Desempenho agronômico e viabilidade econômica do uso de fungicida em cultivares de milho

Abstract

The corn crop has economic importance for society. Fungal diseases reduce corn productivity and there is little information about the use of fungicides by producers and their effectiveness in certain cultivars and environmental conditions. Thus, the objective of this work was to evaluate the agronomic performance and economic viability of maize cultivars, associated with fungicide management in a subtropical environment. Six experiments were carried out with maize in three municipalities in the state of Rio Grande do Sul (Santa Maria, São Vicente do Sul and Frederico Westphalen) at two sowing dates. The experimental design was randomized blocks with split plots. The main plot was formed by the two levels of the fungicide factor (with and without) and the subplot by the six levels of the corn cultivars factor (AG9025, AS1730, P3016, MG300, DKB230 and FEROZ). The morphological characters in eight plants per plot and the measurement of grain mass in the useful area of the 216 experimental plots were evaluated. For the evaluation of the economic viability, the production costs were estimated, considering the cost for two fungicide applications and the average value of commercialization of the product in the last three harvests. For the evaluation of the agronomic performance of the first crop of corn in a subtropical environment, in a year with low rainfall, there is a tendency for greater differences in averages for the cultivar factor than the fungicide use factor. The results of grain yield of cultivars with fungicide application showed high variations in conditions of low incidence of diseases, since the cultivars that had higher grain yield provide greater financial return. The most susceptible cultivars in conditions favorable to the development of diseases, in terms of climate and production system, present better economic returns for the use of fungicide. Regarding the percentage of deteriorated grains variable, for the three sites the second sowing season presented higher percentages of deteriorated grains, indicating that early sowing can be a strategy for the integrated management of diseases that deteriorate the grains. Therefore, for the relationship between agronomic performance and sowing time, in the three cultivation sites the highest productivity averages were in the first season, indicating that for the subtropical environment in southern Brazil it is important to anticipate sowing in first crop cultivation.