Biological control of Eutypa armeniacae. 4. Design and performance of an applicator for metered delivery of protective aerosols during pruning

Abstract

The paper describes the development of a prototype applicator for delivery of protective mixtures, in aerosol form, to the wounded sapwood surfaces exposed during pruning. The equipment has three components : a 2 litre day-service tank, a light weight belt-mounted piston pump, and a modification of a standard pneumatic-powered pruning handgun. Laboratory tests of the applicator have proved its ability to deliver, repeatedly, a uniform dose of aerosol containing sufficient particulate chemical and/or biological matter to protect apricot sapwood from invasion by Eutypa armeniacae. Field tests of the equipment in two orchards demonstrated that from 90-100 per cent of wounds can be treated for the addition of less than 20 per cent to the time required to prune a tree. Over a period of three weeks' use no mechanical defects developed. Estimated volume of protective fluid required per day, treating up to 90 per cent of wounds, is less than two litres.