Foliar Fungicide Application to Maize: Yield and Grain Hardness Enhancement in Different Environmental Conditions

The dry-milling industry is becoming an interesting distribution channel for maize (Zea mays L.) growers. Since kernels with high hardness are more suitable for the dry-milling process, it is important to investigate new ways of improving for this qualitative parameter. The aim of the research was to evaluate when a fungicide containing a demethylation inhibitor and a quinone outside inhibitor could be effective in controlling fungal disease, increasing grain yield, and improving kernel hardness. A mixture of azoxystrobin and propiconazole was tested at two locations from 2009 to 2012, with two application timings: the beginning of stem elongation and at tassel emergence. The two fungicide timings significantly reduced the incidence of northern corn leaf blight symptoms, a foliar disease caused by Exserohilum turcicum, by, respectively, 30 and 61%. A significant increase of grain yield (between 5 and 7%) and kernel hardness was obtained in both sites by this compound application, mainly when the environmental conditions led to a gradual grain filling. The best result was obtained always for the application at the tassel emergence stage; this treatment could contribute to increased competitiveness in maize production systems, especially for the dry-milling uses.