Fungicide resistance management for potato

Given that late blight control requires multiple spray applications there is a need to understand the best strategies for slowing down the development of resistance to fungicides. Principles governing the selection of fungicide insensitive strains have been derived and tested extensively against experimental data and show that reducing the difference in the rate of increase of both sensitive and insensitive strains, slows selection.

Resistance management strategies identified as effective include alternating different modes of action, mixing two modes of action and decreasing the fungicide dose throughout the fungicide programme.

In this project an experimental system designed to test the selection for fluazinam-insensitive strains of Phytophthora infestans will be used to determine the proportion of 37_A2 strains (which is insensitive to fluazinam) in field trials before and after fungicide treatments have been applied. It will provide evidence to determine and rank the effectiveness of commercially relevant fungicide resistance management strategies, which include blocking, alternation and with and without a solo/multisite fungicide.

1. Determine appropriate strategies to slow fungicide resistance selection using alternation, mixtures and multisite fungicides in multi-spray programmes
2. Produce a set of evidence-based guidelines outlining best practice and cost effectiveness for the industry