Distribution and effectiveness of pesticide application with a cold fogger on pepper plants cultured in a greenhouse

Abstract

A cold fogger was evaluated for efficiency of spray-deposit distribution and for control of insect damage and fungal disease on pepper ( Capsicum annuum L.) plants cultured in a greenhouse. The fogger was placed at one end of an 800-m 2 greenhouse, and the distribution and deposition of a fluorescent tracer by the cold fogger was evaluated using quantitative methods and image analysis. An increased cold fogger-dependent air speed, determined by anemometry, was correlated with increased deposition of the fluorescent tracer. A consistent decline of deposition from the area nearest to the cold fogger to the far end of the greenhouse was observed. Nonetheless, no differences were found in the droplet density between the outer and inner parts of the foliage. The average droplet density was 1828 cm −2, but the leaf deposition was restricted to the upper surface of the leaves. The distribution and numbers of thrips ( Thrips sp.) and powdery mildew ( Leveillula taurica [Lev.] G. Arnaud) on leaves were assessed over a period of five months. Thrips control was found to be quite good throughout the greenhouse in response to phytosanitary treatments. Although the control of powdery mildew was generally adequate, there was significant disease development in certain locations in the greenhouse that were distant from the cold fogger. The employment of cold foggers in greenhouses needs to be carefully analysed in terms of the dimensions of the greenhouse and the pests and diseases to be controlled due to the uneven deposition of the sprayed products.