Influence of nutrient medium and air temperature on development of sclerotia of Sclerotinia sclerotiorum (Lib.) de Bary in laboratory

The research was conducted to study the peculiarities of growth and development of sclerotia of the fungus S. sclerotiorum isolated from winter rapeseed and white mustard plants growing in the Western Ciscaucasia to develop the most effective measures to protect these crops from the disease. The experiments were conducted in laboratory conditions in 2024. The sclerotia of the fungus S. sclerotiorum, collected in 2023 from the affected stems of the white mustard variety Raduga (Labinsky district) and in 2024 from the affected stems of the winter rapeseed variety Loris (Krasnodar), were the object of this study. The soils are chernozems with different degrees of leaching. The laboratory study included four variants, each of which was examined using 10 S. sclerotiorum sclerotia: a nutrient semi-synthetic medium PGA (potato-glucose agar) at an air temperature of 25 °C; a nutrient semi-synthetic medium PGA at an air temperature of 27 °C; a Czapek’s nutrient synthetic medium at an air temperature of 25 °C; and a Czapek’s nutrient synthetic medium at an air temperature of 27 °C. Studies of the biological properties of S. sclerotiorum under laboratory conditions are preferably carried out using the PGA nutrient medium. The rate of pathogen sclerotia germination on PGA is higher than the rate of mycelium growth on Czapek’s agar: 1.5 times on average at 25 °C and 3.6 times on average at 27 °C. Using Czapek’s agar to cultivate S. sclerotiorum isolates slows the formation of new fungal sclerotia and reduces their number by 28–35 %.

winter rapeseed (Brassica napus L.), white mustard (Sinapis alba L.), white rot, nutrient medium, air temperature, growth of mycelium