Apparatus and method for automated injection of trees with a treating liquid

Apparatus and method for drilling a borehole into the sapwood of a tree and injecting a chemical solution into the borehole, preferably during withdrawal of the drill bit, including facilities for supplying a liquid through a passageway within the bit and facilities for injecting a quantity of liquid, proportional to the volume of the borehole and allocated simultaneously with and in response to progression of the drill bit, into the borehole as the drill bit is being withdrawn therefrom.

BACKGROUND OF THE INVENTION 1. Field of the Invention 
This invention relates to method and apparatus for drilling a borehole into 
the sapwood of a tree and injecting a chemical solution into the borehole. 
This invention relates particularly to mobile apparatus for injecting a 
quantity of solution proportional to the volume of the borehole into a 
growing pine tree immediately after a borehole is formed therein, to 
chemically induce the formation of lightwood, rich in oleoresin content. 
2. Description of the Prior Art 
It has long been known in the art that trees may be injected with 
appropriate liquids, for example, to supply nutrients to the tree or treat 
the tree for disease. A number of approaches have been disclosed for 
preparing a treatment site through the bark of a tree trunk. For example, 
treatment sites have been prepared by removing a small section of bark to 
expose sapwood; or by boring a small downwardly sloping hole into the 
sapwood. Application of a solution of treating chemical to the above 
treatment sites is made by any convenient means, such as, for example, by 
use of a sprayer or a brush. With regard to the treatment site prepared by 
boring a downwardly sloping hole into the sapwood, the solution is applied 
by pouring it into the hole. 
Another method of treatment site preparation comprises providing on the 
sapwood of a living conifer anywhere from ground level to a height of 
about 10 ft. above ground level at least one elongated, downwardly sloping 
hole and subsequently inserting into the hole an absorbent fibrous 
material for receipt of a treating chemical. The treating chemical will 
usually be applied in the form of a solution thereof in a suitable 
solvent, water preferably. The absorbent fibrous material functions as a 
wick and provides for movement of the solution of treating chemical into 
the conifer. If desired, the treating chemical, alone or in solution, can 
be applied to the absorbent fibrous material prior to insertion of the 
fibrous material into the prepared hole. This method of treatment site 
preparation is disclosed in U.S. Pat. No. 3,971,159 of July 27, 1976, 
reference to which is hereby made. 
The prior art also discloses another two-step operation wherein a borehole 
must first be drilled a suitable depth into the tree trunk, after which a 
nozzle is inserted in the borehole and attached to the tree in a 
leak-proof manner. In such prior devices, the borehole is of a slightly 
larger diameter than the nozzle in order that fluid emitted from the 
nozzle may fill the borehole, thereby obtaining a maximum area for 
absorption of the liquid by the capillary system of the tree. The making 
of a leak-proof connection between the nozzle and the borehole frequently 
resulted in air being trapped in the borehole about the nozzle. Such 
trapped air is objectionable because it tends to close the pores and 
passageways in the substance of the tree and to retard and delay the 
proper diffusion and transfer of the liquid from the point of introduction 
to remote parts of the tree. 
A modification of the aforementioned approach required that the diameter of 
the initial hole drilled into the trunk would be slightly smaller than the 
outer diameter of the threaded nozzle tip. A second hole or counterbore 
having a diameter substantially equal to the nozzle head or sealing ring 
(if provided) would then be added to insure that when the output orifices 
in the nozzle shank reached the sapwood, the nozzle would be sealed. The 
counterbore facilitated sealing by enabling a sealing ring of the inwardly 
directed nozzle head surface portion to firmly seat against the wood. 
Following the drilling operation, the hole would be cleaned out in order 
to insure that the nozzle output orifices could reach the sapwood and that 
the nozzle head would be adequately sealed without interference from loose 
wood particles. In many instances, it was necessary to hammer the 
treatment head into the hole to insure a proper fit for the pressurized 
injection process thereby often damaging the treatment head, as well as 
being a time consuming task. 
