Abstract:
A plant protector is positionable about the base of a young tree or other plant. The protector has first and second shells, each formed of a rigid material and having a semi-cylindrical shaped portion and with flanges extending outwardly from and running longitudinally along the semi-cylindrical portions. Each semi-cylindrical portion may have raised circumferential ribs which are spaced apart at regular intervals to increase strength and rigidity. The opposed flanges abut and the semi-cylindrical portions form a cylindrical tube when the shells are engaged together. The shells are locked together by locking structures formed on at least one of the flanges of the shells. The shells may be held together at one edge by a hinge extending longitudinally along edges of the shells. Various locking structures may be used, such as mating bosses and indentations formed on the flanges on opposite sides of the first and second shells.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to shelters and protectors which are placed around young trees or other plants for the purposes of accelerating growth and preventing damage. 
     BACKGROUND OF THE INVENTION 
     Young trees, grapevines and other plants can be vulnerable to damage from small animals. To help prevent such damage, plant protectors have been wrapped around the base or trunk of the tree or other plant during its early growth. An example of such a protector is a cylindrical plastic tube which is placed around young trees, vines and other types of plants. These protectors can also act as mini-greenhouses to accelerate growth of the young plants. Placing a properly sized and colored tube around a young plant or tree has been shown to enhance plant growth. In the forestry industry, the tubes are used to accelerate growth and promote straight tree trunks. In the viticulture industry, the tubes are used to accelerate plant growth and reduce the time required before the first harvest. Studies have shown that appropriate shape, height, diameter, color, and venting of such tubes can all contribute to enhancing plant growth. Recently, studies have shown that grape vines benefit from the tube well after the vine is tied to the trellis. This discovery has promoted the design of grow tubes that can be removable. In hot climates, studies have concluded that venting of the grow tube by providing holes at selected positions in the tube can help reduce leaf-burn and promote a healthier plant. The disadvantage to such venting is that the vent holes allow herbicides to enter (and possibly damage) the root area. 
     As the tree or plant matures, the tube protectors may begin to engage the plant and inhibit growth. To remove the tube from around the tree or plant, the tube must be pulled off of the plant or the tube must be cut away, either of which might result in damage to the tree or plant. Cutting the tube usually prevents reuse of the tube on another plant. 
     Various plant or tree protectors have been developed in an attempt to protect young trees and plants from damage without the limitation of having to cut away the protector when the tree or plant has matured. One fairly common example of such a plant protector is a plastic sheet which is wrapped around the trunk of a tree, with its two ends joined by a coupling mechanism. The traditional coupling mechanism does not allow for the partial opening of the tree protector. A further disadvantage is that extended use can lead to the deformation of the tree protector. The tree protector may be positioned around the trunk of a tree for a relatively long period of time, sometimes several years, during which time it can tend to conform to the shape of the tree and may sag or otherwise lose its proper shape. 
     A wide variety of other types of tree protectors have been developed. These too have typically been difficult to remove and replace, and often have been too complex and expensive to be practical. 
     SUMMARY OF THE INVENTION 
     A plant protector for providing growth enhancement and protection against damage in accordance with the present invention includes first and second shells, each formed of a rigid plastic material having a semi-cylindrical shaped portion. The shells have flanges at the edges of the semi-cylindrical portions that run longitudinally. Each shell preferably also includes raised ribs running circumferentially in the semi-cylindrical portions, perpendicular to the flanges, and regularly spaced apart so as to provide strength and rigidity to the shells. The ribs face outwardly when the shells come together, and the flanges can be joined such that the shells form a cylindrical tube when engaged together. The shells may be conveniently locked together in place around a tree or other plant by a locking means on the flanges for locking the first shell to the second shell. 
     The plant protector may be placed around a tree or other plant without the concern that it will inhibit growth as the tree or plant matures because the protector can be easily removed by disengaging the locking means when it is appropriate to do so. Further, the locking means can comprise closures formed as snap-fit interlocking parts on the flanges that can be pulled apart by the growing tree, thereby limiting the pressure that can be applied by the plant protector to the growing tree. 
     The plant protector may be partially opened in order to expose part of the tree or plant for purposes of maintenance, repair, or diagnostics, and then reclosed. Some or all of the closures along the length of the protector may be disengaged, as the user may so desire. 
     The plant protector is preferably made of a rigid plastic material in order to resist attack by animals and to withstand an external impact (e.g., from a lawnmower). Due to the rigid structure and the two shell construction of the tree protector, when the tree protector is removed from around a tree, it retains its original shape and physical integrity, and may be applied to another tree or plant or disposed of. 
