Method for vegetation management

Abstract

The present invention relates to a method for vegetation management that comprises treating an area with an aqueous solution of a formate salt.

Description

[0001] Method for vegetation management

[0002] Technical field of the invention

[0003] The present invention relates vegetation management.

[0004] Background of the invention

[0005] The growing environmental and health concerns associated with conventional herbicides underscore the urgent need for new types of herbicides that are less toxic, more environmentally friendly, and sustainable. Modern agriculture relies heavily on chemical weed control, yet the unintended consequences of herbicide use on ecosystems, biodiversity, and human health present significant challenges. To address these issues, the development of innovative herbicidal agents and alternative weed management technologies is essential.

[0006] Conventional herbicides often have limitations such as toxicity to non-target organisms, persistence in the environment, and the potential to contaminate water and soil. For instance, chemicals like paraquat are acutely toxic to humans and wildlife, while atrazine's persistence has led to widespread contamination of water supplies. These issues highlight the need for safer alternatives that minimize collateral damage. Developing herbicides with lower toxicity profiles and reduced environmental persistence would help address these concerns. Such herbicides could break down quickly into harmless byproducts, reducing their potential for bioaccumulation and long-term environmental impact.

[0007] In addition to being less toxic, new herbicides should also be designed to target weeds with greater precision. Advances in molecular biology and genomics provide opportunities to develop herbicides that specifically disrupt metabolic pathways unique to certain weed species.

[0008] Another critical area for innovation is addressing herbicide resistance, which has become a significant challenge in modern agriculture. Many weed species have evolved resistance to widely used herbicides, such as glyphosate, forcing farmers to apply higher doses or resort to older, more toxic chemicals.Furthermore, integrating technological advances into herbicide application methods can maximize the efficiency of new formulations. Precision agriculture tools, such as GPS-guided sprayers and drones equipped with weed detection systems, enable targeted application of herbicides, minimizing waste and reducing the exposure of non-target areas.These technologies not only conserve resources but also enhance the effectiveness of less toxic herbicides by ensuring they are applied precisely where needed.

[0009] Summary of the invention

[0010] Thus, an object of the present invention is to provide an effective alternative to the currently used methods.

[0011] The present inventors have unexpectedly discovered that aqueous solutions of formate salt produce a prolonged suppressive effect on plant growth, thereby being suitable for vegetation management.

[0012] A first aspect relates to a method for vegetation management, wherein the method comprises treating an area with an aqueous solution of a formate salt.

[0013] In the present context, the treatment involving the application of dry formate salt followed by irrigation is also covered under the term "formate salt solution" as it ultimately results in the same outcome, i.e., a solution of the formate salt in water. Whether the solution is prepared beforehand and applied directly or formed in situ through the dissolution of the dry salt during irrigation, the final state is identical.

[0014] The present invention will now be described in more detail in the following.

[0015] In principle, an aqueous solution of formic acid, i.e., the free acid, is also suitable, but it's inherent acidity and smell makes it less suitable to handle. Likewise, it is also contemplated that the liquid formic acid is suitable, but it's inherent acidity and smell makes it less suitable to handle. Furthermore, there is an increased risk of long-lasting damage to the soil's pH balance.

[0016] A second aspect relates to a method for vegetation management, wherein the method comprises treating an area with an aqueous solution of a formate salt or formic acid.

[0017] Detailed description of the invention

[0018] A first aspect relates to a method for vegetation management, wherein the method comprises treating an area with an aqueous solution of a formate salt.A second aspect relates to a method for vegetation management, wherein the method comprises treating an area with an aqueous solution of a formate salt or formic acid.

[0019] Formate salts are ionic compounds derived from the conjugate base of formic acid (HCOOH), known as the formate ion (HCOO-), combined with a corresponding cation. These salts are generally formed through the neutralization of formic acid with a base and have the general formula M(HCOO)X, where M represents the cation and x indicates the stoichiometric ratio required for charge balance.

[0020] A characteristic feature of formate salts is their high solubility in water, which makes them suitable for various applications. They are thermally stable under moderate conditions but can decompose at higher temperatures, often releasing carbon monoxide and leaving behind metal oxides. These salts find widespread use in industries such as de-icing, preservation, leather tanning, and as intermediates in chemical synthesis. However, such salts have never been used for vegetation management.

