ARS | Publication request: Interaction between weed and disease management methods in sugar beet

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract
Publication Acceptance Date: April 30, 2008
Publication Date: July 26, 2008
Citation: Hanson, L.E., Barnett, K.A., Sprague, C.L. 2008. Interaction between weed and disease management methods in sugar beet[abstract]. American Phytopathological Society Annual Meeting. 98:S68.

Technical Abstract: Previous work with an experimental glyphosate-resistant sugar beet variety indicated host resistance to Rhizoctonia crown and root rot could be compromised when plants were exposed to glyphosate. In order to improve disease management recommendations, work was initiated to investigate the interaction between disease control and weed and pest management practices in commercial glyphosate-resistant sugar beet varieties. In greenhouse tests on plants treated with herbicides and subsequently inoculated with Rhizoctonia solani AG-2-2, statistically significant interactions were observed between sugar beet variety by herbicide spray treatment (P = 0.04) and variety by spray by the presence or absence of the pathogen (P = 0.02). A Rhizoctonia-susceptible variety showed no significant difference in disease severity regardless of herbicide treatment (alpha = 0.05), while a Rhizoctonia-resistant variety had significantly greater disease in herbicide treated plants (alpha = 0.05). Herbicides included glyphosate or a mix of phenmedipham, desmedipham, triflusulfuron methyl, and clopyralid. A variety with an intermediate response to Rhizoctonia showed no change in disease severity with glyphosate treatment, but had reduced disease severity when treated with standard beet herbicides (alpha = 0.05). Results indicate that disease management using host resistance may be incompatible with some weed management systems.