Use of Electric Discharge for Simultaneous Control of Weeds and Houseflies Emerging from Soil

SIMPLE SUMMARY: In greenhouse organic farming, soil fertilized with cattle manure frequently harbors weeds and houseflies that result in difficulties for pesticide-free cultivation. The purpose of this study was to devise an electrostatic apparatus to control weeds and houseflies emerging from ground soil simultaneously using electric-field-based techniques. For weed eradication, several identical iron plates were placed in parallel at a predefined interval and negatively charged. Due to their conductive nature, plant shoots emerging from the soil between the plates in the apparatus were subjected to an arc discharge from the charged plate when the rhizosphere soil was electrified. Houseflies emerging from underground pupae were controlled using a similar electrostatic principle; flies that entered the space between the negatively charged and grounded iron plates of the second apparatus were exposed to arc discharge. A practical apparatus was constructed by combining two apparatuses devised to control weeds and houseflies, then surveyed for its functionality in a greenhouse environment. The apparatus remained functional during continuous operation in a greenhouse environment, indicating that the method is a promising tool as a pesticide-alternative approach in organic farming. ABSTRACT: An electrostatic apparatus was developed to control weeds and houseflies emerging from ground soil in a greenhouse simultaneously. Identical iron plates were placed in parallel at a defined interval and fixed in an iron frame. Two sets of fixed iron plates were used, one for weed control and one for fly control. For weed control, all of the iron plates were negatively charged, and negative charges accumulated on the plates were released to weed shoots through arc discharge. Houseflies were introduced into the space between the negatively charged and grounded plates, then subjected to arc discharge from the charged plates. Both plant shoots and adult houseflies are electrically conductive; thus, they were killed by discharge-exposure in the electric field between the charged iron plate and the ground soil, and between the charged and grounded plates, respectively. In practical use, these two devices were assembled as a two-level apparatus for simultaneous control of both targets. Several apparatuses were linked together, which increased the total electricity charge on the plates and produced a stronger discharge force sufficient to kill all targets. Thus, this study provides an electrostatics-based pest-control method for pesticide-independent greenhouse farming.