Impact of seedbed utilization and fungicide application on severity of net blotch [Pyrenophora teres] and production of barley

Abstract

Limited information is available regarding the impact of seed placement and row spacing, and their interaction with fungicides, on leaf diseases and agronomic performance of barley. A direct-seeding field experiment was conducted at three locations in Canada (Lacombe and Beaverlodge (Alberta) and Melfort (Saskatchewan)), in 1999–2000, to evaluate the effect of three seedbed utilization treatments and six foliar fungicide timing and rate treatments on disease severity and production characteristics of barley. Seedbed treatments included row spacing at 23 or 30 cm with a knife opener, or spread bands with a 28-cm sweep and a 23-cm row spacing. Fungicide treatments included full and split applications of propiconazole at Zadoks growth stages (GS) 12, 37, and 58 with an untreated control. Severity of net blotch [Pyrenophora teres] was higher for the 23- and 30-cm distinct row spacings compared with the spread-band placement using sweeps. The interaction between seed placement and fungicide application was not significant for net-blotch severity, indicating that disease response to fungicide did not vary with seed-placement configuration. Overall, grain yield was affected by seed placement, with the spread band having slightly higher yield, especially when compared with the 30-cm distinct row spacing, but the response to seed placement did vary over year × location combinations, and with fungicide treatment. Kernel weight, plumpness, and test weight were greatest for the spread-band placement, although this response varied among year × location combinations. Fungicide applications at late growth stages (GS 37 and GS 58) reduced net-blotch severity and increased grain yield and kernel quality, whereas applications at GS 12 generally had a limited impact. Planting in distinct rows may have resulted in higher disease severity and lower kernel weight, plumpness, and test weight by facilitating spore dispersal and subsequent net-blotch development compared with the spread-band placement.