely believed to be safe to humans, unlike many presently available herbicides and pesticides, the resulting low doses of N-halohydantoin in the harvested plants, fruits and seeds appear to pose no appreciable health hazards to humans consuming them.

Due to the self-regulating quality, N-halohydantoin can also be applied to growing plants by placing solid N-halohydantoin on or in the ground near the rhizosphere of plants, and rain water or irrigation water will dissolve the N-halohydantoin to the plants in appropriate dosages.

If desired, the N-halohydantoin can be applied to the ground before germination of seeds or growth of bulbs, and WO 88/02987 PCT/US87/02257 18 can even be applied to the ground while planting seeds or bulbs, thereby eliminating the need for a separate treatment step. Optionally, or in the alternative, N-halohydantoin can be added as a powder or slurry directly to bulbs or seeds before planting. It is believed that these applications of N-halohydantoin directly to the growth medium or the bulb or seed itself and transportation to the plant by rain or irrigation water is effective in controlling development of unwanted microorganisms and plant diseases without harming higher order plants.

Alternatively, or additionally, N-halohydantoin can be applied topically to plants, fruit or seeds after harvesting. The N-halohydantoin can be dissolved in water I to form a treatment solution. Then, the harvested plants, fruit or seeds can be sprayed or washed with the treatment solution. Or, if so desired, the harvested plants, fruit or seeds can be dusted or coated with N-halohydantoin powder or an N-halohydantcin slurry. Regardless, the harvested plants, fruit and seeds are not harmed nor are they believed toxic to humans. Yet, microorganism development in and on the harvested plants, fruit and seeds is inhibited and so rotting and spoiling is delayed.

Thus, N-halohydantoin can be applied in conjunction with irrigation, applied as a separate treatment or incorporated in water used for other purposes to protect plants unintentionally hit by the water.

Other advantages derived from the practice of this invention will become apparent from the following description and examples: WO 88/02987 PCT/US87/02257 19 EXAMPLE 1 Experiments were conducted to compare the effectiveness of an N-halohydantoin composition with the effectiveness of sodium hypochlorite in producing desired levels of free residual halogen in infested water. A bromochloro-dimethylhydantoin (BCDMH) solution was calibrated so that five drops of the solution added to distilled water (300 ml) resulted in a solution of 1 ppm BCDMH. Water samples were collected from a muddy water seepage area in a canal site. A second set of water samples was collected from a "swamp" at the bottom of an 800-foot well. The swamp water contained 0.5 ppm hydrogen sulfide, 0.8 ppm iron, 5 ppm aromatic hydroxyl compounds and probably other unknown impurities. Drops of the BCDMH solution were added to the water samples (300 ml each) and the free residual bromine in the sample measured to determine the BCDMH concentration necessary to produce 0.6 ppm free residual Brin the sample. The results were compared to the sodium hypochlorite concentration necessary to produce 0.6 ppm free residual Cl- in the sample. The Cl- concentration was measured with a standard Hach test kit. The Brconcentration was measured with a similar test kit. The results were as follows: Canal Water Swamp Water Total NaOCI Added 5.6 ppm 4.2 ppm Free Residual Cl- 0.6 ppm 0.6 ppm Total BCDMH Added 4.0 ppm 3.4 ppm Free Residual Br- 0.6 ppm 0.6 ppm Thus, about 23% to 40% more sodium hypochlorite than BCDMH was required to produce the same level of free residual halogen.

WO 88/02987 PCT/US87/02257 EXAMPLE 2 Chrysanthemums and gladioli were planted in four plots under full-bed culture in EauGallie fine sand. The plants were irrigated by drip irrigation. One week later, BCDMH was introduced into the irrigation water of two of the 50-foot plots. The BCDMH was introduced to the irrigation water by mixing 9% aqueous BCDMH mixture (71 gal.) with water (4000 gal.). The 4071 gallons of total solution were applied to the two 50-foot plots (about 11 acre inches of irrigation) over almost ten weeks. Residual Br- concentration in the water collected from the end of the drip tube during operation was 2 to 2.5 ppm. The following results, showing no adverse effect on either chrysanthemum or gladiolus production, were obtained: Chrysanthemums: Weight/Plant (Ibs.) N6. of Plants Untreated Plot 3.6 100 Treated Plot 3.8 100 Gladiolus: No. of Stems No. of Florets Per Stem Untreated Plot 55 14.2 Treated Plot 49 14.6 No significant difference in microorganism development was apparent between the tubes carrying treated water and those carrying untreated water, but it is believed that the duration of the trial was too short for any significant difference to appear.

