SHARMA, P.N.SHARMA, PRATIBHA2021-03-022021-03-022020-10-29https://krishikosh.egranth.ac.in/handle/1/5810161869Anthracnose, caused by Colletotrichum lindemuthianum is one of the highly variable pathogen that affects common bean production and durability of the resistant varieties deployed over time and space. The knowledge of pathogen population in a given area determines durability of resistant varieties. The shift in cultivation from inorganic farming to organic farming during the past one decade emphasizes the hunt for organic inputs that can be used to manage the plant diseases. The present study was conducted to determine the shift in virulence of C. lindemuthianum and to assess bean germplasm for sources of resistance against the prevalent virulences. In addition, evaluation of various organic bioformulations and biocontrol agents was also attempted for eco-friendly management of the disease. Twenty five isolates of C. lindemuthianum collected from commercial bean growing areas of six districts of Himachal Pradesh were categorized into 23 physiological races on the CIAT bean differential cultivars. Out of the 23 identified races in this study, five races viz., 3, 87, 211, 503 and 631 resembled the previously known races in the respective areas of their occurrence, while the remaining eighteen races were novel to various production areas explored in this study. Two hundred and fourteen common bean accessions screened against three new races (437, 198 and 1015) of C. lindemuthianum revealed the presence of few resistance sources amongst exotic and indigenous germplasm. Five common bean accessions namely EC 500364, EC 500821, EC 400454, EC 400408, and IC 423433 were resistant to all the three races (198, 437, 1015). While three exotic varieties having known Rgenes Cornell 49242 (Co-2), AB 136 (Co-6 and co-8) and G 2333 (Co4, Co5 and Co7) were found resistant to all 23 races identified in this study. Out of six bio-control agents viz., T. harzianum 11, T. harzianum (TH-5), T. koningii (DMA-8), T. koningii (JMA-11), T. viride and bacteria Pseudomonas fluorescens, T. koningii (DMA-8) caused maximum myceilal growth inhibition of 53.69% which statistically at par with T. harzianum(TH-11) (49.14 per cent). Jeevamrit was most effective bioformulation resulting in 100 per cent mycelial growth inhibition at 4% and above concentrations followed by cow urine and Tamerlassi where complete mycelial inhibition was recorded at 6, 8 and 10% concentrations. Under greenhouse conditions, seed treatment of the infected seeds with Jeevamrit (@4%) was found most effective in controlling seed borne infection (75.60%) whereas same formulation when applied after inoculation of the pathogen resulted in almost equal control (75.34%). However, Bavistin as a check showed 100% disease control in both cases. The comparative seed germination and seed vigour index was found to be higher in case of Jeevamrit treated seeds among the other tested bioformulations. Similarly, the disease severity was also minimum in Jeevamrit treated seeds.EnglishThesis