Golf course superintendents generally don’t have time to worry about whether their bentgrass management programs are preventing stress on their greens. With this in mind, Joe Vargas, Ph.D., professor of botany and plant pathology at Michigan State University, reviewed the factors that contribute to stress and the steps that can be taken to combat it in the latest stop of Bayer’s Stomp Out Stress seminar, held last month at Ruth Lake Country Club in Hinsdale, Ill.
The elements that can wreak havoc on bentgrass greens include:
- Poor soil conditions. Situations that lead to increasing turf stress include:
o Compaction.
o Poor drainage.
o Improper particle size/shape. - Poor environmental conditions:
o Lack of air movement.
o Lack of morning sun. Photosynthesis works better in the temperatures that generally occur in the morning, Vargas says.
o Shade. Trees that overshadow a green can be problematic, he says.
o Tree roots. This is another reason trees near greens can spell trouble.
o Poor irrigation water quality.
o Photorespiration. A plant’s loss of its stored carbon.
Understanding what stresses bentgrass is the first step to avoiding the plant’s decline or stopping it once it starts. The next step involves taking the following actions:
- Cultural practices
o Aerification. If you can do it only once, aerify in the spring, Vargas says.
o Syringing.
o Proper topdressing.
o Root pruning. Vargas also recommends installing a root barrier so tree roots don’t grow underneath greens and thwart the plant’s growth.
o Spoon-feeding with foliar nutrition.
o Improving irrigation water quality.
o Increasing air circulation. - Chemical management. Vargas outlined trials that tested various fungicide applications. While Signature is an effective treatment method, it must be combined with a second disease management tool, such as Chipco, Daconil or Tartan, to be most effective, Vargas says. He points to a Chipco formulation as one of the most successful partners in a trial.
- Nutrition
o Nitrogen. On one hand, high levels of nitrogen can increase the severity of diseases such as brown patch and pythium blight, but it also can decrease the severity of dollar spot, anthracnose, crown rotting anthracnose and pink patch.
o Phosphorous. “You may hate phosphorous, but it’s very important to the health of the plant,” Vargas says, adding it aids in seed germination and is a key component of all enzymes in the plant.
Vargas debunked myths about management practices that superintendents are led to believe are important. For instance, many are led to believe it’s important to use potassium to build up a plant’s cell wall, but there’s not much point to doing that, Vargas says. He points out that the oldest leaf on a bentgrass green generally is 14 to 18 days old.
“How thick of a cell wall do you think you have?” he asks.
Turgrass managers who use potassium generally use it for this purpose, but it might not be worth the effort, Vargas says. He points to studies that show no increase in bentgrass quality or wear tolerance after potassium applications. In addition, soil tests have shown potassium deficiency after five years of applications, he says.
“No one ever did a study and proved that potassium decreased disease,” he says.
With the right practices in place, the turfgrass can better guard itself against bentgrass decline, Vargas says.
“There’s not any one thing (that will prevent stress),” he says. “You should do cultural practices, but now chemicals are available too.”