The chemical applicator nozzle disclosed in U.S. Pat. No. 3,968,594 
includes a socket and an integral tapered shank portion having output 
orifices at its tip. The taper of the shank, together with exterior 
threads provided thereon, facilitates self-tapping and self-sealing of the 
nozzle. In this apparatus, the threads of the nozzle shank, rather than 
the inwardly directed surface of the nozzle head or separate sealing ring, 
provides the sealing. This reference also discloses a method including two 
separate operations wherein initially a hole is drilled into the sapwood 
and then a nozzle is inserted therein. Pressurized chemicals are then 
applied through the nozzle into the sapwood. This method also requires 
that the nozzle threadably engage the outer surface of the tree. 
SUMMARY OF THE INVENTION 
This invention relates to apparatus and method for injecting liquid into a 
tree using a drill bit, having a fluid passageway therethrough. The mobile 
apparatus includes the drill bit, facilities for rotating and reversibly 
advancing the drill bit to form a borehole in a tree, facilities for 
supplying a quantity of liquid substantially proportional to the volume of 
the borehole through the passageway within the drill bit, and facilities 
for injecting the liquid allocated simultaneously with, and in response 
to, progression of the drill bit, into the borehole as the drill bit is 
being withdrawn therefrom. 
The method includes drilling a borehole into a tree while simultaneously 
allocating, in response to progression of the drilling, an amount of 
liquid proportional to the volume of the borehole and injecting the 
allocated amount of liquid into the borehole during withdrawal of the 
drilling device. 
The inventive apparatus and method provide a highly efficient approach for 
the chemical treatment of trees. The amount of substantially void-free 
liquid injected into the borehole is proportional to the volume of the 
hole, thereby minimizing waste and overflow onto the bark of the tree. 
Also, the apparatus can be easily moved from tree to tree, thereby 
providing for expeditious treatment of a large number of trees in a short 
period of time.

DESCRIPTION OF THE INVENTION 
Referring now to the drawings, as shown in FIG. 1, a preferred embodiment 
of the tree injection apparatus 10 of this invention is shown positioned 
around a tree 12, for application of a chemical treating solution. The 
tree injection apparatus includes a mobile unit 14 which may be an 
all-terrain skid-steer vehicle. The mobile unit moves to a position 
adjacent to the trunk of tree 12. An hydraulic knuckle boom 16 is mounted 
on the front of mobile unit 14 and is adapted to swing in a horizontal and 
vertical plane. Alternatively, a straight boom, adapted to only swing in a 
substantially horizontal plane could be substituted for knuckle boom 16. 
In the embodiment of FIG. 1, a semi-circular mounting plate 18 is attached 
to the front end of hydraulic boom 16. A pair of V-shaped tree centering 
clamps 20 are pivotally mounted onto mounting plate 18. Centering clamps 
20 are attached to centering clamp cylinders 22 which are positioned on 
mounting plate 18 by clamp mounts 24, as shown in FIG. 2. 
In this embodiment, two injector assemblies 26 are mounted to clamp 
cylinders 22 which are attached to plate 18 around the periphery of tree 
12. Each injector assembly 26 has hollow stem drill bit 28 protruding from 
housing 30 and downwardly disposed toward the trunk of tree 12. 
As shown in FIG. 3, injector assembly 26 is attached to clamp cylinder 22 
by adjustable mounting members 34. Hollow stem drill bit 28, having 
annular passageway 40, is attached to drill shaft 42 which extends into 
housing 30. Hollow stem drill bit 28 is preferably made from a high 
strength material and should have a relatively large chip clearance. Drill 
bit 28, which is similar to the type well known in the art for supplying 
lubricant or a cooling medium during drilling, will remove some chips 
during drilling. Any remaining chips will be removed during drill bit 
reversal and retraction, ahead of the ejected stream of treating liquid 
initially emerging from drill bit 28 at the bottom of the borehole. 
In this preferred embodiment, rotary motion is imparted to drill shaft 42 
by hydraulic motor 44. Associated with hydraulic motor 44 is a rotary 
driving pump and oil reservoir which is not shown in FIG. 3. Although an 
hydraulic motor provides an efficient source of power for rotary motion in 
the field, an electric motor or other power source well known in the art 
could be used. Since hydraulic motor 44 is attached to drill shaft 42, it 
will move toward the borehole during drilling. 
An hydraulic piston 46 is used to impart translational motion to drill 
shaft 42, and also to provide proportioning action for filling a pump 
cavity containing the treating liquid. Fluid from an hydraulic pump (not 
shown) provides displacement of the drill shaft 42 toward and away from 
the borehole. Although in this preferred embodiment, an hydraulic piston 
is used, alternatively, any power source known in the art can be 
substituted to provide the translational motion. 
