The invasive nature of mesquite trees poses significant challenges for ranchers and land managers across the southwestern United States. Once mesquite becomes established, it spreads aggressively and quickly overtakes valuable grazing lands. Without timely and effective intervention, mesquite can drastically reduce the productivity and economic potential of rangelands.
Mesquite trees compete with native forage species for essential resources like sunlight, water, and nutrients. As they spread, these woody invaders form dense thickets and create a closed canopy that shades out desirable grasses and forbs. Once mesquite canopy covers just 30 percent of a pasture, forage production begins to decline sharply, directly impacting livestock performance and grazing capacity.
To protect grazing resources and maintain productive rangeland, effective vegetation management strategies are essential. Whether you're using mechanical, individual plant treatment (IPT), or broadcast herbicide applications, timing is critical. The success of a mesquite control program depends not only on the method of application, but also on applying it at the right growth stage, when the plant is most vulnerable to treatment.
Why is mesquite challenging to control?
Mesquite is considered one of the most persistent and challenging invasive species in rangeland ecosystems. Several biological characteristics contribute to its resilience:
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Prolific seed production and longevity: Mesquite produces an abundance of seeds that can remain viable in the soil for years, leading to a continuous cycle of new growth.
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Drought tolerance: It thrives in dry, arid environments with minimal moisture—conditions that limit the growth of many desirable forage species.
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No natural predators: Mesquite has no significant natural enemies in its native range, allowing unchecked spread without biological control.
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Canopy dominance: Its dense growth habit and ability to form closed canopies suppress the growth of warm-season grasses.
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Herbicide resistance mechanisms: With a deep lateral root system and bipinnately compound leaves (small leaf surfaces), mesquite can be difficult for herbicides to penetrate and effectively kill.
Because of these traits, mesquite is not easily eliminated with a single pass or quick fix. It requires a thoughtful, targeted strategy for control—especially when managing large acreage.
Why is mesquite control worth the challenge?
Despite the challenges, controlling mesquite offers numerous long-term benefits for landowners, livestock, and the land itself:
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Increased forage production: With mesquite removed, native grasses and forbs can thrive, improving grazing capacity and livestock nutrition.
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Better soil moisture retention: Eliminating mesquite reduces competition for water, allowing desired vegetation to better utilize rainfall.
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Enhanced land value and appearance: Clean, open pastures are not only more productive but also more visually appealing and potentially more valuable in the marketplace.
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Reduced harm to livestock: Controlling mesquite lowers the risk of injuries from thorns and minimizes digestive issues caused by seedpods.
Investing in a mesquite control program ultimately helps restore balance to rangelands, improve long-term productivity, and protect the future of your grazing operation.
What conditions create ideal results for mesquite control?
To achieve a high level of control on mesquite using broadcast applications, apply herbicide when the leaves are a uniform dark, olive green color. When the vegetation reaches this color, it is a sign the nutrients are being translocated down to the bud zone which will result in a higher mortality rate.
Another important condition to observe, prior to spraying, is the beans. Are they present? Are they fully elongated and filled out or are they immature and curly? If the beans are absent or filled out, it is an optimal time to spray. However, spraying when there are immature curly beans will result in a less-than-satisfactory kill.
An example of elongated mesquite beans.
Canopy conditions should also be considered prior to spraying. Mesquite leaves, which make canopy coverage, are the gateway for the herbicide into the plant. For this pathway to be accessible, the canopies must be in good condition. Frost and hail can cause damage to the leaves in the spring, and later in the year insects, including cutworms and grasshoppers, can cause enough defoliation of the canopy to make spraying useless.
Why should I use a broadcast application to control mesquite trees?
Undesirable and invasive species can be controlled through mechanical, individual plant treatment (IPT), broadcast, and other methods of control. In small spaces, mechanical weed control may offer instant results and IPT will provide a high mortality rate, but these methods are not efficient or economical in large-scale situations. Broadcast control, however, offers many benefits, including even coverage, cost-effectiveness, and a less labor-intensive application.
Broadcast treatment allows for uniform herbicide distribution across large areas and ensures target species receive consistent coverage. Depending on the density of the mesquite, mechanical application is up to 10 times the price per acre of broadcast herbicide applications. It also causes tremendous soil disturbance which leads to an increase in broadleaf weeds. IPT is practical in small areas or areas with low densities of mesquite but becomes increasingly labor-intensive and costly as the number of acres and density of Mesquite increases. Typically, once an area exceeds 400 mesquite trees per acre, it is more economical to apply broadcast treatment.
To have a satisfactory level of control on mesquite using aerial broadcast application it is necessary to use four gallons of total spray volume per acre and a droplet size of around 400-500 microns. A high-quality adjuvant is also needed in the mixture.
Mesquite treatment begins with a base rate of Sonora at a rate of 21oz/A and it is recommended to mix in Triumph 22K at a minimum of 8 oz/A potentially going as high as 32 oz/A depending on what other species are in the treatment area. This solution will give approximately 55-75 percent mortality two years after treatment. If the area you are treating has a high population of prickly pear, and control is desired, using the 32 oz of the rate of Triumph 22K is recommended.
For landowners looking to selectively take out mesquite trees and cause limited damage to other wildlife-desirable species a treatment of 21 oz/A of Sonora will target mesquite and other legume-type trees while having a minimum effect on other desirable tree species such as hackberry, little leaf sumac, western soapberry, and other wildlife-desirable browse species. This selective brush management method will show a decrease in mesquite mortality, but is an economical solution that allows for a diverse landscape for wildlife.
When using herbicides, it is important to read and follow the instructions on the product label to ensure proper application. For more information, download the Alligare Individual Plant Treatment Guide for mesquite or visit Alligare.com.
