Vol. 8, Special Issue 7, Part A (2024)

Abstract: Castor is an important non-edible oilseed crop having exceptional oil characteristics for the chemical industry. The crop hosts several diseases, among them grey mold is the most destructive one hindering its productivity. The primary target of the fungus are inflorescence and capsules at any developmental stage. The fungus was isolated from infected castor raceme by standard tissue isolation technique and identified as Botryotinia ricini by comparing with the original descriptions. The pathogenicity was established by proving Koch’s postulates. PCR amplification with C729 +/- specific primers revealed amplicon of 600bp confirming the molecular diagnosis of B. ricini. The physiological studies showed that, pH of 4.0 to 4.5 and temperature around 23 to 25 °C were favourable for the pathogen growth and development in both solid and liquid medium. Seed transmission studies revealed that transmission of the fungus from seed to seedling was facilitated by the cotyledon tip remaining attached to the seed coat after germination, allowing the fungus to inoculate the freshly emerged seedlings.