Superintendents have a tough job managing and modifying turfgrass physiology. Golf course turfgrass often exists on the edge of viability because it has less leaf area than unmanaged turfgrass. It is under additional stress from foot traffic, mower blades, heat, drought and humidity.

Superintendents typically focus their management practices on the top half of turfgrass because that's what people see. But focusing on the root system may help improve aboveground performance.

To gain better insight into the role roots play in plant health, I spoke with Dr. Christina Wells, associate professor in the Department of Environmental Horticulture at Clemson University and a plant physiologist.

Root Functions and Size
"Turf roots are a thick, fibrous mass that can be very challenging to work with," said Dr. Wells.

Root system size is influenced by many factors, including the availability of water and nutrients. If water and nutrients are abundant in the soil, then roots won't branch out to find additional resources. There is little point in investing additional biomass and energy to get water and nutrients if they are readily available.

"Turfgrass roots are very efficient at finding water and nutrients," said Dr. Wells. "Think of roots like a factory. If you can get the job done with two or three machines, why would you invest in more? Roots are the same way. The plant invests in the amount of root mass its needs and no more."

Another factor affecting root system size is the removal of material from the top. Mowing turfgrass takes away above-ground biomass, and the plant responds by replacing lost shoot biomass rather than into growing more roots. Above-ground environmental stresses such as high temperature also impact root size: repairing stress-related damage uses carbon that might otherwise be used to help grow the root system.

Disease Control and Plant Health with IntrinsicTM Brand Fungicides
Research from BASF Professional Turf & Ornamentals shows that IntrinsicTM brand fungicides (active ingredient: pyraclostrobin) control a broad spectrum of diseases, as well as providing plant health benefits. IntrinsicTM brand fungicides control fungal diseases by affecting the ability of the fungi to grow and colonize turfgrass. In addition, they allow the plant to use photosynthetically-fixed carbon more efficiently, reducing respiration and increasing growth, particularly under stress. Laboratory and field research have demonstrated pyraclostrobin-based fungicides improve plant nitrogen usage and improve photosynthetic efficiency.

"At Clemson, we did a greenhouse trial where we applied Intrinsic to turf that was well-watered and turf that was drought stressed," said Dr. Wells. "When we applied Intrinsic on the stressed turf, we saw greater root growth and greener tops compared to untreated turf. With sufficient water, treated and untreated turf were similar."

Growing Healthier Roots
Sugars, which are derived from photosynthesis, play a big role in root development. Below ground, they provide the carbon and energy for continued root growth, as well as powering the mechanisms of nutrient uptake.

"In a situation where a lot of the nutrition is being provided for the plant, like on a golf course, it makes more sense to use sugars for energy to drive high rates of uptake," said Dr. Wells. "There's really no reason to grow more roots because it's not necessary. The plant doesn't need to explore to find nutrients when they are right there."

Root systems are larger when the photosynthate supplies from the turfgrass leaves increase. The carbon is freed up to other areas of the plant, such as the roots. Properly balancing that carbon use is important to helping the plant fight disease, withstand stress, and recover faster if a stress event occurs.

Implications for the Turf Manager
There isn't one answer to what a healthy root system looks like. It really depends on the turf manager's point of view.

Why should deeper roots mean a healthier plant? In fact, especially on a golf course, many practices by superintendents promote smaller root systems. Turf is watered and fertilized frequently, and mowed almost daily. With water and nutrients in abundance, and added stress to the plant, roots do not often grow deep.

• If your turf management goal is consistent, dark green turf with no dead or diseased patches, you can achieve that with a minimal root system," said Dr. Wells. However, as we have seen in the past few summers the perfect growing conditions are becoming harder to find. "Superintendents faced with restrictions on irrigation or the amount of nitrogen they can put on their turf should focus on promoting a bigger root system for a healthier plant. It's all about the constraints and turf management goals. A healthy root system is whichever one gets superintendents to their management goals."

Understanding how turfgrass functions below the surface can help superintendents more effectively work through multiple agronomic options and select solutions that are essential to keeping turf healthy and players and course management happy.