WO2005110081A2

WO2005110081A2 - Ragwort control method

Info

Publication number: WO2005110081A2
Application number: PCT/GB2005/001614
Authority: WO
Inventors: Howard Edward Downer; Alison Catherine Wetz
Original assignee: Thurlow Countryside Management Limited
Priority date: 2004-04-15
Filing date: 2005-04-28
Publication date: 2005-11-24
Also published as: GB0410901D0; EP1746879A2; WO2005110081A3

Abstract

A method for controlling senecio jacobaea, or Common Ragwort, involves the preliminary steps of identifying a target Ragwort plant (1) and characterising its growth phase (5) as either 'woody stem' or 'rosette'. A nozzle guard (12, 13) appropriate to the characterised growth phase is then selected (6a, 6b) and fitted to a knapsack sprayer (11). The target Ragwort plant is then isolated (7a, 7b), from its surrounding environment by placing the nozzle guard (12, 13) therearound. Subsequently, an amount of weed-killing composition appropriate to the characterised growth phase is applied to the target plant by spraying (8a, 8b) from a reservoir (14) in the knapsack sprayer (11).

Description

Ragwort Control Method This invention relates in a first aspect thereof to a method for the control of senecio jacobaea, an injurious weed best known as common ragwort (and referred to herein simply as "ragwort"). The invention also relates, in further aspects thereof, to a composition and apparatus for use in such a method. Ragwort is extremely prolific, and propagates in two ways: by blown seeds, and by seeds dropping to the ground at the base of the plant. A single plant may produce 150,000 seeds with a germination rate of 70%. It cannot be satisfactorily eradicated by cutting, digging or pulling : cutting stimulates the plant to produce new shoots, which quickly flower; whilst digging or pulling expose bare soil in which dropped seeds quickly germinate. Furthermore, any root left in the ground will re-grow, and seeds may survive for up to 20 years before germinating. Ragwort is highly toxic to livestock, particularly horses, cattle and sheep and can cause progressive and irreversible liver damage. As little as 1kg of fresh weight of the plant can cause fatal damage when ingested. Common ragwort is most often seen on motorway and bypass embankments and poorly managed pastures. In view of the threat to livestock, there is great concern about its spreading onto, and infesting adjoining farmland from these areas. Since ragwort propagates via airborne seeds, the motorway and trunk road network provides an ideal environment for the weed to flourish, since passing traffic creates a "wind tunnel" effect to carry the seeds. Consequently, ragwort has spread to affect most counties of England, Wales and Scotland. Ragwort is a biennial plant, and its growth cycle can be characterised into at least two distinct stages: an early "rosette" stage, and a later "woody stem" stage (also referred to as the "stem extension" stage). A typical seed will germinate and grow to a rosette during the first year of the plant's growth cycle, and will continue to establish itself up until late spring in the second year. At this point, the weed undergoes stem extension growth, and enters its so-called "woody stem" stage. This followed by flowering during the summer and early autumn of the second year. Conventional methods for the control of common ragwort, such as those recommended by the UK Department for the Environment, Food and Rural Affairs (DEFRA), involve treating the weed with herbicides during its early rosette stage. At the "woody stem" stage the weed becomes extremely resistant to conventional herbicide treatments. Cutting or pulling of the weed when mature may not fully eradicate it, as it will still propagate from roots left in the ground, the existing seed bank, or seeds which may be dispersed during the process of attempting to eradicate the plant. Conventional herbicide treatments for ragwort tend also to involve either blanket spraying a ragwort-infested area with a weed-killing composition or a more targeted approach using a knapsack sprayer - although the targeting of the latter method is generally poorly executed. Neither method is effective on plants at the woody stem and flowering stage. Furthermore, in addition to the evident wastage of composition which falls on ragwort-free ground, methods involving blanket spraying or poorly executed targeted herbicide application also raise environmental concerns. This is because the composition will inevitably be applied to other plants, whilst insects and other small animals may also be affected. The contamination of these plants and animals may then have a knock-on effect to those animals higher up the food chain, deriving from loss of habitat or food source. The present invention seeks to address the above problems by providing a targeted method of ragwort control which will reduce or eliminate the environmental and wastage problems associated with spray drift arising from methods involving blanket spraying or poorly executed targeted herbicide application. The present invention also seeks to provide a method of ragwort control with enhanced kill rates, approaching 100%, which is effective even after the plant has entered its woody stem stage, and which requires less volume of herbicide than conventional methods, thus leading to both economic and environmental benefits. According to a first aspect of the present invention, there is provided a method of controlling common ragwort comprising: - identifying a target ragwort plant, characterising the growth phase of said target plant, and selecting a nozzle and nozzle guard appropriate to said growth phase; - fitting said selected nozzle and nozzle guard to spraying apparatus having: - a reservoir for weed-killing composition; - a spray lance in communication with said reservoir at one end thereof, and having its other end adapted to receive a nozzle and nozzle guard; and - trigger means to activate spraying of said weed-killing composition from said reservoir; - isolating said target plant from its surrounding environment, by placing said selected nozzle guard therearound; and - applying to said target plant from the spraying apparatus through said selected nozzle, an effective amount of a weed-killing composition comprising at least one active component and a sticking agent. The weed-killing composition is preferably an aqueous composition comprising: - at least one active component selected from 2-methyl-4-chloro- phenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, and derivatives thereof; and - a sticking agent selected from polyvinyl alcohols, synthetic latexes, poly-

