Control of anthracnose in lentil using partial resistance and fungicide applications

Partial resistance and fungicide applications were evaluated in 1995 and 1996 for control of anthracnose in lentil (Lens culinaris) caused by Colletotrichum truncatum. Line 458-57 (partially resistant) and cv. Eston (susceptible) were planted in fields with a history of low, partial, and high anthracnose pressures. Unsprayed plots were compared with plots receiving a single application of either 1 or 2 kg a.i./ha of chlorothalonil at the 10- to 12-node stage, and two applications of 1 kg a.i./ha at the 10- to 12-node stage and 10 days later. Anthracnose severity in unsprayed plots was highest (78% for cv. Eston and 62% for 458-57) at high disease pressure, intermediate (62% for cv. Eston and 46% for 458-57) at partial disease pressure, and lowest (26% for cv. Eston and 15% for 458-57) at low disease pressure. Yield losses in unsprayed plots ranged from 26 to 57% in cv. Eston and 20 to 28% in 458-57, with the most significant losses occurring in cv. Eston at high disease pressure. Applications of chlorothalonil suppressed anthracnose and increased yields of both 458-57 and cv. Eston. However, at high disease pressure, anthracnose severity and yield losses in unsprayed plots of 458-57 were lower or similar to those of cv. Eston with a single application of 1 or 2 kg a.i./ha chlorothalonil. Also, under high disease pressure, yield losses of cv. Eston receiving one application of 1 or 2 kg a.i./ha chlorothalonil were significantly reduced compared with the control. The results suggest that partial resistance in 458-57 was effective in reducing disease severity and yield loss under high disease pressure.