GB2083732A - Apparatus for the chemical treatment of crops - Google Patents

Abstract

Apparatus for chemically treating crops comprises a hollow distribution roller 16 which serves as a reservoir for the chemical and an application roller 15 which causes a film of the liquid to be formed therearound for applying to growing plants and the like, as the roller assembly is moved forward, with the roller axes broadside. The interior of the distribution roller 16 is divided up by baffles which do not completely cut off each baffle section from the next, so that the roller can be filled from one filler point but the baffles act as weirs and prevent the liquid from flowing all to one end or the other on inclined or undulating terrain. <IMAGE>

Description

SPECIFICATION Apparatus for the chemical treatment of crops Field ofinvention This invention relates to apparatus for-the chemical treatment of crops and the like, especially the appiication of a chemical weedkillerto weeds growing amongst a crop.

Background For the chemical treatment of growing crops with feeds and pesticides, tractor borne spraying units are commonly employed. However, treatment for weeds can usually only be carried out before the crop starts to grow because any subsequently sprayed-on weedkiller is liable to cause crop damage. Up to the present, therefore, weeds which germinate simultaneously with or subsequent to germination of the crop have generally been left untreated although their presence is materially disadvantageous both during crop growth and maturity and during harvesting. British Patent Specification No. 1508709 describes an apparatus contributing to the solution ofthis problem.

As described therein, apparatus for the chemical treatment of crops and the like comprises a frame adapted in use for securement to a vehicle for towing the frame along the ground, a liquid applicator mounted on the frame so as to be spaced above the ground and having its longitudinal axis substantially parallel to the ground and, during towing, substantially perpendicular to the direction of travel so that, in use, the applicator comes into contact with selected plants at means for continuously depositing a layer of liquid onto the surface of the applicator which contacts said selected plants.

Generally weeds tend to grow higher than the crop especially during the initial stages of growth. Thus if the level of the application roller is pre-set higher than the tops of the crop but below the tops of the intermingled weeds, weedkiller can be successfully applied without crop damage provided also that dripping of the weedkiller can be substantially avoided.

In the invention of my co-pending British Patent Application No.7940356, dripping of the weedkiller is minimised by adding a thickening agent and a particularly advantageous agent has surprisingly been found to be an anti-drift agent previously used in chemical spraying.

In one embodiment of the apparatus described in bdth British Patent Specification 1508709 and in my aforementioned co-pending application, the coating means comprises a plurality of distribution rollers in rolling contact with the application roller each of the distribution rollers being made hollow in order to serve as a reservoir for the thickened liquid for the thickened liquid chemical.

It is an object of the present invention to provide improved forms of this type of apparatus.

The invention According to the present invention there is provided apparatus for the chemical treatment of crops and the like comprising an application roller, means for maintaining the application roller at a predetermined height above the ground, means for driving the application roller in rotation and at least one distribution roller for coating the application roller with a liquid chemical, the distribution roller having baffles sub-dividing the interior of the roller along its length into a plurality of communicating compartments.

Thus, as described in my co-pending application, the height maintaining means may comprise a boom adapted to be mounted on the front or rear of a tractor, more especially a boom which is adapted to be pivotally mounted on the tractor. For example at least one wheel may be mounted on the boom to follow the contour of the ground and to pivot the boom accordingly. In this case, or in the case of any other kind of height maintaining means enabling the roller assembly to tip end to end in a non-level condition, for example to follow the contour of undulating or sloping ground, the liquid chemical has a tendency to flow towards the lower end of the distribution roller, or each such roller, which can result in a non-uniform coating of the application roller.The baffles of the present invention are designed to allow sufficient communication between the compartments in the distribution roller to allow the roller when stationary to be filled without difficulty from a single filling point but at the same time to minimise flow along the roller from one compartment to another when the roller is rotating in use even though the roller may be tipped end to end to a non-level condition as when the apparatus is being moved over undulating or sloping ground.

The baffles may conveniently comprise baffle plates located within the distribution roller in spaced parallel planes normal to the roller axis. Such baffle plates may be annular, having an outer periphery closed against the interior of the roller and a central aperture permitting the liquid chemical to flow into successive compartments, as though over a succession of weirs, when the distribution roller is being filled. Alternatively, the baffle plates may contain a plurality of relatively smaller apertures, for example a ring thereof at an intermediate radial zone. Again, an annular baffle plate with a relatively smaller central aperture may contain supplementary small apertures at an intermediate radium.