1-β-menthene, and derivatives thereof. Most preferably, the aqueous composition comprises the following components: (A) a first active component selected from 2-methyl-4-chloro- phenoxyacetic acid and derivatives thereof, present in a concentration in the range of from 0.90% to 1.10% by volume of the total composition; (B) a second active component selected from 2,4-dichlorophenoxyacetic acid and derivatives thereof, present in a concentration in the range of from 1.35% to 1.65% by volume of the total composition; (C) a sticking agent selected from poly-1-p_.-menthene, and derivatives thereof, present in a concentration in the range of from 0.22% to 0.27% by volume of the total composition; and (D) a non-ionic polymeric colorant, present in a concentration of 0.001% by volume of the total composition. 2-methyl-4-chloro-phenoxyacetic acid and derivatives thereof are commonly referred to as MCPA. It is currently preferred to use a solution of MCPA, present as its sodium, potassium and dimethylamine salts, such as that supplied by Nufarm UK Limited, of Belvedere, Kent, England, under the trade name AGRITOX 50. 2,4-dichlorophenoxyacetic acid and derivatives thereof are commonly referred to as 2,4-D. It is currently preferred to use a solution of 2,4-D, present as its dimethylamine salt, such as that supplied by Nufarm UK Limited, of Belvedere, Kent, England, under the trade name DEPITOX. The preferred sticking agent, poly-1-p-menthene, is supplied by Miller

Chemical & Fertilizer Corporation of Hanover, Pennsylvania, USA, under the trade name NU FILM P. Alternative sticking agents, such as polyvinyl alcohols and synthetic latexes, are supplied by Newman Agrochemicals Limited of Cambridge, England under the trade name BOND. A preferred non-ionic polymeric colorant is supplied by Milliken and