     The first and second shells are conveniently and preferably made by a vacuum forming process, using molds having the shape of each shell. As is conventional in vacuum forming, a flat sheet of plastic is heated to a softening temperature, and the softened plastic is drawn under vacuum into the mold, where the plastic cools and hardens into the shape defined by the mold. 
     The upper and lower edge sections of the semi-cylindrical portions preferably flare outwardly so as to allow room for root expansion at the lower edge, and branch expansion at the upper edge, and to minimize the chance that the top and bottom edges of the protector will chaff against the trunk. 
     The first and second shells are preferably connected by a locking means on the flanges of each of the shells. The use of a locking means on both edges of the shells is not required, however. The first and second shells may be engaged by a locking means at one edge of each of the first and second shells, and with the first and second shells having flanges terminating at a hinge (e.g., an integral “living hinge”) at the other edge of each shell which joins the two shells. The locking means is preferably also a vacuum formed structure formed integrally on the flanges of the first and the second shells. The locking means may comprise several mating bosses and indentations formed on the flanges on opposite sides of the first and second shells and positioned periodically along the longitudinal edge of each flange. Alternatively, the locking means may comprise a longitudinally extending groove and a longitudinally extending ridge formed on the flanges on opposite sides of the first and second shells for locking the shells when the shells are engaged together. The locking means may also take the form of an overlapping lip on one of the flanges of the first shell that envelopes an edge of one of the flanges on the second shell such that the lip and the edge lock together, whereby a cylindrical tube is formed when the first shell and the second shell are engaged together. 
     The plant protector may also have one or more grooves formed on the semi-cylindrical portions for receiving a security stake for stabilizing the plant protector in the ground and one or more apertures at the top of the each flange for passing through a piece of rope to tie the shell portions together or to a stake. 
     The flanges on the two shells may be scalloped wherein an outwardmost part of one flange meets an inwardmost part of the abutting flange so that the flanges can be easily gripped to draw the shells apart or bring the flanges together. 
     Further, the plant protector of the invention may include at least one and preferably several tortuous path vent tubes that extend from the edges of the flanges to communication with the interior of the protector. The vent tubes may conveniently be formed as semi-cylindrical raised portions in the flat flanges, with the indentations in abutting flanges matching with each other to form a complete vent tube. The vent tubes preferably have an upwardly (or vertically) extending section in addition to (radially) inwardly extending sections. The vertical section helps to minimize the migration of liquid herbicides through the vent tubes into the interior of the protector. 
     Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a perspective view of a plant protector in accordance with the present invention. 
     FIG. 2 is a top plan view of the first and second shell portions forming a plant protector as in FIG.  1 . 
     FIG. 3 is a perspective view of a plant protector in accordance with the invention having scalloped edges on each flange and vent tubes. 
     FIG. 4 is a side view of the plant protector of FIG. 3 with the two shells shown separated from each other. 
     FIG. 5 is a side elevation view of the plant protector of FIG.  3 . 
     FIG. 6 is a perspective view of a plant protector in accordance with the present invention with a living hinge and a single locking means joining the two shells. 
     FIG. 7 is a top plan view of the plant protector of FIG. 6 with the two shells forming the plant protector shown in opened position. 
     FIG. 8 is a perspective view of a plant protector in accordance with the present invention having a longitudinally raised hinge portion that enhances the durability of the living hinge. 
     FIG. 9 is a top plan view of the plant protector of FIG.  8 . 
     FIG. 10 is a perspective view of a plant protector in accordance with the present invention having a locking means comprising longitudinally extending grooves and mating longitudinally extending ridges formed on the flanges. 
     FIG. 11 is a top plan view of the plant protector of FIG. 10 with the two shells separated from each other. 
     FIG. 12 is a perspective view of a plant protector in accordance with the present invention having a longitudinally extending groove formed on the semi-cylindrical portion of one shell for receiving a stake. 
     FIG. 13 is a top plan view of the plant protector of FIG. 12 with the two shells separated from each other. 
     FIG. 14 is a perspective view of a plant protector in accordance with the present invention with longitudinally extending ribs in one of the semi-cylindrical portions of one shell for accepting a security stake. 
     FIG. 15 is a top plan view of the plant protector of FIG. 14 with the two shells separated from each other. 
     FIG. 16 is a perspective view of a plant protector in accordance with the present invention with scalloped edges along one flange of each shell, and with a living hinge joining the other edge of each shell. 
     FIG. 17 is a perspective view of a plant protector in accordance with the present invention having a locking means including a lip extending longitudinally along one flange which overlaps an adjacent flange, and with a living hinge joining the other edge of each shell. 
     FIG. 18 is a perspective view of a plant protector in accordance with the present invention with a locking means including a lip extending longitudinally along two of the flanges of one shell. 
     FIG. 19 is a top plan view of the plant protector of FIG. 17 with the two shells separated from each other. 