The importance of thickening the liquid chemical to prevent dripping from the application roller has already been mentioned. The addition of the thickener is also important in the context of the present invention, because the relatively viscous nature of the thickened liquid enables it to flow only relatively slowly, especially through apertures of limited size.

This feature is significant in enabling filling (although possibly more slowly than without the baffles) whilst at the same time minimising flow between the distribution roller compartments during use. Thus, in the case of an aperture at an intermediate radius, which aperture is rotating about the roller axis during use, and assuming a partially emptied distribution roller, which is when the present invention is of increased importance, the aperture will enter, pass through and emerge above the thickened liquid chemical before any appreciable quantity of said liquid is able to flow through said aperture out of one compartment into another.Since it can be assumed that the compartments of the distribution roller are equally filled to start with, and consumption from the compartments is substantially uniform during use, uniform coating of the application roller can be maintained up to and until the time the liquid chemical is substantially used up, even when working over undulating or sloping ground.

According to a preferred embodiment of the present invention, apparatus for the chemical treatment of crops and the like comprises an application roller, means for maintaining the application roller at a pre-determined height above the ground, means for driving the roller in rotation, a single distribution roller for coating the application roller with a liquid chemical, the distribution roller having baffles subdividing its interior along its length into a plurality of communicating compartments, the length of the single distribution roller being commensurate with the length of the application roller.

The last described arrangement is a preferred embodiment since the number of rotating reservoirs is reduced to the minimum and the filling procedure is also simplified and reduced to a single filling operation. Previous designs of applicator have not been able to adopt this simple form of construction reliably unless the apparatus was to be used entirely on totally flat level terrain and it is only as a consequence of the sub-division of the interior of the distribution roller as provided by the present invention that the use of a single distribution roller can be considered in a workable embodiment of this type of apparatus.

According to a preferred feature of the preferred embodiment of the invention, the axis of the distribution roller is displaced from the position of the axis of the application roller measured in the direction of movement of the apparatus over the ground.

Thus the distribution roller may be positioned in advance of or to the rear of the application roller.

Preferably the distance between the two axes is equal to the difference between the radii of curvature of the two rollers so that either the forward most point of the distribution roller is no further ahead than the forward most point of the application roller or the rearward most point of the distribution roller is no further rearwards than the rearwards most point of the application roller.

In particular it has been found that by employing this relative dispiacement of the axis of the two rollers with the distribution roller ahead of the application roller and the application roller rotating in a direction such that the underside of the application roller is always moving in the same direction as the apparatus when the latter is moving in the forward direction over the crop, so there is less tendency for the line of liquid which tends to appear on the outlet side of the nip between the two rollers to produce spatter or cause dripping from the application roller as may otherwise occur.

According to another preferred embodiment of the invention, apparatus for the chemical treatment of crops and the like comprises an application roller, means for maintaining the application roller at a pre-determined height above the ground, a single distribution roller for coating the application roller with a liquid chemical, the distribution roller being hollow in order to serve as a reservoir for the liquid chemical, and being located above the application roller, an endless belt of liquid absorbent material stretched around the two rollers, means for tensioning the endless belt so as to allow drive to be transmitted from one roller to the other, means for driving the application roller, and at least one line of apertures extending along the length of the distribution roller for releasing liquid from the interior of the roller onto the endless belt as the latter passed there around.

In a particularly preferred embodiment of the invention, the distribution roller is prevented from ordinary rotation but is nevertheless adjustably rotatable about its axis so as to allow the line of apertures to be located at a preferred angular position relative to the axis of the distribution roller so as to obtain optimal transfer of liquid to the belt.

According to a further preferred feature of the invention, the distribution roller is biased rotatably by spring means or the like into a first position in which the line of apertures is located in an upwardly facing sector of the circular outline of the distribution roller and the drive transmitted by the endless belt to the distribution roller causes the latter to be rotated at least initially towards a second fixed position in which the line of apertures is closer to the plane containing the axis of the distribution roller so as to allow liquid to flow therefrom onto the belt.It would be appreciated that as soon as drive is removed from the distribution roller, the latter will tend to spring back to its first position in which the apertures are above the level of liquid contained in the distribution roller thereby preventing loss of liquid from the distribution roller when the latter is stationary.

The drive may be removed from the distribution roller either by adjusting the position of one or other of the rollers so as to reduce the tension in the endless belt so as to introduce sufficient slip to enable the distribution rollerto revert to its first position or the drive to the application roller may be removed or stopped so as to inhibit rotation.

