~ 998 ~ International Journal of Chemical Studies 2021; 9(1): 998-1000 P-ISSN: 2349–8528 E-ISSN: 2321–4902 www.chemijournal.com IJCS 2021; 9(1): 998-1000 © 2021 IJCS Received: 14-11-2020 Accepted: 15-12-2020 Bhavik K Patel Main Cotton Research Station MCRS, Navsari Agricultural University (NAU), Surat, Gujarat, India Prashant B Sandipan Main Cotton Research Station MCRS, Navsari Agricultural University (NAU), Surat, Gujarat, India SK Chawada Krushi Vigyan Kendra, Navsari Agricultural University (NAU), Surat, Gujarat, India RK Patel Krushi Vigyan Kendra, Navsari Agricultural University (NAU), Surat, Gujarat, India Corresponding Author: Bhavik K Patel Main Cotton Research Station MCRS, Navsari Agricultural University (NAU), Surat, Gujarat, India Evaluation of different biocontrol agents against Fusarium oxysporum f. sp. vasinfectum (FOV) under in vitro condition of South Gujarat Bhavik K Patel, Prashant B Sandipan, SK Chawada and RK Patel DOI: https://doi.org/10.22271/chemi.2021.v9.i1n.11356 Abstract Cotton (Gossypium spp.) is one of the most important fiber crops playing a key role in economic globe. The symptoms of Fusarium oxysporum f. sp. vasinfectum is both seed borne and soil borne and colonizes the roots and vascular system of susceptible cotton cultivars, causing root and vascular discoloration, wilting and sometimes death of the plant. As the wilt disease is becoming an important and destructive disease in the cotton growing areas. Here in this experiment, in vitro evaluation of native isolated antagonists were tested under dual culture method revealed the growth inhibition of test fungus (Fusarium oxysporum f. sp. vasinfectum) by the test antagonists. Five different biocontrol agents were screened in vitro for the growth inhibition of Fusarium oxysporum f. sp. vasinfectum by dual culture method and found that all the Trichoderma isolates were more effective than bacterial isolates. Among the Trichoderma isolates Trichoderma harzianum showed most promising results compared to other isolates. The highest growth inhibition of Fusarium oxysporum f. sp. vasinfectum was caused by Trichoderma harzianum (71.70%). While, the least growth inhibition was showed by Bacillus substillis (47.29%). Keywords: Cotton, bioagent, inhibition, FOV Introduction In India, the productivity of cotton is very low due to many constraints including diseases. The most common cotton diseases reported in India are wilt (Fusarium oxysporum f. sp. vasinfectum (G.F. Atk.) W.C. Snyder & H.N. Hansen), root rots (Rhizoctonia bataticola (Taubenh.), verticillium wilt (Verticillium dahliae Kleb.), anthracnose (Colletotrichum gossypii Southworth. or C. capsici (Syd.) Butler & Bisby), grey mildew (Ramularia areola G.F. Atk.), blackarm (Xanthomonas campestris pv. malvacearum (Pammel) Dowson), leaf blight (Alternaria macrospora Zimm) and leaf curl (Cotton leaf curl virus). Among them wilt, root rot and verticillium wilt are soil borne diseases of cotton and anthracnose, grey mildew, black arm and leaf blight are foliar diseases of cotton (Ramod, 2016) [10] . Among these diseases, Fusarium wilt caused by Fusarium oxysporum f. sp. vasinfectum (FOV) is one of the most important and serious diseases. It was the first vascular wilt described by Atkison (1892) [2] and this disease is still causing enormous yield losses in several parts of the world and remains a threat to cotton production in the future (Feng et al., 2000) [6] . The disease is responsible for serious losses to the crop in the central and western India on a large scale and on almost all the cultivated varieties of both G. arboreum and G. herbaceum, the two indigenous species, especially in black cotton soils of Maharashtra, Madhya Pradesh, Karnataka and Gujarat. At present the most of cultivated cultivars are susceptible to wilt disease (Fusarium oxysporum f. sp. vasinfectum) and caused 54-60% yield loss (Anon., 2003) [1] because of reduced stand, stunted growth, small bolls and poor lint quality. The symptoms of Fusarium oxysporum f. sp. vasinfectum is both seed borne and soil borne, and colonizes the roots and vascular system of susceptible cotton cultivars, causing root and vascular discoloration, wilting and sometimes death of the plant (Chen et al., 1985, Hillocks, 1992 and Davis et al., 1996) [4, 9, 5] .