WO 88/02987 PCT/US87/02257 21 EXAMPLE 3 Two sets of Yellow Mandalay chrysanthemums (thirty plants per set) were grown and irrigated by subirrigation mats. The plants were fertilized with six ounces of Osmocote per cubic foot of growing medium. One set of plants (control) was not treated with biocide. For the other set of plants (test), BCDMH was injected into the irrigation system at a rate of about 2 to 4 ppm. Bromine levels of the test and control mats were measured daily and the bromine level was maintain 2 to 4 ppm higher than the level of the control. About eleven weeks after planting, leaf samples were collected and analyzed. Table 1 shows levels (in percent by weight) of various nutrients (nutrients for which the fertilizer was the only direct supply) found in the leaves (and compared with desired levels): While the test samples showed lower concentrations of some nutrients, the experiments were not conducted for such analysis and fertilization was not controlled.

Thus, these results are not believed signficant in distinguishing the effects of BCDMH on nutrient uptake. The plants were then evaluated for phytotoxicity. There was no observable phytotoxicity. The plant heights were measured, but no difference was observed between the heights or growth between the treated plants and the control plants.

While considerable algae growth had developed on the mat and fungus gnats had become a problem in the control set, there was no algae growth on the treated mat.

Three weeks later, algae growth still had not appeared on the treated mat.

WO 88/02987 PCT/US87/02257 22 The experiment was repeated with exacum instead of chrysanthemums. Table 2 shows results from the foliar analysis were obtained: TABLE 1 00 00 00 -4 Control Test Des-i red N P K Ca Mq Mn Fe B Cu Zn Al Na 3.742 06.23 4.1 2.2 0.64 -j39 111 20 77.7 181 3 4 2f 5 3.32 0.12 1.6 1.0 0.39 208 54 11 4.6 126 22 21 4.5 0.4 4.0 1.0 0.3 30+ 30+ 30 5.0 30+ TABLE 2 Control Test Desired N P K Ca Mg Mn Fe B Cu Z n Al N a 4.3 2 0.30 1f.21 0.75 0.69 29 897.9 39 4 7 4 9 .7 -20.9 7969 6 4.24 0.37 0.89 0.83 0.80 222 92.7 47.6 5.1 70.6 23.1 9376 4.5 0.4 4.0 1.0 0.3 30+ 30+ 30 5.0 30+ 00 t k,4 wo

(A

WO 88/02987 PCT/US87/02257 24 While the test samples showed lower concentrations of some nutrients, the experiments were not conducted for such analysis and fertilization was not controlled. Thus, these results are not believed signficant in distinguishing the effects of BCDMH on nutrient uptake. Moreover, with the exacum it was noticed that of the 80 plants on the control mat, 50 had roots growing into the mat. Of the remaining plants, many had roots growing out of the pot, but not yet into the mat. However, of the 77 plants on the treated mat, none "stuck" to the mat or had roots growing out of the bottom of the pot. This avoidance of sticking to the mat is desirable for aesthetics and ease of handling.

EXAMPLE 4 The following plants received a drench of foliar application of a saturated (1500 ppm) BCDMH solution: Foliage Crop Potted Plants Pilea Grape Ivy Syngonium Zebra Plant Schefflera Velvet Plant Pepperomia English Ivy Dieffenbachia Christmas Cactus Ficus Benjamina Asparagus Fern Neanthe Bella Perrywinkle Maranta Leuconeura Fibrous Begonia Coleous Impatiens Applications were intermittent for three to six weeks in a greenhouse environment. No phytotoxicity was observed. In Sa separate experiment, the same types of plants received foliar sprays containing 1500 ppm BCDMH. Plants received 3 applications of spray separated by 10 day intervals. No phytotoxicity was observed.

