WO2018167458A1 - Herbicidal compositions comprising a pyrocarbonate - Google Patents

Abstract

The current invention provides for a composition comprising a herbicide and a pyrocarbonate having the general formula R₁-O-CO-O-CO-O-R₂, wherein R₁ and/or R₂ is an alkyl group.

Description

HERBICIDAL COMPOSITIONS COMPRISING A PYROCARBONATE

FIELD OF THE INVENTION

The current invention relates to herbicidal compositions, kits comprising a herbicide and a pyrocarbonate, and methods and uses thereof.

BACKGROUND OF THE INVENTION

Agriculture forms one of the central functions of society, providing the basis for human sustenance. The significant rise in the world's population since the beginning of the 20^th century has been matched by technological innovations which have increased agricultural productivity and assisted with avoiding the Malthusian trap.

Herbicides have played a central role in underpinning these productivity gains. More recently, their integration with genetically modified crops resistant to target herbicides has allowed insect and weed suppression to take place while the crop is growing without damaging the crop. For example, in 2011-2012, Roundup Ready (RTM) GM soy contributed 93-94 % of US production (USD A 2013).

The extensive use of herbicides in modern farming practice, while being a key component of enhancing crop yields, has raised concern within parts of the scientific community and the public at large in relation to the potential effects of such wide-spread and persistent use. These concerns include, but are not limited to, the effect of these products on the natural environment including insect and aquatic life, the build-up of potentially toxic compounds in soils and the risk of elevated levels of toxic compounds entering the animal and human food chains with the risks this entails for human health. Paraquat is an example of a herbicide which has been removed from use in many farming areas on account of concern over its environment impact. An additional problem caused by current farming practices is that of herbicide resistant weeds. These are common weeds having small genetic variations that have enabled them to survive applied herbicides and consequently establish themselves across significant areas of cultivated land. For example, in the US, it is estimated that some 75 million acres (an area the size of Arizona) have now become infested with such weeds. The Weedscience website reports that weeds have evolved resistance to 22 of the 25 known herbicide sites of action and to 157 different herbicides. Herbicide resistant weeds have been reported in 86 crops, in 66 countries.

The significant rise of herbicide resistant weeds in the US since the early 1990s, contrasts with an estimated 10-year development cycle for new herbicide products. This is exacerbated by the removal from use of established herbicides as emerging scientific evidence points to unacceptable toxicological or environmental risks posed by them. This trend of long development cycles for herbicides and early removal of existing products, suggests technological development of new products is not keeping pace with resistance build-up. Society is therefore faced with two challenges, namely (i) how to raise yields without compromising environmental and human health, and (ii) how to develop new products in a timely manner to tackle fast-adapting plant pests.

Therefore the introduction of a novel product which can enhance herbicide efficacy at much lower dosage rates and which is deemed non-toxic to humans and the environment would be of significant value to the farming community and society at large.

It is therefore an aim of embodiments of the invention to overcome or mitigate at least one portion of the prior art described hereinabove.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a composition comprising at least one herbicide and further comprising a pyrocarbonate, wherein the pyrocarbonate has the general formula R1-O-CO-O-CO-O-R2 wherein Ri and/or R₂ is an alkyl group.

According to a second aspect of the invention, there is provided a composition comprising a herbicide and further comprising a pyrocarbonate, in which the pyrocarbonate has the general formula R1-O-CO-O-CO-O-R2, wherein Ri and/or R₂ is an alkyl group, and the pyrocarbonate is in a quantity sufficient to enhance the efficacy of the herbicide.

According to a third aspect of the invention, there is provided use of a composition of the first or second aspects of the invention as a herbicide. According to a fourth aspect of the invention, there is provided a method of inhibiting the growth of a plant within a treatment area, said method comprising applying a composition of the first or second aspect of the invention to said treatment area and/or to said plant.

According to a fifth aspect of the invention, there is provided a method of enhancing the activity of a herbicide, said method comprising mixing a pyrocarbonate with the herbicide, wherein the pyrocarbonate has the general formula R1-O-CO-O-CO-O-R2, wherein Ri and/or R₂ is an alkyl group.

According to a sixth aspect of the invention, there is provided use of a pyrocarbonate as an enhancer of at least one herbicide, wherein the pyrocarbonate has the general formula Ri-O- CO-O-CO-O-R2, and Ri and/or R₂ is an alkyl group.

According to a seventh aspect of the invention, there is provided a kit comprising at least one herbicide and a pyrocarbonate, in which the pyrocarbonate has the general formula Ri- 0-CO-0-CO-0-R₂, wherein Ri and/or R₂ is an alkyl group, and, when combined, the pyrocarbonate enhances the efficacy of the herbicide. The term "herbicide" as used herein (and as defined by the US Environmental Protection Agency; EPA) refers to any substance or mixture of substances intended for preventing, destroying, repelling, suppressing or mitigating any plant. The term "plant" encompasses both vascular and non-vascular plants and therefore also includes bryophytes. Thus, the term "herbicide" refers to any substance or mixture of substance intended for killing, suppressing, inhibiting the growth of, or inhibiting photosynthesis in vascular or nonvascular plants. Herbicides also encompass any substance or mixture of substances intended for use as a plant regulator, defoliant or desiccant. The term "bryophyte" includes moss, liverworts and hornworts.

"Bryophytocidal" as used herein means the ability of a substance to: inhibit the growth of bryophytes; suppress photosynthesis in bryophytes; and/or kill bryophytes.

The first aspect of the invention may provide a composition comprising a first herbicide and a pyrocarbonate of the defined formula. The pyrocarbonate itself has herbicidal activity against both vascular and non-vascular plants, and can therefore be considered a second herbicide in the composition, different to the first herbicide. It has been surprisingly found that the use of pyrocarbonate s in a herbicidal composition comprising at least one further herbicide provides not only herbicidal action by both the pyrocarbonate and further herbicide separately, but the pyrocarbonate has been found to enhance the activity of the further herbicide. The second aspect of the invention provides a composition comprising at least one herbicide and a pyrocarbonate, in which the pyrocarbonate has the general formula Ri-O-CO-O-CO- 0-R₂, wherein Ri and/or R₂ is an alkyl group, and the pyrocarbonate is in a quantity sufficient to enhance the efficacy of the herbicide. The fact that the pyrocarbonate is in a quantity sufficient to enhance the efficacy of the herbicide means that less herbicide is required to achieve a desired effect on plants. In other words, the pyrocarbonate significantly reduces the volume of herbicide required to achieve the same efficacy in crop protection. In addition, pyrocarbonates have been found to accelerate the effect of the herbicide.

The pyrocarbonate may be in a quantity sufficient to enhance synergistically the efficacy of the herbicide. Synergistic enhancement of the efficacy of the herbicide means that significantly less herbicide is required to achieve a desired effect on plants and that the herbicidal effect is significantly accelerated.

The composition of the first or second aspect of the invention may comprise other components. Alternatively the composition may consist of at least one herbicide and a pyrocarbonate, in which the pyrocarbonate has the general formula R1-O-CO-O-CO-O-R2, wherein Ri and/or R₂ is an alkyl group, and the pyrocarbonate is in a quantity sufficient to enhance the efficacy of the herbicide.

The pyrocarbonate may be capable of inhibiting photosynthetic electron transport in vascular plants and/or bryophytes. The pyrocarbonate may be capable of inhibiting the growth of or killing vascular plants and/or bryophytes. Thus, the pyrocarbonate may have herbicidal (including bryophytocidal) activity. Such activities may result from the ability of the pyrocarbonate to react with amino acid chemical groups, including imidazoles, amines and thiols, and alter protein structure and function. The pyrocarbonate may facilitate the carbonylation of imidazole rings, for example in enzymes (e.g. in enzyme active sites) or cellular proteins. For instance, the pyrocarbonate may facilitate the carbonylation of imidazole rings of histidine amino acids. The alkyl group is a functional group that consists of single-bonded carbon and hydrogen atoms connected acyclically, such as methyl or ethyl groups. Alkyl groups have the general formula C_nH -i, where n is an integer, for example, n = 1 for a methyl group (C¾). According to some embodiments, n may be 0-20, 0-10, 0-5, 1-4, 0-3, 1-3, 1-2 or 1. Ri and R2 may be independently selected from methyl, ethyl, propyl, isopropyl or butyl but are preferably independently selected from methyl and ethyl.

In some embodiments, both of Ri and R₂ comprise the same alkyl group, which may be methyl or ethyl.

Examples of pyrocarbonates having the general formula R1-O-CO-O-CO-O-R2, wherein Ri and/or R₂ is an alkyl group, include dimethyl dicarbonate (DMDC) and diethyl dicarbonate (DEDC). The structure of DMDC and DEDC are shown below:

Dimethyl dicarbonate (DMDC)

Diethyl dicarbonate (DEDC) Thus, the pyrocarbonate of the invention may be diethyl dicarbonate or dimethyl dicarbonate. In some embodiments, the pyrocarbonate is dimethyl dicarbonate.

Diethyl dicarbonate is otherwise known as diethyl oxydiformate, ethyoxycarbonyl ethyl carbonate, ethoxyformic anhydride and pyrocarbonic acid diethyl ester and diethylpyrocarbonate (DEPC). Dimethyl dicarbonate is otherwise known as dicarbonic acid dimethyl ester, dimethyl pyrocarbonate and methoxycarbonyl methyl carbonate. Velcorin® is the trade name for DMDC, which is sold by LANXESS®. DMDC is primarily used as a beverage preservative, processing aid, or sterilization agent, e.g. for cold microbial treatment of beverages including but not limited to wines, fruit juices and soft drinks. DMDC is approved in the EU, where it is listed under E number E242, as well as Australia and New Zealand. In addition, the US FDA and the JECFA of the WHO have confirmed the safe use of DMDC in beverages. Fruit juices, beer and white wine to which DMDC was added at a concentration of 4000 mg/L did not induce any adverse effects in short-term or subchronic toxicity studies in rats and dogs. The available data (in vitro and in vivo) did not report a genotoxic potential and no reproductive or developmental toxic effects were reported in rats drinking orange juice treated with DMDC at 4000 mg/L. DMDC is also used in a number of chemical reactions including as a substrate in the generation of high-value heterocyclic compounds, in a process for preparing methyl methylcarbamate and its purification for use as pharmaceutically active compound and as an activating agent in a method for the synthesis of diaryl and alkyl aryl ketones.

DMDC is unstable in aqueous solution and breaks down almost immediately after addition to aqueous solutions. The principal breakdown products in aqueous liquids are methanol and carbon dioxide. Other minor hydrolysis products may include dimethyl carbonate (DMC), methyl ethyl carbonate (MEC) and methyl carbamate (MC). As the boiling point of methanol is 64.7° C, this primary residue would quickly evaporate off plants in normal ambient spraying conditions. Assuming a spray concentration of 4000 ppm of DMDC at a rate of 300 L/hec this implies deposition of 72 g/hec of methanol, which would in normal circumstances rapidly evaporate.

