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.