Reduced efficacy of fluazinam against Phytophthora infestans in the Netherlands
Schepers, H.T.A.M. ; Kessel, G.J.T. ; Lucca, F. ; Förch, M.G. ; Den Bosch, G.B.M. van; Topper, C.G. ; Evenhuis, A. - \ 2018
European Journal of Plant Pathology 151 (2018)4. - ISSN 0929-1873 - p. 947 - 960.
AUDPC - Clonal lineage - Control strategy - Fungicides - Late blight - Potato - Shirlan
Phytophthora infestans is the causal organism of potato late blight, the most important disease in potato, the second most important arable crop in Europe. The P. infestans population in Europe is well known for its sudden changes in composition. Currently it is composed of a wide variety of genotypes, some of which are dominant clonal lines while others are rare or even unique to a year or location. Fungicides play a crucial role in the integrated control of late blight. Since its introduction in the Netherlands in 1992, fluazinam has been used in late blight control strategies in ware and starch potatoes. It has a broad spectrum of activity and is effective against a range of diseases including potato late blight. Fluazinam interrupts the pathogen cell’s energy production process by an uncoupling effect on oxidative phosphorylation. It is considered to have a low resistance risk. Until recently, reduced efficacy against fluazinam was not detected in P. infestans surveys in Europe. In this paper we present the finding of a new clonal lineage (EU_33_A2) of P. infestans in the Netherlands and the reduced efficacy of fluazinam to control one of the EU_33_A2 isolates in field experiments carried out in 2011 and 2015 under high disease pressure. The potential effects of this finding on practical late blight control strategies are discussed.
Controlling highly pathogenic avian influenza outbreaks : An epidemiological and economic model analysis
Backer, J.A. ; Roermund, H.J.W. van; Fischer, E.A.J. ; Asseldonk, M.A.P.M. van; Bergevoet, R.H.M. - \ 2015
Preventive Veterinary Medicine 121 (2015)1-2. - ISSN 0167-5877 - p. 142 - 150.
Control strategy - Economic assessment - Epidemiological model - Highly pathogenic avian influenza - HPAI - Pre-emptive culling - Vaccination
Outbreaks of highly pathogenic avian influenza (HPAI) can cause large losses for the poultry sector and for animal disease controlling authorities, as well as risks for animal and human welfare. In the current simulation approach epidemiological and economic models are combined to compare different strategies to control highly pathogenic avian influenza in Dutch poultry flocks. Evaluated control strategies are the minimum EU strategy (i.e., culling of infected flocks, transport regulations, tracing and screening of contact flocks, establishment of protection and surveillance zones), and additional control strategies comprising pre-emptive culling of all susceptible poultry flocks in an area around infected flocks (1. km, 3. km and 10. km) and emergency vaccination of all flocks except broilers around infected flocks (3. km).Simulation results indicate that the EU strategy is not sufficient to eradicate an epidemic in high density poultry areas. From an epidemiological point of view, this strategy is the least effective, while pre-emptive culling in 10. km radius is the most effective of the studied strategies. But these two strategies incur the highest costs due to long duration (EU strategy) and large-scale culling (pre-emptive culling in 10. km radius). Other analysed pre-emptive culling strategies (i.e., in 1. km and 3. km radius) are more effective than the analysed emergency vaccination strategy (in 3. km radius) in terms of duration and size of the epidemics, despite the assumed optimistic vaccination capacity of 20 farms per day. However, the total costs of these strategies differ only marginally. Extending the capacity for culling substantially reduces the duration, size and costs of the epidemic.This study demonstrates the strength of combining epidemiological and economic model analysis to gain insight in a range of consequences and thus to serve as a decision support tool in the control of HPAI epidemics.