Integrated Management of Cottonball

Cottonball, caused by the fungus Monilinia oxycocci, is an economically important disease on many cranberry marshes in Wisconsin. Cottonball has also been described in the Pacific Northwest and southeastern Canada, but losses in these areas have generally been minor. For reasons that are not known, cottonball has increased in importance in Wisconsin over the past 30 years. In recent years, about 20% of bearing acreage has been treated with fungicides specifically for cottonball control. Where cottonball occurs, the incidence of infected fruit is typically 2-10%, but it can exceed 40% if left unchecked. Control of cottonball has depended largely on fungicides. As we gather more information on the interaction of M. oxycocci and cranberry in the marsh environment, we are developing safer and more sustainable means of controlling this disease.