Número de aplicações de fungicidas, controle de podridão de fusarium spp. em espigas e rendimento de milho

Abstract

The cultivated area with maize (Zea mays L.) has been expanded in Brazil, but the incidence of ear diseases, such as Fusarium spp. rot, is one of the limiting factors to greater productivity. The number of fungicide applications aimed at controlling Fusarium spp. in ears of corn, without and with inoculation of the pathogen, and the effect on yield and productivity of the crop was evaluated. The experiment was carried out in the Experimental Area and in the Plant Pathology Laboratory of the Universidade Federal da Fronteira Sul (UFFS) - Campus Erechim (RS), in the 2022/23 crop season. The Fusarium spp. used, came from infected corn grains and belonged to the fungi collection of the Plant Pathology Laboratory. The corn hybrid was AG9025 PRO3 and the experiment was conducted in a randomized block design, with 5 treatments and 4 replications, as follows: T1) negative control (not inoculated; without fungicides); T2) positive control (inoculated; without fungicides); T3) inoculation + one application of fungicide; T4) inoculation + two fungicide applications; and T5) inoculation + three fungicide applications. The inoculation of Fusarium spp. was carried out at the phenological stage R2. The number of grains per row (NGR), rows per ear (NRE), grains per ear (NGE), thousand grain weight (TGW, g), productivity (kg ha-1) and Fusarium spp. incidence (%) in corn grains through the plating method in potato-dextrose-agar culture medium were evaluated. It was concluded that the lowest incidence of Fusarium spp., in the AG9025 PRO3 hybrid, occurs with two and three fungicide applications. The use of three fungicide applications even in the presence of the pathogen, ensures the highest TGW (334.5 g). Numerically, three fungicide stands out in productivity (7933.17 kg ha-1) and, in relation to inoculated control; 5394.86 kg ha-1, provides an increase of 42.3 sc ha-1.