Mistletoe Eradicator – A Novel Tool for Simultaneous Mechanical and Chemical Control of Mistletoe

The growth regulators used in the work are available in the market after approval by the Central Insecticide Board (http://ppqs.gov.in/central-insecticides-board). Moreover, personal invitations and permissions of the farmers and owners of walnut plantations, who offered their infected trees for experiments, were obtained. Experiments presented here were done by a certified arborist in the closed research and monitoring zone of M.M. Gryshko National Botanical Garden of National Academy of Sciences of Ukraine (Kyiv, Ukraine). Before starting to work with Mistletoe Eradicator in your country, please check the environmental regulation, get permissions for the use of herbicides from the relevant authorities of the country, where Mistletoe Eradicator will be operated, and obtain agreement on its use with the local human communities (farmers, landowners, etc.).

1. Long-term preparations

1. Briefly introduce yourself or/and other users of Mistletoe Eradicator into the basics of mistletoe biology and ecology, and approaches to its control.
2. Optional: Assess the mistletoe incidence, the degree of infestation, host tree mortality rates, and the degree of mistletoe biotic damage of the host trees (e.g., crone defoliation and water stress in host branches acropetal to mistletoe exophyte) to select the priority of mistletoe control on the most infested host trees based on the approaches described in^{20,30,32,37,38}.
3. Check weather forecast including wind direction and strength, temperature, probability of rain, snowing, fog, or frost with a reliable meteorological service. Operate Mistletoe Eradicator under dry weather and under adequate light conditions to see the working area clearly.

2. Assembly of Mistletoe Eradicator

NOTE: All components of Mistletoe Eradicator are publicly available in supermarkets and gardener stores and are better to be custom-tailored and connected with the help of the professional welding engineer. Details and equipment used for the assembly of Mistletoe Eradicator must be modified and adjusted based on the country of use and availability of the components in an open market.

1. Prepare all components according to the list and (Figure 1)³⁶ assemble them as follows: acquire a wooden/plastic/metal telescopic or non-telescopic pole with a light telescopic handle, up to 3 m in length, and connect a pruning saw safely and firmly to the pole (Figure 1A; Figure 3A); prepare a container (10-150 mL) with a metal screw plug cap having a custom-drilled 2 mm aperture (inner diameter) for the growth regulator (Figure 1B) and a nozzle with a 2 mm aperture (e.g., stainless steel hollow-through lamp with hole screw).
   NOTE: The commercial off-the-shelf manual pole saw with further installation of the container for the growth regulator might also be used to construct the Mistletoe Eradicator. Light weight facilitates the work at high peripheral branches of the host tree both from the ground and from the tree. The apertures of both screw plug cap and nozzle might vary in between 2-5 mm and define the herbicide dropping speed. The optimal aperture is 2 mm.
2. Firmly connect all metal details with the welding gun in a way that one side of the nozzle (Figure 1B-4) is connected by welding to the metal screw plug cap (Figure 1B-3) tightly fitting the container (Figure 1B-2), while its opposite side is welded to the upper outer corner of the saw blade (Figure 1B-1). Keep a pore (Figure 1B-5) at the point of the attachment of the nozzle and the cutter blade open (Figure 1D).
3. Fill the container with water for the dropping test, close the screw plug cap firmly and twist the pole in working position – the sharp surface of the saw blade downwards, the container upwards and upside down. Ensure that the liquid slowly drops down on the saw blade (Figure 2A (inset), Figure 3C).
4. In case of clogging, clean the 2 mm-wide nozzle using fine needle (e.g., with a syringe needle or a fine sewing needle) until the clog is removed and the herbicide dropping is restored.
5. For transportation or storage, empty the container and secure Mistletoe Eradicator with a saw cover or scabbard.
   CAUTION: Misuse of Mistletoe Eradicator may result in serious or fatal injuries, so the sharp surface of the blade must be covered.

Figure 1: Variants of Mistletoe Eradicator tool. (A–D) An original Indian prototype constructed, tested on walnuts in Kashmir Valley, and patented in India³⁶: (A) the terminal unit of the tool, which needs to be adjusted on the wooden/plastic/metal telescopic or non-telescopic pole with a length up to 3 m; (B) the junction between the pruning saw blade (1) and the container (2) with the drilled metal screw plug cap with 2 mm aperture (3) welded to the nozzle with 2 mm aperture (4) ending with a pore (5); (C) a pore (5) at the point of the joint of the nozzle with the pruning saw blade; (D) the slow dropping of herbicide through the screw plug cap from the container to the nozzle, and from the nozzle to the pruning saw blade through a pore (5); general scheme. (E) and (F) provide details of an alternative version of Mistletoe Eradicator constructed in Ukraine from a commercial tree manual pole saw (s); perforated garden saw with pole handle (p); (b-n) adjustable bolt-nut connection between the screw cap tube (t) with rounded false bottom and the saw blade. Scale bars for (A) is 5 cm and for (B-D, F) is 2 cm. Please click here to view a larger version of this figure.

Figure 2: Mistletoe Eradicator operation mode. (A) from the ground; (B) from the tree by a certified arborist. Please click here to view a larger version of this figure.

Figure 3: A working prototype of Mistletoe Eradicator tested on walnut trees in Kashmir valley in action. (A, B) A demonstrative tool set up without the growth regulators in hands of the operator. (C) The pruning position of Mistletoe Eradicator in relation to V. album exophyte. At the hidden side of the tool the slow release of the growth regulator from the container through the pore at the distal end of the nozzle occurs at the site of pruning. (D) Alternative on-the-tree operation mode and eradication of V. album parasitizing the peripheral host branch. Please click here to view a larger version of this figure.

