Golf Course Management

APR 2013

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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cutting edge Research in progress Photo by J. Friell Salt-tolerant turf mixtures Turfgrass is often subject to salt stress as a result of poor irrigation water quality or winter de-icing practices. The objective of this research is to identify low-maintenance, salt-tolerant turfgrass mixtures. Fifty-two mixtures of nine cool-season turfgrass species including strong creeping red fescue (Festuca rubra L. ssp. rubra), slender creeping red fescue (F. rubra L. ssp. litoralis), sheeps fescue (F. ovina L.), hard fescue (F. trachyphylla [Hack.] Krajina), Chewings fescue (F. rubra L. ssp. fallax [Thuill.] Nyman), Kentucky bluegrass (Poa pratensis L.), creeping bentgrass (Agrostis stolonifera L.), alkaligrass (Puccinellia species), and tall fescue (F. arundinacea Schreb.) were established at two salt-affected roadside locations in the Minneapolis-St. Paul metropolitan area in August 2011. Turfgrass quality, winter survival and resistance to weed encroachment are being evaluated through spring 2013. Results will identify turfgrass mixtures that can tolerate salts in irrigation water and may be used in low-input applications. — Joshua Friell (frie0250@umn.edu), University of Minnesota Spent coffee and tea topdressing Photo by G. Munshaw Teresa Carson 104 GCM April 2013 + organic treatments had no effect. Surface hardness was softest in C treatments and hardest in control plots. All organic treatments slightly improved CEC, but did not affect percent organic matter. Potassium and phosphorus were most increased by C and least by RS. Only sand + SP and SP reduced pH compared to the control. Electrical conductivity in the topdressing layer was higher for C, T and RS plots than in the control. The thatch layer and the sand layer did not show differences among treatments. — Gregg Munshaw, Ph.D. (gcmunshaw@uky.edu), University of Kentucky, Lexington, Ky.; Barry Stewart, Ph.D., Wayne Philley and Wayne Wells, Ph.D., Mississippi State University, Mississippi State, Miss. Dollar spot sensitivity to DMI fungicides We began a study on DMI baseline sensitivity when the frst DMI fungicide, propiconazole, became registered for use on turfgrass in Canada in 1994. From eight locations in Ontario, we found that most populations of the dollar spot pathogen were very sensitive to DMI fungicides. One population near the American border had reduced sensitivity, and we suspected off-label fungicide use. The study continued in 2003, 10 seasons after the introduction of DMI fungicides, by which time myclobutanil became registered for dollar spot control. We examined nine populations in Ontario Photo by T. Hsiang and found that populations not treated with DMI fungicides during the previous 10 years remained highly sensitive, while treated populations had some reduced sensitivity, but not at an economically signifcant level. We will continue the study in summer 2013 at many of the 1994 and 2003 locations and at other sites where annual DMI fungicide use has been high. We want to see if the shifts toward reduced sensitivity have intensifed, and extrapolate from this data how much fungicide use could lead to full-blown fungicide resistance. — Tom Hsiang, Ph.D. A study was designed to determine the soil chemical and physical effects of topdressed organic materials on Tifway bermudagrass growing in a root zone built to USGA recommendations (90:10 sand:reedsedge peat) maintained at 0.5 inch. Treatments consisted of reed-sedge peat (RS), sphagnum peat (SP), non-composted spent coffee grounds (C), non-composted spent tea leaves (T), sand (S), 50:50 mixes (v:v) of sand with each of the organic treatments, and an untreated control. Treatments were applied every two weeks by hand in August and September to a depth of 0.125 inch/application and brushed into (thsiang@uoguelph.ca), University of Guelph the turf canopy. Organic treatments improved color GCM from mid-August through dormancy and improved water-holding capacity compared to the control; sand Teresa Carson (tcarson@gcsaa.org) is GCM's science editor.

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