Field Assessment, Isolation and Morphological Characterisation of Fusarium oxysporum f sp. vasinfectum Causing Wilt in Cotton (Gossypium spp.) in Hanumangarh District, Rajasthan, India

Abstract

Cotton (Gossypium spp.) is an economically important crop grown globally for its natural fibre and seeds, and its productivity is significantly affected by various biotic stresses. Fusarium wilt caused by Fusarium oxysporum f. sp. vasinfectum (FOV) is a major constraint to cotton production in arid regions of India. The study is focused on disease incidence, distribution, and pathogen variability across major cotton-growing regions of North Rajasthan during Kharif 2023–24 and 2024–25. Disease incidence ranged from 10.8% to 31.2%, with higher levels in Hanumangarh, Sri Ganganagar, and Bikaner, associated with sandy soils, low organic matter, and imbalanced fertilization. Lower incidence in Jhunjhunun and Sikar was associated to crop rotation and balanced nutrient management. Six isolates of the pathogen were obtained from infected roots and characterized morpho-culturally. Significant variability was observed in colony morphology, pigmentation, growth rate (46.82–67.86 mm day⁻¹), and spore dimensions, although all isolates showed typical Fusarium features. The results indicated a diverse and adaptable pathogen population, highlighting the need for integrated management practices, including crop rotation, organic amendments, and balanced fertilization, for sustainable control of Fusarium wilt in cotton-growing regions.