My travels throughout the western U.S. over the past three to four weeks have revealed many instances of compromised root systems in cool-season greens. Prolonged heat, periods of humidity and a great deal of golfer traffic has taken a toll. Additionally, many courses have undergone renovations where sod may have been stripped and replanted or recently seeded turf is in the early stages of growth. Where new turf has been planted into poorly drained rootzones, roots are often shallow. I’ve also seen some greens extensions installed on a much different rootzone than the putting surface. While this new environment may drain better, there is often an interface between the sod and new sand rootzone that limits root depth.
As the day length starts to decrease and nighttime temperatures turn cooler into early and mid-September, initiate practices to improve turf health and root depth and density prior to the onset of cold temperatures. Please consider the following:
- Increase nitrogen application frequency on putting greens, especially on weak greens with shallow root systems. A soluble nitrogen source sprayed twice weekly at low rates (0.10-0.15 pounds of nitrogen per 1,000 square feet per application) will help improve rooting.
- Utilize small-diameter solid tines every 7-14 days to create open channels that will expedite root development.
- Small-diameter hollow tines are also encouraged if the surface strength of the greens is enough to avoid heaving.
- Avoid the urge to lower mowing heights to gain speed. Maintain conservative heights of cut until root density and health has improved.
- Remove growth regulators from the spray program for the time being.
- Decrease mowing and rolling frequency on greens with weaker root systems and poor surface strength.
Most importantly, on greens with weak surface strength and shallow, compromised root systems – keep it simple. Simplify all inputs on the green and focus on the essentials that you can control. Utilize light and frequent applications of nitrogen, decreased traffic, frequent watering to accommodate a shallow root system, and light-intensity cultural practices to disrupt soil layering and mitigate compaction.
Take advantage of the next 8-10 weeks of (hopefully) good growing weather and improve the microclimate around weak greens if appropriate. Open up windows of sunlight to increase sun exposure and remove underbrush to improve air circulation. Finally, communicate to course stakeholders that the compromised root systems and weak surface strength will improve, but patience is key. Now is not the time, despite the temperatures improving, to push for faster green speeds.
West Region Agronomists:
Brian Whitlark, regional director – bwhitlark@usga.org
Cory Isom, senior consulting agronomist – cisom@usga.org