Eradicant and protectant activity

The effects of chemicals on foliar diseases development can be grouped into two main categories (Milne et al., 2007): protectant fungicides, which inhibit spore germination thus reducing the infection frequency and eradicant fungicides, which slow down the growth of mycelium and consequently the sporulation rate.

Each fungicide in a chemical mixture must be characterized by an eradicant (E, 0-1) and a protectant (P, 0-1) activity. The protectant and eradicant activities of the single fungicide at day d are derived as:

where Ad is the protectant or eradicant activity of the single fungicide at day d. In case of a mixture of fungicides, the Bliss independence null reference model (Bliss, 1939) is applied, assuming an independent action of two fungicides. The addition of a fungicide to the mixture will then increase the eradicant and protectant activities according to the Equation below:

where the subscripts 1 and 2 stands for the first and the second chemical in the mixture.

The impact of the chemical treatment at day d on the disease progress is simulated by modulating the efficiency of the infection (Ieff,d, 0-1, in case of protectant effect) and of the sporulation (Sporeff,d, 0-1, in case of eradicant effect) processes, simulated by the DiseaseProgress component:

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