ROOTED INRESEARCH COOL-SEASON LAWN-CLOVER MIXTURES—
By Cale A. Bigelow, PhD
As June transitioned to July here in West Lafayette, it is difficult to believe how quickly the first six months of 2025 have gone. Most notably, the weather has changed substantially in the last three months. If you read my early- season Rooted in Research article, we were nearly begging for Spring to arrive, and at that time, we were notably far behind in terms of accumulated growing degree days. I remember thinking at the time, with the extended cold and periodic frigid winter temperatures, that spring green-up could turn out to be quite interesting for those cultivating bermudagrass and zoysiagrass across the region.
IN SEARCH OF “THE SELF-FEEDING LAWN“ turfgrass areas, especially where there is no supplemental irrigation. Tis, in turn, will likely result in a loss of plant vigor, some loss of turf density, and the occurrence of numerous summer pests and assorted maladies.
Unfortunately, my instincts were correct, and it was a little too interesting in terms of the extent of winterkill. Tis proved especially true across the Ohio River Valley to the Mid-Atlantic, where numerous reports of widespread winterkill occurred. Bermudagrass winterkill is a complex issue with numerous factors, but I think the extended warm-dry conditions throughout October across the region likely had a role in some areas being more predisposed to winterkill.
While it’s a complex topic, there is a newly published open-access resource that others and I authored under the steady hand of senior author, Dr. Wendell Hutchens. Te resource is entitled, Management Strategies for Preventing and Recovering from Bermudagrass Winterkill. It can be freely downloaded at the following link: https://acsess.
onlinelibrary.wiley.com/doi/10.1002/cft2.20302
Fast forward to the June 20th official beginning of summer,
and I think many people living in the Midwest were ready for someone to turn off the blast furnace. Generally, Central Indiana (e.g., Indianapolis) normally averages about 20 days annually with high temperatures > 90 degrees F (32.22 degrees C). As I penned this article, the region has had close to 15 days. I am not sure what that means for the rest of the summer months, but some of the extended heat stress is certainly evident on lawns and other
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In addition to a roller coaster of weather, the other big thing happening in July is that the turfgrass research community is headed to Japan for the International Turfgrass Research Conference (ITRC). Tis event happens every four years and brings together the broader international group of turfgrass scientists for research presentations, networking, and fellowship in a new location. I am sure it will be a great event, and I look forward to seeing some of the exciting turfgrass research papers being published. Perhaps we can highlight some of that work in a future installment of Rooted in Research.
The Self-Feeding Lawn
Now to the task at hand: another look at some research related to the BIG Tree cultural practices: mowing, feeding, and irrigation. For this installment, I wanted to revisit an important topic my research group and others spent time on in the last ten years. In essence, challenging social norms regarding lawn monostands by investigating the feasibility of grass-legume dicultures and ultimately a search for “Te Self-Feeding Lawn.” In other words, is it feasible to plant a lawn species and/or mixture that would be able to supply the nitrogen needed to maintain a dense, healthy turf without the need for supplemental fertilizer sources? And can that lawn mixture persist uniformly over a period of several years?
Te rationale is that, as we all know, nitrogen is the mineral nutrient that turfgrass plants require in the largest amount. Tis nitrogen is associated with more plant vigor, increased shoot density, and a darker green color that most of the public seems to desire. Typically, supplemental lawn fertilization is applied using granular fertilizers. Tis can be problematic both in terms of the risk of overfeeding and/or environmental concerns, such as non-target movement of
TPI Turf News September/October 2025
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