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Influence of glyphosate on Rhizoctonia and Fusarium root rot in sugar beet
- This study tests the effect of glyphosate application on disease severity in glyphosate-resistant sugar beet, and examines whether the increase in disease is fungal or plant mediated. In greenhouse studies of glyphosate-resistant sugar beet, increased disease severity was observed following glyphosate application and inoculation with certain isolates of Rhizoctonia solani Kuhn and Fusarium oxysporum Schlecht. f. sp. betae Snyd. & Hans. Significant increases in disease severity were noted for R. solani AG-2-2 isolate R-9 and moderately virulent F. oxysporum isolate FOB13 on both cultivars tested, regardless of the duration between glyphosate application and pathogen challenge, but not with highly virulent F. oxysporum isolate F-19 or an isolate of R. solani AG-4. The increase in disease does not appear to be fungal mediated, since in vitro studies showed no positive impact of glyphosate on fungal growth or overwintering structure production or germination for either pathogen. Studies of glyphosate impact on sugar beet physiology showed that shikimic acid accumulation is tissue specific and the rate of accumulation is greatly reduced in resistant cultivars when compared with a susceptible cultivar. The results indicate that precautions need to be taken when certain soil-borne diseases are present if weed management for sugar beet is to include post-emergence glyphosate treatments.
Larson, R.L. , Hill, A.L. , Fenwick, A. , Kniss, A.R. , Hanson, L.E. , Miller, S.D.
Beta vulgaris , sugar beet , fungal diseases of plants , Thanatephorus cucumeris , Fusarium oxysporum , plant pathogenic fungi , pathogenicity , virulence , disease control , soil-borne diseases , weed control , glyphosate , application rate , disease resistance , defense mechanisms , shikimic acid , biosynthesis , quantitative analysis , cultivars , genetic variation
- Includes references
- Pest management science 2006 Dec., v. 62, issue 12
Journal Articles, USDA Authors, Peer-Reviewed
- Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.