EPIDEMIOLOGICAL ANALYSIS OF THE EFFECTS OF BIOFUMIGATION ON THE SPREAD OF RHIZOCTONIA SOLANI IN SUGAR BEET

Abstract : Brown root rot, a soil-borne disease caused by Rhizoctonia solani, is becoming more frequent in some sugar beet growing areas. In some cases, this disease can have a significant economic impact and it can be quite difficult to control. Rhizoctonia solani is a saprotrophic polyphagous fungus linving into the soil. During the period when the crop is present it can initiate an epidemic from residuals soil inoculum and spread through secondary infection from plant to plant creating well-documented bare patches of disease. In a disease management perspective biofumigation could present an opportunity to exploit the intercrop period preceding the beet crop. In fact, some scientific works have demonstrated that growing and incorporating mustard could decrease the impact of R. solani on sugar beet. However, from an epidemiological point of view, biofumigation has several effects on the pathogen, some positive and others nega-tive. The balance between these effects could explain the level of success or failure of this biological treatment. Several experimental and modelling results are presented here to show how R. solani spreads in a sugar beet field and how biofumigation affects the epidemic. These research results have the potential to provide strategies for managing the disease.