Plant husbandry – Cover – shade – or screen – Open top
Reexamination Certificate
2000-10-24
2001-07-24
Jordan, Charles T. (Department: 3644)
Plant husbandry
Cover, shade, or screen
Open top
Reexamination Certificate
active
06263613
ABSTRACT:
The invention is directed to devices for enhancing the growth and form of plant seedlings.
Within the past two decades, plant seedling growth enhancers have been developed and used to assist newly planted seedlings to survive and grow at an enhanced rate and improved form during the early stages after planting. Seedling growth enhancers have found their greatest application to date in the forestry industry where they are installed at the time the seedling is planted and typically remain in place for a period of 5-7 years.
Seedling growth enhancers are commonly referred to by the misnomer“tree shelter”, which suggests that the device functions to protect or shelter mature trees. However, it is known in the technology to which these devices pertain that their primary function is to not only protect immature seedlings but, more importantly, to create a micro-environment in which the seedling may flourish in much the same way as a greenhouse enhances the growth of plant seedlings.
Typically, such seedling growth enhancers take the form of a tube of thermoplastic that typically is translucent with a diameter sufficient to encompass the seedling during the period of use and a length that typically is less than the seedling at the time of planting. An example is shown in U.S. Pat. No. 4,899,486 issued to Graham F. Hurlstone on Feb. 13, 1990.
The thermoplastic material used in the formation of tree seedling growth enhancers is often chosen to be degradable when exposed to ultraviolet light. The degrading effect takes place over a time that corresponds generally to the period during which protection and growth enhancement is necessary. Thus, as the tree seedling matures over a number of years, the device progressively degrades in the presence of ultraviolet light and ultimately disintegrates when its function is no longer necessary.
We have found that the principle of seedling growth enhancers may be advantageously applied to other types of seedlings, such as grapevine seedlings which are continuously planted in the grape industry to maintain a necessary level of grape production. If this growth can be enhanced to the point that quality grape production begins at an earlier point in time, this is economically beneficial to the vineyard owner.
Seedling growth enhancers (also known as grow tubes) are advantageously used in connection with grape seedlings. One of the primary benefits is to guide the vine upward in its growth without the need for staking. Without training seedlings to grow upwardly in some manner, they will grow at will along the ground. Grow tubes train the vine to grow upward in a position to be more productive.
Grow tubes also enhance the growth of grape vines by capturing moisture and recycling the moisture as it condenses from vapor on the inner tube surface. Grow tubes also protect the grape vines from herbicides by acting as a barrier or shield to the seedling.
However, conventional grow tubes create a problem insofar that seedling maintenance is concerned because they are in essence permanently installed, and access to the seedling is not possible without removing the plastic tube. Access to the seedling is important because of the possibility of choking weeds, as well as to prune the seedling to ensure that it has only a primary leader during its initial growth stage. In addition, access is necessary to determine whether the seedling is exposed to disease or insect infestation. If access cannot be gained to the grape seedling, its growth may be inhibited or improper for any of these reasons.
These problems have been solved by producing a grow tube having a longitudinal slit over its length together with means for fastening adjacent edges of the slit at the top and/or bottom of the tube. Access to the seedling is gained by spreading the slit at an intermediate point of the tube.
It is important in this regard that, when the opposed tube edges are spread to gain access to the seedling and then released, the access opening is self-closing and the tube returned to its tubular form. This function is not possible if, for example, the tube is formed by simply rolling a flattened rectangular sheet of plastic into a tube. With such a construction, the fastening means holds the opposed edges together but the tendency is for the edges to pull apart. Consequently, the access opening is normally open and the integrity of the tube and the growth-enhancing function are lost.
We have found that the access function is best obtained by forming the device as a continuous plastic tube (e.g., by extrusion) and then slitting the tube longitudinally. In this manner, the tube has inherent resiliency and hence a bias to return to its tubular form after having been spread apart. By fastening the opposed top and bottom edges, access may be gained by spreading the opposed edges at an intermediate point and simply releasing the edges after the pruning and dressing functions have been completed.
However, we have also found that the material from which seedling growth enhancers are conventionally made produces a springiness that, in essence, overbiases the tube edges together, which makes them difficult to spread apart and, accordingly, difficult to use. Specifically, this overspringiness requires use of two hands to spread the tube and to hold it in the spread-apart position, which makes it quite difficult to maneuver the pruning tool into the slit to perform the pruning tasks. Testing has shown that conventional seedling growth enhancers manufactured from polyethylene require at least about 1.5 pounds of force to spread the tube edges a distance of three inches.
In order to operate properly and efficiently, we have found that the amount of force necessary to spread the tube edges three inches apart be no more than about 0.5 pounds. Our testing of various materials indicates that low-density polyolefins (such as low density polyethylene or low density polypropylene) are a suitable material to render this result.
Producing the seedling growth enhancer (or grow tube) in this manner is also advantageous because it enables the device to be reused after the protected seedling has matured to the point that protection is no longer necessary. This is accomplished by releasing the top and/or bottom fastening means, which enables the tube to be spread over its length and hence removed from the grapevine or other seedling. The tube can then be reused by placing it around a new seedling, or stored for further use by nesting a number of the resilient tubes together.
It is conventional to connect the overlapping edges of the grow tube by staples. Stapling is an economic approach to fastening, although a stapling tool is required in the field at the time the grow tube is placed, and it requires some degree of strength and dexterity to properly affix the staples. An alternative embodiment for fastening adjacent edges of the grow tube together takes the form of a unique slidable clip having a H configuration in cross-section with a length that corresponds to the length of the grow tube. The opposed legs of the H-shaped clip are biased together and the distance therebetween, at least at the entry point, is less than that of the thickness of the sheet material from which the grow tube is manufactured. This enables a user to connect the opposed edges of the grow tube either by forcing each edge between the spaced legs of the H-clip, or sliding the H-clip longitudinally over the adjacent edges. In either manner, the edges are quickly and easily joined together without the use of any type of tool. Use of the H-clip is also beneficial in maintaining the tube diameter uniform over its length.
Further, the edges of the grow tube may be easily spread apart by raising the H-clip a sufficient amount to permit edge spreading and access. Also, the grow tube may be reused by removing the H-clip, spreading the edges to the point that the tube can be removed from the seedling, and subsequently rejoined for use on a new seedling.
One of the preferred embodiments of the invention is specifically intended to be placed over the
King Lawrence H.
Lais Joseph F.
Jordan Charles T.
Merchant & Gould P.C.
Palo Francis T.
Treesentials Company
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