Particle size characteristics of putting green root-zone and topdressing sands
Sand topdressing is a routine maintenance practice on golf course putting greens. It is recommended that topdressing sands contain particles of similar diameter classes to those within the root zone; however, use of high-density turfgrass cultivars can
make this challenging. Research was conducted in 2023 to compare the physical composition of topdressing sands to those within root zones of creeping bentgrass (CBG; Agrostis stolonifera L.) and ultradwarf bermudagrass (UDBG; Cynodon dactylon L. x
C. transvaalensis Burtt-Davy) putting greens. Root-zone and topdressing sand samples were collected from 23 putting greens across Tennessee. Ten samples (3.94 inches by 0.75 inch/10 centimeters by 1.9 centimeters) were extracted from root zones using
a soil probe, and 8.8 ounces (250 grams) of topdressing sand was collected from stockpiles. Particle size distributions of root-zone and topdressing sands were analyzed via the ASTM F-1632-03 method. Particle size diameter data were used to calculate
coefficients of uniformity (CU) for each sand sample.
Both root-zone and topdressing sands from UDBG greens contained more fine (0.006-0.01 inch/0.15-0.25 millimeter) and very fine (< 0.006 inch) sand particles than those from CBG greens. Root-zone sand from CBG greens contained more coarse (0.02-0.04
inch/0.5-1 millimeter) and medium (0.01-0.02 inch/0.25-0.5 millimeter) particles than those from UDBG greens. However, topdressing sands for both species did not contain significantly different amounts of coarse and medium particles. For CBG greens,
CUs of root-zone and topdressing sand were not statistically different. Conversely, for UDBG greens, CU of root-zone sand was significantly greater than that of topdressing sand. Results are concerning given that continued use of uniform, fine-textured
sands on UDBG greens may negatively affect edaphic conditions over time.
— Maureen Kahiu (mkahiu@vols.utk.edu) and James T. Brosnan, Ph.D., University of Tennessee, Knoxville
Survey of plant-parasitic nematode populations in Arkansas golf course putting greens
Nematodes are unsegmented roundworms that are ubiquitous in Arkansas soils. Many nematodes are pathogenic and feed on turfgrasses. Golf course putting greens are optimal environments for plant-parasitic nematodes (PPN), as they usually have a porous root
media that allows for the free movement of nematodes. Plant-parasitic nematode populations have not been characterized in Arkansas golf course putting green soils. Therefore, a statewide survey was conducted to determine which PPN species are present
in Arkansas putting green soils.
To date, 17 golf courses across the state have been sampled at a 5.12-inch (13-centimeter) depth for nematode counts. For each course, nine separate putting greens were sampled with approximately 15 sub-samples taken per putting green in a randomized
pattern and homogenized for one representative composite sample per putting green. Samples were sent to the Nematode Diagnostic Laboratory in Hope, Ark., where nematodes were extracted using elutriation and then counted.
Spiral (Helicotylenchus spp.), lance (Hoplolaimus galeatus) and stunt (Tylenchorhynchus spp.) were the most common nematodes found across all golf courses sampled. Lance, sheathoid (Hemicriconemoides spp.), spiral, stubby-root (Trichodorus obtusus) and
stunt nematodes were found in statistically higher amounts in creeping bentgrass (Agrostis stolonifera L.) than in ultradwarf bermudagrass (Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy). Sting nematode (Belonolaimus longicaudatus), one
of the most damaging turfgrass nematodes, was not found in any of the samples. This survey is ongoing, and more golf courses across Arkansas will be sampled in 2024.
— Mike Battaglia (mvb003@uark.edu) and Wendell J. Hutchens, Ph.D., University of Arkansas, Fayetteville
Darrell J. Pehr (dpehr@gcsaa.org) is GCM’s science editor.