Drill shaft 42 extends further through housing 30 into pump head 47 which 
is of the well known piston pump design. Before drilling commences, the 
rear end 48 of drill shaft 42 extends toward the closed end 50 of pump 
head cavity 52. In this embodiment, conduit 54, containing spring valve 
mechanism 56, opens into pump head cavity 52 near its closed end 50. 
Conduit 54 also passes through housing 30 and has attached thereto hose 58 
which terminates at a reservoir (not shown) which contains the tree 
treating liquid for application to a tree. Conduit 60, containing spring 
valve mechanism 62 opens into pump head cavity 52 at a position opposite 
to the termination of conduit 54 near the closed end 50 of pump head 
cavity 52. Conduit 60 passes through housing 30 and has attached thereto 
at fitting 64, flexible conduit 66 which extends along housing 30 toward 
drill bit 28. Flexible conduit 66 terminates forward of housing 30 at 
hollow stem drill unit 68 in communication with annular passageway 40. 
Drill unit 68 contains ring seals which allow it to ride rotating drill 
shaft 42 without rotating itself. A suitable hollow stem drill unit, which 
has been used in the cleaning of boiler tubes, is made by Thomas C. Wilson 
Co., of Long Island City, N.Y. Since flexible conduit 66 is in 
communication with annular passageway 40, liquid can flow from conduit 66 
through passageway 40 of drill bit 28 while drill shaft 42 is rotating. 
In operation, the fluid reservoir, connected to pump head cavity 52 through 
conduit 58, is under pressure. This pressure forces spring valve mechanism 
56 open, allowing pump head cavity 52 to fill with tree treating liquid as 
drill shaft 42 is positively displaced out of cavity 52 in response to 
translational motion supplied by hydraulic piston 46. Spring valve 
mechanism 62 is held in a closed position, preferably by a spring valve 
mechanism, although a sliding valve or another type of valve mechanism 
would be applicable. The length of travel of drill shaft end 48 within 
pump head cavity 52 is proportional to the length of travel, i.e., 
positive displacement, of drill bit 28, as it drills a borehole into a 
tree. The dimensions of pump head cavity 52 are such that the volume of 
treating liquid pumped into cavity 52 from the reservoir is substantially 
proportional to the volume of the borehole made by drill bit 28. 
Therefore, when drill bit 28 reaches the end of its forward travel, i.e., 
upon completion of drilling, there is a volume of treating liquid in pump 
cavity 52 substantially proportional to the volume of the borehole. This 
allocated or predetermined quantity of treating liquid is then ready for 
injection into the borehole. 
As drill bit 28 commences its retraction, spring valve mechanism 62 is 
automatically opened, spring valve mechanism 56 is closed and the reverse 
motion of drill shaft 42 forces the tree treating liquid from pump cavity 
52 through conduit 60, spring valve mechanism 62 and flexible conduit 66 
into drill unit 68. Preferably, fluid will exactly fill the bored hole in 
tree 12 as drill bit 28 is retracted because of the equal displacement of 
fluid from pump head cavity 52 by piston 46. Pumping of fluid will be 
stopped during retraction when drill bit 28 nears the opening of the bored 
hole on the surface of tree 12. Valve 70 will be opened in line 72 from 
pump head cavity 52 to allow fluid to by-pass spring valve mechanism 56 
and conduit 54 and flow into base 58. Preferably, valve 70 is an 
electrically operated solenoid valve which can be actuated by a switch 
attached to and actuated by the position of drill shaft 42. After drill 
bit 28 is completely retracted, the injection apparatus can be moved to 
another location on the same tree or to another tree. 
Once the treating chemical has been applied, it is preferred that the hole 
be sealed or closed to prevent loss of treating chemical and also to help 
protect the living conifer from infestation by insects, fungus, and the 
like. The hole can be sealed or closed by any suitable means and is within 
the skill of the art. Thus, for example, the hole can be closed by 
plugging with a cork, wooden plug, a plastic plug, or a rubber plug. In 
addition, the hole can be sealed by use of a sealant such as wax. 
