Chemicals to Slow Tree Growth
Tree growth regulators are chemicals that inhibit the chemical reactions in trees that stimulate growth. These chemicals are used as a low-cost alternative to pruning near power lines and other areas with limited space. Tree growth regulators are available in several commercial products based on the chemical paclobutrazol. This chemical produces compact growth in trees but requires careful application so that it does not spread to other areas. Does this Spark an idea?
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Chemical Processes
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Paclobutrazol is the active chemical ingredient used in modern tree growth regulators. This chemical suppresses the tree's ability to produce the hormone gibberellin. Gibberellin is responsible for encouraging growing cells in the tree to elongate. Inhibiting gibberellin production results in more compact growth that limits the overall size of the tree. Tree growth regulators affect growing cells in the trunk of the tree and in the stems and leaves. Paclobutrazol also prevents the tree from breaking down abscisic acid, prevents the production of steroids in fungi and increases the concentration and quantity of chlorophyll in the leaves.
Effects
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The ability of paclobutrazol to inhibit chemical processes in trees has several beneficial effects. Trees that are treated with this chemical are less susceptible to physical stress from a lack of water because their compact growth and high levels of abscisic acid reduce water loss. Trees treated with this chemical have darker, greener leaves due to higher concentrations of chlorophyl in their leaves, along with an increased resistance to fungal infections.
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Application
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Paclobutrazol is applied using two techniques: basal drenching and soil injection. These techniques are intended to deliver the chemical to the soil around the base of the tree without spreading it to other areas. The basal drench technique applies the chemical around the tree trunk where it meets the ground. If you are expecting rain, apply the chemical inside a shallow trench around the base of the tree to prevent it from washing away. Soil injection uses a pressurized sprayer to deliver measured doses of tree growth regulator into the root system of the tree. The injection sites are evenly spaced around the base of the tree. The tree growth regulator is injected at a depth of 6 inches under 100 to 200 lbs. per square inch of pressure.
Considerations
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Paclobutrazol is a toxic, water-soluble chemical that is not safe for human consumption. Applying this chemical in a location with a high water table or on a steep slope can spread it to other areas, resulting in contamination of crops or reduced plant growth in the wrong area. Chemicals containing paclobutrazol are not safe for use in trees harvested for fruit, nuts or syrup.
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References
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