Submitted to: ASA-CSSA-SSSA Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 23, 2003
Publication Date: September 2, 2003
Citation: Hanson, L.E. 2003. Effect of treating sugar beet with the herbicide glyphosate on fusarium yellows. ASA-CSSA-SSSA Proceedings. Technical Abstract: Use of herbicide-tolerant crops is likely to alter herbicide usage. The potential impact of such usage on many plant diseases is not well known. Some herbicides can affect disease severity by direct effects on plant pathogens or by affecting the hosts responses to pathogens. Glyphosate can increase severity of diseases caused by Pythium on bean and caused by Fusarium on bean, tomato, and soybean. To examine the effect of glyphosate treatment on disease severity on sugar beet, plants that were tolerant to the herbicide glyphosate were inoculated with a moderately virulent isolate of Fusarium solani, one of three isolates of F. oxysporum, or not inoculated. The disease severity was compared for plants treated with glyphosate and those treated with a surfactant alone. In preliminary results, no significant differences in disease levels were observed with the F. solani isolate and the least virulent F. oxysporum isolate ( =0.05). A highly virulent F. oxysporum isolate killed all plants rapidly and no significant differences in disease levels could be detected. However, for a third F. oxysporum isolate, disease levels were significantly higher following glyphosate use than in plants treated with surfactant alone ( =0.05). Thus glyphosate treatment may increase disease severity for some isolates of Fusarium oxysporum on this crop.