Loads a list of treatment parameters for a specific disease (initialised at 0 , i.e. absence of treatments)
loadTreatment(disease = "no pathogen")a list of treatment parameters:
treatment_degradation_rate = degradation rate (per time step) of chemical concentration,
treatment_efficiency = maximal efficiency of chemical treatments (i.e. fractional reduction of pathogen infection rate at the time of application),
treatment_timesteps = vector of time steps corresponding to treatment application dates,
treatment_cultivars = vector of indices of the cultivars that receive treatments,
treatment_cost = cost of a single treatment application (monetary units/ha)
treatment_application_threshold = vector of thresholds (i.e. disease severity, one for each treated cultivar) above which the treatment is applied in a polygon.
a disease name, among "mildew", "sigatoka" and "no pathogen"
Chemical treatment is applied in a polygon only if disease severity (i.e. I/N) in
this polygon exceeds the threshold given by treatment_application_threshold.
Treatment efficiency is maximum (i.e. equal to the parameter treatment_efficiency)
at the time of treatment application (noted \(t*\)); then it decreases with time
(i.e. natural pesticide degradation) and host growth (i.e. new biomass is not protected
by treatments): protected by treatments):Efficiency of the treatment at time t after the application date is given by:
\( efficiency(t) = treatment\_efficiency / (1 + exp(a-b*C(t))) \)
with \( C(t)= C_1 * C_2\):
\(C_1 = exp(- treatment\_degradation\_rate * \Delta t) \) is the reduction of fungicide concentration due to time (e.g. natural degradation, volatilization, weathering), with \(\Delta t = t - t*\) the timelag passed since the time of treatment application.
\( C_2 = min(1, N(t*) / N(t)) \) is the reduction of fungicide concentration due to plant growth, since new plant tissue is not covered by fungicide. \(N(t*)\) and \(N(t)\) being the number of host individuals a the time of treatment \(t*\) and at time \(t\), respectively.
\(a \in [3.5 ; 4.5]\) and \(b \in [8 ; 9]\) are shape parameters.
setTreatment
treat <- loadTreatment("sigatoka")
treat
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