Joint action of fungicides in Mixtures: Theory and practice

Fungicide mixtures aimed at the control of multiple target organisms have been used since the middle of this century. In the 1970s synergistic mixtures of site-specific (high resistance-risk) fungicides with multi-site (low resistance-risk) fungicides became available with the aim to provide adequate disease control while maximizing evolutionary problems for the pathogen. In the 1980s there were introduced mixtures of negatively correlated fungicides, in which each ingredient is capable of controlling pathogen genotypes resistant to the other ingredient. Such fungicides are currently deployed in the form of homogeneous mixtures (tank mixes, prepacked mixtures). A new strategy is under development in which different fungicides are applied to different adjacent plants. Diversification of cultivars and fungicides in a crop may minimize the buildup of resistance and maximize disease control.