GB2341073A - Barrier device against climbing organisms such as snails - Google Patents

Abstract

A device 10 for preventing the passage of a climbing organism comprises a barrier 12 and at least one freely rotatable member 20 mounted thereon, the clearance between the barrier and the rotatable member being insufficient to allow passage of climbing organism, and the diameter of the rotatable member being sufficiently large that the organism is incapable of bringing its entre of gravity to the highest point of the rotatable member before such member rotates. The device may be used to surround a plant, tree, bush or the like, in order to give protection from slugs and snails. The device may be in modular form, a plurality of barrier sections being attached to posts, an aperture at the top end of each post supporting an axle (14, 16, 18, Figure 2) on which rotatable members in the form of a wheels are supported. The barrier sections, wheel and axle may be of plastics or metal material.

Description

2341073 BARRIERS AGAINST CLIMBING ORGANISMS This invention relates to

barriers for preventing passage of climbing organisms. In particular, but not necessarily exclusively, the invention relates to barriers for protecting plants, bushes, trees or areas of land from gastropods such as slugs and snails.

Slugs and snails present a particular problem to gardeners, as they cause serious damage to foliage. In the past, it has been customary to use slug pellets to kill such pests by poisoning, with the undesirable effect the corpses are left lying on the ground. This presents a health hazard to birds, pets and small children, and a further hazard arises from any pellets which remain unconsumed. Alternatively, the slugs and snails can be removed by hand is and disposed of, but this method is extremely labour intensive and rarely effective. There is therefore a need for a means for protecting plants from the damaging effect of climbing organisms such as slugs-and snails, which does not kill the organisms or require constant vigilance, and which is environmentally friendly.

The present invention provides a device for preventing passage of a climbing organism, the device comprising: a barrier; and at least one freely rotatable member mounted on the barrier in such a manner that the clearance between the barrier and the freely rotatable member(s) is insufficient to allow passage of a climbing organism therethrough, the diameter of the freely rotatable member(s) being chosen with reference to the typical dimensions of a target organism so that the target organism is incapable of bringing its centre of gravity to the highest point of the (or a) freely rotatable member before such member rotates.

Devices according to the present invention are particularly useful in the protection of plants from gastropods, but it will be appreciated that they will also be of use in protecting bushes, trees, areas of land 2 containing a number of plants, bushes or trees, or indeed any kind of object, from any species of climbing organism. For the sake of clarity, the following description will refer to the protection of plants from slugs, but such references are not to be taken as limiting the scope of the invention.

In preferred embodiments, the device is provided with a plurality of freely rotatable members in the form of wheels, and the barrier takes the form of a substantially vertical wall. As a slug climbs the wall, it encounters the rotatable wheels. As soon as it attempts to climb onto a wheel, the weight of the slug creates a moment about the wheel's axis, tending to rotate the wheel. The slug is thereby impeded from ascending, because the wheel tends to rotate whenever the slug obtains a grip on it. Nevertheless, it may still be possible for the slug to obtain sufficient purchase on the wall with the posterior portion of its body to be able to push its anterior portion upwards onto the wheel. It is therefore important that the wheels be of sufficiently large diameter that no normally sized slug is able to progress far enough to place its centre of gravity beyond the highest point of the wheel's rotation before it loses grip on the wall. Using correctly dimensioned wheels, the furthest position the slug is able to reach is one in which its entire body is attached to the wheel, from which position it is impossible to traverse the wall.

The width of the wheels should preferably be no greater than the typical width of a slug. This minimises 30 the possibility of interference between adjacent climbing slugs, which could otherwise result in one slug immobilising wheel, thus permitting another slug to surmount the wheel.

The distance between adjacent wheels should be kept to minimum, as an overly large gap may permit the passage of 35 a slug, thus defeating the object of the invention. Nevertheless, the wheels must not be so close that they interfere with each other, and they are therefore preferably separated by washers. The clearance between the wheels and the wall is also of critical importance. Ideally, the clearance should be as small as practically possible, and in any event should be carefully chosen, having in mind the typical dimensions of the organism from which protection is sought, so that the gap is substantially too small for the organism in question to pass therethrough. A suitably fine clearance may readily be achieved by use of wheels which are uniformly circular in cross-section, and which are mounted on a fixed axle attached to the wall.

Where the plant or area to be protected is situated in the ground, for example in a flower bed, the device may conveniently be pushed into the ground surrounding the plant so that the bottom portion of the wall penetrates the soil, thus avoiding any possibility of access to the plan'. under the wall. In the case of potted plants, for example situated on a patio, the wall may rest on the patio, if the latter is sufficiently flat to leave no substantial gaps under the wall. Alternatively, the device may be incorporated into the pot holding the plant, with the wall of the pot forming the barrier, and the wheels either mounted at the upper peripheral rim of the pot or mounted to protrude outwardly from a lower point on the outer surface of the pot wall.

