bio ecology and management of reniform nematode wilt disease complex in cotton

Abstract

ABSTRACT newlineBIO ECOLOGY AND MANAGEMENT OF RENIFORM NEMATODE WILT newlineDISEASE COMPLEX IN COTTON newlineBY newlineC. MATHIVATHANI, M.Sc., newlineDegree : Doctor of Philosophy newlineChairperson : Dr. K. POORNIMA, Ph.D., newlineProfessor and Head, newlineDepartment of Nematology, newlineTamil Nadu Agricultural University, newlineCoimbatore 641 003. newline2019 newlineCotton is an influential crop grown globally for its natural fiber and seed. Among the newlineparasitic nematodes infesting cotton, reniform nematode is dominant and limits the newlinecommercial quality of the lint worldwide including India. The severity is provoked by the newlineassociation of wilt pathogen, Fusarium oxysporum f. sp. vasinfectum leading to disease newlinecomplex in cotton. As all the chemical conventional methods used for the management of newlinedisease complex was expensive and hazardous, investigation on ecofriendly and cost newlineeffective bio agents were investigated for management studies. newlineRandom survey conducted in cotton growing districts of Tamil Nadu viz., Salem, newlineCoimbatore, Tuticorin, Perambalur, Trichy and Madurai revealed that the maximum newlinenematode population was observed in Tuticorin district and greater wilt per cent at Salem newlinedistrict. Soil type experiment revealed that sandy and sandy loam soil with larger pore size newlineshowed maximum nematode multiplication compared to other soil types. newlineThe nutrient and pH analysis in soil showed higher nematode multiplication at newline12.5 ppm total phosphorus, 0.283 per cent total nitrogen, 148 ppm total potassium and newlinefavorable soil pH for nematode reproduction ranged from 7.0 to 7.8. The moisture experiment newlinewith 10, 15, 20, 25, 30, 35 and 40 per cent showed that 30 per cent moisture in pots recorded newlinegreater nematode population in soil and root samples under pot condition. newlineBiology and life cycle studies conducted in vitro and in vivo revealed that life cycle of newlinereniform nematode was completed in 7 to 23 days and the embryonic development took about newline72 - 96 hours. The morphometric characters of immature females, males and adult females newlinewere measured using stage and ocular micrometer. M