Chemicals used to induce oleoresin deposition are a class of substituted 
bipyridylium (bipyridinium) salts (see U.S. Pat. No. 3,839,823). Examples 
of such treating chemicals are 
##STR1## 
where n=1 or 2, y=1 or 2, and n.times.y=2, and R=CH.sub.3, CH.sub.3 
CH.sub.2 --, CH.sub.3 CH.sub.2 CH.sub.2 --, 
##STR2## 
and higher aliphatic alkyl groups, either straight chain or branched, and 
x is any anion that makes the compound water soluble, such as, but not 
limited to, the following: 
______________________________________ 
Cl.sup.- (chloride) 
Br.sup.- (bromide) 
F.sup.- (fluoride) 
I.sup.- (iodide) 
SO.sub.4.sup.- (sulfate) 
NO.sub.3.sup.- (nitrate) 
OH.sup.- (hydroxyl) 
CH.sub.3 SO.sub.4.sup.- 
(methyl sulfate) 
______________________________________ 
The aqueous solution of treating chemical is absorbed into the ray cells 
and the vertical cells resulting in the production of oleoresin. 
The solution is made by dissolving a predetermined amount of the treating 
chemical in water. Since some of the chemicals are commercially available 
as aqueous solutions, the only preparation may involve further dilution by 
the addition of water. 
Once applied in the form of an aqueous solution, the chemical is mobile and 
may be carried to distant areas within the living conifer. The chemical 
continues to induce oleoresin production wherever it is located. 
In one embodiment of this invention, two diametrically opposed injection 
devices 26 can be used as shown in FIG. 2. The drills should enter the 
tree trunk with a 5.degree.-45.degree. downward inclination, preferably 
about 30.degree. plane, as shown in FIG. 4. Preferably each injection 
assembly 26 should be displaced about 1 to 2 inches vertically from each 
other to preclude contact near the end of travel of each respective drill 
bit 28. In addition, preferably each drill bit 28 should be skewed 
approximately 20.degree.-45.degree. laterally to the same side of a line 
running through the axis of the tree, in a substantially horizontal plane, 
as shown in FIG. 5. This angle preferably should be about 30.degree.. This 
horizontal offset is used, so that the interior portion of the tree, i.e., 
heartwood 70, will not be affected by the treating solution. Since this 
interior column is dead, there are no transpiration streams to provide any 
movement of the treating solution through the tree. 
The cross-sectional diameter of the drilled borehole should have a diameter 
of about 1/4 inch to about 1 inch and preferably from about 3/8 inch to 
about 5/8 inch. The axes of drilling for both drills preferably should 
extend on one side of the center of the tree, as shown in FIG. 5. 
Facilities for controlling the depth of penetration or for sensing when 
the ends of each drill have reached a predetermined point should be 
provided. One embodiment of such means is a mechanical device, mounted on 
the non-rotating portion of injector assembly 26, which would move 
forward, i.e., in the direction of drilling. Suitably calibrated, this 
sensor can activate a switch whenever it reaches a position proportional 
to the center line of mounting plate 18. 
This injection process will provide treatment for approximately 50% of the 
active area of the tree along cross-sections of the tree near the 
injections. It is an important requirement that approximately 50% of the 
tree be left unimpregnated by the treating solution so that nutrients 
which have to travel through the tree will have a passageway for 
maintenance of life in the tree. 
Although the process described in the preferred embodiment of this 
invention uses two injector assemblies, conceivably, a plurality of 
injector assemblies could be used simultaneously. In addition, drilling 
could proceed sequentially. 
While the above description has been directed to the use of this invention 
for injecting specific treating chemicals that will induce oleoresin 
deposition in a conifer, it is to be understood that the invention can be 
used for injecting other treating chemicals that will induce oleoresin 
deposition. Also, the invention can be used, if desired, for the injection 
of other treating chemicals, such as, for example, systemic insecticides. 
Furthermore, it will be more desirable and efficient in some cases to use 
a single injector assembly with the apparatus of this invention, which 
will drill a single borehole in each tree. 
It is to be understood that the above description and drawings are 
illustrative of this invention and not in limitation thereof. As will be 
evident to those skilled in the art, various modifications can be made in 
light of the foregoing disclosure and discussion, without departure from 
the spirit or scope of the disclosure or from the scope of the claims.