The occurrence of powdery mildew on crested hairgrass in different growing conditions

Crested hairgrass (Koeleria gracilis Pers., syn. K. macrantha (Ledeb.) is classed as a good turfgrass. A first cultivar 'Ilo', released by the Jõgeva Plant Breeding Institute was entered into the Estonian Variety List in 1997. Seed production agrotechnics of crested hairgrass cultivar 'Ilo' was studied in field experiments at the Jõgeva PBI in 2001-2005. It has been recognized that the incidence and severity of disease level and seed yield losses are influenced by pathogens and weather. For four seasons the severity of the occurrence of powdery mildew (Blumeria graminis DC.) was investigated in these field trials. Disease infection was scored by visual assessment of full plants at shooting, flowering and seed ripening stages and at post- harvest re-growth on a 5-point scale. Infection was more intensive in the flowering stage: 2.6 points (2002), 3.0 (2003) and 3.7 (2004). Infection at post-harvest re-growth was assessed at 3.1 points in 2002.