Company of Spartanburg, South Carolina, USA, under the trade name BLAZON. The colorant assists the operative in enabling him to identify plants or areas which have already been sprayed, thus reducing wastage of composition. The addition of colorant to the composition also increases the droplet size being delivered from the nozzle of the spraying apparatus, thus reducing spray drift. The initial method step of characterising the growth phase of the target ragwort plant involves a trained operative determining, by visual inspection, whether the plant is in its early rosette stage, or its later woody stem stage. Once this determination has been made, the operative then selects either a small or large nozzle and nozzle guard, respectively, each such nozzle guard being generally conical in shape. A small nozzle guard for use in the method of the present invention has a height of substantially 145mm, an upper diameter of substantially 100mm and a lower diameter of substantially 210mm, and is thus suitable for surrounding a rosette stage ragwort plant. The small nozzle selected for use with such a nozzle guard will typically be of the type commercially available under the trade name Luremark 30 FCX04. A large nozzle guard for use in the method of the present invention has a height of substantially 250mm, an upper diameter of substantially 100mm and a lower diameter of substantially 290mm, and thus can accommodate a ragwort plant in its stem extension stage. The large nozzle selected for use with such a nozzle guard will typically be of an adjustable cone type. The spraying apparatus is preferably provided with pressure regulating means to maintain the delivery of the weed-killing composition at a substantially constant pre-determined pressure. To ensure reliable delivery of the required volume of weed-killing composition per unit time, it is currently preferred that the pressure regulating means is arranged to maintain a delivery pressure of substantially 100kPa (1bar). A pressure gauge is preferably fitted to the spray lance to enable the operative to monitor the delivery pressure. Where the target ragwort plant is in its rosette stage, an effective amount of weed-killing composition may thus be applied to the plant by activating and instantly releasing the trigger means of the spraying apparatus. The ragwort plant is thus sprayed for less than 0.4 seconds. With the spraying apparatus calibrated to provide a constant delivery pressure of substantially 1bar, this results in the target ragwort plant receiving a volume of weed-killing composition in the range of from 4 to 4.5 ml. The spraying apparatus is preferably of the type commonly referred to as a knapsack sprayer, in which the reservoir is adapted to be carried on the operative's back. The knapsack sprayer reservoir typically has a volume of substantially 20 litres. Where the target ragwort plant is in its stem extension stage, an effective amount of weed-killing composition is again applied to the plant by activating and instantly releasing the trigger means of the spraying apparatus, so as to spray the plant for less than 0.4 seconds. However, since the adjustable cone nozzle allows a greater volume of composition to flow therethrough than does the small nozzle, this results in the target ragwort plant receiving a volume of weed-killing composition in the range of from 9 to 11 ml. For a mature target ragwort plant, an effective amount of weed-killing composition is applied thereto by activating and holding the trigger means for a period of time in the range of from 0.9 to1.2 seconds, thus delivering a volume of composition in the range of from 14 to 16 ml. And where the target ragwort plant is a large mature plant, an effective amount of weed-killing composition is applied thereto by activating and holding the trigger means for a period of time in the range of from 1.9 to 2.2 seconds, thus delivering a volume of composition in the range of from 29 to 31 ml. The internal surface of the nozzle guard may preferably be treated with a dispersant coating, to encourage run-off of weed-killing composition from said surface onto the target ragwort plant. A suitable dispersant coating is available for automotive applications under the trade name RAINEX. According to a second aspect of the present invention there is also provided spraying apparatus for use in a ragwort control method as hereinbefore described. According to a third aspect of the present invention there is further provided a weed-killing composition for use in a ragwort control method and/or in spraying apparatus as hereinbefore described. Whilst the present invention is not limited by any theory, it is currently believed that the sticking agent acts to adhere the weed-killing composition to the plant, thus prolonging the time period during which the herbicide is in contact with the plant. The prolonged time during which the herbicide is in contact with the plant promotes penetration of the active components into the plant, which enables the composition to be used on plants in their woody stem stage. The use of sticking agents in the composition also makes the process more resistant to wind, rain and cooler temperatures, and enables spraying of ragwort plants later in the growing season than has previously been possible. A further advantage of this is that mature ragwort plants can be prevented from seeding, thus preventing the spread of the weed. Treatment at the mature flowering stage does not always prevent seeding, but trials indicate that seeds from treated plants are rendered infertile. Where plants are already in seed, treatment according to the present invention results in the sticking agent binding them together, making wind dispersal less likely. Additional benefits of the present invention arise from the targeting and isolation of individual plants rather than blanket spraying of whole infected areas. This leads to a reduced volume of weed-killing composition being used - with clear environmental and economic advantages. In order that the present invention may be more fully understood, a preferred embodiment thereof will now be described in detail with reference to the accompanying drawings, in which: Figure 1 is a flow chart representing a method of ragwort control according to the present invention; and Figures 2a and 2b are schematic representations of a knapsack sprayer for use in the method of Figure 1 , fitted with a small and large nozzle guard, respectively. In a method ragwort control according to the present invention, as represented in flow chart form in Figure 1, a trained operative starts by identifying a target plant (1) and determining whether or not it is common ragwort. This is an important preliminary step, as a number of other plants have a similar appearance, and might be mistaken for common ragwort by an untrained observer. Examples of such similar-looking plants are Oxford Ragwort, Groundsel, St. Johns Wort and Bird's Foot Trefoil. If the operative determines that the target plant is one of these species - or any other species other than common ragwort - no spraying takes place (2). The operative then examines the area for other target plants (3), and if any are found, returns to stage (1). If a common ragwort plant is identified, the next stage (4) is to remove any obvious signs of insects or small animals which might be present on the plant, so as to minimise the environmental impact of the ragwort control method. In particular, a common ragwort plant is likely to be home to a number of cinnabar moth larvae, which should be removed prior to the plant being sprayed. The trained operative then examines the plant (5) in order to determine whether it is in its early rosette growth phase or its later woody stem growth phase. The growth phase is in fact largely determined by the time of year, (i.e. the stage in the growing season), and the operative will therefore have a reasonable idea of whether to expect rosettes, woody stems or a mixture of the two, prior to beginning the process. If the operative characterises the growth phase of the plant as being rosette stage he selects a small nozzle and nozzle guard (6a) for attachment to his knapsack sprayer. This will be discussed in more detail below with reference to Figure 2a. Having attached the small nozzle guard to his sprayer, the operative then isolates the rosette by placing the nozzle guard over it (7a). The rosette is then sprayed (8a) by activating and immediately releasing the trigger means of the spraying apparatus. If, on the other hand, the operative characterises the growth phase of the plant as being woody stem stage, he instead selects a large nozzle and nozzle guard (6b) for attachment to his knapsack sprayer. This will be discussed in more detail below with reference to Figure 2b. Having attached the large nozzle guard to his sprayer, the operative then isolates the woody stem by placing the nozzle guard over it (7b) - the increased volume of the large nozzle guard allowing for the increased size of the woody stem as compared to a rosette. The woody stem is again sprayed (8b) by activating and immediately releasing the trigger means of the spraying apparatus - though the larger nozzle will permit delivery of a larger volume of weed-killing composition. For larger and flowering ragwort plants, the trigger means may be held for several seconds in order to deliver the required volume of composition. In either case, the weed-killing composition applied to the ragwort plant is made up as shown in Table 1 below: Table 1