The preceding information demonstrates that DMDC has a long-established range of uses in food processing and chemical catalyst applications. The features that make it particularly attractive in relation to food processing is its speed of hydrolysis in the presence of water and the minimal toxicity of remaining post-hydrolysis residues. Indeed, it can be shown from the aforementioned that DMDC has long been subjected to wide ranging investigations in a number of non-related scientific fields. However, none of these investigations has sought to consider DMDC as a herbicide in particular, or DMDC's efficacy as an enhancer of the efficacy of a herbicide. In fact, the known literature suggests that DMDC and other pyrocarbonates can be used as a fungicide on plants, at specific concentrations and in specific compositions, and therefore it is surprising that it has now been found that pyrocarbonates such as DMDC and DEDC can be used as a herbicide itself but also as an agent capable of enhancing the efficacy of another herbicide.

Advantages of DMDC include its ability to hydrolyse quickly into non-toxic substances. At 20° C, DMDC has a half-life of 17 minutes (and full hydrolysis occurs in 120-450 minutes), at 10° C it has a half life of 40 minutes, and at 4° C it has a half life of 70 minutes. By avoiding the production of toxic residues, DMDC provides a more sustainable solution for controlling plants. DEDC has similar advantages.

The invention also provides a composition comprising a herbicide and a pyrocarbonate, in which said pyrocarbonate is in a quantity sufficient to enhance the efficacy of at least one herbicide in the composition, and preferably all of the herbicides. The pyrocarbonate may function by carbonylation (e.g. methoxycarbonylation) of enzymes and/or produce methanol and C0₂ as by-products. The pyrocarbonate may react with amino acid chemical groups, including imidazoles, amines and thiols, and alter protein structure and function. For example, the pyrocarbonate may facilitate the carbonylation of imidazole rings, e.g. imidazole rings of histidine amino acids located in enzyme active sites. The pyrocarbonate may be a pyrocarbonate having the general formula R1-O-CO-O-CO-O-R2, wherein Ri and/or R₂ is an alkyl group, as defined and described hereinabove.

The composition may comprise less than 10% (v/v) water, or less than: 9% (v/v), 8% (v/v), 7% (v/v), 6% (v/v), 5% (v/v), 4% (v/v), 3% (v/v), 2% (v/v), 1% (v/v) or 0.5% (v/v) water. The composition may be an anhydrous composition (e.g. a dry composition), to which a solvent (such as water) could be added immediately prior to use. Anhydrous compositions are preferred because pyrocarbonates such as DMDC are rapidly hydrolysed upon contact with water. The composition of the invention may inhibit photosynthetic electron transport in a plant. The plant may be a vascular plant and/or a bryophyte (such as moss, liverworts and horn worts).

The pyrocarbonate may accelerate said herbicidal effect of the herbicide, or may increase the strength, effect or action of the herbicide. The pyrocarbonate in the composition may cause greater than 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% inhibition of photosynthetic and/or respiratory electron transport in a plant relative to a composition comprising the same herbicide (or the total amount of the same) but lacking the pyrocarbonate, e.g. over the course of 1 hour, 2 hours, 4 hours, 8 hours, 12 hours, 18 hours, 24 hours, 36 hours, 48 hours, 3 days, 4 days, 5 days, 6 days, 1 week or 2 weeks. Said inhibition of photosynthetic and/or respiratory electron transport may be the total amount of inhibition, the rate of inhibition or both, for example.

In some embodiments, the or each herbicide is not a pyrocarbonate. In some embodiments, the or each herbicide is not a herbicide having the general formula R1-O-CO-O-CO-O-R2, wherein Ri and/or R₂ is an alkyl group. In some embodiments, the or each herbicide is not dimethyl dicarbonate.

The pH of the composition may be at least pH 1, at least pH 1.5 or at least pH 2. The pH of the composition may be no more than pH 10, no more than pH 9, or no more than pH 8.

The pH of the composition may be pH 2-8 or pH 2-7. The composition may have an acidic pH. An advantage of maintaining DMDC (or other pyrocarbonates falling within the general formula defined hereinabove) at low pH is that the un-dissociated form of DMDC predominates at low pH, and this form can penetrate cell membranes more rapidly than dissociated ionic forms. Once inside the plant cell where the pH is close to neutral, a large proportion of the DMDC dissociates into membrane-impermeable ions, which become trapped inside the cell membrane.

The composition may comprise an adjuvant. The adjuvant may enhance the efficacy of at least one of the herbicide and/or pyrocarbonate. The mechanisms of action of adjuvants include buffering water to a pH at which a specific herbicide is most active, water conditioning (for example when using hard water to dilute herbicides, they reduce the potential inhibitory effects of minerals such as calcium and magnesium), reducing the surface tension of water ("wetting agents") so that the herbicide has greater leaf coverage. Adjuvants may contain organic solvents which make the leaf cuticle and/or cell membranes more penetrable to herbicides, or they may contain nutrients which encourage plant growth which may assist herbicides that are more efficacious against actively growing plants. Some adjuvants are defoaming agents, some reduce drift during spraying, and some may reduce evaporation and herbicide volatility. The adjuvant may act as a: pH buffering agent; water conditioning agent; wetting agent; leaf cuticle and/or cell membrane penetration aid; plant growth enhancer; defoaming agent; spray drift reducing agent; and/or an evaporation reducing agent. The adjuvant may be in the form of a crop protectant spray additive and/or a surfactant. The adjuvant may increase the permeability of plant cuticles and/or cell membranes. The adjuvant may be a non-ionic spreading and a penetration aid; and/or act to reduce surface tension of the composition.

The adjuvant may enhance the herbicidal activity of said pyrocarbonate, for example by increasing permeability of cuticles and/or cell membranes. The adjuvant may enhance the herbicidal activity of said pyrocarbonate, for example by increasing permeability of plant cuticles and/or cell membranes. The adjuvant may reduce pH and/or bicarbonate levels in spray solutions.

The adjuvant may be an additive for crop protectant sprays, such as a surfactant; a non-ionic spreading and a penetration aid; and/or act to reduce surface tension of the composition, for example. The adjuvant may comprise an activator adjuvant or a utility adjuvant.

Activator adjuvants are compounds that when added to the composition comprising the pyrocarbonate, enhance the herbicidal activity thereof. Activator adjuvants include surfactants, oil carriers such as phytobland (not harmful to plants) oils, crop oils, crop oil concentrates (COCs), vegetable oils, methylated seed oils (MSOs), petroleum oils, and silicone derivatives, as well as nitrogen fertilizers, for example.

Utility adjuvants, which are sometimes called spray modifiers, alter the physical or chemical characteristics of the composition mixture making it easier to apply, such as by increasing its adherence to plant surface so that it is less likely to roll off, or increasing its persistence in the environment. One or more oils may be used as an adjuvant carrier or diluent for the pyrocarbonate.

Salts may also be used as activator adjuvants, such as to increase the uptake and effect of the pyrocarbonate in a target plant over time.

One or more surfactant adjuvants may be present in the composition to facilitate or enhance the emulsifying, dispersing, spreading, sticking or wetting properties of the composition. Surfactants reduce surface tension in the spray droplets of the composition, when the composition is applied to the plant, which aids the composition to spread out and cover the target plant with a thin film, leading to more effective or quicker absorption of the composition into the plant. Surfactants may also affect the absorption of the composition when sprayed on stems or leaves of a plant, by changing the viscosity and crystalline structure of waxes on leaf and stem surfaces, so that they are more easily penetrated by the pyrocarbonate of the composition.

The surfactant may be chosen to enhance the herbicidal properties of the composition, through any one or more of: a) making the composition spread more uniformly on the plant; b) increasing retention (or 'sticking') of the composition on the plant; c) increasing penetration of the composition through hairs, scales, or other leaf surface structures of a plant; d) preventing crystallization of the composition; and/or e) slowing the drying of the composition.

The or each surfactant may be selected from a non-ionic surfactant, an ionic surfactant, an amphoteric surfactant or a zwitterionic surfactant, or any combination thereof.

Non-ionic surfactants are generally biodegradable and are compatible with many fertilizers and so may be preferable in compositions of the invention. Some non-ionic surfactants are waxy solids and require the addition of a co-solvent (such as alcohol or glycol) to solubilize into liquids. Glycol co-solvents are generally preferred over alcohols, as the latter are flammable, evaporate quickly, and may increase the number of fine spray droplets (making the formulation likely to drift when sprayed).

The non-ionic surfactant may comprise an organosilicone or silicone surfactant (including siloxanes and organosiloxanes). Organosilicone surfactants significantly reduce surface tension of the composition, enabling the composition, in use, to form a thin layer on a leaf or stem surface of a plant. Silicone surfactants also decrease surface tension and may allow the composition to penetrate the stomates of a plant leaf. Silicone surfactants also provide a protective effect to the compositions of the invention by making the compositions very difficult to wash off after they are applied. Silicone surfactants can also influence the amount/rate of herbicide that is absorbed through the cuticle of a leaf. In other embodiments, the non-ionic surfactant may comprise a carbamide surfactant (also known as a urea surfactant). The carbamide surfactant may comprise monocarbamide dihydrogen sulphate, for example.

Suitable ionic surfactants include cationic surfactants and anionic surfactants. Suitable cationic surfactants include tallow amine ethoxylates. Suitable anionic surfactants include sulphates, carboxylates, and phosphates attached to lipophilic hydrocarbons, including linear alkylbenzene sulphonates, for example.

Amphoteric surfactants contain both a positive and negative charge and typically function similarly to non-ionic surfactants. Suitable amphoteric surfactants include lecithin (phosphatidylcholine) and amidopropylamines, for example.

Utility adjuvants, which are sometimes called spray modifiers, alter the physical or chemical characteristics of the compositions of the invention making the composition easier to apply, which may increase its adherence to a plant surface so that the compositions have a reduced risk of being removed from said surface; or increasing the persistence of the composition in the environment or treatment area in which the composition is present.

Examples of different functional categories of utility adjuvants suitable for use in the compositions and uses of the invention include wetting agents, spreading agents, drift control agents, foaming agents, dyes, thickening agents, deposition agents (stickers), water conditioning agents, humectants, pH buffers, de-foaming agents, anti-foaming agents and UV absorbents. Some utility adjuvants may function in more than one of the aforesaid functional categories. Some activator adjuvants are also utility adjuvants.

Wetting agents or spreading agents lower surface tension in the compositions, and allow the compositions to form a large, thin layer on the leaves and stems of a target plant. Since these agents are typically non-ionic surfactants diluted with water, alcohol, or glycols they may also function as activator adjuvants (surfactants). However, some wetting or spreading agents affect only the physical properties of the composition, and do not affect the behaviour of the composition once it is in contact with plants.

