Reflecting on 2024: Exceptional research contributions of the year

As 2024 comes to a close, we’re looking back at the list of outstanding research articles that appeared in Golfdom this year. We want to thank all the authors for working closely with us to bring you the results of their excellent research.

I hope this has been an excellent year for you all, and we wish you all the best in 2025!

January: Factors affecting re-establishment of golf course putting greens following winterkill

By Michelle DaCosta, Eric Watkins and Dominic Petrella

• We evaluated a set of 12 creeping bentgrass cultivars for differences in seedling vigor and establishment in response to low temperatures and variable light intensities.
• Exposure of creeping bentgrass seedlings to freezing temperatures temporarily inhibited photosynthesis and growth of some cultivars more than others, with cultivars such as Piranha, Declaration, T1 and Penn A4 showing the highest tolerance to freezing events.
• Creeping bentgrass cultivars differ in their overall seedling vigor when grown under lower nutrient availability and at lower temperatures.
• Based on replicated field experiments in Minnesota and Norway, using shade cloths to achieve 50 to 90 percent reductions in light intensity increased photochemical efficiency and growth of creeping bentgrass seedlings during low temperatures typical of spring months.
• Different creeping bentgrass cultivars did not significantly vary in their overall establishment rate, but synthetic permeable cover decreased the time needed to achieve 50 percent turf coverage during spring establishment.

February: Nematodes and their control

By John Rowland

• Not all nematodes found in the soil are detrimental. Some feed on soil pests, mineralize nutrients and decompose organic matter.
• If you think nematodes are responsible for turf damage, proper sampling is essential to determine the species present and the population sizes.
• Tolerance thresholds for plant-parasitic nematodes can vary greatly depending on the species of nematode, turf species and variety, soil type and condition, location and climate.
• Cultural practices — particularly adequate irrigation and fertilization — may allow you to manage nematode issues under light to moderate pressure without chemical applications.
• Test control products on a small scale first to determine their effectiveness to avoid wasting time and money on larger applications that may not work.

March: A look at factors impacting tissue N content in creeping bentgrass

By Qiyu Zhou and Douglas J. Soldat

• Nitrogen is the main factor controlling tissue nitrogen content in creeping bentgrass.
• Weather, irrigation and foot traffic have little impact on tissue N in creeping bentgrass.
• The average tissue nitrogen of creeping bentgrass is about 3.9 percent over a growing season.

April: Fungicide evaluations for dollar spot control on creeping bentgrass

By Lee Miller and Matthew Carpenter

Putting Green Trials

• Following final applications in late August, Maxtima and Xzemplar had lower dollar spot severity than Traction on the ‘Crenshaw’ green in September, but all fungicide treatments performed better than the untreated control throughout the course of the study.
• On the ‘Pennlinks’ green, Lexicon, Maxtima and Navicon treatments provided excellent dollar spot control throughout the season.

Fairway Trial

• Plots treated with Encartis (3 fl. oz./1000 sq. ft. – 14 days), Encartis (3.5 fl. oz./1000 sq. ft. – 21 days), both Xzemplar rates and program-treated plots had the fewest dollar spot infection centers several weeks after the final application.
• Encartis rates and application timing did not significantly affect dollar spot control. However, plots treated more frequently (14 and 21 days) with Encartis at lower rates had fewer dollar spot infection centers than Encartis applied at a higher rate and 28-day intervals.
• Different application rates and timing within Xzemplar and Maxtima treatments did not significantly affect dollar spot control during the study.
• Daconil Ultrex and Secure, both individually and combined, provided less residual dollar spot control than other treatments. This is not surprising for contact-protectant fungicides, which are more prone to removal through mowing or environmental degradation than systemic fungicides that get into the plant. Contact fungicides are less prone to resistance development and are important tools for fungicide resistance management.

May: Investigating irrigation requirements for cool-season fairway species

By Jada Powlen and Cale Bigelow

• Irrigating with a green-coverage-based approach reduced irrigation needs compared to an 80 percent ETo replacement approach.
• A Mid-Atlantic type Kentucky bluegrass and tall fescue required the least supplemental irrigation.
• Turf-type tall fescue maintained acceptable quality with less irrigation than creeping bentgrass.

