Evaluating an isotonic aqueous formulation of Chaetomium globosum Kunze for the management of potato black scurf disease caused by Rhizoctonia solani Kuhn in India

Black scurf in potatoes is caused by the pathogenic fungus Rhizoctonia ( R. ) solani , and is a serious disease that results in both quantitative and qualitative losses in potato yields worldwide. To manage this disease in an eco-friendly manner, isotonic aqueous formulation of Chaetomium ( C. ) globosum was developed and tested for disease control efficacy under both glasshouse and field conditions. A total of 40 fungal isolates was tested in vitro, among which C. globosum Cg-6 exhibited maximum inhibition potential of R. solani (60%) and an increased vigor index (1960.0) in potatoes assessed by the roll towel method. The isotonic solution amended with glycerol supported a maximum fungal population (1.9 × 10 7 cfu per ml) up to 6 months and retained the most antagonistic activity compared to other preservatives tested (glycine, trehalose, and polyvinylpyrrolidone). Results showed that combined application of C. globosum Cg-6 as a tuber treatment, soil application, and foliar spray effectively reduced the incidence of black scurf (7.6%) and enhanced the germination (94%) of tuber under glasshouse conditions. During field trials, a treatment consisting of C. globosum (TNAU Cg-6; 5 ml per kg of seed), soil application (5 ml per kg of farm-yard manure), and foliar application of 5 ml per litre of water (6 sprays), was shown to reduce black scurf in potatoes and enhanced tuber yield.