[0021] Among the most common formate salts, sodium formate (NaHCOO) is a white, water-soluble solid widely used as a de-icing agent, food preservative, and buffering agent. It also plays a role in textile dyeing and printing. Potassium formate (KHCOO), which is highly soluble in water, is frequently used in de-icing and as a component in drilling fluids for oil and gas extraction. Calcium formate (Ca(HCOO)2), which is less soluble than its sodium and potassium counterparts, is commonly employed as a cement additive to accelerate curing, as a preservative in animal feed, and in leather tanning. Another example, ammonium formate (NH4HCOO), is a hygroscopic solid that decomposes upon heating to produce formamide and water, making it useful in analytical chemistry and organic synthesis. Calcium Magnesium Formate (CMF) is also used in de-icing.

[0022] Other formate salts include iron(II) formate (Fe(HCOO)2), which is used in specialized chemical processes, and lithium formate (LiHCOO), known for its stability and application as a standard in nuclear magnetic resonance (NMR) spectroscopy. Formate salts are valued for their environmental compatibility, exhibiting low toxicity and biodegradability compared to many other salts. Their properties make them ideal for applications that balance performance with ecological considerations, including de-icing, preservation, catalysis, and now also vegetation management.

[0023] In one or more embodiments, the formate salt is selected from the group consisting of Sodium formate (NaHCOO), Potassium formate (KHCOO), Calcium formate (Ca(HCOO)2), Ammonium formate (NH4HCOO), Lithium formate (LiHCOO), Magnesium formate (Mg(HCOO)2), Iron(II) formate (Fe(HCOO)2), Zinc formate (Zn(HCOO)2), Copper(II) formate (Cu(HCOO)2), Barium formate (Ba(HCOO)2), and Calcium Magnesium Formate (CaMg(HCOO)4, CMF).In the present context, the term "vegetation management" is to be understood as the practice of controlling, suppressing, or eliminating unwanted plant growth to achieve specific environmental, agricultural, or industrial objectives. This includes the use of chemicals, such as herbicides, defoliants, or desiccants. Vegetation management is commonly applied in contexts such as agriculture, forestry, landscaping, and utility maintenance to maintain desired vegetation or prevent hazards.

[0024] Herbicide application involves using chemicals specifically designed to kill or suppress the growth of plants, such as weeds or invasive species.

[0025] Defoliation with chemicals (defoliants) are often used to remove leaves from plants, especially in agricultural practices like cotton or potato farming.

[0026] Desiccation uses chemical desiccants to kill plants or dry out plant tissues, usually to aid in crop harvesting.

[0027] Plant termination and crop topping may also involve chemical methods, depending on the specific agricultural practice.

[0028] All these methods are to be understood covered under the term "vegetation management".

[0029] The application of the aqueous solution of the formate salt to the area (e.g., a surface, a plant surface, or a surface area, such as the both the plant and soil surface) of interest may be done with different means. The use of nozzles to apply aqueous solutions of the formate salts, either as aerosols or sprayed solutions, serves an essential purpose in achieving uniform and efficient chemical distribution over a target surface. The primary goal of such systems is to ensure consistent coverage of the treated area, which is crucial for effective vegetation management. By distributing the solution evenly, untreated patches are avoided, reducing the risk of regrowth.

[0030] Nozzles are designed to optimize chemical usage by providing precise application, minimizing waste, reducing operational costs, and limiting the environmental impact of excessive chemical use. Depending on the intended purpose, the nozzle type and spray pattern can be adjusted to control droplet size. Fine droplets, often produced as aerosols, are ideal for coating large areas with minimal liquid volume, making them suitable for systemic herbicides (the inventors speculate that this is the case with the formate salts) that are absorbed through the leaves. Larger droplets are better suited for targeted application, particularly when drift must be minimized in windy conditions or when more precise delivery is required.While nozzles are the most common solution, alternative methods can also be employed in specific circumstances. For example, drip or drizzle systems can deliver the formate salts directly to the base of plants or into the soil using controlled streams or droplets. These systems are particularly effective for soil-applied herbicides, where targeting root zones is critical (this may also be the case for the formate salts). Drip irrigation systems can combine the formate salts with water, applying them precisely to areas of interest. This method minimizes drift and evaporation.

