The resistance strategy for acylalanine fungicides1

Since the commercial introduction of metalaxyl and the outbreaks of resistance that followed soon thereafter, a number of new acylalaninc‐type fungicides have been developed which have or will shortly come onto the market. Based on the understanding that anti‐resistance strategies can only be effective if they are followed by all manufacturers, there has been considerable effort over the past few years to coordinate anti‐resistance strategies among the companies involved. The most important of these is that acylalanine fungicides will only be available in prepacked mixtures with residual contact fungicides so that the use of the single product is excluded. At the same time only two to four applications per season arc recommended and no curative use of the products. In order to ensure the success of such restrictions, it is necessary that their need should be recognized and their enforcement supported by extension and advisory bodies.