Drift control agents may be used to reduce spray drift of the composition, for example when the composition is sprayed onto a plant, which most often results when fine (< 150 μπι diameter) spray droplets are carried away from the target area by air currents. Drift control agents alter the viscoelastic properties of the spray solution, yielding a coarser spray with greater mean droplet sizes and weights, and minimizing the number of small, easily-airborne droplets. Suitable drift control agents may comprise large polymers such as polyacrylamides, polysaccharides and certain types of gums. Suitable deposition agents (stickers) include film-forming vegetable gels, emulsifiable resins, emulsifiable mineral oils, vegetable oils, waxes, and water-soluble polymers, for example. Deposition agents may be used to reduce losses of composition from the target plant, due to the evaporation of the composition from the target surface, or beading-up and falling off of the composition. Deposition agents are particularly suitable for compositions of the invention in the form of dry (wettable) powder and granule formulations.

De-foaming and antifoam agents reduce or suppress the formation of foam in containers in which the compositions of the invention may be contained. Suitable de-foaming agents include oils, polydimethylsiloxanes and other silicones, alcohols, stearates and glycols, for example. The adjuvant or adjuvants may comprise BREAK-THRU® S 240, BREAK-THRU® SP 131, BREAK-THRU® SP 133, BREAK-THRU® S 233, BREAK-THRU® OE 446, Aduro (RTM) and/or Transport Ultra (RTM). BREAK-THRU® S 240 is a polyether trisiloxane that imparts super spreading and dramatically reduces surface tension. BREAK- THRU SP131 is composed of polyglycerol fatty esters and polyglycols, and it improves the performance of herbicides.

BREAK-THRU® SP 133 is based on polyglycerol esters and fatty acid esters. BREAK- THRU® S 233 is a non-ionic trisiloxane surfactant, which increases the deposition of agrichemical sprays and improves the penetration of pesticide actives into plant tissue. BREAK-THRU® OE 446 is a polyether polysiloxane. Transport Ultra (RTM) comprises a blend of non-ionic surfactants, ammoniated ions, water conditioning agents and an antifoam agent.

Aduro (RTM) comprises a monocarbamide dihydrogen sulphate and alkylamine ethoxylates. In some preferred embodiments, at least one adjuvant is selected from a silicone, a siloxane, an alkylamine ethoxylate or a carbamide. Said adjuvants are particularly useful at enhancing the effect of the pyrocarbonate, or otherwise increasing or speeding up the take-up of the pyrocarbonate by plants (particularly vascular plants and mosses). In some embodiments, the adjuvant may comprise: a non-ionic surfactant; and/or antifoam agent; and/or ammonium ions; and/or water-conditioning agent; and/or polyether- polymethylsiloxan-copolymer; and/or polyether polysiloxane; and/or polyglycerol fatty esters and polyglycols; and/or polyglycerol esters and fatty acid esters; and/or non-ionic trisiloxane. In preferred embodiments, the composition comprises at least one surfactant, which may be a non-ionic surfactant. In some embodiments, the composition comprises at least one silicone or siloxane, which silicone or siloxane may act as a surfactant and/or an anti-foam agent and/or a wetting agent. In some embodiments, the pyrocarbonate comprises dimethyl dicarbonate or diethyl di carbonate and the adjuvant comprises a silicone or siloxane. In some embodiments, the pyrocarbonate may be dimethyl dicarbonate and the adjuvant may be Transport Ultra. The invention also provides a composition consisting of dimethyl dicarbonate and Transport Ultra.

Transport Ultra is advantageous because inter alia it aids absorption by increasing permeability of the plant cuticle and/or cell membranes and it increases the proportion of DMDC in its undissociated, membrane-permeable form by decreasing the pH of the composition to about pH 2.6.

In some embodiments, the adjuvant is not an alkylphenyl polyethyl glycol, a halogenoformic acid ester, or a combination thereof. Thus in some embodiments there is provided a composition comprising a pyrocarbonate and a herbicidal adjuvant, said pyrocarbonate having the general formula R1-0-CO-0-CO-0-R2, wherein Rl and/or R2 is an alkyl group, and wherein the adjuvant is not an alkylphenyl polyethyl glycol, a halogenoformic acid ester, or a combination thereof.

In some embodiments, the ratio of the concentration of pyrocarbonate to the concentration of adjuvant or total amount of adjuvants in the composition is in the range 50: 1 to 1 : 1, in the composition, such as between 20: 1 and 1 : 1, between 10: 1 and 1 : 1 or between 5: 1 and 1 : 1, for example.

The pyrocarbonate may have bryophytocidal activity and the adjuvant may enhance said activity. The adjuvant may reduce pH and/or bicarbonate levels in spray solutions. The adjuvant may comprise polyethoxylated tallow amine.

The herbicide may be a non-selective herbicide; a selective herbicide; a systemic herbicide; a contact herbicide; a translaminar herbicide; and/or a broad-spectrum herbicide. The herbicide may (a) inhibit an enzyme; (b) interfere with photosynthetic and/or respiratory electron transfer; (c) disrupt the surface coating of a target plant; or (d) adversely affect cell function.

The or each herbicide may be independently selected from a plant growth regulator, an amino-acid biosynthesis inhibitor, a fatty acid or lipid biosynthesis inhibitor, a seedling growth inhibitor, a photosynthesis inhibitor, a cell membrane disruptor (including a detergent), a pigment inhibitor, a phosphorylated amino acid (N-metabolism inhibitor) or a combination of any of the above.

The or each herbicide in the composition may be independently selected from the following: a) Inhibitors of acetyl CoA carboxylase (ACCase). These compounds act to block ACCase. This enzyme helps the formation of lipids in the roots of grass plants, for example. Without lipids, susceptible plants die. Examples include aryloxyphenoxy propionates, cyclohexanediones and phenylpyrazolin. b) ALS/AHAS inhibitors. These chemicals block the normal function of acetolactate (ALS) actohydroxyacid synthase (AHAS). This enzyme is essential in amino acid (protein) synthesis. Examples include imidazolinones, sulfonylamino-carbonyltriazolinones, amides, sulfonyl ureas, pyrazole, triazolopyrimidines and triazolones. c) Microtubule assembly inhibitors, which inhibit cell division in roots. Examples includes dinitroanilines. d) Synthetic auxins, which disrupt plant cell growth in newly forming stems and leaves; they affect protein synthesis and normal cell division, leading to malformed growth and tumors. Examples include benzoic acids, carboxylic acids, picolinic acid and phenoxy compounds. e) Photosynthetic inhibitors at Photosystem II, which interfere with photosynthesis and disrupt plant growth, ultimately leading to death. Examples include phenyl carbamates, triazines, triazinones, uracils, benzthiadiazoles, nitriles and ureas. f) Lipid synthesis inhibitors (not ACCase inhibition), which inhibit cell division and elongation in the seedling shoots before they emerge above ground. Examples include thiocarbamates. g) Inhibitors of EPSP synthesis, which inhibit amino-acid synthesis. Examples include glyphosphate. h) Inhibitors of glutamine synthetase. Examples include glufosinate-ammonium. i) Inhibitors of carotenoids biosynthesis. Examples include triazoles. j) Inhibitors of chlorophyll synthesis and heme biosynthesis. Examples include aryl triazones. k) Inhibitors of cell growth and division. Examples include chloroacetamides and pyrazoles.

1) Auxin transport inhibitors, allowing build-up in the meristem area. Examples include semicarbazones. m) Cell membrane disrupters, which disrupt the internal cell membrane and prevent cells from manufacturing food. Examples include bipyridyliums. n) Inhibitors of plant pigment biosynthesis and photosynthesis. Examples include benzopyrazoles. o) Cell membrane disruptors acting on photosystem I. Examples include paraquat. p) Detergents. Examples include limonene