     FIG. 20 is a top plan view of the plant protector of FIG. 18 with the two shells separated from each other. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the drawings, wherein like numerals refer to like parts in each of the several views, a plant protector in accordance with the present invention is shown generally at  20  in FIGS. 1 and 2, at  21  in FIGS. 3-5, at  22  in FIGS. 6 and 7, at  23  in FIGS. 8 and 9, at  24  in FIGS. 10 and 11, at  25  in FIGS. 12 and 13, at  26  in FIGS. 14 and 15, at  27  in FIG. 16, at  28  in FIGS. 17 and 19, and at  29  in FIGS. 18 and 20. Each plant protector  20 - 29  includes a first shell  31  having a semi-cylindrical portion  31 A, a second shell  32  having a semi-cylindrical portion  32 A, and flanges  35  and  37  on the first shell and flanges  36  and  38  on the second shell. The flanges  35 - 38  are preferably formed integrally with and extend radially outwardly from the respective semi-cylindrical portions  31 A and  32 A of the shells  31  and  32 . In the plant protectors  20 ,  21 ,  24 , and  29  (of FIGS. 1,  3 ,  10  and  17 ), the first shell  31  is engaged with the second shell  32  with all of the flanges  35 ,  36 ,  37 , and  38  engaged together with a locking means  34  in the locked position. In the plant protectors  22 ,  23 ,  25 ,  26 ,  27 , and  28  (of FIGS. 6,  8 ,  12 ,  14 ,  16 , and  17 ), a locking means  34  at one set of abutting flanges is used to lock the first shell  31  to the second shell  32  to form a cylindrical tube from the joined semi-cylindrical portions  31 A and  32 A, with a hinge  52  being formed at the other set of abutting flanges. The flange  35  of the first shell  31  abuts the flange  36  of the second shell  32 , and the flange  37  of the first shell  31  abuts the flange  38  of the second shell  32 , when the first shell  31  and the second shell  32  are placed together. 
     The semi-cylindrical portion  31 A is formed as half a cylinder which is joined at both edges of the semi-cylinder with the flanges  35  and  37 , and the semi-cylindrical portion  32 A is joined at its edges with the flanges  36  and  38 . Preferably, raised circumferential ribs  30  are formed integrally in the semi-cylindrical portion  31 A perpendicular to the flanges  36 - 38 , and the ribs  30  are spaced apart at regular intervals so as to provide increased strength and rigidity. The ribs  30  preferably face outwardly when the shells come together so as not to interfere with a plant within the protector. The circumferential ribs  30  provide a convenient place for words, phrases or other decoration which may serve as identification, such as serial numbers or addresses. 
     A locking means  34  is preferably integrally molded on the flanges  35 - 38 . As shown in FIGS. 1-8 and  12 - 16 , the locking means may comprise a boss  39  or a plurality of bosses formed on the flange  35  of the first shell  31 , a boss  42  (or several bosses) formed on the flange  38  of the second shell  32 , an indentation  40  (or several indentations) formed on the flange  36  of the second shell  32  that mates with the boss  39 , and an indentation  41  (or several indentations) formed on the flange  37  of the first shell  31  that mates with the boss  42  formed on second shell  32 . Thus, when the shells of the plant protector are locked together, the boss(s)  39  on the first shell  31  and the indentation(s)  40  on the second shell  32  are press engaged, and the mating boss(s)  41  on the first shell  31  and the indentation(s)  42  on the second shell  32  are press engaged so that the first shell  31  and the second shell  32  are locked together and the semi-cylindrical portions  31 A and  32 A form a cylindrical tube. 
     Each flange  35 - 38  may include an aperture  33  which define a hole through the engaged flanges by which the user may mount the plant protector to a stake or may tie the two shell portions more securely together. 
     Referring now to FIGS. 3-5, the plant protector  21  includes the principal features of the plant protector  20  and additional preferred features. The plant protector  21  includes sections at an upper edge  43  of the first shell  31 , at an upper edge  44  of the second shell  32 , at a lower edge  45  of the first shell  31 , and at a lower edge  46  of the second shell  32 , that taper or flare outwardly from the general circumference of the semi-cylindrical portions  31 A and  32 A. Vertical (or longitudinal) raised ribs  30 A extend between the circumferential ribs  30  to provide resistance to vertical compression and to enhance the overall strength and rigidity of the structure. Scalloped edges  47  and  49  are formed on the flanges  35  and  37 , respectively, of the first shell  31 , and scalloped edges  48  and  50  are formed on the flanges  36  and  38 , respectively, of the second shell  32 . The outwardmost portions of the scalloped edges  47  and  49  meet with the inwardmost portions of the scalloped edges  48  and  50 , and vice versa, so that a user can readily grasp the edges of the abutting flanges to pull the flanges apart and release the locking means. Additionally, a plurality of air vent tubes  51  are formed in the abutting flanges by semi-cylindrical raised portions on the mating flanges  47  and  48  and  49  and  50  of the shells  31  and  32 . The vent tubes  51  formed by the mating semi-cylindrical raised portions have an upwardly extending section  51 A, as best shown in FIG. 5, in addition to radially inwardly extending sections  51 B. The upward section  51 A and the generally tortuous path provided by the sections  51 A and  51 B help to minimize the ability of liquid herbicide to migrate through the vent tubes  51  into the interior of the protector. A plurality of the vent tubes are preferably formed on each side of the protector near the bottom (or at both ends, either of which may be the bottom). 
