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United States Department of Agriculture

Agricultural Research Service

Title: Cercospora Resistance and Yield in Commercial Hybrids

Authors
item Smith, Garry
item Campbell, Larry

Submitted to: Sugarbeet Research and Extension Reports
Publication Type: Research Notes
Publication Acceptance Date: January 15, 1995
Publication Date: N/A

Interpretive Summary: Cercospora leaf spot is one of the most widespread and destructive foliar diseases of sugarbeet. Combining leaf spot resistance with high yield has been a difficult task for sugarbeet breeders. Forty commercial hybrids, all recommended for Cercospora-threat areas, were grown in a Cercospora-free and diseased environment in 1991 and 1992. The trial in the diseased environment confirmed the value of resistance in the presence of the disease. In the absence of the disease, root yields increased 2.7 Mg / ha for each increment of increased susceptibility characteristic of the hybrid. Despite the limited efforts and / or success in developing resistant commercial hybrids, the demonstrated ability of Cercospora to produce fungicide resistant strains and the possibility that effective fungicides will not be available provide incentives to seek genetic resistance through breeding efforts.

Technical Abstract: This report documents the difficulty breeders have experienced in combining resistance to Cercospora leaf spot (causal agent Cercospora beticola Sacc.) with high yield in sugarbeet (Beta vulgaris L.). Forty commercial hybrids, all recommended for Cercospora-threat areas, were grown in a Cercospora-free and a diseased (inoculated) environment in 1991 and 1992. A 2.9 Mg/ha decrease in root yield associated with each increment increase in susceptibility confirmed that under a severe epiphytotic (1991) Cercospora resistance provided substantial protection. Under less-severe disease conditions (1992) there were no apparent relationship between yield and resistance, suggesting that the benefits of resistance were similar to the yield potential sacrificed to obtain the resistance. In the absence of the disease, root yields increased 2.7 Mg/ha for each increment of increased susceptibility. There was no evidence of association between sucrose concentration and resistance in the Cercospora-free environment. Despite the limited efforts and/or success in developing resistant commercial hybrids, the demonstrated ability of Cercospora to produce fungicide-resistant strains and the possibility that effective fungicides will not be available provide incentives to seek genetic resistance through breeding efforts.

Last Modified: 8/29/2014
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