3. Herbicide preparation

1. Choose local, commercially available analogue of mistletoe growth regulator(s), ethephon (2-Chloroethylphosphonic acid) or glyphosate (N-(Phosphonomethyl)glycine. Check the correspondence of the chosen herbicides to local legislation since ecological permissions and licenses might be necessary.
2. Dilute plant growth regulators according to their specification sheets and manufacturer instructions to prepare stock solutions for short-term storage (not longer than 1-2 days) at 4 °C. On the day of work, prepare 4% -10% working solutions from stock solutions ex tempore.
   NOTE: Treatments with the growth regulators must be performed by certified workers and arborists according to the current legislation in the country of operation.

4. On-site safety rules

1. For all operator(s) and assistant(s) allowed to operate Mistletoe Eradicator from the ground, provide sufficient personal protection (Figure 2A; Figure 4B): nonslip steel toe work boots; liquid-proof, chemical-resistant coverall or a suit with a hood; a helmet; a chemical respirator due to the risk of inhaling herbicide fumes; an eye/face shield/protecting goggles that conforms to ANSI Z87.1 or CE safety standard; chemical-resistant gloves to protect hands from mechanical damage and/or chemical injuries or heavy nonslip gloves for improved grip. In the neighborhood of the operation area, ensure water access is available in case of emergency.
2. Ensure that only licensed arborists with at least one assistant is allowed to operate Mistletoe Eradicator from the tree, using safe gear, bright ropes, arborist lanyards and other professional equipment (Figure 2B). Do not use Mistletoe Eradicator in recreational places. Mark the operation zone and trees with bright stripe tape to prevent the presence of outsiders.

Figure 4: An alternative version of Mistletoe Eradicator tested in Ukraine. (A) Free-hand ground-based pruning of the European mistletoe (Viscum album subsp. album L.) exophyte parasitizing the red buckeye (Aesculus pavia L.) branch in M.M. Gryshko National Botanical Garden, National Academy of Sciences of Ukraine, Kyiv, Ukraine. (B) An arborist with the tool. (C) Close-up of the tool on the tree bifurcation. (D) Pruned exophyte, (E) cable tie (c) and adjustable bolt-nut connection (b-n) between the screw cap tube (t) with rounded false bottom and the perforated garden saw blade (s) saw blade with traces of the demonstrative liquid (prepared using a dry E-160с food color additive) mimicking the growth regulator. (F) V. album exophyte stub treated with the demonstrative liquid. Scale bar is 2 cm. Please click here to view a larger version of this figure.

5. Mistletoe Eradicator operation mode

1. Prune the mistletoe foliage before their fruiting with sticky viscin-covered berries, and after the harvesting of the host trees. Remove the saw cover or scabbard from the tool and check the reliability of the connection between all parts of Mistletoe Eradicator. Do not operate a damaged, improperly adjusted, or not completely or insecurely assembled tool.
   CAUTION: Do not hit rocks, stones, or other foreign objects with the blade of Mistletoe Eradicator. Do not cut solid metal, sheet metal, plastics or any non-wood materials with it.
2. Evaluate the distance from the operator to the targeted mistletoe on the peripheral host branches and adjust the appropriate length of the telescopic stick to get free access to the attachment point of mistletoe with the host tree (Figure 2A). Ensure that there are no obstructions in the way of Mistletoe Eradicator toward the mistletoe on the tree.
3. Find an appropriate saw position (~45° of inclination) in relation to the mistletoe exophyte present in the closest proximity to the host branch/stem (Figure 2A (inset), Figure 3C, Figure 4A).
4. Fill the container up to ¾ of its volume with only one growth regulator in working concentration, close the screw plug cap firmly and place Mistletoe Eradicator in a non-working position – the sharp surface of the saw blade upwards, the container downwards, no liquid dropping (Figure 1A).
5. Stand closer to the tree and place the tool in the working position by twisting the pole (Figure 2A, inset). Operate Mistletoe Eradicator with both hands while maintaining a safe distance from the assistant(s) and any bystanders (Figure 2A).
6. Ensure a good firm grip on the tool and prune an exophyte with short sawing movements of the cutting blade (Figure 4A). Ensure that the distal end of the saw blade does not touch the neighboring host branches and/or stem which might damage them and the container.
7. Add more growth regulator as it gets exhausted. The amount of herbicide for one V. album stub varies between 1-5 mL depending on the nozzle diameter.
8. After the pruning of one mistletoe exophyte, place the Mistletoe Eradicator in non-working position and let the air come inside the container through the pore. Relocate to another mistletoe exophyte, place Mistletoe Eradicator in working position and repeat the procedure.
   NOTE: If the Mistletoe Eradicator is operated from the tree by a trained arborist (Figure 2B), the rules for high-altitude work in the country of operation must be followed.

6. Mistletoe foliage piling and finishing

1. Pile the pruned exophytes between the host trees. Mistletoe pruned using Mistletoe Eradicator cannot be collected for pharmacological, ritual, or forage purposes because of the potential danger posed by the growth regulators to human and animal health.
2. Dispose the growth regulators following manufacturer instructions and local environmental regulations.
3. Clean the tool mechanically after work, empty and thoroughly wash the container with tap water and dry it. Discard the disposable protective gloves and respirators in special containers. Thoroughly rinse the reusable cloth, boots, helmets, and eye protection with tap water, dry, and store separately.
4. Protect the sharp part of the Mistletoe Eradicator with a saw cover or scabbard.