Efficiency of a computerised decision support system as a tool to reduce fungicide input for the control of potato late blight

The VNIIFBlight decision support system is intended to identify weather conditions favourable or unfavourable for the late blight outbreaks on potato. To provide an improved choice of fungicide treatment dates, we investigated the use of a standard five-day weather forecast based disease management decision support system VNIIFBlight as well as the use of information about the late blight resistance level of the cultivars used. The efficiency of this decision support system was compared with a seven-day routine program of fungicide treatments in the course of four-year field trials in Moscow region and six-year "virtual" trials in four regions of Russia, three regions of Lithuania, and single regions of Canada, Ukraine, Poland, and the Netherlands. According to the results of field experiments, in the case of a high infection pressure (2004 and 2008), yield losses caused by late blight in the untreated control made up 62% and 39%, respectively, whereas the losses for both compared schemes of protection did not exceed 8.2% for both years. In the case of weak disease development (2005 and 2007), for all studied treatments, including the untreated control, yield losses did not exceed 3%. In all years, the use of the VNIIFBlight decision support system significantly reduced the number of fungicidal treatments as compared to the routine scheme of protection; this reduction in 2004, 2005, 2007 and 2008 made up 62, 50, 50 and 17 %, respectively. According to the results of "virtual" trials, the use of the VNIIFBlight decision support system reduced the number of fungicide treatments of susceptible and resistant potato cultivars by 50% and 60% on average, respectively, as compared with the routine program.