In Vitro and in Field Response of Different Fungicides against Aspergillus flavus and Fusarium Species Causing Ear Rot Disease of Maize

Abstract

<i>Aspergillus flavus</i>, the main aflatoxin B₁ producing fungal species, <i>Fusarium graminearum</i>, a deoxynivalenol producer, and the fumonisin-producing species <i>F. proliferatum</i> and <i>F. verticillioides</i> are the main toxigenic fungi (TF) that colonize maize. Several strategies are available to control TF and related mycotoxins, such as chemical control. However, there is poor knowledge on the efficacy of fungicides on maize plants since few molecules are registered. The sensitivity of <i>F. graminearum</i>, <i>F. proliferatum</i>, <i>F. verticillioides</i>, and <i>A. flavus</i> to eleven fungicides, selected based on their different modes of action, was evaluated in both in vitro assays and, after selection, in the field. In vitro, demethylation inhibitors (DMI) showed excellent performances, followed by thiophanate-methyl and folpet. Among the succinate dehydrogenase inhibitors (SDHI), isopyrazam showed a higher effectiveness against Fusarium species than boscalid, which was ineffective against Fusarium, like the phenyl-pyrrole fludioxonil. Furthermore, both SDHIs and fludioxonil were more active against <i>A. flavus</i> than Fusarium species. In field trials, prothioconazole and thiophanate-methyl were confirmed to be effective to reduce <i>F. graminearum</i> (52% and 48%) and <i>F. proliferatum</i> contamination (44% and 27%). On the other hand, prothioconazole and boscalid could reduce <i>A. flavus</i> contamination at values of 75% and 56%, respectively.