Wzrost wystepowania form odpornych grzyba Venturia inaequalis [Cooke] Aderh. na fungicydy strobilurynowe w polskich sadach jabloniowych

Monitoring of the occurrence of V. inaequalis resistance to strobilurins (QoI - Quinone outside Inhibitors) was conducted in selected orchards in Poland in 2004 - 2009. During the first years of monitoring (2004 - 2007), a high level of resistance to strobilurins was observed in 54.7% of the orchards, with only some resistant forms or no resistance noted in the others. Monitoring carried out in the two last years, 2008 and 2009, indicated a significant spread and increase in the frequency of occurrence of resistant forms of V. inaequalis. The problem of resistance affected 79.7% of the monitored orchards and only in 20.3% the level of resistance was low. The results showe that in Polish orchards the resistance to strobilurins has increased strongly. It has happened in spite of the reduction in strobilurins use recommended by FRAC.