Many people view honey mesquite (Prosopis glandulosa) as a poor quality rangeland plant. However, it provides cover and food for wildlife and livestock; plus it is a legume that has the ability to fix nitrogen back into the soil. When unmanaged, mesquite can dominate a rangeland, reducing the available forage for livestock. Mesquite is very adaptable to our rangelands due to its drought tolerance and ability to grow in most soils. The primary reason that mesquite is so hard to control is due to its ability to resprout. Cutting or burning only top-kills mesquite, allowing it to resprout from the base of the stem.
Wildlife and livestock use mesquite beans as a food source in some areas. This is mainly why mesquite is easily spread across our rangelands, and, without proper diligence and control by a land manager, mesquite can quickly dominate a pasture. Mesquite beans can cause weight loss and even death if they are the primary food source for livestock.
There are many ways to control mesquite. The most effective way to control mesquite is to mechanically or chemically kill the buds at the base of the stem to prevent resprouting. This can be accomplished by root plowing, grubbing (digging up the roots of individual plants) or use of herbicides. Additional management options include the use of prescribed fire. When using herbicides, be sure to follow label directions for lawful and safe use.
One herbicide control method is to spray cut stumps with a mixture of 25 percent Remedy® and 75 percent diesel or vegetable oil, which is labor intensive, but effective. Another method is to spray stems from ground level to a height of 18 inches with a mixture of 15 percent Remedy® and 85 percent diesel or vegetable oil when the stems are less than 1.5 inches in diameter. If the stems are 1.5-4 inches in diameter, use a mixture of 25 percent Remedy® and 75 percent diesel or vegetable oil. These stem treatments can be applied any time of year. Another herbicide treatment is to spray the leaves with a mixture of 0.5 percent Reclaim®, 0.5 percent Remedy® and 0.25 percent surfactant mixed with water. The best time to leaf spray is during late spring (May-June) when the soil temperature reaches 75 degrees at a 12-inch depth. Make sure there is no leaf damage before you spray and the leaves should be a dark green color. When using herbicides to treat mesquite, it is a good idea to add 1 ounce of dye per gallon of mixture to help you identify which trees have been treated.
Velpar® is another herbicide that can be used to control mesquite. Velpar® can be applied to the soil with an exact delivery handgun applicator within 3 inches of the mesquite root collar. Apply 2-4 milliliters for every inch of stem diameter at breast height. Do not apply more than 1/3 gallon of Velpar® per acre per year. Try to avoid treating soils that are wet or expecting rain within 24 hours because this can reduce the chemical's efficacy.
Prescribed fire is not an effective tool for killing mesquite; however, it can be used to suppress mesquite growth. It will top-kill young mesquite with "slick bark," and a fire return interval of three to five years should keep regrowth suppressed.
The Oklahoma Chapter of The Wildlife Society will be hosting their annual meeting in conjunction with the Bollenbach Wildlife Symposium in Ardmore, Okla., and the surrounding areas on Sept.10-11, 2009. This event is open to the public, so if you're interested, contact Steven Smith (firstname.lastname@example.org, 580-224-6465) for more information.