In order to improve the dispensing qualities of the embodiment one or more nips may be provided in advance of the underside of the path of the endless belt, the nip or nips being located between one or more nip rollers and the application roller so as to squeeze the belt before it passes around the underside of the application roller therey causing liquid within the belt to be squeezed into the surface of the belt just before the latter is at its position of likely impact with plants.

Preferably where such a nip is provided, an interlock is provided so as to remove the nip from the belt when the belt stops or when the upper distribution roller reverts to its first position due for example to the removal of the drive thereto or the removal of drive to the application roller.

The distribution roller may be constructed in accordance with the invention in that a plurality of baffles may be located at spaced positions along its interior to sub-divided the interior of the distribution roller into a series of communicating compartments.

However, this feature may not always be necessary on other than the most undulating ground if the line of holes in the distribution roller follows a slightly curved path from one end of the roller to the other rather than a straight line with the central region of theline of holes being relatively higher than the two end regions of the line of holes (when the roller is rotated into its second position). It will be seen that where this configuration of the outlet apertures is used, the liquid level in the distribution roller need not be uniform along the length of the roller for it to still flow through the apertures to the belt.However, for general application, the baffles provided by the present invention would generally be required to ensure that a reasonable depth of liquid is maintained at all points along the length of the distribution roller even on severely undulating ground.

Extract from co-pending application no. 7940356 There now follows an extract from the co-pending application, referring to Figures 1 to 5 of the drawings which accompany the same and are also incorporated in the present application as Figures 1 to 5: In the accompanying drawings: Figure 1 is a diagrammatic perspective view of a preferred arrangement of crop treating apparatus in accordance with the invention, mounted at the front end of a tractor; Figure 2 is a cross-section on the line A-A of Figure 1, Figure 3 is a cross-section on the line B-B of Figure 2; Figure 4 is a cross-section on the line C-C of Figure 3; Figure 5 is a diagrammatic side view of the preferred arrangement mounted on the tractor.

In Figure 1, the reference 10 designates a tractor and the reference 11 designates a boom or transverse framework supporting the crop treating apparatus in accordance with the invention. The rear of the boom 11 is mounted on the front arms 12 of the tractor 10 (see FigureS), this mounting including a pivotal connection (not shown) enabling the boom to pivot on its mounting about a horizontal axis. The front of the boom 11 carries a pair of ground wheels 13. In use, the wheels 13 follow the contour of the ground, and the mounting ofthe boom 11 enables it to pivot accordingly. The mean level at which the boom is supported above the ground is adjustable by varying the level of the wheels 13 relative to the front of the boom framework.A manual adjustment for this purpose is indicated at 14; alternatively this adjustment may be made by means of any hydraulic ram powered from the tractor hydraulics.

A transversely extending roller assembly is carried by the boom 11, generally on the underside thereof.

This assembly comprises an application roller 15 and two distributing rollers 16 (see Figures 1,3 and 5). The roller assembly is employed, for example, to apply weedkiller to weeds growing amongst a crop and projecting above the level of the top of the crop.

Thus, by means which will be later described, the application roller 15, i.e. the lowermost roller, is rotated while being continuously coated with a liquid chemical weedkiller. The height of the front end of the boom is set such that this rotating application roller 15 lies at a pre-determined level above the ground which is above the height of the top of the crop but below the height of the tops of the weeds. When the tractor 10 is driven through the crop, the weedkiller coating on the roller 15 is brushed on to the weeds, but the crop is untouched.

The ground wheels 13 ensure that the said predetermined level of the roller 15 substantially follows the ground contour.

The construction of a distribution roller 16 is shown in detail in Figures 3 and 4. It comprises a hollow plastics pipe 17, for example of polyviny Bichloride, closed at its ends 18. It is provided with a countersunkfiller plug 19, and two rows of holes 20 extending along its length, adjacent opposite sides of the filler plug in the circumferential direction. In a typical case, the pipe 17 may be of about 12.5 cm diameter, with the holes 20 spaced apart about 5 cm in the longitudinal direction. From Figure 1 it will be clear that each distribution roller 16 spans a half of the length of the application roller 15, but it would be possible to employ a single full length distribution roller, or alternatively more than two such rollers.

The apertured pipe 17 is covered with a layer 21 of felt or similar porous material. Furthermore, as each distribution roller 16 is in rolling contact with the application roller 15 and in use is rotationally driven thereby, it may be preferred to cover the felt or like layer 21 with a thin perforated outer layer (not shown) of rubber or plastics material.

