Effect of temperature, seeding date, fungicide seed treatment and inoculation with Fusarium avenaceum on seedling survival, root rot severity and yield of lentil

Abstract

Early seeding of lentil is necessary on the northern prairies to ensure that the crop has time to mature. However, planting into cold soils in spring results in slow germination, which may predispose seedlings to infection by soil-borne pathogens. In a controlled-environment study of the impact of temperature on infection of lentil seedlings (cv. Eston) byFusarium avenaceum, root rot symptoms were most severe at warm temperatures (20° to 27.5 °C) and declined in warmer or cooler soils. Field plots were seeded on three dates, which were spaced about 2 wk apart between early May and early June in four station years. Seedling emergence was most consistent and seed yield was highest in three of four sites at the second seeding date. Emergence and yield were substantially lower for the latest seeding date. Inoculation with F. avenaceum reduced establishment and seed yield. Seed treatment with Crown (thiabendazole and carbathiin) improved seedling survival, reduced root rot severity and increased seed yield relative to the inoculated control. Vitaflo-280 (thiram and carbathiin) also improved establishment and yield, but the effect was not as strong or consistent. Treatment with Raxil (tebuconazole) and Apron (metalaxyl) had no effect. The pathogenicity of aggressive isolates of F. avenaceum from lentil on a range of crop species was evaluated. All crops were susceptible to some degree, which indicates that the pathogen, once established, is likely to persist in a field for some time. This study demonstrated that early planting was required for maximum yield, that certain isolates of F. avenaceum were pathogenic on a wide range of hosts, and that seed treatment can be used to minimize losses from seedling blight and root rot in lentil. Key words: Lentil (Lens culinaris Medikus), Fusarium avenaceum, root rot, seeding date, thiabendazole, carbathiin, thiram, tebuconazole