WO 88/02987 PCT/US87/02257 The following plants were sprayed with BCDMH solutions of 1, 10, 100 and 1000 ppm in the spring: Potted Plants Flats 8" Zonal Geranium Fibrous Begonia 3" Tomatoes Seed Geranium 6" Pot Mums Non-Stop Begonias 4" Gebera Petunias Impatiens Except for occasional pinpoint burns on some flowers sprayed with the most concentrated solution, no other signs of phytotoxicity were observed. Undissolved particles of BCDMH are believed to have caused the pinpoint burns.

Unopened buds were not harmed.

The following plants in 4-inch pots were sprayed with BCDMH solutions of 1, 10, 100 and 1000 ppm in the summer: Potted Plants Pteris Cretica Gloxinia African Violet Gerbe:a Non-Stop Begonia Mild phytotoxicity symptoms were observed on open flowers at 100 and 1000 ppm.

EXAMPLE Seeds were planted in several plots. Several sets of seeds were coated with various powder compositions. Some of the compositions comprised the commercially available products phygon, the dichlone 2,3-dichloro- 1,4-naphthoquinone, which is a trade designation of Uniroyal, and Vitavax, a carboxin, which is a trade designation of Uniroyal. The formulas of these products are not WO 88/02987 PCT/US87/02257 known. One set of seeds in each plot were uncoated. The coatings for each set and the amounts of the coating (in ounces per hundred weight) were as follows: Set Coating Comoosition 1 none 2 Pentachloronitrobenzene 3 Phygon 27X 4 Phygon 27X and Vitavax 30C Phygon 27 and Vitavax 30C 6 Phygon 29 and Vitavax 30C 7 Phygon 27 8 Phygon 27 and Vitavax 30C 9 Phygon 29 Phygon 29 and Vitavax 30C 11 Particulate 92.5% BCDMH 12 Particulate 92.5% BCDMH Amount of Coating' 12 12 10 and 3.3, resp.

10 and 3.3, resp.

10 and 3.3, resp.

7 7 and 3.3, resp.

7 7 and 3.3, resp.

following survived) plot 3): The seeds were planted in various plots, with the survival rates (in percent of planted seeds that of the seeds (sets 11 and 12 were planted only in Set 1 2 3 4 6 7 8 9 11 12 Minimum significant differences: Plots: 3 43 58 63 69 41 58 46 47 58 11 11 The minimum significant difference indicates the confidence range within which there is no significant difference. For example, for the survival rate of set 12 WO 88/02987 PCT/US87/02257 27 there is no significant difference between survival rates between 47% and 69%. Thus, it appears from the data that the BCDMH seed coating is at least as effective as the other coatings.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

AI

Claims (24)

1. A method for controlling diseases caused by microorganisms or growth of unwanted microorganisms in or on a growing higher order plant without harming the plant, the method comprising: providing contact, in the presence of water, between an N-halohydantoin and the plant, the rhizosphere of the plant, or a growth medium in which a seed or bulb for the plant is planted, the N-halohydantoin being selected from the group consisting of a l-bromo-3-chloro-5,5-dialkyl- hydantoin and a 1,3-dibromo-5,5-dialkylhydantoin, and being o provided in an amount sufficient to control said disease or microorganisms. *eo o 2. A method as claimed in claim 1 wherein said higher order plants are irrigated and treated for control of diseases caused by microorganisms or growth of microorganisms, the method comprising the steps of: incorporating N-halohydantoin in water to produce treated water having a concentration of N-halohydantoin sufficient to inhibit the growth of microorganisms; and irrigating said higher order plants with the treated water.

3. A method as claimed in claim 2 wherein the plants are irrigated by means of spray irrigation. S° 4. A method as claimed in claim 2 wherein the concentration of N-halohydantoin is between 1 ppm and 1500 ppm by weight. A method as claimed in claim 4 wherein the N-halohydantoin concentration is between 2 ppm and 10 ppm by weight. NT w V*. I-i 29

6. A method as claimed in claim 5 wherein the N-halohydantoin concentration is between 5 ppm and 10 ppm by weight.

7. A method as claimed in claim 2 wherein the N-halohydantoin comprises an N-halogenated dimethyl- hydantoin.

8. A method as claimed in claim 7 wherein the N-halohydantoin comprises l-bromo-3-chloro-5,5-dimethyl- hydantoin. 00@

9. A method as claimed in claim 7 wherein the N-halohydantoin comprises 1,3-dibromo-5,5-dimethylhydantoin.

10. A method as claimed in claim 2 wherein higher order plants are irrigated by transportation of water to the plants by water absorbent material, the method comprising the steps of: arranging the plants and the water-absorbent material so that water may be transported through the water- absorbent material and contact the plants or growth medium in which they are rooted; incorporating N-halohydantoin in water to produce treated water having a concentration of N-halohydantoin sufficient to inhibit the growth of microorganisms; and delivering said treated water to said water S. absorbent material, thereby effecting transport of treated Sewater to said plants or said growth medium.

