Successful Management of Cercospora Leaf Spot of Sugar Beet.

The sugar beet industry has a total economic activity of $3 billion in Minnesota and North Dakota. One of the major limiting factors for sugar beet production is the foliar disease, Cercospora leaf spot caused by the fungus Cercospora beticola. Cercospora leaf spot is one of the most destructive foliar diseases of sugarbeet worldwide and results in significant reduction in root yield, recoverable sugar, and percent sucrose, and increases concentration of impurities resulting in higher processing costs. In 1998, growers at one of the three largest sugar cooperative lost $45 million because of ineffective disease control and growers surveyed indicated Cercospora leaf spot as their worst production problem. Collaborative research, funded by growers, was conducted to determine how best to control Cercospora leaf spot with experimental and labeled fungicides. Research sites were used for demonstration at field days. Research results were disseminated to growers, other educators, and advisors of growers at seminars, using research reports, bulletins, and a weekly radio program conducted during the growing season. Growers quickly adopted the research-based recommended practices and successfully controlled Cercospora leaf spot, saving millions of dollars in the process. Fungicide usage was reduced by 58% from an average of 3.74 applications in 1998 to 1.56 applications in 2009, disease control cost was reduced by $14 million, and growers who considered Cercospora leaf spot as their worst production problem decreased from 36% to less than 1%.