Integration of host resistance and fungicide use1

Abstract

The current strategies for using host resistances and fungicides encourage the increase of pathogen strains with matching pathogenicity or insensitivity. Diversification of cultivars and fungicides is recommended, but involves only diversification between crops and does not include integration of the two methods of control. A strategy of complete or total diversification requires diversification within as well as between crops. For example, the system of using cultivar mixtures can provide assured high yields, even though control of pathogen development is incomplete. Within‐crop diversification of fungicides applied to seed is becoming a practical possibility with the development of film‐coating of carriers that can adhere different materials firmly to different seeds whilst maintaining uniform seed‐flow characteristics. An ideal system would involve integrated total diversification of host cultivars and fungicides. Field data indicate that this can provide excellent profit margins and disease control, while maximising evolutionary problems for the pathogen. The system is technically feasible using developed methods of cultivar mixing together with the new technique of film‐coating.