The herbicide may be a herbicide against a vascular plant or plants. The herbicide may be a non-selective biocide; a selective biocide; a systemic biocide; a contact biocide; a translaminar biocide; and/or a broad-spectrum biocide. The biocide may (a) inhibit an enzyme; (b) interfere with photosynthetic and/or respiratory electron transfer; (c) disrupt the surface coating of a target plant; or (d) adversely affect cell function. The herbicide may be a non-selective bryophytocide; a selective bryophytocide; a systemic bryophytocide; a contact bryophytocide; a translaminar bryophytocide; and/or a broad- spectrum bryophytocide. The bryophytocide may (a) inhibit an enzyme; (b) interfere with photosynthetic and/or respiratory electron transfer; (c) disrupt the surface coating of a target plant; or (d) adversely affect cell function. The herbicide may comprise one or more of the following: amide herbicides, allidochlor, amicarbazone, beflubutamid, benzadox, benzipram, bromobutide, cafenstrole, CDEA, cyprazole, dimethenamid, dimethenamid-P, diphenamid, epronaz, etnipromid, fentrazamide, flucarbazone, flupoxam, fomesafen, halosafen, huangcaoling, isocarbamid, isoxaben, napropamide, napropamide-M, naptalam, pethoxamid, propyzamide, quinonamid, saflufenacil, tebutam, tiafenacil, anilide herbicides, chloranocryl, cisanilide, clomeprop, cypromid, diflufenican, erlujixiancaoan, etobenzanid, fenasulam, flufenacet, flufenican, ipfencarbazone, mefenacet, mefluidide, metamifop, monalide, naproanilide, pentanochlor, picolinafen, propanil, sulfentrazone, triafamone, arylalanine herbicides, benzoylprop, flamprop, flamprop-M, chloroacetanilide herbicides, acetochlor, alachlor, amidochlor, butachlor, butenachlor, delachlor, diethatyl, dimethachlor, ethachlor, ethaprochlor, metazachlor, metolachlor, S-metolachlor, pretilachlor, propachlor, propisochlor, prynachlor, terbuchlor, thenylchlor, xylachlor, sulfonanilide herbicides, benzofluor, cloransulam, diclosulam, florasulam, flumetsulam, metosulam, perfluidone, profluazol, pyrimisulfan, sulfonamide herbicides, asulam, carbasulam, fenasulam, oryzalin, penoxsulam, pyroxsulam, sulfonylurea herbicides, thioamide herbicides, bencarbazone, chlorthiamid, aromatic acid herbicides, benzoic acid herbicides, cambendichlor, chloramben, dicamba, 2,3,6-TBA, tricamba, pyrimidinyloxybenzoic acid herbicides, bispyribac, pyriminobac, pyrimidinylthiobenzoic acid herbicides, pyrithiobac, phthalic acid herbicides, chlorthal, picolinic acid herbicides, aminopyralid, clopyralid, florpyrauxifen, halauxifen, picloram, quinolinecarboxylic acid herbicides, quinclorac, quinmerac, arsenical herbicides, cacodylic acid, CMA, DSMA, hexaflurate, MAA, MAMA, MSMA, potassium arsenite, sodium arsenite, benzoylcyclohexanedione herbicides, fenquinotrione, ketospiradox, lancotrione, mesotrione, sulcotrione, tefuryltrione, tembotrione, benzofuranyl alkyl sulfonate herbicides, benfuresate, ethofumesate, benzothiazole herbicides, benazolin, benzthiazuron, fenthiaprop, mefenacet, methabenzthiazuron, carbamate herbicides, asulam, carboxazole, chlorprocarb, dichlormate, fenasulam, karbutilate, terbucarb, carbanilate herbicides, barban, BCPC, carbasulam, carbetamide, CEPC, chlorbufam, chlorpropham, CPPC, desmedipham, phenisopham, phenmedipham, phenmedipham-ethyl, propham, swep, carbonate herbicides, bromobonil, dinofenate, iodobonil, tolpyralate, cyclohexene oxime herbicides, alloxydim, butroxydim, clethodim, cloproxydim, cycloxydim, profoxydim, sethoxydim, tepraloxydim, tralkoxydim, cyclopropylisoxazole herbicides, isoxachlortole, isoxaflutole, dicarboximide herbicides, cinidon-ethyl, flumezin, flumiclorac, flumioxazin, flumipropyn, uracil herbicides, dinitroaniline herbicides, benfluralin, butralin, chlornidine, dinitramine, dipropalin, ethalfluralin, fluchloralin, isopropalin, methalpropalin, nitralin, oryzalin, pendimethalin, prodiamine, profluralin, trifluralin, dinitrophenol herbicides, dinofenate, dinoprop, dinosam, dinoseb, dinoterb, DNOC, etinofen, medinoterb, diphenyl ether herbicides, ethoxyfen, nitrophenyl ether herbicides, acifluorfen, aclonifen, bifenox, chlomethoxyfen, chlornitrofen, etnipromid, fluorodifen, fluoroglycofen, fluoronitrofen, fomesafen, fucaomi, furyloxyfen, halosafen, lactofen, nitrofen, nitrofluorfen, oxyfluorfen, dithiocarbamate herbicides, dazomet, metam, fumigant herbicides, cyanogen, methyl bromide, methyl iodide, halogenated aliphatic herbicides, alorac, chloroacetic acid, chloropon, dalapon, flupropanate, hexachloroacetone, methyl bromide, methyl iodide, SMA, TCA, imidazolinone herbicides, imazamethabenz, imazamox, imazapic, imazapyr, imazaquin, imazethapyr, imide herbicides, chlorphthalim, pentoxazone, inorganic herbicides, ammonium sulfamate, borax, calcium chlorate, copper sulfate, ferrous sulfate, potassium azide, potassium cyanate, sodium azide, sodium chlorate, sulfuric acid, nitrile herbicides, bromobonil, bromoxynil, chloroxynil, dichlobenil, iodobonil, ioxynil, pyraclonil, organophosphorus herbicides, amiprofos-methyl, amiprophos, anilofos, bensulide, bilanafos, butamifos, clacyfos, 2,4-DEP, DMPA, EBEP, fosamine, glufosinate, glufosinate-P, glyphosate, huangcaoling, piperophos, shuangjiaancaolin, oxadiazolone herbicides, dimefuron, methazole, oxadiargyl, oxadiazon, oxazole herbicides, carboxazole, fenoxasulfone, isouron, isoxaben, isoxachlortole, isoxaflutole, methiozolin, monisouron, pyroxasulfone, topramezone, phenoxy herbicides, bromofenoxim, clomeprop, 2,4-DEB, 2,4-DEP, difenopenten, disul, erbon, etnipromid, fenteracol, trifopsime, phenoxyacetic herbicides, clacyfos, 4-CPA, 2,4-D, 3,4-DA, MCPA, MCPA-thioethyl, 2,4,5-T, phenoxybutyric herbicides, 4-CPB, 2,4-DB, 3,4-DB, MCPB, 2,4,5-TB, phenoxypropionic herbicides, cloprop, 4-CPP, dichlorprop, dichlorprop-P, 3,4-DP, fenoprop, mecoprop, mecoprop-P, aryloxyphenoxypropionic herbicides, chlorazifop, clodinafop, clofop, cyhalofop, diclofop, fenoxaprop, fenoxaprop-P, fenthiaprop, fluazifop, fluazifop-P, haloxyfop, haloxyfop-P, isoxapyrifop, kuicaoxi, metamifop, propaquizafop, quizalofop, quizalofop-P, trifop, phenylenediamine herbicides, dinitramine, prodiamine, pyrazole herbicides, azimsulfuron, difenzoquat, halosulfuron, metazachlor, metazosulfuron, pyrazosulfuron, pyroxasulfone, benzoylpyrazole herbicides, benzofenap, pyrasulfotole, pyrazolynate, pyrazoxyfen, tolpyralate, topramezone, phenylpyrazole herbicides, fluazolate, nipyraclofen, pinoxaden, pyraflufen, pyridazine herbicides, credazine, cyclopyrimorate, pyridafol, pyridate, pyridazinone herbicides, brompyrazon, chloridazon, dimidazon, flufenpyr, metflurazon, norflurazon, oxapyrazon, pydanon, pyridine herbicides, aminopyralid, cliodinate, clopyralid, diflufenican, dithiopyr, florpyrauxifen, flufenican, fluroxypyr, halauxifen, haloxydine, picloram, picolinafen, pyriclor, pyroxsulam, thiazopyr, triclopyr, pyrimidinediamine herbicides, iprymidam, tioclorim, pyrimidinyloxybenzylamine herbicides, pyribambenz-isopropyl, pyribambenz-propyl, quaternary ammonium herbicides, cyperquat, diethamquat, difenzoquat, diquat, morfamquat, paraquat, thiocarbamate herbicides, butylate, cycloate, di-allate, EPTC, esprocarb, ethiolate, isopolinate, methiobencarb, molinate, orbencarb, pebulate, prosulfocarb, pyributicarb, sulfallate, thiobencarb, tiocarbazil, tri-allate, vernolate, thiocarbonate herbicides, dimexano, EXD, proxan, thiourea herbicides, methiuron, triazine herbicides, dipropetryn, fucaojing, trihydroxytriazine, chlorotriazine herbicides, atrazine, chlorazine, cyanazine, cyprazine, eglinazine, ipazine, mesoprazine, procyazine, proglinazine, propazine, sebuthylazine, simazine, terbuthylazine, trietazine, fluoroalkyltriazine herbicides, indaziflam, triaziflam, methoxytriazine herbicides, atraton, methometon, prometon, secbumeton, simeton, terbumeton, methylthiotriazine herbicides, ametryn, aziprotryne, cyanatryn, desmetryn, dimethametryn, methoprotryne, prometryn, simetryn, terbutryn, triazinone herbicides, ametridione, amibuzin, ethiozin, hexazinone, isomethiozin, metamitron, metribuzin, trifludimoxazin, triazole herbicides, amitrole, cafenstrole, epronaz, flupoxam, triazolone herbicides, amicarbazone, bencarbazone, carfentrazone, flucarbazone, ipfencarbazone, propoxycarbazone, sulfentrazone, thiencarbazone, triazolopyrimidine herbicides, cloransulam, diclosulam, florasulam, flumetsulam, metosulam, penoxsulam, pyroxsulam, uracil herbicides, benzfendizone, bromacil, butafenacil, flupropacil, isocil, lenacil, saflufenacil, terbacil, tiafenacil, urea herbicides, benzthiazuron, cumyluron, cycluron, dichloralurea, diflufenzopyr, isonoruron, isouron, methabenzthiazuron, monisouron, noruron, phenylurea herbicides, anisuron, buturon, chlorbromuron, chloreturon, chlorotoluron, chloroxuron, daimuron, difenoxuron, dimefuron, diuron, fenuron, fluometuron, fluothiuron, isoproturon, linuron, methiuron, methyldymron, metobenzuron, metobromuron, metoxuron, monolinuron, monuron, neburon, parafluron, phenobenzuron, siduron, tetrafluron, thidiazuron, sulfonylurea herbicides, pyrimidinyl sulfonylurea herbicides, amidosulfuron, azimsulfuron, bensulfuron, chlorimuron, cyclosulfamuron, ethoxysulfuron, flazasulfuron, flucetosulfuron, flupyrsulfuron, foramsulfuron, halosulfuron, imazosulfuron, mesosulfuron, metazosulfuron, methiopyrisulfuron, monosulfuron, nicosulfuron, orthosulfamuron, oxasulfuron, primi sulfur on, propyrisulfuron, pyrazosulfuron, rimsulfuron, sulfometuron, sulfosulfuron, trifloxysulfuron, zuomihuanglong, triazinyl sulfonylurea herbicides, chlorsulfuron, cinosulfuron, ethametsulfuron, iodosulfuron, iofensulfuron, metsulfuron, prosulfuron, thifensulfuron, triasulfuron, tribenuron, triflusulfuron, tritosulfuron, thiadiazolylurea herbicides, buthiuron, ethidimuron, tebuthiuron, thiazafluron, thidiazuron, unclassified herbicides, acrolein, allyl alcohol, amino cyclopyrachlor, azafenidin, bentazone, bentranil, benzobicyclon, bicyclopyrone, buthidazole, calcium cyanamide, chlorfenac, chlorfenprop, chlorflurazole, chlorflurenol, cinmethylin, clomazone, CPMF, cresol, cyanamide, o-dichlorobenzene, dimepiperate, dimethyl disulfide, endothal, fluoromidine, fluridone, flurochloridone, flurtamone, fluthiacet, funaihecaoling, herbimycin, huancaiwo, indanofan, methoxyphenone, methyl isothiocyanate, OCH, oxaziclomefone, pelargonic acid, pentachlorophenol, phenylmercury acetate, prosulfalin, pyribenzoxim, pyriftalid, quinoclamine, rhodethanil, sulglycapin, tavron, thidiazimin, tridiphane, trimeturon, tripropindan or tritac.

The herbicide may comprise one or more of the following plant growth regulators: antiauxins, clofibric acid, 2,3,5-triiodobenzoic acid, auxins, 4-CPA, 2,4-D, 2,4-DB, 2,4- DEP, dichlorprop, fenoprop, IAA, IBA, naphthaleneacetamide, a-naphthaleneacetic acids, 1-naphthol, naphthoxyacetic acids, potassium naphthenate, sodium naphthenate, 2,4,5-T, cytokinins, 2iP, benzyladenine, 4-hydroxyphenethyl alcohol, kinetin, zeatin, defoliants, calcium cyanamide, dimethipin, endothal, ethephon, merphos, metoxuron, pentachlorophenol, thidiazuron, tribufos, ethylene inhibitors, avi glycine, 1- methylcyclopropene, ethylene releasers, ACC, etacelasil, ethephon, glyoxime, gametocides, fenridazon, maleic hydrazide, gibberellins, gibberellins, gibberellic acid, growth inhibitors, abscisic acid, ancymidol, butralin, carbaryl, chlorphonium, chlorpropham, dikegulac, flumetralin, fluoridamid, fosamine, glyphosine, isopyrimol, jasmonic acid, maleic hydrazide, mepiquat, piproctanyl, prohydrojasmon, propham, tiaojiean, 2,3,5-triiodobenzoic acid, morphactins, chlorfluren, chlorflurenol, dichlorflurenol, flurenol, growth retardants, chlormequat, daminozide, flurprimidol, mefluidide, paclobutrazol, tetcyclacis, uniconazole, growth stimulators, brassinolide, brassinolide-ethyl, DCPTA, forchlorfenuron, hymexazol, psoralen, pyripropanol, triacontanol, unclassified plant growth regulators, bachmedesh, benzofluor, buminafos, carvone, choline chloride, ciobutide, clofencet, cloxyfonac, cyanamide, cyclanilide, cycloheximide, cyprosulfamide, epocholeone, ethychlozate, ethylene, fuphenthiourea, furalane, heptopargil, holosulf, inabenfide, karetazan, lead arsenate, methasulfocarb, prohexadione, pydanon, sintofen, triapenthenol, trinexapac. The herbicide may comprise one or more of the following plant activators: acibenzolar, aspirin, chitosan or probenazole.