11. A method as claimed in claim 1 wherein an N-halohydantoin is applied to a growth medium in which the plant is rooted, the N-halohydantoin being dissolved in, and conveyed to said rhizosphere by, precipitation or irrigation water received by said growth medium. 30

12. A method as claimed in claim 11 wherein the N-halohydantoin comprises an N-halogenated dimethyl- hydantoin.

13. A method as claimed in claim 12 wherein the N-halohydantoin comprises l-bromo-3-chloro-5,5-dimethyl- hydantoin.

14. A method as claimed in claim 12 wherein said N-halohydantoin comprises 1,3-dibromo-5,5-dimethylhydantoin.

15. A method as claimed in claim 1 wherein harvested higher order plants are produced, the method comprising: contacting growing higher order plants with an N-halohydantoin; and harvesting said growing plants to collect harvested a. *plants, whereby rotting or spoiling of the harvested plants is inhibited.

16. A method as claimed in claim 1 wherein higher order plants are treated with N-halohydantoin and harvested fruit or seeds are produced from the treated plants, the method comprising the steps of: *I contacting growing higher order plants bearing fruit or seeds with an N-halohydantoin; harvesting fruit or seeds from the said higher order plants to collect harvested fruit or seeds, whereby rotting or spoiling of the harvested fruit or seeds is inhibited.

17. A method as claimed in claim 16 wherein the growing plants ate contacted with'the N-halohydantoin by: 31 dissolving the N-halohydantoin in water to produce a disinfectant solution having a concentration of N-halohydantoin sufficient to inhibit growth of micro- organisms; and contacting the growing plants bearing fruit or seeds with the disinfectant solution.

18. A method as claimed in claim 17 wherein the plants are contacted with the disinfectant solution by applying the disinfectant solution as irrigation water to the growing plants.

19. A method as claimed in claim 17 wherein the concentration of N-halohydantoin is between 1 ppm to 1500 *fe ppm by weight.

20. A method as claimed in claim 19 wherein the N-halohydantoin concentration is between 2 ppm and 10 ppm by weight.

21. A method as claimed in claim 20 wherein the N-halohydantoin concentration is between 5 ppm and 10 ppm by weight.

22. A method as claimed in claim 17 wherein the N-halohydantoin comprises an N-halogenated dimethyl- hydantoin. 0* S s* 23. A method as claimed in claim 22 wherein the N-halohydantoin comprises l-bromo-3-chloro-5,5-dimethyl- hydantoin.

24. A method as claimed in claim 22 wherein the N-halohydantoin comprises 1,3-dibromo-5,5-dimethylhydantoin. Ibt A I. 32 A method as claimed in claim 1 wherein the N-halohydantoin is applied to a growth medium in which a seed or bulb for the plant is implanted, the N-halohydantoin being dissolved in and conveyed by precipitation or irrigation water received by said growth medium to said seed, bulb, or plant resulting from germination of said seeds or bulb.

26. A method as claimed in claim 25 wherein the N-halohydantoin comprises an N-halogenated dimethyl- hydantoin.

27. A method as claimed in claim 26 wherein said N-halohydantoin comprises l-bromo-3-chloro-5,5-dimethyl- hydantoin.

28. A method as claimed in claim 26 wherein the N-halohydantoin comprises 1,3-dibromo-5,5-dimethylhydantoin. DATED this 24th day of January, 1990. GREAT LAKES CHEMICAL CO. U.S. S06 WATERMARK PATENT TRADEMARK ATTORNEYS, 290 Burwood Road, HAWTHORN, VIC. 3122. AUSTRALIA. LCG:KJS:JZ (10.5) -7 iNTERNATIONAL SEARCH REPORT international A oolicatiun V-CT/ US 8 7/ 0 22 57 C LAS~iFICATIO~c OF SUB.JECT MA rTER 'it seyeral classfication symools apply, ndicate ait) i U.S.C1.: 514/389; 71/3, 67 11, FIELDS SEARCH.ED -Minimum Documentation Searched4 Classirication Systemn Classification Symools 514/389; 71/3, 67 Documentation Searched other than Minimum Documentation to the E2lent that such Documents are Included in the Fields Searched6

