Epidemiological Evaluation and Varietal Screening of Alternaria Blight of Linseed

Linseed (Linum usitatissimum L.) is a crucial oilseed crop with significant economic and health implications. The study investigated the impact of sowing dates and environmental factors on Alternaria blight disease development and grain yield. Field trials were conducted during the Rabi season 2022-23 at Birsa Agricultural University, Ranchi, using the linseed variety ‘T 397’. Sowing dates were staggered at seven days interval from 4th November to 16th December, and subsequently disease severity and environmental parameters recorded. Early sowing on 4th November resulted in the lowest disease severity of 13.2% and highest grain yield of 1052.31 Kg/ha, while late sowing on 16th December recorded the highest disease severity of 36.5% and lowest yield of 817.99 Kg/ha. Environmental conditions (temperature: 7.7-26.0°C, relative humidity: 69.5-86.3%, sunshine: 8.0-8.2 hrs) significantly influenced disease development. Statistical analysis revealed significant correlations between percent disease index (PDI) and minimum temperature, evening relative humidity, morning relative humidity, and sunshine hours. Varietal screening of 118 linseed entries showed that 52 entries were resistance to Alternaria blight. The study highlighted the importance of early sowing and varietal selection in managing Alternaria blight in linseed cultivation.