     Referring now to FIGS. 6 and 7, a plant protector  22  is shown which additionally includes a living hinge  52  (i.e., an integral section of usually thinner plastic) which is formed at the outermost edges of the flange  37  of the first shell  31  and the flange  38  of the second shell  32 , such that the plant protector  22  may be formed of a single piece of vacuum formed plastic. As a result, there is a single locking means  34  comprising at least one boss  39  formed on the flange  35  of the first shell  31  and at least one indentation  40  formed on the flange  36  of the second shell  32 . The two shells of the plant protector  22  rotate around the living hinge  52 , and the first shell  31  and the second shell  32 , when closed on each other, may be held together by the single locking means  34 . 
     FIGS. 8 and 9 show a plant protector  23  which includes the principal features of the plant protector  22  and additionally includes a hinge  52  with a portion  53  that facilitates bending. The portion  53  is a cylindrical integral section of plastic that extends longitudinally along the flanges  37  and  38 , and provides added strength and durability for applications in which the plant protector  23  is repeatedly opened and closed. 
     FIGS. 10 and 11 show a plant protector  24  wherein the locking means  54  comprises longitudinally extending grooves  55  and  58  formed on the flange  35  of the first shell  31  and on the flange  38  of the second shell  32 , respectively, and corresponding longitudinally extending ridges  56  and  57  formed on the flange  36  of the second shell  32  and on the flange  37  of the first shell  31 , respectively. FIG. 10 shows the locking means  54  when it is in the locked position and FIG. 11 shows the first shell  31  and the second shell  32  when they are uncoupled. 
     FIGS. 12 and 13 show a plant protector  25 , and FIGS. 14 and 15 show a plant protector  26 , which each include the principal features of the plant protector  22  and additionally include a longitudinally extending groove  59  formed on the semi-cylindrical portions  31 A or  32 A of either of shells  31  or  32  in which a stake  60  is placed for securing the plant protector in the ground. FIGS. 14 and 15 show a plant protector  26  which additionally comprises longitudinally extending ribs  61  within the longitudinally extending groove  59  for holding a security stake  60 . The groove  59  or the ribs  61  may be in either or both semi-cylindrical portions  31 A and  32 A. The stake(s) may be used to secure the plant protector  26  so as to prevent rotation or inhibit theft. 
     FIG. 16 shows a plant protector  27  that includes the principal features of the plant protector  22  and additionally includes a scalloped edge  47  formed on the flange  35  of the first shell  31  which is out of phase with (i.e., outermost and innermost portions of the abutting flanges meet) a scalloped edge  48  formed on the flange  36  of the second shell  32 , facilitating the opening and closing of the plant protector  27  by the user in a manner similar to the protector  21  of FIGS. 3-5. 
     The plant protector  28  which is shown in FIGS. 17 and 19 has a single locking means  62  which comprises a longitudinally extending lip  61  on the flange  35  of the first shell  31  that is folded over the edge of the flange  36  of the second shell  32  to lock the first shell  31  and the second shell  32  together. A living hinge  52  is formed at the other ends of the semi-cylindrical portions  31 A and  32 A. The plant protector  29 , which is shown in FIGS. 18 and 20, has an additional locking means  63  comprising a longitudinally extending lip  63  formed on the flange  37  of the first shell  31  which is folded over the edge of the flange  38  of the second shell  32  to lock the first shell  31  and the second shell  32  together. 
     Each of the plant protectors  20 - 29  in accordance with the present invention is preferably made of a vaccum formed molded plastic, for example, vacuum formed polystyrene, which allows structures such as hinges, locking means, vent tubes and ribs to be easily and integrally formed. Colorants may be added to the plastic material, as desired, to provide additional protection against harmful light wavelengths and/or to enhance the effectiveness of the plant protector as a mini-greenhouse. However, the invention is not limited to such processes or materials. 
     It is understood that this invention is not confined to the particular construction and arrangement of parts herein illustrated and described, but embraces all such modified forms thereof as come within the scope of the following claims.