Tatsiana Espevig

The potential of a surfactant to restore turfgrass quality on a severely water-repellent golf green.

Soil water repellency (SWR) is a common phenomenon on sand-based golf greens. Soils are considered severely water repellent if water droplets remain on the surface of undisturbed, air-dried soil samples for more than 600 seconds before penetrating. The objective of this research was to evaluate the potential of a surfactant to overcome SWR and restore turfgrass quality on a green with severe drought symptoms. The surfactant Aqueduct® was applied at a rate of 25 L ha−1 at weekly intervals from 4 June through 25 June 2008, either alone or after aeration with solid tines to 5 cm depth before each application. The experiment was irrigated uniformly corresponding to 1.65 times pan evaporation values from 4 June till 12 June, after which irrigation was not necessary due to natural rainfall. Conspicuous and statistically significant improvements in turfgrass quality occurred 10–12 days after the first application of surfactant, and the difference from untreated control plots continued to increase for about two and a half months after the completion of treatments. The improvement was accompanied by a significant increase in the SWC of the 0–20 cm soil layer and a deeper root system. The difference in WDPT between treated and untreated plots was significant at 1 cm, but not at 2, 3, 5 or 10 cm soil depths which were always far more water repellent than the thatch layer. Repeated aeration had no significant effect on turfgrass quality, and there was no significant interaction between surfactant and aeration treatments.

Effects of rootzone composition and irrigation regime on performance of velvet bentgrass putting greens. I. Turf quality, soil water repellency and nutrient leaching

Abstract The use of velvet bentgrass (Agrostis canina L.) on putting greens is limited by sparse knowledge on optimal maintenance. The objectives of this study were to determine the effects of rootzone composition (SS, straight sand; or GM, sand amended with 20% v/v garden compost) and irrigation regime (LF, light and frequent; or DI, deep and infrequent) on turfgrass visual quality, soil water repellency and nutrient leaching. The study was conducted from August 2007 to October 2009 on an experimental USGA green seeded in June 2007 with velvet bentgrass ‘Legendary’ at a coastal location in Norway (Landvik, 58° N). Better turf performance on GM than on SS was associated with less water repellency at most investigated depths in the 10-cm top layer, 88% lower nitrogen loss in the form of nitrate/nitrite during the first year after sowing, less injury caused by Microdochium nivale, and quicker recovery during both spring periods. A decrease in turf visual quality on SS receiving light and frequent irrigation in the second year was associated with strong water repellency in the mat layer. Compared with light and frequent irrigation, deep and infrequent irrigation resulted in better turf quality and lower drainage volumes.

Fungicide strategies for the control of turfgrass winter diseases

It is a goal of the turf industry to reduce fungicide use, maximize fungicide efficacy, and minimize the risk of fungicide resistance. Based on these integrated pest management principles and current fungicide labels, our objective was to elucidate the optimal use of propiconazole (Banner Maxx, 156 g a.i. L–1), azoxystrobin + propiconazole (Headway, 62.5 + 104 g a.i. L–1), and fludioxonil (Medallion TL, 104 g a.i. L–1) for the control of the winter-active pathogens Micordochium nivale and Typhula incarnata. Five experiments were conducted on greens and fairways at four sites in Norway and Sweden during the winter seasons of 2011–2012 and 2012–2013. Iprodione (Chipco Green, 250 g a.i. L–1), which was used in Scandinavia until 2009 and is still a widely used fungicide internationally, was included in two experiments. One application of propiconazole (468 g a.i. ha–1) or azoxystrobin + propiconazole (187.5 + 312 g a.i. ha–1) in October controlled 80% of the microdochium patch, and the control of both microdochium patch and typhula blight usually exceeded 90% if the first application of one of these fungicides was followed by at least one application of fludioxonil (375 g a.i. ha–1) before snow cover. After an initial application of propiconazole or azoxystrobin + propiconazole in October, two applications of fludioxonil in late autumn were more efficient in improving visual turf quality in spring than one application of fludioxonil in autumn plus one application of propiconazole just after snow melt in spring. Fludioxonil gave the same level of control of microdochium patch as iprodione despite a much lower use of the active fungicide ingredient. In conclusion, one application of propiconazole or azoxystrobin + propiconazole while the turf is still growing, followed by one applications of fludioxonil after growth cessation, will usually provide adequate control of the winter diseases in turfgrass.

Effects of root zone composition and irrigation regime on performance of velvet bentgrass putting greens. II. Thatch, root development and playability

Abstract The use of velvet bentgrass (Agrostis canina L.) on putting greens is limited by sparse knowledge on optimal maintenance. The objectives of this study were to determine the effects of rootzone composition (SS, straight sand, or GM, sand amended with 20% v/v garden compost) and irrigation regime (LF, light and frequent, or DI, deep and infrequent) on thatch formation, root development and playability. A study was conducted from August 2007 to October 2009 on a USGA green seeded in June 2007 with velvet bentgrass ‘Legendary’ at a coastal location in Norway (Landvik, 58° N). Compared with light and frequent irrigation, deep and infrequent irrigation improved root development in the 10- to 20-cm soil layer in the second year after sowing. A decrease in turf visual quality on SS receiving light and frequent irrigation in the second year was associated with low infiltration rate. Neither thickness nor content of organic matter in the mat layer were significantly affected by the treatments. A 20% higher surface hardness on SS vs. GM persisted only during the first year of the study.