[0031] Another advanced alternative is electrostatic spraying, which enhances conventional spraying by charging liquid droplets as they are released. The electrostatically charged droplets are attracted to plant surfaces, improving coverage, even on complex leaf structures. This method increases efficiency, reduces chemical waste, and ensures that more of the formate salt reaches the target surface, minimizing runoff or drift.

[0032] The spraying systems may integrate nozzles or other delivery methods into mobile units, i.e., vehicles, such as tractors, trucks, or drones, providing automation and efficiency for weed control. Technologies like GPS and sensors enable precise application, ensuring chemicals are only applied where needed. This level of automation reduces waste and increases operational efficiency, especially when combined with advanced methods like electrostatic spraying.

[0033] In one or more embodiments, the aqueous solution is applied as a spray, such as an aerosol, or a sprayed solution. Aerosols er fine droplets or mists that remain suspended in the air for a period of time, while sprayed solutions are relatively larger droplets that are applied directly to surfaces or plants.

[0034] The temperature of the spray solution of the aqueous solution of a formate salt may play a critical role in both the stability of the formate and its effectiveness when applied to target plants. The temperature of the aqueous solution can influence how well the formate performs and how efficiently it is absorbed by the plants. At higher temperatures, the formate salts may degrade more rapidly due to chemical breakdown processes, which can significantly reduce their effectiveness. To avoid such issues, the spray solutions should generally be kept within a moderate temperature range, ensuring the formate salt remains chemically stable.

[0035] The solution temperature may also directly impact herbicidal efficacy. Warmer solutions can improve the absorption of the formate into plants, especially if the formate formulations rely on uptake through leaves and movement within the plant's vascularsystem. Higher temperatures tend to enhance plant metabolism, which increases formate uptake, and reduce the surface tension of the solution, allowing it to spread more efficiently across plant surfaces. However, excessively high solution temperatures can cause the droplets to evaporate too quickly, reducing the time the formate remains on the plant and limiting its absorption. This rapid evaporation is particularly problematic in dry, warm environments where fine droplets are used, as it reduces coverage and overall effectiveness.

[0036] On the other hand, solutions that are too cold can also present challenges. Low temperatures may slow the absorption of the formate due to reduced plant metabolism and can increase the viscosity of the solution, making it less effective at spreading evenly on the plant surface. In addition, some herbicides may not dissolve fully in cold water, which can further limit their performance.

[0037] For optimal results, formate spray solutions should be maintained as close to ambient temperatures as possible, typically within a moderate range that avoids extremes.

[0038] Moderately warm solutions offer advantages such as improved solubility, better spread across plant surfaces, and enhanced absorption into the target plants. Excessively hot or cold solutions, by contrast, risk reducing the formate's stability, coverage, and overall efficacy. By carefully controlling the spray solution temperature, operators can ensure that the formate is applied efficiently and effectively, minimizing waste while maximizing its intended impact.

[0039] In one or more embodiments, the spray solution has a temperature of within the range of 10-90 degrees Celsius, preferably within the range of 15-70 degrees Celsius, e.g., 20-60 degrees Celsius, such as 25-50 degrees Celsius, more preferably within the range of 20-40 degrees Celsius.

[0040] Weeds belonging to the Poa genus, such as annual bluegrass (Poa annua), rough bluegrass (Poa trivialis), Kentucky bluegrass (Poa pratensis, Meadow grass), couch grass Elymus repens, also known as Elytrigia repens'), and others (see below), are common in agricultural fields, turfgrass systems, and disturbed areas. Poa weeds are highly competitive, thriving in disturbed soils, compacted areas, and regions with high moisture levels. Species like annual bluegrass can outcompete crops and turf by germinating rapidly, forming dense mats, and utilizing available resources (water, nutrients, light) more efficiently. Their rapid growth can lead to reduced crop yields or poor turf quality, necessitating chemical treatment for effective control. Many Poa species produce a large number of seeds that can remain viable in the soil for years. For example, annual bluegrass can produce thousands of seeds per plant in a single growing season. Chemicaltreatments help prevent seed production and reduce the soil seed bank, minimizing future infestations

[0041] In one or more embodiments, the targeted weed is selected from the Poa genus.

