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United States Department of Agriculture

Agricultural Research Service

Research Project: BREEDING SELECTION AND MOLECULAR CHARACTERIZATION FOR IMPROVED SUGAR BEET GERMPLASM

Location: Sugarbeet and Bean Research

Title: Influence of glyphosate on Rhizoctonia crown and root rot (Rhizoctonia solani) in glyphosate-resistant sugarbeet (Beta vulgaris L.)

Authors
item Barnett, Kelly -
item Sprague, Christy -
item Kirk, William -
item Hanson, Linda

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 20, 2011
Publication Date: January 1, 2012
Citation: Barnett, K.A., Sprague, C.L., Kirk, W.W., Hanson, L.E. 2012. Influence of glyphosate on Rhizoctonia crown and root rot (Rhizoctonia solani) in glyphosate-resistant sugarbeet (Beta vulgaris L.). Weed Science. 60(1):113-120.

Interpretive Summary: Previous greenhouse studies with a non-commercial glyphosate-resistant sugarbeet variety indicated that susceptibility to Rhizoctonia crown and root rot could increase after glyphosate was applied. Greenhouse and field experiments were conducted in 2008 and 2009 to determine if the herbicide glyphosate influenced disease severity in potential commercially-available varieties of glyphosate-resistant sugarbeet. In the first greenhouse experiment in 2008, the most tolerant variety to Rhizoctonia crown and root rot exhibited an increase in disease severity when the herbicide was applied. There were no significant differences between herbicide treatments in a second variety and herbicide treatment decreased disease severity in a third variety when compared with the no-herbicide treatment. Experiments conducted to determine if the herbicide influenced the growth of the fungus in Petri dishes indicated that the herbicide did not increase the growth at field rates. Field and additional greenhouse experiments were conducted using four commercial varieties. Differences in disease severity were observed when comparing varieties, but herbicide treatments did not significantly influence the severity of Rhizoctonia crown and root rot when compared with the no-herbicide treatment. Results indicate that choosing a glyphosate-resistant sugarbeet variety with the best demonstrated tolerance to Rhizoctonia crown and root rot is an important factor in reducing disease severity.

Technical Abstract: Previous greenhouse studies with a non-commercial glyphosate-resistant sugarbeet variety indicated that susceptibility to Rhizoctonia crown and root rot could increase after glyphosate was applied. Greenhouse and field experiments were conducted in 2008 and 2009 to determine if glyphosate influenced disease severity in potential commercially-available varieties of glyphosate-resistant sugarbeet. In the first greenhouse experiment in 2008, Hilleshög 9027RR, the most tolerant variety to Rhizoctonia crown and root rot, exhibited an increase in disease severity when glyphosate was applied. There were no significant differences between herbicide treatments in Hilleshög 9028RR, and glyphosate decreased disease severity in Hilleshög 9032RR when compared with the no-herbicide treatment. Experiments conducted to determine if glyphosate influenced Rhizoctonia solani Kühn growth in vitro, indicated glyphosate did not increase the growth and a 10x rate of glyphosate plus ammonium sulfate (AMS) decreased the rate of radial growth of R. solani. Field and additional greenhouse experiments were conducted using four commercial varieties. Differences in disease severity were observed when comparing varieties, but glyphosate did not significantly influence the severity of Rhizoctonia crown and root rot when compared with the no-herbicide treatment. Results indicate that choosing a glyphosate-resistant sugarbeet variety with the best demonstrated tolerance to Rhizoctonia crown and root rot is an important factor in reducing disease severity.

Last Modified: 8/31/2014
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