Effect of pydiflumetofen onGibberella ear rot andFusarium mycotoxin accumulation in maize grain

Abstract

In Ontario, Canada, Fusarium graminearum Schwabe causes Gibberella ear rot (GER) in maize, resulting in the accumulation of mycotoxins, mainly deoxynivalenol (DON), DON-3-glucoside (DON-3G) and zearalenone (ZEN) in infected kernels. Fungicides can be an important tool for managing GER and DON and other Fusarium mycotoxins in maize. Until recently, all fungicides available to growers were triazoles, thus no resistance management strategy through fungicide use was possible. In this study, a novel carboxamide fungicide active ingredient (pydiflumetofen) was evaluated against conventional triazole fungicides and mixtures for: (1) effectiveness on mycotoxins (2) optimal application timing; and (3) efficacy of application, with and without an insecticide, under natural and inoculated-misted conditions. The best timing for fungicide application was at full silk, resulting in the highest reduction of GER symptoms and lowest accumulation of F. graminearum mycotoxins in harvested grain. DON and DON-3G concentrations were reduced by at least 50% with a fungicide application at full silk. Fungicide treatments did not affect fumonisin concentrations in grain. Pydiflumetofen (94 g active ingredients (AI)/ha) and fungicides containing pydiflumetofen (75-94 g AI/ha) were similar to standard triazole fungicides (prothioconazole at 200 g AI/ha and metconazole at 90 g AI/ha) for reducing GER and F. graminearum mycotoxins under misted-inoculated plots and commercial field conditions; as a result, we expect pydiflumetofen to be competitive with triazole-only chemistries in the marketplace, which should delay the onset of fungicide resistance.

The Effect of Foliar Fungicide and Insecticide Application on the Contamination of Fumonisins, Moniliformin and Deoxynivalenol in Maize Used for Food Purposes

“…The application of prothioconazole + tebuconazole did not result in any yield benefits for any of the considered timings, thus confirming the results of Limay-Rios and Schaafsma [ 21 ] and Eli et al [ 23 ]. By applying a QoI and DMI fungicide mixture, selected for the control of foliar disease and physiological benefits (azoxystrobin + propiconazole), Blandino et al [ 24 ] reported a significant grain yield increase for an application between the nine leaf (GS19) and silking (GS65) stages, with the greatest effect at the stem elongation stage (GS35), while no productive benefit was found for an application at the milk stage (GS75).…”

“…Furthermore, although FBs, MON and other emerging mycotoxins such as beauvericin and enniatins were only found in small quantities, they were not affected by the fungicide application. The same research group has recently reported that pydiflumetofen, a carboxamide active ingredient, sprayed at silking (GS65) reduced the DON content by 50%, and showed a similar efficacy to that of prothioconazole [ 23 ]. Again in this study, the fungicide treatments did not affect the FB content in the grains.…”

“…Furthermore, all the previously reported infection pathways are possible in temperate areas, thus the infection through open wounds during ripening should not be excluded for F. graminearum or A. flavus . In studies in Ontario in which a fungicide was shown to lead to high efficacy [ 21 , 23 ], there was no evident insect damage on maize ears, in part because, according to Limay-Rios and Schaafsma [ 21 ], only Bt transgenic hybrids were cultivated. The occurrence of ECB injuries during maize ripening recorded in the present experiment, even in insecticide-protected plots, in addition to the moderate Fusarium Discolor section infection, could support the lack of control of DON when a fungicide is applied at maize silking.…”

“…Although the ability of several fungicide active ingredients (a.i.) to control the Fusarium of both the Liseola and Discolor sections has been demonstrated under in vitro conditions [ 20 ], only a few studies have investigated the effect of fungicide treatments on mycotoxin occurrence in maize fields [ 17 , 18 , 21 , 22 , 23 ]. Moreover, these field studies compared just one possible fungicide application timing (at the flowering or at the milk stage, in combination with an insecticide treatment), and they have reported contrasting results.…”

Associative and Physical Mapping of Markers Related to Fusarium in Maize Resistance, Obtained by Next-Generation Sequencing (NGS)

“…Fusarium graminearum invokes ear rot in maize, and was the main cause of maize cob fusariosis, among others, in Canada [ 27 ], China [ 28 ], and also in Europe in Italy [ 5 , 25 ].…”