June: A deeper dive into Pythium root rot control on bentgrass and ryegrass

By Mike Kenna

• All treatments at North Carolina State University significantly suppressed Pythium root rot based on AUDPC values except for Subdue MAXX. The rotation of Segway with Serata almost completely suppressed the development of Pythium root rot.
• In July at Clemson, Serata had comparable control of Pythium root rot disease to Segway. Tank mixing a lower rate of Serata (0.4 fluid ounces) with Fame SC 0.36 fl. oz. provided comparable control to higher rates of Serata or Segway alone.
• At Rutgers, AUDPC values on ryegrass rough for all treated plots were significantly lower than those for the untreated check. Plots treated with Banol had lower values than Segway at both rates but were not different from plots treated with Union and Subdue Maxx.
• For peak disease on perennial ryegrass in July at Rutgers, Banol (severity of 5.6 percent) was not statistically different from Subdue Maxx with 17.1 percent disease severity.

July: Imazapic growth suppression of hybrid bermudagrass

By Benjamin Pritchard, Devon E. Carroll, Tyler Carr, Gregory Breeden and James T. Brosnan

• In 2020 and 2021, researchers at the University of Tennessee evaluated imazapic, a herbicide labeled for weed control in pastures, rangeland and non-crop areas, for growth suppression of four hybrid bermudagrasses.
• Separate experiments on ‘TifTuf,’ ‘Tifway,’ ‘Tahoma 31’ and ‘Latitude 36’ hybrid bermudagrass.
• Normalized differential vegetation index (NDVI) data were collected, and growth suppression was quantified via reductions in dry clipping weight.
• Hybrid bermudagrass injury increased with imazapic rate for all cultivars, and peak injury (> 30 percent) following all imazapic treatments occurred within 14 days.
• At the lowest imazapic rate of 0.5 ounces per acre (35 g ha–1), the injury was transient, with all hybrid bermudagrass cultivars fully recovered by 28 days.
• All rates of imazapic reduced hybrid bermudagrass dry clipping weight for 21 days on all cultivars.

August: Another look at winter rain’s impact on snow mold fungicides

By Paul Koch

• Winter rains and snow melts led to rapid degradation of both propiconazole and chlorothalonil.
• The presence of snow did not impact the persistence of either fungicide.
• Transfilm slightly increased the persistence of chlorothalonil but not propiconazole.

September: Precision spring dead spot control

By Jordan Booth, Dana Sullivan, Shawn Askew, Kevin Kochersberger and David McCall

• Spring dead spot (SDS) is a destructive disease that affects bermudagrass and hybrid bermudagrass in the Transition Zone of the United States.
• The study aimed to develop SDS incidence maps using digital imagery captured with an unmanned aerial vehicle (UAV) and evaluate the efficacy of targeted, site-specific penthiopyrad treatments guided by these maps.
• The results showed that targeted penthiopyrad treatments based on SDS incidence maps had significantly less disease than tebuconazole and the non-treated control in 2016-2017.
• Full-coverage penthiopyrad was superior to targeted penthiopyrad and tebuconazole in 2017-2018 for both diseased area (DA) and patch count (PC).
• Targeted penthiopyrad using SDS incidence maps required 51 percent fewer fungicides in 2016-2017 and 65 percent less in 2017-2018 compared to full-coverage penthiopyrad.
• Our results suggest that targeted, site-specific management of SDS can reduce the amount of fungicide applied and lower costs while still providing acceptable suppression of the disease.

October: Factors influencing stormwater pond nutrients and algae

By Charles Nealis

• The stepwise regression model identified key predictors for total phosphorus (TP), total nitrogen (TN) and chlorophyll-a concentrations in clear and colored stormwater ponds, refining variables through least squares fitting.
• Littoral shelf coverage and grass clippings emerged as significant predictors, with complex relationships between pond type and nutrient concentrations impacting TP, TN and chlorophyll-a levels.
• Littoral shelves and submerged vegetation influence nutrient dynamics, with higher plant coverage generally reducing TN and TP concentrations while affecting chlorophyll-a in varying ways.
• Residential fertilizer application and management practices such as chemical treatments and aeration were significant factors influencing nutrient levels, with restrictions on fertilizer use effectively reducing TP and TN concentrations.
• Surrounding land use, including natural areas and wetlands, contributes to nutrient dynamics and shows complex relationships that sometimes contradict conventional expectations regarding runoff from developed areas.

<p>The post Reflecting on 2024: Exceptional research contributions of the year first appeared on Golfdom.</p>