An Electrostatic Nursery Shelter for Raising Pest and Pathogen Free Tomato Seedlings in an Open-Window Greenhouse Environment

The electrostatic nursery shelter reported in this work was a transparent film-covered rectangular box with three electric field screens on each of the long sides of the box. This arrangement prevents flying pests and airborne fungal pathogens from entering the nursery space. Insulated conducting wires (ICWs) were used as electrodes to create electric fields. The ICWs were arrayed in parallel, and linked to direct-current voltage sources. The ICW layers were negatively or positively charged with equal voltages to form dipoles; i.e., ICW(–) and ICW(+). The electric field screen consisted of three layers of the ICWs; i.e., an ICW(–) layer on either side of an ICW(+) layer. Four species of major tomato pests were used in a blowing assay- whiteflies (Bemisia tabaci), western flower thrips (Frankliniella occidentalis), green peach aphids (Myzus persicae) and tomato leaf miner flies (Liriomyza sativae). The ICWs were located to capture test pests that were mechanically blown into the electric-field screen. The electrostatic force to capture the insects was directly proportional to the applied voltage, and at voltages of 1.2 kV or greater, the screen exerted sufficient force to capture all of the test pests. An assay in a pest-infested greenhouse revealed that the ICWs captured all the pests that approached the screen, and the plants within the shelter remained pest-free. In addition, we show that the electric-field-screened shelter remained spore-free in the presence of continuous exposure to the conidia of tomato powdery mildew (Oidium neolycopersici).