The herbicide may comprise one or more of the following herbicide synergists: bucarpolate, dietholate, jiajizengxiaolin, octachlorodipropyl ether, piperonyl butoxide, piperonyl cyclonene, piprotal, propyl isome, sesamex, sesamolin, sulfoxide, tribufos, or zengxiaoan. The composition of the invention may result in: (a) inhibition of the growth of a target plant; (b) inhibition of photosynthesis and/or respiration in a target plant; or (c) death of a target plant. The composition may result in inhibition of photosynthetic electron transport in a vascular plant or bryophytes.

As used herein, the term "herbicide" refers to herbicides which are used to control, destroy or inhibit the growth of unwanted plants (i.e. weeds), such as vascular plants or bryophytes (including moss). Herbicides may be in the form of substances (e.g. chemical substances) or preparations. Herbicides that destroy or inhibit the growth of moss are known as bryophytocides.

The herbicide may (a) inhibit an enzyme, wherein optionally said enzyme is 5- enolpyruvylshikimate-3 -phosphate and/or glutamine synthetase; (b) interfere with electron transfer, e.g. photosynthetic and/or respiratory electron transfer; (c) disrupt plant waxy cuticles; or (d) adversely affect cell function.

The herbicide may comprise or consist of one or more of the following: N- (phosphonomethyl) glycine, N,N'-dimethyl-4,4'-bipyridinium dichloride, glufosinate, glufosinate-ammonium and/or l-methyl-4-(l-methylethenyl)-cyclohexene; or a salt, ether, amide, ester, solvate, isomer or other derivative thereof.

N-(phosphonomethyl) glycine (also known as glyphosate) is non-selective and systemic, i.e. it is transported via the leaf surface throughout the plant tissue and works in areas of the plant beyond that which is sprayed. Its mode of action involves inhibition of the enzyme 5- enolpyruvylshikimate-3 -phosphate (EPSP) synthase, and it subsequently interferes with the synthesis of the amino acids phenylalanine, tyrosine and tryptophan. Proteins cannot be produced, growth ceases within hours, and several days later the plant tissue is killed. Because of this mode of action, it is only effective on actively growing plants and is not effective in preventing seeds from germinating. Glyphosate is commonly used for agriculture, horticulture, viticulture, and silviculture purposes, as well as garden maintenance (including home use). In addition to its use as a herbicide, glyphosate is also used for crop desiccation (siccation) to increase harvest yield, and as a result of desiccation, to increase sucrose concentration in sugarcane before harvest. Glyphosate is sold under the trade name Roundup (RTM). Roundup Optima+ (RTM) is a systemic herbicide comprising glyphosate (170g/L) and surfactant (polyethoxylated tallow amine, 15%).

N,N'-dimethyl-4,4'-bipyridinium dichloride (also known as paraquat) is a non-selective contact herbicide, i.e. it only affects the plant tissue it comes into contact with. Paraquat is an oxidant that interferes with electron transfer, and in plants it acts by inhibiting photosynthesis. In light-exposed plants, paraquat accepts electrons from photosystem I and transfers them to molecular oxygen. In this manner, destructive reactive oxygen species are produced. In forming these reactive oxygen species, the oxidized form of paraquat is regenerated, and is again available to shunt electrons from photosystem I to restart the cycle. Paraquat is among the most commonly used herbicides. The key characteristics that distinguish paraquat from other agents used in plant protection products are: that it kills a wide range of annual grasses and broad-leaved weeds and the tips of established perennial weeds; it is very fast-acting; it is rain-fast within minutes of application; and it is partially inactivated upon contact with soil. Gramoxone-200 comprises paraquat (at 200 g/L) and a wetting agent, and it rapidly kills plant tissue on contact. When ingested, Pure paraquat is highly toxic to mammals, including humans, potentially leading to acute respiratory distress syndrome (ARDS). Ingesting paraquat causes symptoms such as liver, lung, heart, and kidney failure within several days to several weeks that can lead to death up to 30 days after ingestion. Chronic exposure can lead to lung damage, kidney failure, heart failure, and oesophageal strictures.

Glufosinate, also known as phosphinothricin, is a naturally-occurring broad-spectrum systemic herbicide produced by several species of Streptomyces soil bacteria. Glufosinate irreversibly inhibits glutamine synthetase, an enzyme that plays an essential role in the metabolism of nitrogen by catalyzing the condensation of glutamate and ammonia to form glutamine, giving it antibacterial, antifungal and herbicidal properties. Application of glufosinate to plants leads to reduced glutamine and elevated ammonia levels in tissues, halting photosynthesis, resulting in plant death. Glufosinate is sold in formulations under brands including Kurtail Gold, Basta, Rely, Finale, Challenge and Liberty. For instance, Kurtail Gold comprises glufosinate-ammonium. It is used to control important weeds (such as mare's tail, also known as horsetail along with a wide range of grasses and broad leaf weeds), and it is applied to young plants during early development for full effectiveness. Glufosinate is typically used as a directed spray for weed control, including in genetically modified crops and as a crop desiccant to facilitate harvesting.

As glufosinate is often used as a pre-harvest desiccant, residues can also be found in foods that humans ingest. The herbicide is also persistent; it has been found to be prevalent in spinach, radishes, wheat and carrots that were planted 120 days after the treatment of the herbicide. Its persistent nature can also be observed by its half-life which varies from 3 to 70 days depending on the soil type and organic matter content. The EPA classifies the chemical as 'persistent' and 'mobile' based on its lack of degradation and ease of transport through soil. l-Methyl-4-(l-methylethenyl)-cyclohexene (also known as limonene) is a colourless liquid hydrocarbon classified as a cyclic terpene. The more common d-isomer possesses a strong smell of oranges. It is used in chemical synthesis as a precursor to carvone and as a renewables-based solvent in cleaning products, and as an organic herbicide. Its mode of action relies on its detergent properties which destroy the waxy cuticle of the plant surface and lead to desiccation over several days. Because limonene is a natural extract, it is accepted for organic use. The composition may comprise at least 0.0001% v/v pyrocarbonate, at least 0.001% v/v, 0.01% v/v, at least 0.02% v/v, at least 0.05% v/v, at least 0.075% v/v, at least 0.1% v/v, at least 0.15% v/v, at least 0.2 % v/v, at least 0.25% v/v, at least 0.3% v/v, at least 0.4% v/v or at least 0.5% v/v pyrocarbonate.

The composition may comprise no more than 75% v/v pyrocarbonate, no more than 60% v/v, no more than 50% v/v, no more than 40% v/v, no more than 30% v/v or no more than 25%) v/v pyrocarbonate.

The composition may comprise: 0.0001-20%) (v/v) of the pyrocarbonate; 0.02-10%) (v/v) of the pyrocarbonate; 0.3-5% (v/v) of the pyrocarbonate; 0.5-4% (v/v) of the pyrocarbonate; 0.6-2% (v/v) of the pyrocarbonate; 0.7-1.5%) (v/v) of the pyrocarbonate; 0.8-1.2%) (v/v) of the pyrocarbonate; or 1% (v/v) of the pyrocarbonate. The above concentrations of pyrocarbonate may represent the final working concentrations of the pyrocarbonate (e.g. for use as a herbicide such as when diluted or suspended in a suitable carrier).

The composition may comprise at least 0.0001%> v/v herbicide, at least 0.0005% v/v, at least 0.001% v/v, at least 0.005% v/v, at least 0.0075% v/v, at least 0.01% v/v, at least 0.02% v/v, at least 0.05% v/v, at least 0.075% v/v, at least 0.1% v/v, at least 0.15% v/v, at least 0.2 % v/v, at least 0.25% v/v, at least 0.3% v/v, at least 0.4% v/v or at least 0.5% v/v herbicide.

The composition may comprise no more than 75% v/v herbicide, no more than 60% v/v, no more than 50% v/v, no more than 40% v/v, no more than 30% v/v or no more than 25% v/v herbicide. The above concentrations of herbicide may represent the final working concentrations of the herbicide, such as when diluted or suspended in a suitable carrier.

The composition may comprise: 0.00001-20% (v/v) of the herbicide; 0.001-10% (v/v) of the herbicide; 0.002-5% (v/v) of the herbicide; 0.003-2.5% (v/v) of the herbicide; 0.004-2% (v/v) of the herbicide; or 0.005-1.5%) (v/v) of the herbicide. These concentrations of herbicide may represent the final working concentrations of the herbicide, separately or together.

The ratio of pyrocarbonate to herbicide, or the ratio of pyrocarbonate to the total amount of herbicide, in the composition may be between 1 :0.00001 and 1 : 100, such as between 1 :0.0005 and 1 : 1 or between 1 :0.005 and 1 : 1. In other embodiments the ratio of herbicide to pyrocarbonate, or the ratio of the total amount of herbicide to pyrocarbonate in the composition may be between 1:0.00001 and 1:100, such as between 1:0.0005 and 1:1 or between 1:0.005 and 1:1.

The ratio of pyrocarbonate to herbicide, or the ratio of pyrocarbonate to the total amount of herbicide, in the composition may be at least 1:0.00001, at least 1:0.0001, at least 1:0.0005, at least 1:0.001, at least 1:0.005, at least 1:0.01, at least 1:0.05, at least 1:0.1 or at least 1:0.5.

Alternatively, the ratio of herbicide to pyrocarbonate, or the ratio of the total amount of herbicide to pyrocarbonate in the composition may be at least 1:0.00001, at least 1:0.0001, at least 1:0.0005, at least 1:0.001, at least 1:0.005, at least 1:0.01, at least 1:0.05, at least 1:0.1 or at least 1:0.5.

When the herbicide is an inhibitor of EPSP synthesis, such as Roundup (RTM), the ratio of pyrocarbonate to herbicide may be between 1:0.01 and 1:1, such as between 1:0.05 and 1:1 or between 1:0.1 and 1:0.75.

When the herbicide is a detergent, such as limonene, the ratio of pyrocarbonate to herbicide may be between 1:0.01 and 1:2, such as between 1:0.05 and 1:1.5 or between 1:0. and 1:1.

When the herbicide is a cell membrane disruptor, such as paraquat or glutamine synthetase inhibitor such as phosphinothricin (Kurtail Gold (RTM), the ratio of pyrocarbonate to herbicide may be between 1:0.00001 and 1:0.5, such as between 1:0.00005 and 1:0.1, or between 1:0.0005 and 1:0.05. The composition may be sold in a concentrated form, solvent-free form and/or carrier-free form, which is diluted prior to use. For example, the composition may be diluted by 5-fold, 10-fold, 20-fold, 30-fold, 40-fold, 50-fold, 100-fold, 1000-fold, etc. prior to use.

