Sugar beet root-rot illnesses caused by Rhizoctonia: pathogen diversity, pathophysiology

Sugar beet, a biennial root crop, is primarily grown in temperate regions and is increasingly recognized in the biofuel industry as a raw material for ethanol production. It is susceptible to over 20 fungal and 10 bacterial pathogens, which can cause severe damage to the plant and result in significant yield losses, affecting the profitability of growers. One such pathogen is Rhizoctonia spp., a soil-borne fungus that causes root and crown rot diseases and losses during storage periods. Rhizoctonia species live in the soil or on decomposing and drying sections of plants as saprophytes or weak parasites. Factors promoting the disease's development include heavy rainfall, organic-rich soil, heavy soils, high moisture content, temperatures between 35° and 40°C, and a pH of 6.0 to 8.0. Poor drainage systems in the soil also contribute to the development of the disease. Crown rot, first discovered in 1858, is one of the common and devastating diseases that affect sugar beet crops. The causative agent of this disease is Rhizoctonia solani, which can survive under soil for a long time and is particularly severe in heavy soils and soils with inadequate drainage systems.