Physiological Studies of Fusarium oxysporum Causing Root Rot of Mulberry in Maharashtra

Abstract

A Scientific Investigation of mulberry root rot was conducted in 18 districts of Maharashtra State to assess disease incidence in farmers' fields. The disease incidence was recorded based on the number of infected or dead plants showing typical root rot symptoms. The pathogen was isolated from infected mulberry roots and identified as Fusarium oxysporum through morphological characteristics. Physiological studies were carried out to determine the nutritional requirements of the pathogen using Czapek’s Dox agar medium supplemented with different carbon, nitrogen, phosphate, amino acids, vitamins, salts, oxides, and trace elements. Among carbon sources, D-glucose, maltose, mannitol, D-xylose, and lactose supported maximum growth, while D-galactose was least favourable. Calcium nitrate, potassium nitrate, magnesium nitrate, and urea were most effective nitrogen sources, whereas ammonium salts were less supportive. Di-potassium hydrogen orthophosphate and calcium phosphate enhanced growth among phosphate sources. Several amino acids, including L-cysteine, L-glutamic acid, glycine, and L-lysine, promoted abundant growth. Inositol and thiamine were found to be the most favourable vitamins, while others such as folic acid and niacin were less effective. Magnesium chloride showed growth comparable to control among salts. Molybdenum oxide and ferric oxide were stimulatory among oxides, while magnesium sulphate, manganese sulphate, and sodium sulphate enhanced growth among trace elements. These findings highlight the wide physiological adaptability of F. oxysporum and provide insights into its nutritional ecology, which may be useful in devising management strategies for mulberry root rot disease.