EFFECT OF THE NITROGEN FERTILIZATION ON THE SELECTIVITY OF POST-EMERGENCE HERBICIDES FOR THE CULTURE OF THE CORN

Abstract

The selectivity of the herbicides to the plantations can be the interfered by external factors to the application. In the case of the culture of the corn, there is a concern of not applying the herbicide nicosulfuron for time of the nitrogen fertilization because the risk of causing phytotoxicitys. However, this information does not contain scientific backrest, since there are no works proving the fact. The present work will be developed with the objective of analyzing the interaction between the nitrogen fertilization and also the moment of the application of post-emergence herbicides in the selectivity for the culture of the corn. The experiment will be developed starting from December/2009 in the FEP-FEIS-UNESP, located in the municipal district of Selvíria, MS. The experimental area will be prepared conventionally for the corn sowing (hybrid). The experimental design will be blocks at random with four replications, in the factorial outline 4 x 8, the factor 1 will be the herbicide type and the factor will be 2 the moment of the application of the herbicides. Each portion will consist of 4 lines with 5 m of length and 4 m of width. The treatments will be applied in post-emergency of the culture being used a costal pulverizer with constant pressure (CO2) of 45 lb/pol2, with a bar equipped with beaks of the fan type and with volume of syrup of 200 L/ha. The selectivity evaluations will be accomplished weekly until the disappearance of the phytotoxicitys symptoms using a visual scale in offense percentage where 0% = any symptom and 100% = total death of the culture. The evaluation of the productivity of the culture will be accomplished by collecting the grains of the useful area.