Research Team:

1. Dr. Priti Patel (PI) - Assistant Professor, GUNI-MUIS
2. Dr. Sucheta Karande (Co-PI) - Associate Professor, GUNI-MUIS
3. Dr. Jasmee Patel (Co-PI), Assistant Professor (Plant Pathology), GUNI-KKIASR

Objectives:

• To survey for the incidence of Alternaria leaf spot disease of cotton in Mehsana, Banaskantha, Sabarkantha and Patan districts of North Gujarat and to assess the cultural and pathogenic variations among the causative isolates.
• To identify the effective native antagonist(s) for the management of the leaf spot disease and to assess the effect due to application of individual and combination of antagonists on the biometrics and leaf spot of cotton.
• To develop an integrated management practice for the effective management of cotton leaf spot disease
• To study the induction of defense related enzymes in cotton plants pretreated with biocontrol agents, organic amendment and challenge inoculated with the pathogen

Alternaria leaf spot, also known as Alternaria leaf blight, is a fungal disease of cotton (Gossypium spp.) caused by Alternaria macrospora Zimm. First identified in the United States in 1918, the disease has since been reported worldwide, including in India where it is prevalent in Maharashtra, Gujarat, and Karnataka. Though historically considered minor in some regions like Arizona, the disease is frequently associated with senescing tissues and plants under physiological stress. Cotton, often referred to as “white gold,” is a critical commercial crop contributing significantly to the textile industry, particularly in India, where it occupies 5% of the total cultivated area. Among the 30 reported diseases of cotton in India, 17 are of fungal origin, with Alternaria leaf spot being a notable example. The disease affects all four cultivated Gossypium species and is primarily seed-borne, though transmission can also occur via soil, air, and collateral hosts. Symptoms include seedling wilt, leaf lesions, and boll spots. Effective disease management strategies include the use of biocontrol agents such as Pseudomonas fluorescens, Bacillus subtilis, and Trichoderma spp., as well as botanical extracts from Allium sativum, Azadirachta indica, and other plants. Studies have demonstrated the efficacy of these agents in reducing mycelial growth and disease severity. Additionally, resistant Bt cotton genotypes have been identified, offering potential for integrated disease management. Recent research by Yi Zhu et al. (2019) has further explored the etiology of Alternaria leaf spot in Southern New Mexico, contributing to the global understanding of this important cotton disease.