Thus, the pyrocarbonate of the invention may be used as the key active ingredient in a range of herbicides for agricultural and horticultural use. The composition, herbicide and/or pyrocarbonate described above may be a photosynthetic and/or respiration inhibitor. Thus, the invention provides a photosynthetic inhibitor comprising a pyrocarbonate and a herbicide, said pyrocarbonate having the general formula R1-O-CO-O-CO-O-R2, wherein Ri and/or R₂ is an alkyl group. The invention provides in one aspect use of a composition of the invention as a herbicide. This use may relate to one or two of the following uses as a: herbicide and/or bryophytocide. For example, there is provided use of a composition of the invention as a herbicide and as a bryophytocide. There is also provided use of the composition as a herbicide against vascular plants and as a bryophytocide. In preferred embodiments, there is provided use of the composition of the invention as a herbicide and more preferably as a herbicide against vascular plants and/or bryophytes.

There is also provided use of the composition of the invention as a herbicide and/or as a bryophytocide. The invention provides in one aspect a method of inhibiting the growth of a plant within a treatment area, said method comprising applying the composition of the invention to said treatment area or to a plant in said treatment area. The plant may be a vascular plant (i.e. a higher plant) or non-vascular plant (such as a bryophyte).

The invention provides in one aspect a method of killing vascular plants and/or bryophytes in a treatment area and/or inhibiting photosynthetic electron transport in vascular plants, and/or bryophytes in a treatment area, said method comprising applying a composition of the invention to said treatment area. There is provided a method of killing vascular plants and/or bryophytes in a treatment area, said method comprising applying the composition to said treatment area. There is also provided a method of inhibiting photosynthetic electron transport in vascular plants and/or bryophytes in a treatment area, said method comprising applying the composition to said treatment area.

The composition may be in the form of an emulsifiable liquid concentrate, emulsifiable gel, wettable powder or granules, liquid, dry flowable powder or granules, microencapsulated or encapsulated powders or granules, pellets, a suspension of composition in a carrier, a solution of composition in a carrier (such as water or an aqueous solvent) or a suspension of microencapsulated or encapsulated powder or granules of composition in a carrier (such as water or an aqueous solvent), for example.

Emulsifiable concentrates are liquid compositions in which the herbicide and pyrocarbonate, are dissolved in one or more hydrophobic, such as petroleum-based, solvents. An emulsifier may be added to cause the composition to form tiny globules that disperse in water. The compositions will then mix with water for application. Emulsifiable gels are compositions comprising emulsifiable liquids formulated as gels. The gels may be packaged in water-soluble bags (WSB) and are stable at temperatures ranging from -20 to 500°C. In addition, the gelling process reduces the need for non-aqueous solvents, compared to standard non-aqueous emulsifiable concentrate compositions. Wettable powders may comprise finely ground, dry particles that may be dispersed and suspended in water. They may contain from 25 to 80 percent weight herbicide and pyrocarbonate, in total.

Soluble liquid and soluble powders dissolve in water to form a solution. Once the soluble liquid or powder is dissolved, the mixture may require no additional mixing or agitation. Dry flowable powders or granules, also called water-dispersible granules or dispersible granules may comprise wettable powders formed into prills so they pour easily into a container without clumping or producing a cloud of dust.

Flowables, suspension concentrates and aqueous suspensions may comprise finely ground, wettable powders or solids already suspended in a liquid carrier so they can be poured or pumped from one container to another.

Microencapsulated and encapsulated suspensions may comprise the herbicide and/or pyrocarbonate encased in an encapsulating material that can be suspended in a liquid carrier (such as water or an aqueous solvent, with or without adjuvants) and pumped and applied with normal equipment. Granules of composition may be formulated with a premixed carrier. The carrier may be fertilizer, clay, lime, vermiculite, or ground corn cobs, for example. Such compositions may be applied directly (dry) to soil without further dilution, if required, or may be suspended or dissolved in a carrier (such as water or an aqueous carrier) before use.

Pellets are similar to granules but are compressed into larger cylinders of between 3-10 mm long. Compositions of the invention formulated as pellets may contain from 5 to 20 percent herbicide and pyrocarbonate, in total.

The compositions of the invention may be applied to the treatment area, directly to the ground (soil) on which the plants are growing, and/or to the leaves, stems or other parts of plants. The compositions of the invention may be applied in any one or more of the following processes, for example: a) Broadcast: applied over the entire treatment area b) Band: applied to a narrow strip (over a crop row, for example) in a treatment area c) Directed: for example, applied between rows of crops in a treatment area with little or no composition applied to the crop foliage, or applied directly to the whole of a weed- infested treatment area. d) Spot treatment: applied to small, weed-infested areas within the treatment area

The timing of the application of the compositions of the invention to the treatment area will depend on the plants which require removal, suppression or inhibiting, but may be any one or more of the following, for example: a) when the treatment area is ground (e.g. soil) - applied to the treatment area and mechanically incorporated into the top 2 to 3 inches of soil in the treatment area before any desirable crop is planted b) Preplant: applied to treatment area before any desirable crop is planted c) Preemergence: applied after any desirable crop is planted but before it emerges d) Postemergence: applied after desirable crop emergence

The treatment area may be a field, a grass verge, a container, a plot of land, a hard surface or the like, for example. Alternatively the treatment area may be part of a plant or plants, such as leaves, stems, fruit or bark of a plant or plants, for example.

In one aspect, the invention provides a method of enhancing the activity of at least one herbicide, said method comprising mixing a pyrocarbonate with the or each herbicide, wherein the pyrocarbonate has the general formula R1-O-CO-O-CO-O-R2, wherein Ri and/or R₂ is an alkyl group. In some embodiments of the methods and compositions of the invention, the compositions of the invention comprise a herbicide and pyrocarbonate in a carrier or diluent. The pyrocarbonate may be present in a carrier or diluent (such as water or an aqueous carrier) in a concentration of at least 0.001% v/v, at least 0.15% v/v, at least 0.2% v/v or at least 0.25% v/v and may be present at between 0.25% v/v and 50% v/v. In such embodiments, the herbicidal adjuvant may be present in a concentration of at least 0.01% v/v, at least 0.02%) v/v or at least 0.05% v/v, and may be present in a concentration of between 0.01% v/v and 10% v/v. In some embodiments, the pyrocarbonate is present in a concentration of between 0.001% v/v and 50% v/v, such as between 0.25% v/v and 5% v/v, and the herbicidal adjuvant is present in a concentration of between 0.01% v/v and 10% v/v, such as between 0.05% v/v and 2.5% v/v. In preferred embodiments, the composition comprises an aqueous solution of between 0.001%) v/v and 5% v/v pyrocarbonate and between 0.05% v/v and 5% v/v adjuvant or total concentration of adjuvants.

Whilst aqueous compositions have been described hereinabove, it is to be noted that the pyrocarbonate may be present in a composition comprising a non-aqueous solvent (which may be mixed with water). Such non-aqueous solvents may include alcohols such as isopropanol, for example. In other embodiments, the compositions may comprise a hydrophobic carrier, such as a wax, oil or fat.

It is to be understood that, in use, any aqueous composition may be prepared immediately before application to the desired treatment area or plants, such as within 5 minutes, 10 minutes, 15 minutes, 20 minutes, 30 minutes, 45 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, or 180 minutes before application.

In one aspect, the invention provides use of a pyrocarbonate as an enhancer of a herbicide, wherein the pyrocarbonate has the general formula R1-O-CO-O-CO-O-R2, and Ri and/or R₂ is an alkyl group. The term "enhancer" may refer to the action of the pyrocarbonate in accelerating the effect of a herbicide, to the action of increasing the potency, strength or kill efficacy of the herbicide, a combination thereof, or to any other effect that enhances, synergistically or otherwise, the herbicide.

The invention provides in one aspect a kit comprising a herbicide and a pyrocarbonate, in which the pyrocarbonate has the general formula R1-O-CO-O-CO-O-R2, wherein Ri and/or R₂ is an alkyl group, and, when combined, the pyrocarbonate enhances the efficacy of the herbicide. The herbicide may be in one container and the pyrocarbonate may be in another container. The pyrocarbonate may comprise less than 10% (v/v) water, or less than: 9% (v/v), 8% (v/v), 7% (v/v), 6% (v/v), 5% (v/v), 4% (v/v), 3% (v/v), 2% (v/v), 1% (v/v) or 0.5% (v/v) water or it may be anhydrous. The kit may also include instructions for use.

The kit may comprise a solvent (such as water) for addition to pyrocarbonate immediately prior to use. The kit or the solvent in such a kit, may comprise an adjuvant as defined above. Anhydrous compositions are preferred because pyrocarbonates such as DMDC are rapidly hydrolysed upon contact with water.

The herbicide and/or the pyrocarbonate may be provided in a concentrated form which is diluted prior to use. In some embodiments, the kit comprises a concentrated form of the herbicide and/or the pyrocarbonate, which is diluted prior to use.

Particular non-limiting embodiments of the present invention will now be described with reference to drawings.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1. Line graph showing the relative photosynthetic electron transport rate (ETR) in basil leaves at increasing photon flux densities (measured in μπιοΐ m^"2 s^"1), 24 hours after treatment with 0%, 0.5%, 1%, 2% and 4% (v/v) dimethyl dicarbonate (DMDC) in deionised water.

Figure 2. Line graph showing the relative photosynthetic electron transport rate (ETR) in basil leaves at increasing photon flux densities (measured in μπιοΐ m^"2 s^"1), 24 hours after treatment with deionized water (as a negative control), 1% (v/v) D-limonene, 1% (v/v) DMDC, and 1% (v/v) D-limonene + 1% (v/v) DMDC.

Figure 3. Line graph showing the relative photosynthetic electron transport rate (ETR) in basil leaves at increasing photon flux densities (measured in μπιοΐ m^"2 s^"1), 24 hours after treatment with deionized water (as a negative control), 0.005% (v/v) Gramoxone-200, 1% (v/v) DMDC, and 0.005% (v/v) Gramoxone-200 + 1% (v/v) DMDC.

Figure 4. Line graph showing the relative photosynthetic electron transport rate (ETR) in basil leaves at increasing photon flux densities (measured in μπιοΐ m^"2 s^"1), 24 hours after treatment with deionized water (as a negative control), 0.005% (v/v) Kurtail Gold, 1% (v/v) DMDC, and 0.005% (v/v) Kurtail Gold + 1% (v/v) DMDC. Figure 5. Line graphs showing the relative photosynthetic electron transport rate (ETR) in basil leaves at increasing photon flux densities (measured in μιηοΐ m^"2 s^"1), 0 hours, 1 hour, 4 hours and 8 hours after treatment with: 0.5% (v/v) Gramoxone-200 (Figure 5a); and 0.5% (v/v) Gramoxone-200 + 1% (v/v) DMDC (Figure 5b). Figure 6. Line graphs showing the relative photosynthetic electron transport rate (ETR) in basil leaves at increasing photon flux densities (measured in μιηοΐ m^"2 s^"1), 0-hours, 24- hours, 48-hours and 72-hours after treatment with: 0.5% (v/v) Roundup (Figure 6a) and 0.5% (v/v) Roundup + 1% (v/v) DMDC (Figure 6b).

