Under dry conditions sclerotia have retained their viability more than 10 years. Control of Sclerotinia diseases must be accomplished by using a combination of cultural and chemical means. To date resistant cultivars have not been developed with sufficient resistance to make this a feasible means of control. Activity of these pathogens is favored by high soil moisture, high air humidity, and cool temperatures. Research has shown that the use of drip irrigation can dramatically reduce both factors near the soil surface and thereby reduce the incidence of Sclerotinia diseases.
Crop rotation is another important tool in reducing the sclerotial population in the soil.
Lettuce is highly susceptible to both S. sclerotiorum and S. minor . Rotation with any other crop will help reduce S. minor , but may not reduce the S. sclerotiorum population. S. sclerotiorum can be reduced by planting such non-host crops as corn, small grains or grasses. It should be mentioned that a non-crop fallow period does little to reduce the sclerotial population. The wetting and drying of soil that occurs during a cropping cycle is much more effective in reducing the number of active sclerotia in the soil.