[0042] In one or more embodiments, the targeted weed is selected from the group consisting of Annual bluegrass (Poa annua), Kentucky bluegrass (Poa pratensis, Meadow grass), Rough bluegrass (Poa trivialis), Canada bluegrass (Poa compressa), Bulbous bluegrass (Poa bulbosa), Wiregrass (Poa tenerrima), Sand bluegrass (Poa ammophila), Couch grass (Elymus repens, also known as Elytrigia repens), and Alpine bluegrass (Poa alpina).

[0043] Weeds belonging to the Tripleurospermum genus, such as odorless chamomile (Tripleurospermum inodorum), scentless mayweed (Tripleurospermum perforatum), and sea mayweed (Tripleurospermum maritimum), can become problematic in agricultural systems. Weeds like odorless chamomile and scentless mayweed compete aggressively with crops for resources such as light, water, and nutrients. Their rapid growth and ability to thrive in disturbed soils make them highly competitive in cereals, root crops, and oilseed rape fields. Severe infestations can lead to significant yield reductions, particularly in crops like wheat and barley. Tripleurospermum weeds are prolific seed producers, with a single plant capable of producing thousands of seeds. These seeds can remain viable in the soil for several years, creating a persistent seed bank that contributes to ongoing infestations. Hence, chemical control is essential for reducing seed production and preventing the replenishment of the seed bank.

[0044] In one or more embodiments, the targeted weed is selected from the Tripleurospermum genus.

[0045] In one or more embodiments, the targeted weed is selected from the group consisting of Odorless chamomile (Tripleurospermum inodorum), Scentless mayweed (Tripleurospermum perforatum), Sea mayweed (Tripleurospermum maritimum), and False mayweed (Tripleurospermum ambiguum).

[0046] Weeds belonging to the Cirsium genus, such as field thistle (Cirsium arvense), bull thistle (Cirsium vulgare), and swamp thistle (Cirsium muticum), are highly invasive and problematic in agricultural systems, pastures, and natural areas. Cirsium species, especially field thistle (Cirsium arvense), compete aggressively with crops for resources such as light, water, and nutrients. These weeds are particularly problematic in row crops, pastures, and grain fields, where their presence significantly reduces yields. Their tall growth habit shades out lower-growing crops, further diminishing productivity. ManyCirsium weeds, including field thistle, spread through extensive creeping root systems (rhizomes) that allow them to form dense colonies. Mechanical removal often leaves fragments of roots in the soil, which can regenerate into new plants. Chemical treatments are often the most effective way to target the entire root system and prevent regrowth. Cirsium species are prolific seed producers. For instance, bull thistle can produce thousands of seeds per plant, and these seeds can remain viable in the soil for years. Seeds are easily dispersed by wind, allowing infestations to spread rapidly. Herbicides help reduce seed production by killing plants before they flower and set seed.

[0047] In one or more embodiments, the targeted weed is selected from the Cirsium genus.

[0048] In one or more embodiments, the targeted weed is selected from the group consisting of Field thistle (Cirsium arvense), Bull thistle (Cirsium vulgare), Woolly thistle (Cirsium eriophorum), Swamp thistle (Cirsium muticum), Yellow thistle (Cirsium horridulum), Nodding thistle (Cirsium nutans), Slender thistle (Cirsium acaule), Pasture thistle (Cirsium discolor), Marsh thistle (Cirsium palustre).

[0049] The practice of killing potato plants with herbicides prior to harvesting, known as desiccation, serves several important purposes in modern agriculture. By terminating the plants, the foliage becomes dry and brittle, making it easier to remove during mechanical harvesting. This minimizes the risk of clogging machinery and ensures a smoother harvesting process.

[0050] Additionally, desiccation promotes the maturation of potato skins. After the plants are killed, the tubers are left in the soil for a curing period, during which their skins thicken. This process enhances the durability of the potatoes, reducing the likelihood of damage such as bruising or cracking during harvest and improving their resistance to diseases, which is particularly important for storage.

[0051] Another critical benefit is the reduction of disease transmission. Living potato foliage can harbour pathogens like late blight, which may spread to the tubers during harvesting. By killing the plants, farmers minimize this risk, ensuring healthier yields. Furthermore, desiccation halts tuber growth, which helps standardize their size, a feature that is especially valuable for meeting market demands, particularly in the processing industry.