Normally, the device will completely surround the plant or area, so as to allow no entry route for an attacking slug. As the diameter of the device is dictated at least in part by the size of the plant, and the sizes of plants vary greatly, there is a need for the devices of the invention to be available in a range of different diameters. Most conveniently, this may achieved by a modular construction, in which the device is made up of a number of separate elements, each element consisting of a section of wall surmounted by a wheel (or a number of wheels) mounted on a discrete axle portion. Preferably, each wall element is provided with means for secure attachment to adjacent wall 4 elements on each side. A user of the device may them select as many elements as are required to construct a suitably sized device.

In preferred embodiments, the wall is perforated by a plurality of apertures, designed to reduce the slug's grip on the wall by interfering with its ability to adhere to the wall by suction. The diameters of the apertures may for example be in the range 1mm. to 5mm, and the centre-to-centre spacing in the range 2mm to 3cm. For slugs, the apertures may beneficially be approximately 2mm in diameter and have a centre-tocentre spacing of from 4mm to 1cm. The precise diameters and spacings of the apertures should be chosen in relation to the size and characteristics of the target organism, and may in some cases be outside the ranges quoted above.

The invention will hereinafter be described in more detail by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of an embodiment of device according to the invention; and Fig. 2 is a perspective view of the embodiment illustrated in Fig. 1, with the rotating wheels removed.

Referring to Fig. 1, device 10 consists of a number of separate modular wall elements 12 (in this case eight). As will be seen from Fig. 2, wall elements 12 alternate with posts 14. Wall elements 12 may be attached to posts 14 by conventional means, for example by means of clips, a tongue and groove arrangement, or the like. The wall elements may be supplied separately from the posts, or alternatively each wall element may be permanently attached to a post at one edge; the latter arrangement reduces the number of separate pieces, and may, therefore be preferred from the point of view of simplicity. Each post 14 is provided at its upper end with an aperture 16, the apertures supporting an axle - 18. which in turn supports wheels 20.

Where the device is required for use on soil, the wall is secured in position, preferably in a vertical or near vertical orientation, by pushing the base portions of the 5 wall elements into the ground. For use on a flat surface (such as a patio), on the other hand, the device may be supported by an integral flat base, or by base support members adapted for attachment to the wall elements or the posts. Alternatively, in many cases, the interconnection of the wall elements forms a sufficiently stable structure for no further means of support to be required.

Devices according to the invention may be constructed from any suitable durable material. The wall elements and wheels, for example, may be constructed from plastics is materials (preferably those which resist degradation upon prolonged exposure to sunlight), or from metals. Nonferrous metals are generally preferred, so as to avoid rust, and aluminium is a particularly favoured option. For the axle, stainless steel is preferred for its strength, but other metals or plastics may also be used.

The overall dimensions of the devices may be chosen according to individual need, depending on the typical size of the target organism. Generally a device having walls approximately SOmm in height, surmounted by wheels of diameter 60mm to 70mm, will be effective as a barrier against slugs.

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Claims (15)

1 A device for preventing passage of a climbing organism, the device comprising: a barrier; and at least one freely rotatable member mounted on the barrier in such a manner that the clearance between the barrier and the freely rotatable member(s) is insufficient to allow passage of a climbing organism therethrough, the diameter of the freely rotatable member(s) being chosen with reference to the typical dimensions of a target organism so that the target organism is incapable of bringing its centre of gravity to the highest point of the (or a) freely rotatable member before such member rotates.

2. A device according to claim 1, comprising a plurality of freely rotatable members in the form of wheels.

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3. A device according to claim 2, wherein the wheels are spaced apart from each other by a distance insufficient to allow passage of a target organism between the wheels.

4. A device according to claim 2 or claim 3, wherein the width of the each of the wheels ischosen to be at most the typical width of a target organism.

5. A device according to any of claims 2 to 4, wherein the clearance between the wheels and the barrier is insufficient to allow passage of a target organism between the wheels and the barrier.

6. A device according to any preceding claim, wherein the barrier is adapted to surround completely an object to be protected from attack by the target organism.

7. A device according to claim 6, wherein the object to be protected is a plant.

8. A device according to claim 7, wherein the barrier is adapted to penetrate the ground surrounding the plant.

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9. A device according to claim 7, wherein the barrier is adapted to stand on a flat surface (such as a patio), in such a manner as to leave insufficient clearance between the barrier and the flat surface to permit passage of a target 5 organism.

10. A device according to any preceding claim, wherein the barrier is perforated by a plurality of apertures.

11. A device according to any preceding claim, wherein the barrier is a substantially vertical wall.

12. A device according to claim 7, wherein the barrier is Provided by a portion of the pot accommodating the plant.

13. A device according to any of claims 1 to 11, the device being provided in modular form and comprising a plurality of barrier sections, each provided with at least 15 one freely rotatable member.

14. A device according to any preceding claim, wherein the target organism is a gastropod.

15. A device substantially as hereinbefore described, with reference to and as shown in the drawings.