Predicting the combined efficacy of host resistance and fungicides
Integrating strategies for the control of late blight caused by Phytophthora infestans on potato, such as epidemic rate limiting host resistance combined with reduced fungicide doses, has been demonstrated to successfully decrease foliar disease severity. A simple multiplicative survival model (MSM) was devised to predict disease severity on cultivars with differing disease resistance treated with different fungicide doses. AUDPC data were obtained from field experiments testing cultivar by fungicide treatment combinations. The effectiveness of the host resistance was expressed as the proportion of disease remaining on each of the more resistant cultivars compared with the most susceptible cultivar. The effectiveness of fungicide treatment was calculated using data from the most susceptible cultivar to parameterise a dose response curve function. This allowed calculation of the proportion of disease remaining at any given dose. The MSM model was then used to predict the AUDPC of other variety by fungicide dose combinations. A regression line fitted to the observed and predicted data explained 68% of the variation in AUDPC. Aspects of experimental design which could be addressed to improve predictive value are described.
Other Titles/Title of Conference
Sixteenth EuroBlight Workshop, Aarhus, Denmark
Stichting Wageningen Research
PAGV - Special Report no.18