PC‐based disease warning systems for use by apple growers¹

Abstract

To protect apple orchards from diseases efficiently, growers need farm‐based rather than regional disease warning systems. This paper describes three PC‐based systems from Horticulture Research International (GB). These systems, VENTEM, PODEM and NECTEM, provide warnings in the form of infection alerts and disease forecasts of Venturia inaequalis (scab), Podosphaera leucotricha (powdery mildew) and Nectria galligenu (European canker and fruit rot), respectively. The modular structure, operation and practical implementation of these systems are described and compared. A major input is weather data recorded automatically by Metos weather stations sited on farms. Each system has a weather‐driven dynamic model simulating inoculum production and the infection process. The systems use information on quantity of inoculum, cultivar susceptibility and other host factors to produce disease forecasts which are specific to individual orchard blocks and cultivars.