Few discussions regarding turf grass management on Scottsdale Private Golf Courses get more emotional than discussions on whether or not to overseed with perennial Ryegrass. However one fact about overseeding is indisputable: overseeding with perennial Ryegrass can, and often does, have an adverse effect on Bermudagrass. Nevertheless, Scottsdale Golf Course at management practices can be implemented that significantly reduce the impact of overseeding on Bermudagrass health. The most important of those practices is getting rid of the perennial Ryegrass by late spring. One of the troubling trends occurring on golf courses is the increasing practice of Overseeding too early in the fall and keeping the Ryegrass too late in the spring/summer. If Bermudagrass does not have sufficient time to grow during the summer without competition from the Ryegrass the Bermudagrass will decline. This may occur in as little as one year and more often occurs gradually over a period of several years. Why does this happen? A fundamental principle in weed science is that plants compete with one another for four basic resources: 1) Water 2) Nutrients 3) Carbon Dioxide 4) Light. Light is the most crucial of these four for the benefit of the Bermudagrass. In overseeded environments, when Bermudagrass begins to come out of dormancy in spring, perennial Ryegrass growth is at its maximum. As a result, the Ryegrass provides significant shade to the Bermudagrass.
Allowing Ryegrass to grow at Scottsdale Golf Course into June in the Desert South West limits the Bermudagrass growing season and contributes to poor quality Bermudagrass. By late spring it is time for Bermudagrass to emerge from winter dormancy. Bermudagrass utilizes carbohydrates stored in underground rhizomes to produce new leaves every spring when temperatures in the top four inches of the soil reach about 65 degrees Fahrenheit. Bermudagrass has about three chances to produce new leaves while trying to emerge from under the shade and competition of overseeded grasses before it will strike out and die. If a new leaf is unable to capture sunlight- strike one. This process repeats itself until, you guessed it, strike two and strike three. After strike three the Bermudagrass has spent its entire carbohydrate reserve and when sampling the soil it will reveal the hollow rhizomes.
A proactive management regime at Scottsdale Golf Course is necessary to encourage successful Bermudagrass recovery. Here are the five key components for the Desert South West:
1) Height of cut – The height of cut is critical. We begin lowering the height of cut on all overseeded areas come mid-February and progressively lower throughout the following weeks.
2) Soil moisture management- Dry conditions equal poor Bermudagrass recovery during late spring and early summer. It is critical to prevent areas from becoming chronically dry as it will delay the Bermudagrass transition.
3) Chemical removal- Many courses use a variety of tactics to chemically remove overseeded Ryegrass without injuring the understory Bermudagrass. However, we must not wait until June to employ this strategy because much of the Bermudagrass may have already struck out. This tactic is much more effective when used the end of April through May.
4) Nutrient inputs- Nutrient sources should be applied in coordination with chemically removing overseeded grasses. This will stress Ryegrass during warm daytime temperatures while providing nutrients for emerging Bermudagrass.
5) 100 Days Plus- It would be nice to give Bermudagrass 162 days of growth in the absence of competition from Ryegrass. However, 100-120 days is the guideline courses should keep in mind when planning overseed dates and timing chemical removal of overseeded grasses. If Ryegrass growth is retained well into June, the ability of Bermudagrass to develop the rhizome growth necessary to recuperate the following year will be severely limited. In other words, maintaining Ryegrass into June could result in a season-ending injury for Bermudagrass.
Growing two grass crops at Scottsdale Private Golf Courses annually is a tenuous situation. Extending the Ryegrass growing season into June at the expense of Bermuda grass health is a season-ending injury.
No comments:
Post a Comment