The distribution rollers 16 serve as reservoirs for a liquid weedkiller 22 which, in use, is coated on the application roller 15.

The application roller 15 is a hollow roller of plastics material such as polyvinylchloride or a metal roller, closed at its ends.

The rollers 15 and 16 are shaft mounted on the boom framework 11 for rotation about their respective axes. The support shafts for the distribution rollers 16 are designed 23 in the drawings, and the support shaft for the application roller 15 is designated 24. The latter may take the form of stub shafts at opposite ends of the application roller 15 if desired.

Mounted at one end of the boom 11 is an electric motor (not shown) for applying a rotational drive to the application roller 15. Conveniently, this motor may take the form of a speed controllable d.c. series motor having a variable resistance in its supply lead.

This supply lead is conveniently adapted for connection into the battery circuit of the tractor 10.

Relatively little power is required to drive the rollers 15, 16, so that a small electric motor will usually suffice. However, if a heavy drive unit is employed, for example an hydraulic motor powered from the tractor hydraulics, it will be preferable to mount a counterweight at the remote end of the boom.

In use, the distribution rollers 16 are loaded with liquid chemical weedkiller, thickened with a thicken ing agent for the reason later discussed, and the boom 11 is attached to the tractor 10. The mean level of the application roller 15 is set to the required pre-determined level, the rotational roller assembly drive is started into operation, and the tractor 10 is driven through the crop to be treated. As the distribution rollers 16 rotate, driven by the rotating application roller 15, weedkiller is fed into the felt layers 21 and is continuously coated on to the application roller 15, one distribution roller coating each half of the length of the application roller.The latter roller 15 brushes the weedkiller on to the weeds, and more weedkiiler is drawn out of the reservoir, through the porous layers 21 of the distribution rollers 16, to maintain the coating on the application roller 15 as crop treatment proceeds.

Conveniently, when the treatment is completed and the roller assembly drive is stopped, means may be provided to ensure that the distribution rollers 16 come to rest with the filler plug 19 and the rows of holes 20 uppermost. In Figure 2, the reference 25 denotes a support for maintaining the generally horizontal condition of the boom 11 when it is disconnected from the tractor.

It will be clear from the above description of the arrangement of the roller assembly and its method of use that a primary aim of the invention is to be able to brush a liquid chemical on to plants at a higher level without contaminating other plants at a lower level. It is, therefore, clearly important to avoid dripping of the liquid chemical in question. The above-described arrangement is specifically designed to minimise leakage, for example by the use of sealed bearings at the ends of the distribution rollers through which their support shafts extend. In addition, however, it is necessary to minimise dripping due to surpluses of liquid chemical collecting on the surfaces of the rollers 15 and 16. For this reason, as previously mentioned, a thickening agent is added to the liquid chemical, to convert said liquid into a gel.One thickening agent which can be employed is the material known by the Trade Mark Polycell, but this is not wholly satisfactory as the gel tends to solidify if not used relatively quickly. More suitable agents are the anti-drift agents commonly employed as additivies to chemicals used for crop spraying. One such sutiable agent is that sold by Nalflock (U.K.) Ltd.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 6 is an axial cross-section through a preferred construction of distribution roller.

Figure 7 is a transverse cross-section on the line 7-7 of Figure 6, Figure 8 is a diagrammatic end view of a preferred arrangement of a two roller applicator, and Figure 9 is a diagrammatic end view of another embodiment of the two roller applicator.

Description of embodiment ofpresent invention The distribution roller 40 shown in Figures 6 and 7 is a replacement for each of the two distribution rollers 16 shown in Figures 1 to 5. More particularly, Figure 6 shows one end portion of the distribution roller 40, which has an end closure generally designated 42 and a supporting shaft 44 which enables the rotation of said roller during use by means of the frictional engagement of said distribution roller with the driven application roller.

Like either roller 16, the distribution roller 40 comprises a pipe 46, e.g. of plastics material, apertured in its cylindrical wall at 48, with a covering layer 50 of felt or similar porous material. The roller 40 again serves as a reservoir for a thickened liquid chemical, which in use penetrates the apertures 48 to wet the porous sleeve 50, which in turn applies a uniform coating of liquid chemical to the application roller.

The present invention concerns the baffles 52 which are provided in the distribution roller 40, which baffles serve to sub-divide the roller along its length into a series of communication compartments 54.

