At this time, turfgrass diagnostic services at MU remain suspended due to the COVID-19 pandemic. An anticipated opening date of July 15 is planned to complete an online submission system and catch the dog days of summer. When we do open, anticipate limited hours, strict sample submission guidelines and no sample drop offs. Some of the diagnostic labs open at this time include University of Wisconsin, North Carolina State University, and Kansas State University. We appreciate your patience.
A Little Above Average, But Not Bad
While most things have gone poorly in 2020, the weather thus far has not been terrible in Missouri (knock on wood). June temperatures are running above normal in the state, particularly the Kansas City region, which is running 4-5 degrees above normal. The air has been dry though, and several breaks of nighttime lows in the low 60s and high 50s have minimized the impact of our usual sustained disease and heat stress periods. Not much has gone right in the first half of the year, but the growing weather has been fairly accommodating. The solstice is also behind us, meaning daylength and potential periods of heat stress for cool-season turfgrass is getting shorter. It's no late September out-of-the-woods celebration, but considering everything going on… it's something.
Problems this year have mostly revolved around water, either too much rainfall at one time or not enough of it. June rainfall centered itself right down the middle of the state as the remnants of Cristobal meandered through. Some areas in the center of the state have received 7-10 inches of rainfall in June. Last week, St Louis also received their monthly allotment in a few days, as some areas received 4-5 inches last week. The western part of the state, however, has been very dry, with some areas receiving very little June rainfall.
Forecasts indicate a departure from the cool nights and the return of humid, summer-like weather. Rain chances through Monday indicate 0.25 – 0.5 inches expected for much of Missouri, with hopefully a bigger pocket over the Kansas City area. Take this forecast with a grain of salt, however, since as our state climatologist says it is Missouri, after all.
Rain in the Middle, Dry on the Sides
Putting Green Roots - Check 'em
In historically weak and strong areas check root depth, moisture and consistency.
Forceful Fairy Ring
Be Like Water
Just a few weeks ago, I, like many, watched the Bruce Lee 30 for 30 documentary, and his famous quote has been ringing through my ears while attempting to help managers remotely through photos and descriptions. The quote relays the power of being freely adaptable to any situation and changing practices with the circumstance. The one weather curveball we have had this season, as with most seasons, just happens to be water - lack or abundance of rainfall.
Too much water early may inhibit root systems, and if dry conditions follow a "flash drought" situation can occur. In KC, STL and southern MO, which in some areas had double the normal amount of rainfall in May, several turfgrass stands are going into a quick dormancy state which is being mistaken for widespread disease occurrence. This is especially true for newly sodded lawns as pictured above. New sod and their compromised root systems aren't able to adapt to the quick changes of heavy rainfall to no rainfall. In these situations, it's critical to monitor the rooting or "take" of the sod by gently pulling on a few areas, and delivering smaller, more frequent pulses of irrigation to the depth of the roots and not too the point of runoff. A recipe for brown patch on tall fescue… yep. However, in this case, the disease is better than losing the new sod to permanent wilting of the stand… and that's a turfgrass pathologist stating that.
These yin and yang of periods of heavy rainfall followed by dry conditions can also spur, and make quickly apparent, preferential water flow in soil caused by localized dry spot (LDS). It's probably no coincidence that we are seeing early, damaging fairy ring occurrence this year and reports of problematic LDS on putting greens. Low humidity, yet still suitable growing conditions for cool-season turfgrass is also increasing the load and importance of water transport, making these LDS stand out.
Natural soils are not immune, but sand-based putting greens are much more prone to LDS due to particle size and structure. Dr. Stan Kostka on June 8 pointed out a study done by Tim Bauters at Cornell that found only 3% of hydrophobic sand added to a wettable sand was enough to render the whole mix non-wettable. That's not a lot considering the ample amount of organic matter that can transition to hydrophobic organic coatings upon microbial breakdown. Conduct a simple water droplet test. Consider wetting agent options (there are a ton of them) and consult with others on their experience with them.
Bruce Lee didn't incorporate this into the analogy, but perhaps should have. Adapting practices to the water needs of turfgrass is an ever flowing, changing dynamic in summer. Irrigation systems, whether they are on a sports facility, golf course or home lawn are not set it and forget it devices and require constant adjustment during the season to follow plant water needs. Decisions should be made on areas that absolutely require water to maintain a stand, versus turfgrass species such as tall fescue that have robust drought dormancy mechanisms. Although going brown, established turfgrass stands on lawns or lower amenity areas rarely perish completely and are simply biding time until rainfall occurs again. They move with the water. A movement away from the necessity of a perfectly green lawn (or out-of-play area) every day of the year in fluctuating environmental conditions is perhaps another of the flowing, water-like changes necessary in the collective public psyche.