Submitted to: Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2015
Publication Date: 12/2/2015
Citation: Williams, M.M. II, Bradley, C.A., Duke, S.O., Maul, J.E., Reddy, K.N. 2015. Goss’s wilt incidence in sweet corn is independent of transgenic traits and glyphosate. Horticultural Science. 50:1791-1794.
Interpretive Summary: Weed and insect pest management in dent corn has changed dramatically since commercialization of transgenic glyphosate-resistant (GR) crops nearly two decades ago. Using the same transgenic traits employed in dent corn, GR sweet corn cultivars were commercialized in 2011. Recently, claims have been made that glyphosate use and the GR trait increase risk of plant diseases in crops. The purpose of this study was to determine if glyphosate and/or the GR trait in sweet corn affect incidence of Goss’s wilt, a disease that has emerged in the central cornbelt. Based on field experiments in four environments, results showed Goss’s wilt incidence in sweet corn was unaffected by glyphosate or the GR trait. Contrary to a detrimental outcome, several yield traits were higher with the presence of the GR trait and glyphosate use. This work provides research-based knowledge concerning the GR trait and glyphosate use in a food crop, which may impact adoption and use of such products.
Technical Abstract: Recently claims have been made that the use of glyphosate and transgenic crop traits increases the risk of plant diseases. Transgenic traits used widely for years in dent corn are now available in commercial sweet corn cultivars, specifically, the combination of glyphosate resistance (GR) and Lepidoptera control (Bt). The objective was to assess the interactions of the GR+Bt trait, glyphosate, and Goss’s wilt on sweet corn. Nine treatments were tested under weed-free conditions at two sites in 2013 and 2014. Treatments included two isogenic cultivars differing only in the presence or absence of GR+Bt, with and without postemergence application of glyphosate, and inoculation with the causal agent of Goss’s wilt (Clavibacter michiganensis subsp. nebraskensis) before glyphosate application, after glyphosate application, or no inoculation. Results failed to show glyphosate or the GR+Bt trait influenced sweet corn susceptibility to Goss’s wilt. The only factor affecting Goss’s wilt incidence was whether or not plants were inoculated with C. michiganensis subsp. nebraskensis. In the absence of glyphosate application, yet under weed-free conditions, several yield traits were higher in sweet corn with the GR+Bt trait. Results showed the GR transgene confers the same level of tolerance to glyphosate in sweet corn as observed previously in dent corn. If true, recent claims about glyphosate and transgenic traits increasing plant disease would be of major concern in sweet corn; however, no relationships were found between the GR+Bt trait and/or glyphosate to Goss’s wilt incidence in sweet corn.