Following the spraying of the plant, the operative examines the area for further plants (3), and if any are found, returns to stage (1) of the process. Referring now to Figures 2a and 2b, these show an operative 10, using a knapsack sprayer 11 in a method of ragwort control according to the present invention. The knapsack sprayer 11 shown in Figure 2a is fitted with a small nozzle guard 12 having a height of substantially 145mm, an upper diameter of substantially 100mm and a lower diameter of substantially 210mm, and which is suitable for spraying rosette stage ragwort plants. The knapsack sprayer 11 shown in Figure 2b - which is otherwise identical - is fitted with a large nozzle guard 13 having a height of substantially 250mm, an upper diameter of substantially 100mm and a lower diameter of substantially 290mm, and which is suitable for spraying woody stem stage ragwort plants. Each knapsack sprayer 11 has an internal reservoir 14 which holds substantially 20 I of a weed-killing composition as detailed in Table 1 above. The reservoir 14 communicates with one end 15 of a spray lance 16, having a delivery nozzle 17 at its other end, adjacent the small or large nozzle guard 12,13. The spray lance 16 is provided with a trigger 18, by means of which the operative 10 can activate spraying of the weed-killing composition from the reservoir 14 through the delivery nozzle 17. The trigger 18 communicates with a pressure regulator 19 adapted to maintain a constant delivery pressure of 100 kPa (1 bar). The operative 10 carries the knapsack sprayer 11 on his back by means of shoulder straps 20.

Claims

1. A method of controlling common ragwort comprising: - identifying a target ragwort plant, characterising the growth phase of said target plant, and selecting a nozzle and nozzle guard appropriate to said growth phase; - fitting said selected nozzle guard to spraying apparatus having: - a reservoir for weed-killing composition; - a spray lance in communication with said reservoir at one end thereof and having its other end adapted to receive a nozzle and nozzle guard; and - trigger means to activate spraying of said weed-killing composition from said reservoir; - isolating said target plant from its surrounding environment, by placing said selected nozzle guard therearound; and - applying to said target plant from the spraying apparatus, an effective amount of a weed-killing composition comprising at least one active component and a sticking agent.

2. A method as claimed in claim 1 , wherein the weed-killing composition is an aqueous composition comprising: - at least one active component selected from 2-methyl-4-chloro- phenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, and derivatives thereof; and - a sticking agent selected from polyvinyl alcohols, synthetic latexes, poly- 1-p_-menthene, and derivatives thereof.

3. A method as claimed in claim 2, wherein the aqueous composition comprises the following components: (A) a first active component selected from 2-methyl-4-chloro- phenoxyacetic acid and derivatives thereof; (B) a second active component selected from 2,4-dichlorophenoxyacetic acid and derivatives thereof; (C) a sticking agent selected from poly-1-p.-menthene, and derivatives thereof; and (D) a non-ionic polymeric colorant.

4. A method as claimed in claim 3, wherein in the aqueous composition: - component (A) is present in a concentration in the range of from 0.90% to 1.10% by volume of the total composition; - component (B) is present in a concentration in the range of from 1.35% to 1.65% by volume of the total composition; - component (C) is present in a concentration in the range of from 0.22% to 0.27% by volume of the total composition; and - component (D) is present in a concentration of 0.001% by volume of the total composition.

5. A method as claimed in any of the preceding claims, wherein the nozzle guards are generally conical in shape.

6. A method as claimed in claim 5, wherein the growth phase of the target ragwort plant is characterised as being either rosette stage or woody stem stage, and the nozzle guard is selected from a small nozzle guard and a large nozzle guard, respectively.