111. DOCUMENTS CONSIDERED TO BE RELEVANT 1 Category j Citation of Document, 16 with indication, where appropriate. of the relevant Passage$ IT Relevant to Claim No.,i A A, 3,412,021 (PATERSON) 19 November 1-ii14 1968, see column 1. Y A, 4,058,618 (OVICHINNIKOV ET AL), 1-114 November 1977, see the abstract. Y A, 4,167.,832 (ZETTERQUIST ET AL), 1-114 18 September 1979, see abstract and columns 1 and 2. Y A, 4,198,423 (RENTZEA ET AL), 15 1-114 April 1980, see the abstract. A A, 4,454,133 (BERKE ET AL), 12 June 1-114 1984, see the abstract. AP A, 4,655,815 (JAKUBOWSKI) 7 April 1-114 1987, see abstract. *Special categories of cited Jocuments: 15 later document Publshed after the international fiting date document defining the general state of the art i *ot or iority date and not in conflict with the application 0ut cnieetobe of particular relevance cited to inderstand the principle or theory underlying the consdere toinvention E"earlier document but published on or after the *i'.-izonal document of particutar relevance: the claimed invention n lng date cannot be considered novef of cannot be considered to document vhlch may throw joubts on Priority 1 is or involve an inventive step which is cited to 4stabtisn the publication date o! i-3ther document of Darttcular relevance; the claimed invention Citation or other special reason (as spectified) cannot be considered to involve an inventive stec when the document referring to an orat disclosure, use, anhiution or document is combined with onet or more other such docu- other means ments, such combination being obvious to a person sktilled document published prior to the international filing date but in the art. later then the priority date claimed document member of the %ame petent family IV. C1111TIFICATION Date of the Actual Completion of the International Search I Date of Meilting of this International Search ReportI DECEMBER 1987 1 2 JAN 1988-7 International Searching Authority t i o rrd 2 I SA/U5 )>-Cr<RoCTlins Foam PT/fSA/20 (sscdsh~1t (Mey 1986) internaticnal A oolicatton No, PCT/11S87/O 2257 FURTHER INFORMATION CONT!NUED rRO.M THE SECONO SHEET B, 1,472,049 (OVCHINNIKOV ET AL) 27 April 1977, see the abstract. A B, 53-34923 (KENKYLU) 31 March 1978 see abstract. Y A 552,973 (OVCHINNIKOV ET AL), 29 April 1977 see abstract. 1 -114 1-114 W OBSERVATIONS WHERE CERTAIN CLAIMS WERE FOUID UNSEARCHASLE '0 This international searcn report itas not been established in respect of certain claims under Article 17(2) for the following reasons: Claim numbers because !hey relate to subject matter ti' sot required to be searched by this Authority, namnely:. 2.17' Claim numbers because they relate to oaris of the international application that do not comply with the prescribed require- ments to such an extent that no meaningful international search can be carried out 13, specifically; Vf4. OBSERVATIONS WHERE UNITY OF INVENTION IS LACKING It This International Searching Authority found multiple inventions In this international application as follows: I.jAs all required additional search fees were timeiy -aid by the applicant, this International search report covers all iearchaole :am of the international application. 2.1As only some of the required additional searcrr lees vYera timel', paid by the -applicanit, this international search report covers only those claims of the international application for Nnicri lees vere paid, specifically claims, 37,No required additional search tees were timely paid by the applicant, Consequently, this international search (apart Is restricted to the invention first mentioned in the claims: illis covered by claim numbers: 4.1' As all searchable claims could be itearcheo -without etlort justifying an additional fee, the International Searching Authority did not Invite payment of any additional lee. Renmarh an Protest The additional searcn fees cvore accompanied by 3oolicant's protest. 0No protest accompanied tne payment ;3t additional sarcn lees. Form PCT1ISAfl21O (sUppliarrain she"12 t2 May 1986)