The invasive nature of mesquite trees can cause significant challenges for ranchers. Effective vegetation management strategies are essential to mitigate the impact of mesquite on grazing areas and rangelands. For best results, timing is critical.
Why is mesquite challenging to control?
Mesquite is a woody invader that grows throughout the rangelands of southwestern United States. This invasive species is difficult to treat due to the many seeds it produces and their lengthy lifespan, how little moisture it requires, and mesquite is not utilized by any natural enemies. With the ability to create a closed canopy and the highly dense plant-per-acre ratio, warm-season forage production is limited when mesquite is present. Once 30 percent of the pasture area is occupied by mesquite canopy, grass production decreases. This challenging-to-control woody weed has a large lateral root system and bipinnately compound leaves which form a small leaf surface to absorb the herbicide.
Why is mesquite control worth the challenge?
- forage production increases
- soil moisture levels will increase for desired forage
- land appears improved, which may increase property values
- decreased harm to livestock from thorns and digestive complications
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 many vegetation management 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 alternative 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 unwanted vegetation 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 Sonora at a rate of 21oz/A mixed with Triumph 22K at 8 oz/A. 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, increase the rate of Triumph 22K to 32 oz/A.
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.
