The mesquite tree, belonging to the Prosopis genus, is resistant to removal. Its deep taproot system, which can extend to depths of 40 feet or more, allows it to survive extreme drought conditions and makes simple cutting ineffective. The tree possesses an underground bud zone, or root crown, which resprouts when the above-ground trunk is cut or damaged. For successful, long-term eradication, any control method must specifically target and destroy this root crown.
Physical Removal for Small and Large Trees
Physical removal offers a non-chemical route, though it requires precise action to succeed. For mesquite seedlings and small saplings, hand-pulling or grubbing is effective. This method is only successful if the entire taproot is extracted intact, as any part of the root crown left behind will produce multiple new stems.
For larger trees, mechanical removal requires specialized equipment to sever the root crown beneath the soil surface. Tools like a root grubber or specialized plow hook the taproot 10 to 12 inches below ground level, pulling the entire root ball out of the earth. This physical extraction ensures the destruction of the root crown and prevents resprouting that occurs when a trunk is merely cut at the surface. Simply cutting the trunk above the ground (top-killing) stimulates the plant to produce multi-stemmed regrowth, making future control more difficult.
Targeted Herbicide Application Methods
Targeted herbicide application is often the most reliable method for achieving permanent root-kill in mesquite. The key to chemical success is ensuring the herbicide is translocated down to the root system, which requires specific application techniques and timing. Three primary methods are used, depending on the tree’s size and structure.
Cut-Stump Treatment
The cut-stump method is highly effective for trees with trunk diameters larger than 6 inches. It involves cutting the mesquite trunk as close to the ground as possible, then immediately treating the freshly exposed surface. The herbicide, typically a concentrated mixture of triclopyr or picloram, must be applied to the outer ring of sapwood and cambium layer within minutes of cutting. Rapid application prevents the tree from sealing off the cut surface, which would block the herbicide from moving down to the roots.
Basal Bark Treatment
The basal bark method is suitable for smaller trees, generally those with smooth bark and trunks less than 4 to 6 inches in diameter. This involves spraying an oil-soluble herbicide, such as an ester formulation of triclopyr, mixed with a commercial basal oil carrier. The mixture is applied to the entire circumference of the intact trunk, saturating the bark from the ground line up to 12 or 18 inches. The oil carrier allows the herbicide to penetrate the bark and reach the vascular tissue, effectively poisoning the root system.
Foliar Spray
Foliar spraying targets the leaves and is best reserved for dense stands of small, brushy regrowth or plants less than 8 feet tall. Success relies on precise timing to coincide with the mesquite’s natural nutrient cycle. The ideal period is typically 42 to 84 days after the plant’s buds break (late spring to early summer), when the leaves are dark green and actively transporting carbohydrates downward to the roots. Herbicides like a mix of triclopyr and clopyralid are used, often with a non-ionic surfactant to help the solution adhere to the waxy leaf surfaces.
Preventing Regrowth and Long-Term Control
Mesquite control is rarely a one-time event; long-term management is necessary to prevent re-infestation. After initial treatment, monitoring the area for new suckers or resprouts emerging from the treated root crown is necessary. These new shoots must be promptly treated with a targeted herbicide application (such as a basal bark spray) to prevent the root system from recovering and re-establishing the tree.
New mesquite seedlings continue to germinate from seeds dropped by the parent tree or carried in by livestock. Effective long-term management requires continuous monitoring and the removal of these young plants before they establish deep taproots. Control programs often require follow-up treatments every five to seven years to manage new growth and maintain a cleared area. Addressing both established trees and new germination significantly reduces the overall population over time.