Effect of fungicide application for leaf blight control on yield components in maize hybrids

Abstract

Corn crop   (Zea mays   L.)   is continuously exposed to several biotic stresses. The situation that is accentuated in northern Argentina,  where the most frequent disease that affects it is the leaf blight caused by Exserohilum turcicum. In order to evaluate the effect of the application of fungicides for the control of leaf blight on the performance components of corn hybrids, an experiment was installed at the National University of the Northeast (UNNE), Corrientes, Argentina. Four hybrids (‘P1833H’, ‘31Y05HR’, ‘P2049H’ and ‘P1780Y’) planted-late were evaluated, in combination with five moments of a fungicide application. The moments with fungicide (Picoxystrobin 20% + Cyproconazole 8%) were: untreated control (M1), application between V8 and V10 (M2), application at R1 (M3), application at R4 (M4), and the three joint applications (2 + 3 + 4) (M5). The incidence of blight, biomass, yield in grain and its components was analyzed. Statistically significant differences were found in yield, with respect to hybrids and application moment (p = 0.0001). At R5, the lower levels of incidence were found for the R1 application moment (M3) and for the three applications (M5). Regarding the components of the yield, among the treatments with fungicide, the variable affected was the thousand grains weight (TGW).In addition, the number of grains (NG) also showed significant differences, although with greater emphasis on hybrids (P=0.0001). The incidence of leaf blight negatively affected the yield, with a reduction in the number of grains at early stages and restriction of grain filling in the late stages.