[0052] Using herbicides also allows farmers to precisely control the timing of vine desiccation. This scheduling flexibility is crucial for large-scale operations, especially when weather conditions are variable. However, the practice is not without concerns. Chemical residues from herbicides like diquat or glyphosate may linger in the soil or on the crop, raisingenvironmental and health-related questions. Additionally, the impact on soil health and microbial communities from prolonged herbicide use is a consideration that warrants attention.

[0053] In one or more embodiments, the targeted plant is selected from the Solanum genus, preferably the Solanum tuberosum species.

[0054] In one or more embodiments, the targeted weed is selected from the group consisting of meadow grass, odorless chamomile, field thistle, and couch grass.

[0055] It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

[0056] Examples

[0057] Initial experiments showed that a dosage of formate salt of about 10 g / m2is proper. However, this does not limit the scope of the invention to this exact dosage, and dosages within the range of 1-100 g / m2is also contemplated to be within the scope of the invention.

[0058] Example 1

[0059] Objective:

[0060] To investigate the effect of an aqueous solution of a formate salt (the potassium salt) on two weed species: annual meadow grass (Poa annua) and scentless chamomile (Matricaria perforata), established at two developmental stages.

[0061] Experimental Design:

[0062] A three-factorial pot experiment with three replications.

[0063] Experimental Factors:

[0064] Weed Species:

[0065] Two types:

[0066] Annual meadow grass (Poa annua).

[0067] Scentless chamomile (Matricaria perforata).

[0068] Developmental Stage:

[0069] Two growth stages:

[0070] 1-2 true leaves.

[0071] 4-5 true leaves.Number of Pots:

[0072] 2 weed species x 2 growth stages x 3 replications = 12 pots.

[0073] Additional 4 pots for microscopic analysis: 1 pot per weed species, and growth stage.

[0074] Total: 16 pots.

[0075] Experiment Setup:

[0076] Pot Arrangement: Pots are placed in a semi-field system and positioned within a test frame for treatment applications.

[0077] Planting: 10 seeds are sown per pot, germinated outdoors, and thinned to ensure a consistent plant density.

[0078] Soil Conditions: Pots are filled with soil to the brim without a stone top layer.

[0079] Treatment Applications:

[0080] The dosage of formate salt is maintained at a constant 10 g / m2.

[0081] Data Collection:

[0082] The pots are harvested 3-4 weeks after treatment.

[0083] The dry matter content of the plants is determined.

[0084] Example 2

[0085] Objective:

[0086] To investigate the effect of an aqueous solution of a formate salt (the potassium salt) on two weed species: Field thistle Cirsium arvense) and Couch grass Elymus repens'), established at one developmental stage.

[0087] Experimental Design:

[0088] A three-factorial pot experiment with three replications.

[0089] Experimental Factors:

[0090] Weed Species:

[0091] Two types:

[0092] Field thistle Cirsium arvense).

[0093] Couch grass Elymus repens).

[0094] Developmental Stage:

[0095] 2-3 true leaves.Number of Pots:

[0096] 2 weed species x 1 growth stage x 3 replications = 6 pots.

[0097] Additional 2 pots for microscopic analysis: 1 pot per weed species.

[0098] Total: 8 pots.

[0099] Experiment Setup:

[0100] Pot Arrangement: Pots are placed in a semi-field system and positioned within a test frame for treatment applications.

[0101] Thistle and couch grass fragments are pre-germinated in trays. Subsequently, the fragment along with the shoot is weighed before being planted in each pot at a depth of 5 cm, with one shoot per pot. The shoots continue to grow outdoors.

[0102] Treatment Applications:

[0103] The dosage of formate salt is maintained at a constant 10 g / m2.

[0104] Data Collection:

[0105] The pots are harvested 3-4 weeks after treatment.

[0106] The dry matter content of the plants is determined.

[0107] Both experiments successfully demonstrated that the treatment applied achieved a complete herbicidal effect (100% efficacy) on all four weed species, annual meadow grass (Poa annua), scentless chamomile (Matricaria perforata), field thistle Cirsium arvense), and couch grass Elymus repens') at the developmental stages tested.

[0108] These results indicate that the dosage parameter employed was effective under the tested conditions. The uniformity of the effect across weed species and developmental stages highlights the robustness of the formate treatment in controlling these specific weeds.

[0109] The findings confirm the potential of formate as a highly effective herbicidal solution for managing annual meadow grass and scentless chamomile in agricultural or controlled settings.