7. A method as claimed in claim 6, wherein the small nozzle guard has a height of substantially 145mm, an upper diameter of substantially 100mm and a lower diameter of substantially 210mm, and the large nozzle guard has a height of substantially 250mm, an upper diameter of substantially 100mm and a lower diameter of substantially 290mm.

8. A method as claimed in claim 6 or claim 7, wherein the spraying apparatus is further provided with pressure regulating means to maintain the delivery of the weed-killing composition at a substantially constant predetermined pressure.

9. A method as claimed in claim 8, wherein the pressure regulating means is arranged to maintain the delivery pressure at substantially 100 kPa (1 bar).

10. A method as claimed in claim 9, wherein the target ragwort plant is in its rosette stage, and wherein the effective amount of weed-killing composition is applied to said plant by activating the trigger means, and holding said trigger means for a period of time of up to 0.4 seconds before releasing, thereby to deliver to said plant a volume of weed-killing composition in the range of from 4.0 to 4.5 ml.

11. A method as claimed in claim 9, wherein the target ragwort plant is in its woody stem stage, and wherein the effective amount of weed-killing composition is applied to said plant by activating the trigger means, and holding said trigger means for a period of time of up to 0.4 seconds before releasing, thereby to deliver to said plant a volume of weed-killing composition in the range of from 9 to 11 ml.

12. A method as claimed in any of the preceding claims, wherein the internal surface of the nozzle guard is treated with a dispersant coating, to encourage run-off of weed-killing composition from said surface onto the target ragwort plant.

13. A method as claimed in claim 1 and substantially as herein described with reference to the accompanying drawings.

14. Spraying apparatus for use in a ragwort control method as claimed in any of the preceding claims, said spraying apparatus comprising: - a reservoir for weed-killing composition; - a spray lance in communication with said reservoir at one end thereof and having at its other end a nozzle adapted to receive a nozzle guard; and - trigger means to activate spraying of said weed-killing composition from said reservoir.

15. Spraying apparatus as claimed in claim 14 further comprising interchangeable small and large nozzle guards adapted for connection to said spray lance, whereby in use said small and large nozzle guards are capable of surrounding and isolating ragwort plants in their rosette and woody stem growth phases respectively.

16. Spraying apparatus as claimed in claim 15, wherein said nozzle guards are generally conical in shape.

17. Spraying apparatus as claimed in claim 16, wherein the small nozzle guard has a height of substantially 145mm, an upper diameter of substantially 100mm and a lower diameter of substantially 210mm, and the large nozzle guard has a height of substantially 250mm, an upper diameter of substantially 100mm and a lower diameter of substantially 290mm.

18. Spraying apparatus as claimed in any of claims 15 to 17, further comprising pressure regulating means to maintain the delivery of the weed-killing composition at a substantially constant pre-determined pressure.

19. Spraying apparatus as claimed in any of claims 15 to 18, wherein the internal surface of the nozzle guard is treated with a dispersant coating, to encourage run-off of weed-killing composition from said surface onto the target ragwort plant.

20. Spraying apparatus as claimed in claim 14 and substantially as herein described, with reference to the accompanying drawings.

21. A weed-killing composition for use in a ragwort control method as claimed in any of claims 1 to 13, and/or in spraying apparatus as claimed in any of claims 14 to 20, said composition comprising at least one active component and a sticking agent.

22. A composition as claimed in claim 21 , being an aqueous composition comprising: - at least one active component selected from 2-methyl-4-chloro- phenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, and derivatives thereof; and - a sticking agent selected from polyvinyl alcohols, synthetic latexes, poly-

1-p_.-ment.hene, and derivatives thereof.

23. A composition as claimed in claim 22, comprising the following components: (A) a first active component selected from 2-methyl-4-chloro- phenoxyacetic acid and derivatives thereof; (B) a second active component selected from 2,4-dichlorophenoxyacetic acid and derivatives thereof; (C) a sticking agent selected from poly-1-p_-menthene, and derivatives thereof; and (D) a non-ionic polymeric colorant.

24. A composition as claimed in claim 23, wherein: - component (A) is present in a concentration in the range of from 0.90% to 1.10% by volume of the total composition; - component (B) is present in a concentration in the range of from 1.35% to 1.65% by volume of the total composition; - component (C) is present in a concentration in the range of from 0.22% to 0.27% by volume of the total composition; and - component (D) is present in a concentration of 0.001% by volume of the total composition.

25. A composition as claimed in claim 21 and substantially as herein described.