The prime golf season is revving up in the Southwest, and many courses are putting their best foot forward with healthy ryegrass fairways. Although the ryegrass growing season has yet to reach its peak, it is now time to start shifting the competitive advantage to the understory bermudagrass. Here are five key strategies to encourage bermudagrass growth and recovery from overseeding without negatively influencing ryegrass aesthetics or playability:
1. Lower mowing heights: Encouraging sunlight penetration through the overseeded ryegrass canopy so it reaches emerging bermudagrass leaves is critical. Lower the fairway mowing height to a range between 0.3 and 0.5 inch. Lower the mowing height of overseeded rough to 1 inch, then to 0.75 inch at the end of February and finally to 0.625 inch by the end of April.
2. Thin out overseeded ryegrass: Golf course superintendents use a variety of methods to improve sunlight penetration reaching the understory bermudagrass by opening overseeded ryegrass canopies. Vertical mowing with blades set slightly below the mowing height will slowly thin overseeded ryegrass. Fairway mowers outfitted with grooming blades or out-front brushes also bolster the amount of ryegrass harvested during mowing.
3. Manage moisture: Prolonged periods of saturated soils result in decayed bermudagrass rhizomes and poor recovery. Dry conditions at soil depths of 2-5 inches delays bermudagrass recovery. Utilize soil moisture meters outfitted with various probe lengths to monitor soil moisture in collars, fairways and even the rough. Dry conditions below course-specific moisture thresholds can harm bermudagrass.
4. Feed the bermudagrass: Apply nitrogen fertilizer when temperatures are high enough to stress ryegrass. Apply approximately 2 pounds of nitrogen per 1,000 square feet from late April or early May through the middle of June. The nitrogen will encourage bermudagrass recovery and stress overseeded ryegrass.
5. Avoid overregulating putting green collars: Common plant growth regulators regulate taller turf more than turf mowed at putting green height. Therefore, they can impair the recovery of bermudagrass collars. Consider using new spraying technology that applies products only where desired. If using class-A growth regulators, which are actively transported through turf leaves, immediately wash overspray from collars to reduce plant uptake.
These five strategies are important ways to encourage bermudagrass recovery while continuing to provide excellent overseeded conditions.
For more information on optimizing the transition into and out of overseeding, contact your regional USGA Agronomist.
West Region Agronomists:
Patrick J. Gross, regional director – pgross@usga.org
Larry W. Gilhuly, agronomist – lgilhuly@usga.org
Brian S. Whitlark, agronomist – bwhitlark@usga.org
Information on the USGA’s Course Consulting Service