Control of Dalbulus maidis in maize crop with electrostatic spraying

Abstract

Among the pests that attack the maize, the maize leafhopper, which causes direct damages by sap-sucking and indirect ones, stands out as being a vector of pathogens and viruses, and can cause losses of up to 100% of the production. An alternative to improve the chemical control of this pest is the use of electrostatic spraying technology. However, there is no research support. This study aimed to evaluate the deposition of spray in the maize crop and the effectiveness in the chemical control of the maize leafhopper, using the electrostatic spraying system, at different application rates, compared to the conventional spraying system. The experiment was conducted in a randomized block design with five treatments, in a 2x2 + 2 factorial scheme: presence or absence of electrostatic spraying system, two application rates (35 and 50 L ha-1), an additional treatment using a hydraulic spray nozzle and a rate of 100 L ha-1, and other additional treatment without the application of insecticide, in order to support the study of pest infestation. Each treatment consisted of eight replicates, in which the spray deposition in the maize canopy and the efficiency in the control were evaluated. For the insecticide applications, a boom sprayer with induction electrostatic spraying system was used with indirect electrification. To evaluate the deposition, the Brilliant Blue FCF marker was added to the spray to be detected by absorbance in spectrophotometry. For the biological efficacy of the maize leafhopper, the insecticide composed of thiamethoxam and lambda-cyhalothrin was used compared with the control without the application. There was a significant increase in the spray deposition, both in the upper and lower maize leaves, with the use of electrostatic spray technology compared to the conventional spray system. The control of the maize leafhopper was also superior. The electrostatic spraying also made it possible to reduce the application rate by approximately three times in relation to that used in conventional hydraulic spraying.

Spray Deposition on Maize Using an Electrostatic Sprayer

“…The deposition observed by the electrostatic technique in the upper third of the maize plant surpassed the conventional application in almost 50 % of the tracer mass retained in the first application and almost 30 % in the second application (Table 4). These results are in agreement with the results reported by Marques et al (2019) for the same crop and position in the plant canopy, where the authors achieved an increase of 64 % in the tracer deposition with the use of the electrostatic technique. TABLE 4.…”

“…Averages followed by similar letters in the column do not differ by Tukey' s test (p < 0.05). CV (%) = coefficient of variation Losses to the soil in the first and second applications showed that the electrostatic technique decreased the risk of environmental contamination and the waste of spray solution, as demonstrated by other studies (Marques et al, 2019;Zhou et al, 2012). The electrostatic sprayer can create a zone of electromagnetic interference; thus, when the droplets are sufficiently electrified, they tend to follow the trajectory of the electromagnetic field lines that are created due to the difference in the electric potential among the soil, vegetation, and electrified nozzle.…”