3/21/2024 - By Dr. Raymond Snyder

Turf managers have been using plant health inputs for years as they have observed their value when included in their agronomic programs. Turf manager plant response observations include increased turf color/quality, drought tolerance, heat stress tolerance, and improved root characteristics. The timing, positioning, and implementation of plant health inputs by turf managers have been instinctual and accurate, even without scientific confirmation of each input's direct value.

More recently, scientific support for the utilization of plant health inputs is increasing. Dr. Xunzhong Zhang, a professor at Virginia Tech University, has scientifically documented plant health inputs such as humic/fulvic acid, seaweed extracts, mycorrhizae, and amino acids as eliciting desirable plant health responses, especially when turf is under stress. These beneficial plant health responses have occurred in both growth chamber and field studies in warm and cool season turfgrass types. Perhaps not surprisingly, the scientifically documented beneficial plant responses corroborate the anecdotal value observed by turfgrass managers for years.

Plant Inputs “Modes of Action”

The scientific body of work may help to further optimize the utilization of plant health inputs due to a greater understanding of how each input functions. Each plant health input has a specific “mode of action” that contributes to overall plant health, especially when the plant is under stress. As in weed or disease management, proper utilization of each input’s mode of action, and the utilization of multiple modes of action, may help to increase the effectiveness of plant health input programs. The net effect of “stacking the technology” based on a multiple mode of action program, might provide an overall better plant health condition relative to relying on a single plant health input.

Plant Inputs – Stacking the Technology

An example of “stacking the technology” was observed in work we conducted with Dr. Michelle DaCosta. Over the course of this experiment, we found that the best-performing treatment was the combination of several modes of action, especially when the number of heat stress days increased up to day 42. In this case, the combination of a phosphite, seaweed extract, fulvic acid, and pigment resulted in higher quality turf more than any of the treatments by themselves.

Another example utilizing multiple modes of action is work conducted by Dr. Billy Crow in which nematicides were combined with three plant health input products in an attempt to further improve the plant response associated with nematicides by themselves. After this two-year field study, the greatest root length was observed when nematicides were combined with plant health inputs relative to the untreated control, plant health inputs, and nematicides.

Positive Plant Health Response to Inputs

The scientific evidence associated with positive plant health responses to inputs containing microbial populations is expanding through recent efforts. For example, research work conducted at Virginia Tech University demonstrated that regular inputs of EarthMAX® Organic, to saline stress bentgrass increased leaf color, chlorophyll content, photochemical efficiency, and root characteristics. Furthermore, Virginia Tech University also conducted research work applying azospirillum brasilense to bentgrass under mild heat/drought stress and observed increased turf quality, leaf color, photochemical efficiency, chlorophyll content, and root characteristics.

Finally, as noted above, monthly inputs of mycorrhizae can also improve plant health characteristics such as leaf color, photochemical efficiency, and root characteristics as demonstrated in a bentgrass field study at Virginia Tech University. Scientific work conducted more recently may demonstrate that the incorporation of multiple plant health modes of action, including those that contain verified microbial species, are beneficial and should be considered when creating agronomic programs.

Learn More from Your Harrell’s Rep

In summary, turf managers have long used plant health inputs to increase turfgrass health based on their own experiences. Scientific research supports turfgrass manager's observations relative to plant health input use, and this research may also provide a greater understanding of each plant health’s input role in promoting turfgrass health. To learn more and figure out what combinations of plant health inputs work best for you, reach out to your local Harrell's Rep.