7/26/2022 - By Dr. Paul Giordano

I’m going to tell a story about poor turf roots with three maps. These three maps hold information that is key to understanding why many turfgrass managers in the northern half of the country are battling issues like take-all patch, summer patch, root dysfunction, drought stress, and fairy ring among other soil-borne maladies.

Stemming back to late summer 2021, weather patterns that included record setting rainfall, and dramatic fluctuations in both temperature and soil moisture have created challenging conditions, wreaking havoc on turfgrass root systems.

The Story in the Maps

The Choke Out Phase: June - November 2021

Late Summer through fall of 2021 was one of the wettest on record in many parts of the Midwest and northeastern U.S. This excessive amount of precipitation created long-term saturation of root zones. Especially problematic was the over saturation during the fall - a period when cool season turfgrass normally dedicates much of its energy to root growth and recovery. Lack of oxygen and excessive moisture in the upper soil profile inhibited the development of new, healthy roots.

Most cool season turfgrasses experience a typical summer “retraction” of roots and rely on optimal growing conditions in the fall to recover and recuperate. Worse yet, these same wet fall conditions likely favored an influx of new infections from root-dwelling pathogens like those that cause take-all patch, summer patch, and pythium root rot and dysfunction.

The Dry Down Period: May - June 2022

After the wet fall, it was a slow start coming out of winter for many. At best, the bentgrass was groggy and Poa seed heads were a plenty. At worst, there was widespread winter damage affecting weaker, more vulnerable areas on the golf course. As we transitioned into spring and early summer, a significant dry down started to occur in many regions.

What Does This Mean?

Those three maps tell a long and dire story, one that has not played out well for turf areas that were already struggling. Compromised roots can keep plants on life support through low stress growing conditions in the spring, but as soon as abiotic stress like heat or drought sets in, things go south quickly.

A perfect recipe for patch disease and root dysfunction occurred over the past several months. Excessively wet, cool spring conditions followed by a hot and dry early summer have resulted in a slew of summer patch and take-all patch reports. When I’ve had the opportunity to view samples under the microscope, a common trend I have noticed is bad roots.

When I say "bad roots," I mean roots that are discolored, infected, or compromised by pathogens, cells sloughed off and largely devoid of root hairs or any indications of new growth. And while most other diseases like dollar spot and brown patch have been quiet thus far in 2022 - the root diseases have had a perfect storm of favorable conditions, and are starting to rear their ugly heads.

What's Next?

For many, the next couple months will be a war of attrition. With minimal or compromised root systems, summer heat and stress mean nursing the most vulnerable turf areas through the challenging weather with judicious use of nutrition, water, and plant protection. In areas that are clearly suffering from a root disease, curative approaches are difficult and often slow to correct the issue. However, remedial applications can help to prevent new infection to surrounding areas and protect any remaining healthy roots and crown tissues.

The strobilurin (QoI’s) and sterol inhibitors (DMI’s) tend to be the most consistent performers when it comes to summer patch and take-all patch efficacy. The important part to applying these fungicides is to get them watered-in with AT LEAST 0.125” of post application irrigation. Most “failures” are due to not getting product sufficiently into the target area of the root zone.

Product Recommendations

Aside from fungicides, water management is going to be critical to ensure sufficient moisture in the upper portion of affected root zones. When turf roots are compromised by disease, they are usually very short, sparse, lack proper structure, and will struggle to take up water or nutrition. Hand-watering and judicious use of wetting agents like Fleet® 100 and Symphony® can help nurse areas through the tough stretches of summer.

Finally, as we look to help these plants grow new roots and recover into the cooler temperatures of fall, we can lean on certain products that have been proven to aid in root function, photosynthetic efficiency and overall root growth. Bio stimulants like Amino Pro V, EarthMAX® Organic, BioMAX® 4-0-0, Seaweed A+E, and Mycorrhizae Pro are excellent tools to incorporate into soil-targeted applications. All of these products have been specifically tested and included into the Harrell’s Balanced Approach programs, aimed specifically at root growth promotion.

Harrell’s has a full suite of offerings to help in the prevention, recovery, and programmatic approach against root and other soil borne issues. Reach out to your Harrell's Territory Representative to see how our Balanced Approach can help.