Different flat fan type nozzle on the control of fallarmyworm on maize

Abstract

Four field experiments were conducted to control the fall armyworm, Spodoptera frugiperda on maize (Zea mays L.). Different insecticides were tested, applied each one with a regular flat fan nozzle of different angles and opening sizes. Initially the insecticides methomyl, chlorpiriphos ethyl, diazinon, and trichlorphon were tested, each one applied with two dosages and two growth stage of the crop, 30 and 50 centimeters tall. The flat fan nozzles number 8001, 8002, 8003 and 8004 were used. In the second experiment only the best treatments from the first one were tested. In the two last experiments, another insecticide (thiodicarb) was included and also nozzles of angle 65 were used. In all experiments artificial infestation was used with five second-instar larvae per plant two days before insecticide application. Spray insecticide applications were made by using a costal-manual sprayer with an adapted pressure gage permitting the pressure to be maintained at 2.8 kg/cm² (40 psi). The evaluation system used was based in the number of living and dead larvae per plant 48 hours after the insecticides application. It was concluded that with the exception of the insecticide applications with the nozzle of opening size 01 (0.378 liters per minute or 0,1 gallon per minute) which were not efficient in controlling the fall armyworm, the other ones, independing of the nozzle type or the insecticide, gave a very good control of fall armyworm an maize.