Submitted to: Sugarbeet Research and Extension Reports
Publication Type: Proceedings
Publication Acceptance Date: 1/27/2003
Publication Date: 1/31/2003
Citation: WEILAND, J.J. A SURVEY FOR THE PREVALENCE AND DISTRITUBTION OF CERCOSPORA BETICOLA TOLERANT TO TRIPHENYLTIN HYDROXIDE AND RESISTANCE TO THIOPHANATE METHYL IN 2002. SUGARBEET RESEARCH AND EXTENSION REPORT,. COOPERATIVE EXTENSION SERVICE, NORTH DAKOTA STATE UNIVERSITY. 2003. V. 33. P. 241-246.
Interpretive Summary: Crop protection involves the use of crop management strategies that include the planting of robust varieties and proper plant husbandry. Fungicide use to reduce plant diseases remains a valuable means to protect crops from yield losses. When fungi that cause plant disease become resistant or tolerant to the fungicides used to control them, growers must be alerted and changes control practices. The following study is part of an ongoing survey to monitor resistance to fungicides in the fungus that causes leaf spot disease in the nation's sugarbeet crop.
Technical Abstract: Cercospora beticola populations in Minnesota and North Dakota were evaluated for resistance and tolerance to fungicides commonly used in the region. For the growing season of 2002, samples exhibiting tolerance to triphenyltin hydroxide ranges from 35-85% (0.2 ppm level) and 11-52% (1.0 ppm level). Samples exhibiting resistance to the benzimidazole fungicide thiophanate methyl tested at the 5 ppm level ranged from 40-76%. After declining in recent years, the number of samples surveyed in 2002 that exhibited resistance to thiophanate methyl increased in the southern Minnesota growing area. Tolerance to the triazole fungicide tetraconazole increased in 2002 from 2001 level, ranging from 3-15% of the samples tested at the 2 ppm level and 0-11% of the samples tested at the 10 ppm level.