The effect of mixing a low-risk and a high-risk fungicidea on the number of growing seasons before resistance to the high-risk fungicide emergesb,c in a population of M. graminicola on winter wheat.

aThe low-risk fungicide was assumed to be not at-risk of resistance development, but unable to provide sufficient disease control when used alone. The resistant strain was assumed to be completely insensitive to the high-risk fungicide.bThe resistant strain was considered to have emerged when the number of resistant lesions reaches or exceeds a threshold (see text).cThe emergence times in the table were calculated for the default scenario, which assumes that i) fitness costs of resistance reduce the infection efficiency of the resistant strain by 10%, ii) resistance to the high-risk fungicide is complete and iii) a mutation probability amounting to 1.13•10−16.dFungicide doses are expressed as a fraction of the label recommended dose.eCombinations of dose rates of the low-risk and high-risk fungicide that do not provide sufficient control of an average epidemic of M. graminicola on winter wheat. Effective disease control was defined as a disease-induced loss of healthy leaf area duration during the yield forming period equal to or below 5% [18].