Figure 7. Line graph showing the relative photosynthetic electron transport rate (ETR) in basil leaves at increasing photon flux densities (measured in μιηοΐ m^"2 s^"1) after the following treatments: (a) 1% (v/v) DMDC at 0 hours and then 0.005% (v/v) Gramoxone-200 at 24 hours; (b) 0.005% (v/v) Gramoxone-200 at 0 hours and then 1% (v/v) DMDC at 24 hours; and (c) 0.005% (v/v) Gramoxone-200 + 1% (v/v) DMDC at 0 hours and then 0.005% (v/v) Gramoxone-200 + 1% (v/v) DMDC at 24 hours. Figure 8. Line graph showing the relative photosynthetic electron transport rate (ETR) in non-treated basil leaves at increasing photon flux densities (measured in μιηοΐ m^"2 s^"1) after the following treatments of a remote basil leaf on the same basil plant: (a) 1% (v/v) DMDC; (b) 0.15% (v/v) Roundup; and (c) 0.15% (v/v) Roundup + 1% (v/v) DMDC.

DETAILED DESCRIPTION OF THE INVENTION EXAMPLES

Example 1 - effect of pyrocarbonates on photosynthetic ETR

Method

The effect of various concentrations of dimethyl dicarbonate (DMDC) on the relative photosynthetic electron transport rate (ETR) in culinary basil (Ocimum basilicum) plants was tested. DMDC (obtained from Merck & Co, Germany) was added to deionised water exactly 5 minutes before the plants were treated and shaken vigorously to dissolve it. The following four concentrations of DMDC were tested: 0.5% (v/v), 1% (v/v), 2% (v/v) and 4% (v/v). Pure deionised water (i.e. 0% (v/v) DMDC) was used as a negative control. Culinary basil plants were obtained from a local supermarket on the day of the experiments. Leaves were cut off the stems immediately before the experiments and placed in a petri dish (9 cm diameter) containing a circle of kitchen roll (approximately 9 cm diameter) dampened with 0.5mL deionised water. Each leaf was sprayed with the treatment solution whilst in the petri dish. Application of solutions was via a 50 mL plastic spray bottle. Each treatment comprised 5 sprays, which is equivalent to approximately 400 μΙ_, of the solution. Immediately after spraying the leaves, the petri dish was covered with its lid and sealed at the edges with a strip of Parafilm to maintain a high humidity around the leaf and thus prevent desiccation. Petri dishes containing the treated leaves were incubated in a Sanyo environmental test chamber maintained at 20° C under constant light, at photon flux densities (PFDs) between 100 and 125 μιηοΐ m^"2 s^"1.

Chlorophyll fluorescence was measured at various photon flux densities (PFD) in the cut leaves using a Hansatech FMS 1 modulated chlorophyll fluorometer, at PFDs from 0 to 1650 μπιοΐ m^"2 s^"1. These measurements were used to determine the relative photosynthetic electron transport rate (ETR), by multiplying 0PSR (ratio of Variable Fluorescence FV against Maximum Fluorescence FM in dark adapted photosynthetic tissue) by PFD. Three to five replicates were used for each treatment.

Results

Figure 1 is a dose response line graph showing the photosynthetic ETR at increasing photon flux densities (measured in μπιοΐ m^"2 s^"1), 24 hours after treatment with 0%, 0.5%, 1%, 2% and 4% (v/v) DMDC. The DMDC caused a concentration-dependent inhibition of photosynthetic ETR, which increased as the PFD increased. Thus, at 1650 μπιοΐ m^"2 s^"1, 0%, 0.5%, 1%), 2% and 4% (v/v) DMDC all produced a marked reduction in photosynthetic ETRs. The greatest inhibition of photosynthetic ETR was caused by 4% (v/v) DMDC, followed by 2% (v/v) DMDC, then 1% (v/v) DMDC and 0.5% (v/v) DMDC.

Example 2 - effect of pyrocarbonate and D-limonene on photosynthetic ETR

Method

The effect of treatment with 1% (v/v) D-limonene, 1% (v/v) DMDC, and 1% (v/v) D- limonene + 1% (v/v) DMDC on the relative photosynthetic electron transport rate (ETR) in culinary basil (Ocimum basilicum) plants was tested using the method described in Example 1. D-Limonene (pure, Darrant Chemicals UK) was made up in deionised water within 10 minutes of application. Deionized water was used as a negative control.

Results

Figure 2 is a line graph showing the photosynthetic ETR at increasing photon flux densities, 24 hours after treatment with deionized water (as a negative control), 1% (v/v) D-limonene, 1% (v/v) DMDC, and 1% (v/v) D-limonene + 1% (v/v) DMDC.

At 1650 μιηοΐ m^"2 s^"1, 1% (v/v) DMDC caused a 6% reduction in photosynthetic ETR and 1% (v/v) D-limonene caused a 38% reduction in photosynthetic ETR. However, 1% (v/v) D-limonene + 1% (v/v) DMDC caused a near total (96%) inhibition of photosynthesis. This concentration of D-limonene is 6 times less than the concentration (per unit surface area) of D-limonene recommended by the manufacturer of Avenger (an organic herbicide comprising 17.5% D-limonene plus surfactants in water). Thus, adding 1% (v/v) DMDC to 1%) (v/v) D-limonene causes an unexpected, synergistic inhibition of photosynthetic ETR.

Example 3 - effect of pyrocarbonate and Gramoxone on photosynthetic ETR Method

The effect of treatment with 0.005% (v/v) Gramoxone-200; 1% (v/v) DMDC; and 0.005% (v/v) Gramoxone-200 + 1% (v/v) DMDC on the photosynthetic ETR in culinary basil plants was tested using the method described in Example 1. Gramoxone-200 (200 g paraquat/L) was made up in deionised water within 10 minutes of application. Deionized water was used as a negative control.

Results

Figure 3 is a line graph showing the photosynthetic ETR at increasing photon flux densities, 24 hours after treatment with deionized water (as a negative control), 0.005% (v/v) Gramoxone-200, 1% (v/v) DMDC, and 0.005% (v/v) Gramoxone-200 + 1% (v/v) DMDC. At 1650 μιηοΐ m^"2 s^"1, 1% (v/v) DMDC caused a 6% reduction in photosynthetic ETR and 0.005%) (v/v) Gramoxone-200 caused an 8% reduction in photosynthetic ETR. However, 0.005% (v/v) Gramoxone-200 + 1% (v/v) DMDC caused a near total (93%) inhibition of photosynthesis. This effect was achieved using Gramoxone-200 at a quantity 450 times smaller than that recommended by the manufacturer (in terms of the concentration/ volume used per unit surface area). Thus, adding 1% (v/v) DMDC to 0.005% (v/v) Gramoxone-200 causes an unexpected, synergistic inhibition of photosynthetic ETR.

Example 4 - effect of pyrocarbonate and glufosinate ammonium on photosynthetic ETR

Method

Kurtail Gold (RTM) comprises 150g/L (w/v) glufosinate ammonium. The effect of treatment with 0.005% (v/v) Kurtail Gold; 1% (v/v) DMDC; and 0.005% (v/v) Kurtail Gold + 1%) (v/v) DMDC on the photosynthetic ETR in culinary basil plants was tested using the method described in Example 1. Kurtail Gold was made up in deionised water within 10 minutes of application. Deionized water was used as a negative control.

Results

Figure 4 is a line graph showing the photosynthetic ETR at increasing photon flux densities, 24 hours after treatment with deionized water (as a negative control), 0.005% (v/v) Kurtail Gold, 1% (v/v) DMDC, and 0.005% (v/v) Kurtail Gold + 1% (v/v) DMDC.

At 1650 μιηοΐ m^"2 s^"1, 1% (v/v) DMDC caused a 6% reduction in photosynthetic ETR and 0.005%) (v/v) Kurtail Gold did not cause any reduction in the photosynthetic ETR. However, 0.005% (v/v) Kurtail Gold + 1% (v/v) DMDC caused a 70% inhibition of photosynthesis. Addition of DMDC resulted in a 60-73% greater inhibition in 24h than 0.005% Kurtail Gold alone. This effect was achieved using Kurtail Gold at a quantity 150 times less than that recommended by the manufacturer (in terms of the concentration/ volume used per unit surface area). Thus, adding 1% (v/v) DMDC to 0.005% (v/v) Kurtail Gold causes an unexpected, synergistic inhibition of photosynthetic ETR.

Example 5 - effect of pyrocarbonate and Gramoxone on photosynthetic ETR over time Method

The effect of 0.5% (v/v) Gramoxone-200; and 0.5% (v/v) Gramoxone-200 + 1% (v/v) DMDC on photosynthetic ETR was tested 0 hours, 1 hour, 4 hours and 8 hours after treatment of culinary basil plants, using the method described in Example 1. Gramoxone- 200 (200 g paraquat/L) was made up in deionised water within 10 minutes of application. Deionized water was used as a negative control.

Results

Figure 5a is a line graph showing the photosynthetic ETR at increasing photon flux densities, 0 hours, 1 hour, 4 hours and 8 hours after treatment with 0.5% (v/v) Gramoxone-200. Figure 5b is a line graph showing the photosynthetic ETR at increasing photon flux densities, 0 hours, 1 hour, 4 hours and 8 hours after treatment with 0.5% (v/v) Gramoxone-200 + 1% (v/v) DMDC.

In both cases, 0.5% (v/v) Gramoxone-200 causes a time-dependent inhibition of photosynthetic ETR and this inhibition increased as the PFD increased. However, the presence of DMDC accelerated this inhibition. Indeed, more than double the rates of inhibition are achieved in the presence of DMDC. For example, treatment with 0.5% (v/v) Gramoxone-200 causes an 80% reduction in photosynthetic ETR (at 1650 μιηοΐ m^"2 s^"1) after 4 hours; whereas 0.5% (v/v) Gramoxone-200 + 1% (v/v) DMDC causes a similar reduction (76%) in photosynthetic ETR after only 1 hour.

Example 6 - effect of pyrocarbonate and Roundup on photosynthetic ETR over time

Method

Roundup Optima+ comprises 170g/L glyphosate and the surfactant polyethoxylated tallow amine, 15%. The effect of 0.5% (v/v) Roundup; and 0.5% (v/v) Roundup + 1% (v/v) DMDC on photosynthetic ETR was tested 0 hours, 24 hours, 48 hours and 72 hours after treatment of culinary basil plants, using the method described in Example 1. Roundup Optima+ was made up in deionised water within 10 minutes of application. Deionized water was used as a negative control.

