Yucca plants, which are also called soapweed by many people, have become a serious problem on much of our rangeland.
Several years of drought and overgrazing have caused deterioration of many desirable range plants throughout western and central Nebraska. One plant that has flourished throughout the area is yucca. While able to produce attractive flowers, dense stands of yucca can devastate grass production.
Yucca plants develop rapidly once established on drier rangeland sites. Yucca produces a deep taproot that competes aggressively for limited water. Since cattle rarely eat it during summer, grass production decreases while yucca thrives.
Herbicides like Remedy, Tordon, or a mixture of Rangestar and Ally can control yucca, but only when each individual plant is sprayed directly. General spraying of rangeland is cost prohibitive, although small patches can and should be controlled before they expand.
When yucca becomes established in large areas of rangeland if may not be cost effective to control with herbicides. Another method that may be used to reduce its impact is to winter graze. During winter, yucca often is the only green plant available. Cows have been observed to get down on their knees, lay their head sideways on the ground, and chew through the base of the plant to get to the moist, tender parts. After several consecutive winters of grazing, yucca stands can be reduced so grass again thrives during spring and summer.
Here is a method for controlling yucca using the herbicide (Remedy™) + Oil Whorl Spray.
Prepare Equipment: The herbicide spray can be applied with a pump-up garden sprayer, backpack sprayer, or sprayer mounted on a 4-wheel all-terrain vehicle (ATV). The spray gun should be tipped with a ConeJet™ 5500-X1 adjustable cone nozzle. To reduce clogging and dripping, place a 100-mesh screen/check valve behind the nozzle.
Mix the Herbicide with Diesel: Use a mixture of Remedy™ herbicide and diesel fuel oil or vegetable oil for yucca control. The oil ensures that the herbicide will cover the plant thoroughly and be absorbed into the plant. The recommended mixture is 15% Remedy™ and 85% diesel fuel or vegetable oil.
Mixing Formula: To get a 15% mix, add 19 oz. of Remedy™ to one gallon of diesel fuel or vegetable oil.
Using vegetable oil instead of diesel fuel oil increases the cost but may be desirable in some situations. One vegetable oil known to mix well with Remedy™ is JLB Oil Plus™. When mixing Remedy™ with oil, pour the required quantity of Remedy™ into a mixing container or spray tank and then add enough oil to get the total volume desired. Shake or agitate the mixture vigorously until it is thoroughly mixed.
A "pre-mix" of Remedy™ and vegetable oil also is available. This "pre-mix" is called Remedy RTU™. To use this product, simply pour Remedy RTU™ from the container into the sprayer and apply to yucca following the Brush Busters directions for the Remedy + Oil Whorl Spray.
One ounce of Hi-Light™ blue spray-marking dye can be added for each gallon of spray mix or Remedy RTU™ to help identify treated plants.
Spray the Yucca: The Remedy + Oil Whorl Spray is most effective if applied during the growing season. Make sure your spray gun is equipped with the 5500-X1 nozzle. Position the nozzle in the center of each whorl and spray for at least 2 seconds (slowly say "one Mississippi, two Mississippi: while depressing the trigger on the spray gun).
The Remedy + diesel fuel mix will be the least expensive combination of herbicide and oil - about 2 cents per plant if applied properly. The cost will be higher if vegetable oil or Remedy RTU™ is used.
Keep these points in mind:
• Follow the directions on the herbicide label.
• The cost of treatment escalates rapidly as the number of yucca plants and whorls per acre increases.
• This method will also control smooth-bark mesquite when applied as a stem spray (see Extension publication L-5144, "How to Beat Mesquite").
• Do not spray when yuccas are wet.
