Effects of Host, Inoculum Concentration, Wetness Duration, Growth Stage, and Temperature on Anthracnose of Lentil

The effects of concentration of conidia, duration of the wetness period, plant growth stage, and temperature on the development of anthracnose (Colletotrichum truncatum) on lentil (Lens culinaris) were assessed in growth-chamber and greenhouse studies using cv. Indianhead and line 458-57, which have partial resistance, and susceptible cv. Eston. Each genotype was assessed for incubation period (IP), latent period (LP), number of lesions (LN) per stem, and disease severity (DS). Both IP and LP decreased linearly with increasing conidial concentration, wetness duration, and temperature. Both IP and LP also became progressively shorter as the plants aged between 2 to 6 weeks and increased between 6 to 8 weeks after seeding. Both LN and DS increased linearly with increasing inoculum concentration, wetness duration, and temperature. Both LN and DS also increased with plant age between 2 to 4 weeks and decreased between 4 to 8 weeks. The growth stage and temperature required for optimal disease development ranged, respectively, from 4 to 6 weeks and 20 to 24°C when plants were inoculated at a concentration of 4 × 10⁴ conidia/ml and provided with a wetness period of 24 h. Generally, cv. Indianhead and line 458-57 had significantly longer IP and LP and lower LN and DS than cv. Eston.