Effect of in vitro glyphosate on Fusarium spp. growth and disease severity in maize

Abstract

BACKGROUND Glyphosate (GP) is one of the main pesticides used for maize production. Fusarium sp. is a fungal genus with several phytopathogenic species and toxigenic features. In this study, the culturable soil mycota was evaluated using the surface‐spray method. The effect of GP on the growth parameters (growth rate and lag phase) of Fusarium spp. was also tested on solid media conditioned with different water activities. Finally, the GP effect on disease severity caused by Fusarium sp. in maize seedlings was studied. RESULTS The results showed that Fusarium species are frequently isolated from GP‐exposed soils. The GP concentrations tested had a significant effect on F. graminearum, F. verticillioides and F. oxysporum growth parameters on solid media. The pathogenicity tests showed that the disease severity of the maize seedlings significantly increased with increasing GP concentrations. CONCLUSIONS This study showed that Fusarium species are frequently isolated from pesticide‐exposed soils and the GP concentrations tested had a significant effect both on growth parameters and disease severity in maize. This study provides an approach to the effect of GP on Fusarium sp. growth and pathogenicity that reinforces the importance of evaluating all the factors that could affect feed and food production. © 2019 Society of Chemical Industry

Indirect Effects of the Herbicide Glyphosate on Plant, Animal and Human Health Through its Effects on Microbial Communities

“…Despite the observed increases in root disease severity, spore germination and mycelium growth of these and other pathogens are mostly delayed and reduced by glyphosate in vitro (Figure 5) (Barnett et al, 2012;Benito et al, 2020;Carranza et al, 2019;Duke, 2018;Larson et al, 2006;Mengistu et al, 2013;Sanogo et al, 2000). This supports the notion that increased root disease in glyphosate treated soil comes about through reduced plant resistance or suppression of beneficial microorganisms rather than enhanced growth of plant pathogens like Fusarium and Rhizoctonia species (Duke, 2018).…”

“…Hammerschmidt (2018) argued against increased disease severity by glyphosate applications on GR soybean plants and attributed increased disease risk to pathogen growth in dying and dead plant materials. More recently however, glyphosate (Roundup ControlMax ® at 30, 100, and 300 mmol L−1 or 5.1, 16.9, and 50.7 mg ml −1 of glyphosate) also increased disease severity on seedlings of transgenic maize inoculated with Fusarium graminearum, F. verticillioides, and F. oxysporum under controlled conditions, when no plant debris was present (Figure 4) (Carranza et al, 2019).…”

Impact of glyphosate and glyphosate-based herbicides on phyllospheric Methylobacterium

“…in McIntosh seedlings (unchallenged: 40 µg, pathogen challenge: 10–15 µg) [ 123 ]. Furthermore, increases in disease incidence was associated with glyphosate application in more unique and geographically diverse crop systems including: banana [ 124 ], canola [ 125 ], cotton [ 126 ], maize [ 127 ], sugar beet [ 128 ], and tomato [ 129 ]. Studies examining the soybean rhizosphere in response to application of GBH’s also indicate significant disruption to population and diversity [ 130 ], including certain members responsible for reducing manganese (Mn) and secreting indole acetic acid (IAA) [ 131 ].…”

Impact of Glyphosate and Glyphosate-Based Herbicides on Phyllospheric Methylobacterium

“…in McIntosh seedlings (unchallenged: 40 µg, pathogen challenge: 10-15 µg) [122]. Furthermore, increases in disease incidence was associated with glyphosate application in more unique and geographically diverse crop systems including: banana [123], canola [124], cotton [125], maize [126], sugar beet [127], and tomato [128].…”