As will be clear from Figure 7, each baffle comprises a circular plate 56 occupying the full internal cross-section of the distribution roller 40 around an inner sleeve 58 surrounding the central shaft 44, said plate containing a ring of apertures 60 at an intermediate radius. The reference 62 denotes thickened liquid chemical in the reservoir constituted by the distribution roller 40.

When the apparatus is to be used, the distribution roller 40 is filled through a filling plug 64. The roller is at this time stationary, and the liquid chemical is able to flow via the apertures 60 to load successive compartments 54. At the end of filling, each compartment 54 will contain substantially the same amount of liquid chemical 62.

During use, the apparatus will often be traversed over undulating or sloping ground, the roller assembly, inciuding the distribution rollers 40, will be tipped end to end. At this time, and especially as the overall level of liquid in the roller 40 tends to fall the liquid chemical is not readily able to flow through the apertures 60, since these are rotating into and out of the liquid. Thus, in the transit time available while any one aperture 60 is immersed, the relatively viscous thickened liquid chemical is substantially unable to flow through said aperture from one compartment at a higher level on the slope to the next lower compartment. In consequence, even when the roller assembly is tipped, the outer porous sleeve 50 of the distribution roller 40 remains uniformly wetted along its length, and is able to maintain a uniform coating of liquid along the length of the application roller.

In an alternative construction which will be clear without illustration, the circular plates 56 are replaced by annul plates having a single larger central aperture communicating each compartment with the next. Such an arrangement becomes effective once the distribution roller has been partially emptied during use, which is the time when the present invention becomes important to maintain a uniform coating action.

It will also be clear that baffle plates can be employed which have a smaller central aperture and a ring of supplementary apertures at an intermediate radius. Furthermore, it is not essential for the communicating apertures to be arranged in a ring at a single intermediate radius, nor indeed for said apertures to be arranged in any particular pattern or formation.

Figure 8 shows a preferred arrangement when a single distribution roller is employed. To this end the distribution roller 66 is located above the application roller 68, the distribution roller 66 being constructed in a manner similar to that shown in Figures 6 and 7 and with its axis located in advance of the axis of the application roller by a short distance. The best position for the distribution roller will normally be found by experiment but tests have lead us to believe that the preferred position for the distribution roller is one in which the foremost point of the distribution roller is no further ahead (measured in the direction of travel) than the foremost position of the application roller.

The directions of rotation and forward movement of the apparatus shown in Figure 8 by arrows 70,72 and 74. Arrow 74 denotes the forward direction of travel of the apparatus whether it is towed or pushed by the tractor.

Figure 9 shows an alternative embodiment of the invention. Here the distribution roller 76 is mounted above the application roller 78 and an endless belt 80 of fabric material such as multiply canvass or the like is located around the two rollers. The length of the belt 80 is such that it is slack unless the two rollers are displaced slightly out of contact and a belt tensioning device which may include one or more springs (not shown) is shown at 82. The action of this device is to lift the axis of the roller 76 so as to move it away from the roller 78 and thereby tension the belt 80.

The axis of the roller 78 is fixed at a particular height relative to the ground in any convenient manner and is also fixed relative to a frame 84 to which the tensioning means 82 is attached. Thus the two rollers 76 and 78 move as one as far as inclinations or disturbances of the apparatus are concerned due to undulations or inclinations of the terrain over which the apparatus is carried.

A motor 86 drives the lower roller 78 through an endless belt 80 or a chain drive or great train (not shown) and a gearbox may be used where appropriate.

Means (not shown) is provided for removing the drive from the roller 78 either by switching off the motor 86, or reducing the tension in the belt or chain 88 or disengaging wheels or toothed wheels or a clutch (not shown).

The distribution roller 76 is in the form of a hollow drum and includes a line of apertures 90 through which liquid can flow from the inside of the container to the outside surface thereof to be picked up by the moving belt 80.

The position of the line of apertures as denoted by reference numeral 90 is the active position for the apertures since in this position liquid can flow to the belt and thereafter be transferred to plants or the like through direct contact with the belt as it passes around the underside of the drum 78.

In orderto reduce the risk of dripping etc., when stationary, the upper drum 76 is capable of limited rotation from a first position in which the line of apertures 90 is at the point shown by reference numeral 92 into the active position shown by reference numeral 90. To this end the belt must be driven in the direction shown by arrow 94 which immediately determines the direction of rotation of the roller 78.

