Dennis Hancock, Univ. of Georgia
Though bermudagrass is expected to be a long-lived, productive species, there are situations where stands begin to thin or totally die over time. Larry Redmon, Texas A&M AgriLife extension forage specialist, offers the following possible reasons for declining bermudagrass stands.
1. Fertility: This may be the number one cause of reduced productivity and stand loss. Nitrogen is important for forage production, but Redmon points out that it is often the only nutrient applied. Don’t forget about phosphorus and potassium; both are critical for performance and persistence. Potassium is needed for forage, stolon and rhizome production. It also improves tolerance to winterkill and some diseases such as Helminthosporium leaf spot. Phosphorus availability is reduced under low soil pH conditions. Many times the addition of limestone to increase soil pH to over 6.0 can be an important aspect of improving plant-available phosphorus for bermudagrass. Redmon suggests soil testing bermudagrass fields to determine nutrient status and make appropriate corrections.
2. Stocking rate: A heavy stocking rate places excessive grazing pressure on bermudagrass stands; both animal performance and plant vigor suffer. Low plant vigor reduces leaf area; this results in less capacity for photosynthesis and carbohydrate production. With reduced plant-stored energy, metabolic functions are limited and a smaller amount of carbohydrates are stored in the root system for winter.
3. Overseeded, cool-season forages: Cool-season annual forages that are seeded into bermudagrass stands provide additional productivity and nutrition in the fall and winter; but they must be removed in the spring prior to bermudagrass breaking dormancy. If this is not done, bermudagrass suffers by competing with the cool-season annual for sunlight, moisture and nutrients. In some cases, spraying with glyphosate while bermudagrass is still dormant may be necessary to remove the cool-season forage.
4. Drought: Redmon notes that not much can be done to control the weather, but following best management production practices can minimize the impact of drought on bermudagrass productivity.
5. Pests: Invasive weeds and insect pests such as grasshoppers or armyworms need to be scouted for frequently and controlled as needed through management or pesticide applications. When using pesticides, always follow label directions.