Yield loss assessment due to Alternaria blight disease in rapeseed and mustard: Yield loss due to alternaria Blight in rapeseed and mustard

Abstract

Alternaria blight disease in rapeseed-mustard caused by Alternaria brassicae and A. brassicicola is the important disease of rapeseed-mustard crop in India. The experiment was conducted to assess the yield losses due to Alternaria blight in different released cultivars of rapeseed-mustard during Rabi 2016-17 and 2017-18 at Student’s Instructional Farm of the A. N. D. University of Agriculture and Technology, Kumarganj, Ayodhya by planting 15 varieties of the rapeseed-mustard namely RH-749, Pusa gold, KBS-3, GSL-5, GSL-2, Pusa mustard-27, Jhumka, Anuradha, PT-30, T-27, PM-25, Pusa aditya, PT-303, Sheetal, TMLC-2 in six replications (three protected and three unprotected under natural conditions). Seed of each variety were treated with Apron @ 6g/kg and three spray of Trifloxystrobin 25% + Tebuconazol 50% (Nativo) @ 0.08% in protected replication. The minimum disease severity on leaves and pods were recorded in protected and unprotected conditions in the variety GSL-5 (2.65% and 16.26%), (1.75% and 6.32%) followed by GSL-2 (3.20% and 19.72%), (1.89% and 6.75%) Pusa aditya (6.91% and 19.89%), (2.18% and 7.20%) and Sheetal (7.99% and 23.13%), (3.21% and 7.43%), respectively. On the basis of mean values the minimum infection rate on pods was recorded GSL-2 (0.083 and 0.042) followed by Pusa aditya (0.089 and 0.045), respectively. The minimum AUDPC on leaf under protected and unprotected was recorded on cultivar GSL-5 (76.40 and 496.20) followed by GSL-2 (88.80 and 596.85), Pusa aditya (205.35 and 588.25), Sheetal (241.70 and 717.30) and RH-749 (244.95 and 950.85), respectively. Whereas the minimum AUDPC on pod was recorded with variety GSL-5 (32.10) and Pusa aditya (200.25) followed by [GSL-2 (34.65) and Sheetal (206.65)], [Pusa aditya (39.35) and RH-749 (566.41)] and [Sheetal (60.95) and Pusa mustard-27 (741.75)], respectively. The maximum yield avoidable loss (%) was recorded T-27 (46.67%) followed by Jhumka (44.53%, Anuradha (40.00%), KBS-3 (38.77%) and Pusa gold (34.13%), respectively. Minimum avoidable loss (%) was recorded on cultivar GSL-5 (11.09%) followed by Anuradha (14.36%), GSL-2 (17.73%), RH-749 (17.90%) and Pusa aditya, respectively. In present investigation out of 15 genotypes examined for blight resistance, GSL-5, Pusa Aditya, Sheetal and GSL-2 exhibited good level of partial resistance i.e. moderately resistance. Other 11 varieties RH-749, Pusa gold, Pusa mustard-27, Jhumka, Anuradha, PT-30, PT-303, T-27, KBS-3, TMLC-2 and PM-25 were susceptible based on the mean basis severity (PDI), reduced apparent infection rate and lesser value of AUDPC.