Pesticide loss reduction by automatic adaptation of spraying on globular trees

Pesticide treatments in citrus and olive tree orchards in Spain make up 30 and 42% of the production costs. One reason for the high cost of these trea tments is due to the high percentage loss of pesticide out of the tree, due to the globular shape of their canopies and to the application of chemical s in the absence of trees. This wastage also produces an important environm ental issue. The problem is similar in other cultures, and has lead to desi gn alternative systems all over the world. With the aim of achieving a quality product and with consideration for the environment, Institute Valenciano de Investigaciones Agrarias has developed an automatic sprayer that, by means of an electronic control system, adapt s the dose of product to the actual amount of leaf mass. The system is base d on a cheap, 8-bit, conventional microcontroller, that receives informatio n about the tree shape from two ultrasound sensors, and actuates through se veral electro-hydraulic valves mounted on a specially designed hydraulic ci rcuit. The system allows the spraying higher doses in the central part of t he tree, where there is more vegetation in globular shaped canopies. Under the conditions of our field test experiments, the system achieved savings o f up to 37% of the product while maintaining the quality of the treatment. These savings depend on the size, shape and distance between trees in each particular orchard. (C) 2001 Silsoe Research Institute.