Pasture and Forage Minute: Yucca Control and Fall Irrigation
Reducing Yucca in Rangeland
Yucca plants, which are also called soapweed, can be quite common on rangeland in western and central Nebraska. In some areas, they can be quite thick and significantly reduce grass production. There are ways, though, to reclaim those grazinglands.
Once established, yucca plants can increase on drier rangeland sites. They produce a deep taproot that competes aggressively for the limited water in these soils. With sharp leaves protecting the plant, cattle rarely eat it during summer.
Herbicides like Remedy, Tordon, Velpar or Cimarron Plus can control yucca, but only when each individual plant is sprayed directly. General broadcast spraying to control yucca on rangeland is cost prohibitive, although small patches can and should be controlled before they expand. Herbicides are most effective when applied in spring or summer.
When yucca covers too much land to spray, the only cost-effective way to reduce its impact is to winter graze. During winter, yucca often is the only green plant around. Sometimes cows actually will 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. It has been observed, though, that it can take some time for animals to learn to graze yucca and there may be some animals in the herd that will not graze it while others can be quite proficient. After several consecutive winters of grazing, yucca stands can be reduced so grass again thrives during summer.
Now that summer range is going dormant for the winter, grazing will do little harm to your grasses. This might be a good year to reclaim some of your rangeland back from yucca. Winter grazing is your best tool.
Late Fall Irrigation
Fall frosts have ended the life cycle of many annual plants. In some cases, below-freezing temperatures have reduced insect numbers and finally ended the harvest challenges of extended green soybean stems and corn plants. Despite the cold nighttime temperatures, many crops are still growing. So, the question arises: “How much irrigation should be applied in late fall for perennial and winter annual crops like alfalfa, wheat, rye and triticale?”
Generally, the fall goal is to have adequate stored moist in the upper two feet of soil profile while leaving enough storage room to take full advantage of off-season precipitation. For sandy soils, it may require two inches of water to fill the top two feet of soil, while clay soils may need four inches of water to fill the two-feet profile.
When extreme dry conditions occur in the fall, irrigators will usually water after the winter annual seeds have been sown. Ideally, fall-drilled wheat and rye should have available soil water below the planted seeds. When extreme dry conditions occur in the fall, irrigators will usually apply 1.0 to 2.0 inches of water following drilling season.
For alfalfa, daily water use drops significantly in the fall to less than one-fourth-inch per day due to cooler days. Overall, alfalfa requires six to seven inches per cutting for optimum production.
More Nebraska Extension fall crop irrigation publications are available on our website: NebGuide G1778 “Irrigation Management and Crop Characteristics of Alfalfa” and EC731 “Producing Irrigated Winter Wheat”.