[0110] Example 3

[0111] Objective:

[0112] To evaluate the effectiveness and impacts of formate for desiccating potato plants of two varieties, Ydun and Spunta, under controlled conditions.Setup:

[0113] Plants: Use 20 potato plants grown in individual pots (30 cm in diameter) under uniform conditions. Select 10 plants of Ydun and 10 plants of Spunta to represent genetic and phenotypic variation.

[0114] Conditions: Ensure all pots are of the same size, with identical soil composition, watering schedule, and sunlight exposure. Place the pots in a controlled greenhouse or outdoor space to minimize environmental variability.

[0115] Herbicide Treatment:

[0116] Divide the plants into two groups:

[0117] Group 1: 10 Ydun plants treated with a dosage of 10 g / m2of formate, which equals about 0.7 g / m2of formate per pot.

[0118] Group 2: 10 Spunta plants treated with a dosage of 10 g / m2of formate, which equals about 0.7 g / m2of formate per pot.

[0119] Data Collection Parameters:

[0120] Desiccation Rate: Measure the rate at which the plants lose green foliage using a visual scale or digital imaging (e.g., percentage of foliage desiccated) over a 7-14 day period.

[0121] Skin Maturation: After the desiccation period, harvest the tubers and evaluate their skin thickness and maturity using a standard skinning resistance test.

[0122] Yield Quality: Assess the tubers for size, weight, and visible damage (e.g., cracking or bruising).

[0123] Residual Analysis: Test the soil and harvested tubers for herbicide residues to evaluate potential chemical persistence.

[0124] Disease Impact: Check for any signs of disease on the tubers to understand whether the herbicide impacted pathogen transmission.

[0125] The experiment evaluated the efficacy of formate in desiccating potato plants of two varieties, Ydun and Spunta. Results demonstrated that formate performed similarly to traditionally used commercial herbicides across multiple parameters, including desiccation rate, tuber skin maturity, and overall yield quality.

Claims

Claims1. A method for vegetation management, characterized in that the method comprises treating an area with an aqueous solution of a formate salt.

2. The method according to claim 1, characterized in that the type of vegetation management is selected from the group consisting of weed control, defoliation, desiccation, and plant termination.

3. The method according to any one of the claims 1-2, characterized in that the aqueous solution is applied as a spray.

4. The method according to claim 3, characterized in that the spray has a temperature of within the range of 10-90 degrees Celsius.

5. The method according to any one of the claims 1-4, characterized in that the targeted weed is selected from the Poa genus.

6. The method according to any one of the claims 1-4, characterized in that the targeted weed is selected from the group consisting of Annual bluegrass (Poa annua), Kentucky bluegrass (Poa pratensis), Rough bluegrass (Poa trivialis), Canada bluegrass (Poa compressa), Bulbous bluegrass (Poa bulbosa), Wiregrass (Poa tenerrima), Sand bluegrass (Poa ammophila), and Alpine bluegrass (Poa alpina).

7. The method according to any one of the claims 1-4, characterized in that the targeted weed is selected from the Tripleurospermum genus.

8. The method according to any one of the claims 1-4, characterized in that the targeted weed is selected from the group consisting of Odorless chamomile (Tripleurospermum inodorum), Scentless mayweed (Tripleurospermum perforatum), Sea mayweed (Tripleurospermum maritimum), and False mayweed (Tripleurospermum ambiguum).

9. The method according to any one of the claims 1-4, characterized in that the targeted weed is selected from the Cirsium genus.

10. The method according to any one of the claims 1-4, characterized in that the targeted weed is selected from the group consisting of Field thistle (Cirsium arvense), Bull thistle (Cirsium vulgare), Woolly thistle (Cirsium eriophorum), Swamp thistle (Cirsiummuticum), Yellow thistle (Cirsium horridulum), Nodding thistle (Cirsium nutans), Slender thistle (Cirsium acaule), Pasture thistle (Cirsium discolor), Marsh thistle (Cirsium palustre).

11. The method according to any one of the claims 1-4, characterized in that the targeted plant is selected from the Solanum genus, preferably the Solanum tuberosum species.

12. The method according to any one of the claims 1-4, characterized in that the targeted weed is selected from the group consisting of meadow grass, odorless chamomile, field thistle, and couch grass.