It will be seen that if the tension in the belt 80 is insufficient, the roller 90 will occupy its passive position in which the apertures 90 occupy the position shown at 92 and no liquid will transfer to the belt. By increasing tension in the belt, the upper roller 76 will be driven around until the active position is reached and at that point a stop is provided to prevent the roller 76 from rotating any further (the stop is not shown in the drawings).

The continued rotation of the drum 78 causes the endless belt 80 to rotate and pass around the now stationary upper roller 76 but as the belt passes the apertures 90 so liquid transfers from the interior of the roller 76 to the belt. The latter, therefore, becomes saturated and as it passes around the underside of the roller 78, so the liquid film on the outside surface of the belt can be transferred to plants and the like.

In order to further increase the film of liquid on the outside surface of the belt, a nip roller 96 is provided so as to squeeze the belt 80 as it begins to travel around the underside of the roller 78.

The distribution roller 76 is preferably constructed in accordance with the design shown in Figures 6 and 7 so that liquid slopping from one end of the roller to the other does not upset the smooth transfer of liquid to the belt.

In an alternative arrangement, the line of apertures 90 is curved so that the ends of the line are at a lower point than the middle of the line relative to the axis of the roller 76. In this way the liquid level in the upper roller can become displaced relative to the axis of the roller 76 without loss of flow through the apertures.

In orderto cause the roller 76 to rotate into its first position a spring, such as spring 98, is provided.

Claims (10)

1. Apparatus for the chemical treatment of crops and the like comprising an application roller, means for maintaining the application roller at a predetermined height above the ground, means for driving the application roller in rotation and at least one distribution roller for coating the application roller with a liquid chemical, wherein the distribution roller is provided with baffles sub-dividing the interior of the roller along its length into a plurality of communicating compartments.

2. Apparatus as claimed in claim 1 in which the baffle plates are annular, having an outer periphery closed against the interior of the roller and a central aperture permitting the liquid chemical to flow into successive compartments, as though over a succession of weirs, when the distribution roller is being filled.

3. Apparatus as claimed in any of the preceding claims characterised by a single distribution roller for coating the application roller with a liquid chemical, the distribution roller having baffles subdividing its interior along its length into a plurality of communicating compartments, and wherein the length of the single distribution roller is commensurate with the length of the application roller.

4. Apparatus as claimed in claim 5 in which the position of the axis of the distribution roller is displaced from the position of the axis of the application roller (measured in the direction of movement of the apparatus over the ground).

5. Apparatus as claimed in claim 4 in which the distance between the two axes (measured in a direction parallel to the direction of movement of the apparatus) is equal to the difference between the radii of curvature of the two rollers.

6. Apparatus as claimed in claim 4 or 5 in which the distribution roller axis is ahead of the application roller axis (measured in parallel to the direction of travel) and the application roller rotating in a direction such that the underside of the application roller is always moving in the same direction as the apparatus when the latter is moving in the forward direction over the crop.

7. Apparatus for the chemical treatment of crops and the like comprising an application roller, means for maintaining the application roller at a predetermined heigh above the ground, a single distribution roller for coating the application roller with a liquid chemical, and wherein the distribution roller is hollow in order to serve as a reservoir for the liquid chemical and is located above the application roller, and may include spaced internal baffles to form communicating compartments an endless belt of liquid absorbent material stretched around the two rollers, means for tensioning the endless belt so as to allow drive to be transmitted from one roller to the other, means for driving the application roller, and at least one line of apertures extending along the length of the distribution roller for releasing liquid from the interior of the roller onto the endless belt as the latter passes there around.

8. Apparatus as claimed in claim 7 in which the distribution roller is prevented from ordinary rotation but is adjustably rotatable about its axis so as to allow the line of apertures to be rotated around the axis of the distribution roller to any desired angular position so as to secure transfer of liquid to the belt.

9. Apparatus as claimed in claim 7 or 8 in which the distribution roller is biased rotatably into a first position in which the line of apertures is located in an upwardly facing sector of the circular outline of the distribution roller and the drive transmitted by the endless belt to the distribution roller causes the latter to be rotated into and to remain in a second position in which the line of apertures is close to or in the horizontal plane containing the axis of the distribution roller so as to allow liquid to flow therefrom onto the belt.

10. Apparatus as claimed in claim 9 in which one or more nips are provided in advance of the downwardly facing convex sector of the path of the endless belt, the nip or nips being formed by one or more nip rollers acting against the application roller so as to squeeze the belt before it passes around the underside of the application roller, thereby causing liquid within the belt to be squeezed into the surface of the belt just before the latter is at its position of likely impact with plants.