Results Figure 6a is a line graph showing the photosynthetic ETR at increasing photon flux densities, 0 hours, 24 hours, 48 hours and 72 hours after treatment with 0.5% (v/v) Roundup. Figure 6b is a line graph showing the photosynthetic ETR at increasing photon flux densities, 0 hours, 24 hours, 48 hours and 72 hours after treatment with 0.5% (v/v) Roundup + 1% (v/v) DMDC. In both cases, 0.5% (v/v) Roundup causes a time-dependent inhibition of photosynthetic ETR and this inhibition increased as the PFD increased. In the absence of DMDC, Roundup causes approximately a 30% inhibition in 48 hours and this inhibition did not increase at 72 hours. In the presence of DMDC, Roundup caused a 60% greater inhibition (compared to Roundup without DMDC) at 24 hours and almost complete inhibition was achieved at 72 hours. Thus, the presence of DMDC significantly accelerated the photosynthetic inhibition caused by Roundup.

Example 7 - effect of timing of pyrocarbonate addition

Method The photosynthetic ETR in basil leaves at increasing photon flux densities was measured after the following treatments: (a) 1% (v/v) DMDC at 0 hours and then 0.005% (v/v) Gramoxone-200 at 24 hours; (b) 0.005% (v/v) Gramoxone-200 at 0 hours and then 1% (v/v) DMDC at 24 hours; and (c) 0.005% (v/v) Gramoxone-200 + 1% (v/v) DMDC at 0 hours and then at 24 hours, using the method described in Example 1. Gramoxone-200 (200 g paraquat/L) was made up in deionised water within 10 minutes of application. Deionized water was used as a negative control.

Results

As shown in Figure 7, the smallest amount of photosynthetic inhibition was observed when the basil leaves were treated with 0.005% (v/v) Gramoxone-200 at 0 hours and then 1% (v/v) DMDC at 24 hours. Reversing this order of treatments (i.e. treating with 1% (v/v) DMDC at 0 hours and then 0.005%) (v/v) Gramoxone-200 at 24 hours) caused a 23% increase in the photosynthetic inhibition at 1650 μπιοΐ m^"2 s^"1.

In contrast, treating basil leaves with 0.005% (v/v) Gramoxone-200 + 1% (v/v) DMDC at 0 hours and then at 24 hours caused an 86% reduction in photosynthetic ETR (relative to treating with 0.005% (v/v) Gramoxone-200 at 0 hours and then 1% (v/v) DMDC at 24 hours). Thus, a composition comprising a pyrocarbonate and a herbicide has a much greater efficacy than compositions comprising only one of these components.

Example 8 - effect of pyrocarbonate on the efficacy of glyphosate (Roundup) systemic action against plants Method

Sprigs of basil were cut from a whole basil plant and the stems placed in beakers containing deionised water. For each sprig, a single leaf was sprayed five times (250uL) with either 0.15% (w/v) N-(Phosphonomethyl)glycine (glyphosate) dissolved in deionised water; 1% (v/v) DMDC dissolved in deionised water; or 0.15% (w/v) N-(Phosphonomethyl)glycine (glyphosate) and 1% (v/v) DMDC dissolved in deionised water, using a small plastic atomiser. A paper towel was used to shield the remaining plant to ensure that the glyphosate and/or DMDC solution was deposited only on the target leaf. Immediately after spraying the sprigs in beakers were placed in a growth incubator and maintained at 20°C, constant light at 100-120 μπιοΐ m^"2 s^"1. Humidity around the leaves was raised by placing the beakers on a square of dampened paper towel and covering with a larger beaker. After 24h incubation, chlorophyll fluorescence of a sprayed leaf positioned directly opposite the glyphosate-sprayed leaf on the basil stem, was measured to therefore determine whether the synergistic effect of glyphosate and DMDC affected just the treatment surface or if it increased herbicidal efficacy in areas of the plant that weren't in direct contact with the glyphosate/DMDC solution.

Results

Figure 8 is a line graph showing the relative photosynthetic electron transport rate (ETR) in non-treated basil leaves at increasing photon flux densities (measured in μπιοΐ m^"2 s^"1) after the following treatments of a remote basil leaf on the same basil plant: (a) 1% (v/v) DMDC; (b) 0.15% (v/v) Roundup; and (c) 0.15% (v/v) Roundup + 1% (v/v) DMDC.

From Figure 8 it can be seen that the smallest amount of photsynthetic inhibition in leaves that weren't directly contacted with Roundup and/or DMDC occurred using DMDC alone, followed by Roundup alone. The biggest inhibition occurred using a combination of Roundup and DMDC, which indicates that the DMDC and Roundup act synergistically to inhihibit ETR and photosynthesis systemically thoughout a plant, and not just locally.

Although the present invention has been described with reference to preferred or exemplary embodiments, those skilled in the art will recognize that various modifications and variations to the same can be accomplished without departing from the spirit and scope of the present invention and that such modifications are clearly contemplated herein. No limitation with respect to the specific embodiments disclosed herein and set forth in the appended claims is intended nor should any be inferred.

All documents cited herein are incorporated by reference in their entirety.

Claims

CLAIMS:

1. A composition comprising a herbicide and a pyrocarbonate having the general formula R1-O-CO-O-CO-O-R2, wherein Ri and/or R₂ is an alkyl group.

2. A composition comprising a herbicide and a pyrocarbonate, in which the pyrocarbonate has the general formula R1-O-CO-O-CO-O-R2, wherein Ri and/or R2 is an alkyl group, and the pyrocarbonate is in a quantity sufficient to enhance the efficacy of the herbicide.

3. The composition of claim 1 or 2, wherein the pyrocarbonate is in a quantity sufficient to enhance synergistically the efficacy of the herbicide.

4. The composition of any one of claims 1 to 3, wherein the herbicide is:

a) a non- sel ective herbi ci de ;

b) a selective herbicide;

c) a systemic herbicide;

d) a contact herbicide;

e) a translaminar herbicide; and/or

f) a broad-spectrum herbicide.

5. The composition of any preceding claim, wherein the composition results in:

(a) inhibition of the growth of a target plant;

(b) inhibition of photosynthesis and/or respiration in a target plant; or

(c) death of a target plant.

6. The composition of any preceding claim, wherein the composition or herbicide:

(a) inhibits an enzyme;

(b) interferes with photosynthetic and/or respiratory electron transfer;

(c) disrupts the surface coating of a target plant;

(d) adversely affects cell structure; or

(e) adversely affects cell function.

7. The composition of any preceding claim, wherein the herbicide has a herbicidal effect and the pyrocarbonate accelerates said herbicidal effect.

8. The composition of any one of claims 1 to 7, wherein the composition results in inhibition of photosynthetic electron transport in a plant.

9. The composition of claim 8, wherein the herbicide:

(a) inhibits an enzyme, wherein optionally said enzyme is 5- enolpyruvylshikimate-3 -phosphate and/or glutamine synthetase;

(b) interferes with electron transfer, e.g. photosynthetic and/or respiratory electron transfer;

(c) disrupts plant waxy cuticles;

(d) adversely affects cell structure; and/or

(e) adversely affects cell function.

10. The composition of claims 8 or 9, wherein the herbicide is: N- (phosphonomethyl) glycine, N,N'-dimethyl-4,4'-bipyridinium dichloride, glufosinate, glufosinate-ammonium and/or l-methyl-4-(l-methylethenyl)- cyclohexene; or a salt, ether, amide, ester, solvate, isomer or other derivative thereof.

11. The composition of any preceding claim, wherein the pyrocarbonate causes greater than 10%, 15%, 20%, 40% or 60% inhibition of photosynthetic and/or respiratory electron transport in a plant relative to a composition comprising the same herbicide but lacking the pyrocarbonate.

12. The composition of any preceding claim, wherein in use the composition comprises:

0.001-20% (v/v) of the pyrocarbonate;

0.02-10%) (v/v) of the pyrocarbonate;

0.3-5%) (v/v) of the pyrocarbonate;

0.5-4%) (v/v) of the pyrocarbonate;

0.6-2%) (v/v) of the pyrocarbonate;

0.7-1.5%) (v/v) of the pyrocarbonate;

0.8-1.2%) (v/v) of the pyrocarbonate; or

1%) (v/v) of the pyrocarbonate.

13. The composition of any preceding claim, wherein in use the composition comprises:

0.00001-20% (v/v) of the herbicide;

0.001-10% (v/v) of the herbicide;

0.002-2% (v/v) of the herbicide;

0.003-1.5% (v/v) of the herbicide;

0.004-1.3% (v/v) of the herbicide; or

0.005-1% (v/v) of the herbicide.

14. The composition of any preceding claim, wherein the pyrocarbonate has herbicidal and/or bryophytocidal activity.

15. The composition of any preceding claim, wherein the pyrocarbonate facilitates the carbonylation of imidazole rings, for example in enzymes or cellular proteins.

16. The composition of any preceding claim, wherein the pyrocarbonate is diethyl dicarbonate or dimethyl dicarbonate.

17. The composition of any preceding claim, wherein the pyrocarbonate is dimethyl dicarbonate.

18. The composition of any preceding claim, wherein the composition comprises an adjuvant.

19. The composition of claim 18, wherein the adjuvant enhances the efficacy of the composition, herbicide and/or pyrocarbonate.

20. The composition of claim 18 or 19, wherein the adjuvant acts as a: pH buffering agent; water conditioning agent; wetting agent; leaf cuticle and/or cell membrane penetration aid; plant growth enhancer; defoaming agent; spray drift reducing agent; or an evaporation reducing agent.

21. The composition of any one of claims 18 to 20, wherein the composition has bryophytocidal activity and the adjuvant enhances said activity.

22. The composition of any preceding claim, in which the composition is a herbicide composition and/or a plant protection product.

23. Use of the composition of any preceding claim as a herbicide.

24. A method of inhibiting the growth of a plant, killing a plant or suppressing a plant within a treatment area, said method comprising applying the composition of any of claims 1 to 21 to said treatment area and/or plant in said treatment area.

25. The method of claim 24, wherein the plant is a vascular plant and/or bryophyte.

26. A method of enhancing the activity of a herbicide, said method comprising mixing a pyrocarbonate with the herbicide, wherein the pyrocarbonate has the general formula R1-O-CO-O-CO-O-R2, wherein Ri and/or R₂ is an alkyl group.

27. Use of a pyrocarbonate as an enhancer of a herbicide, wherein the pyrocarbonate has the general formula R1-O-CO-O-CO-O-R2, and Ri and/or R₂ is an alkyl group.

28. A kit comprising a herbicide and a pyrocarbonate,

in which the pyrocarbonate has the general formula Ri-O-CO-O-CO-

0-R₂, wherein Ri and/or R₂ is an alkyl group,

and, when combined, the pyrocarbonate enhances the efficacy of the herbicide.

29. The kit of claim 28, wherein the herbicide and/or the pyrocarbonate are in a concentrated form which is diluted prior to use.

30. A kit as claimed in claim 28 wherein the herbicide and/or pyrocarbonate is present in liquid or solid form.

31. A kit as claimed in any one of claims 28 to 30 further comprising at least one herbicidal adjuvant.