Resistance of Venturia inaequalis to strobilurin and dodine

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% of forms resistant to strobilurins 90 80 70 60 50 40 30 20 10 0 77.475.8 71.6 69.6 42.6 32.2 14.8 13.3 4.2 3.9 2.4 2.2 1.8 1.4 1.2 0.7 0.5 0.5 0.4 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Orchard Figure 3. Percentage of strobilurin-resistant forms in V. inaequalis populations in 2005 % of forms resistant to dodine 60 50 40 30 20 10 0 53.8 51.7 49.4 38.1 36.4 15.514.2 13.3 13.2 7.2 369 5.9 5.3 4.7 2.6 1.7 1 0 0 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Orchard Figure 4. Percentage of dodine-resistant forms in V. inaequalis populations in 2005 to QoI are very heterogeneous. Moderate to high resistance was observed in Southern France, Northwest Italy (Piedmont and Po Valley), Poland and Eastern Germany. Low to moderate resistance was noted in Spain, Belgium and Western Germany. Low resistance was found in Northeast Italy (Terentino, Alto Adige) and Northern France (Loire Valley). No resistance was detected in the UK, Portugal, Lake Constance area of Germany, Canada, New Zealand. Resistance was also confirmed in the USA, South Africa and Greece. This information indicates that V. inaequalis resistance to QoI is a serious problem in many countries. The mechanism of V. inaequalis resistance to QoI is very complex. In the case of its mutation in cytohrom b gene and induction of alternative pathway respiration is observed. But mutation does not always explain the QoI resistant phenotype /Fernández-Ortuńo et al., 2008/. 0
% of forms resistant to dodine % of forms resistant to strobilurins 60 50 40 30 20 10 0 51.5 50.3 34.1 26 21 370 4.4 1.4 0.83 0.53 0 0 1 2 3 4 5 6 Orchard 7 8 9 10 11 Figure 5. Percentage of strobilurin-resistant forms in V. inaequalis populations in 2006 20 18 16 14 12 10 8 6 4 2 0 18.9 17.4 14.3 6.6 6.2 5 1.6 0.6 0.6 0 0 0 0 0 0 1 2 3 4 5 6 7 8 Orchard 9 10 11 12 13 14 15 Figure 6. Percentage of dodine-resistant forms in V. inaequalis populations in 2006 Monitoring conducted in 1998–1999 showed that in some Polish orchards more than 50% of fungus strains in the population were resistant to dodine /Meszka, Bielenin, 2001/. In 2004, the conidial germination tests showed that a level of resistance in 4 of 15 monitored orchards was very high (above 50%). In 5 orchards it ranged from 30.1 to 49.7% and in the remaining 6 orchards it was low (below 6%) (Figure 2). In 2005, in 2 of 20 monitored orchards the percentage of resistant forms was above 50%, in 3 orchards it amounted from 36.4 to 49.4%, in the remaining 11 orchards it varied from 1 to 15.5%. Only in 4 orchards the resistance to dodine was not observed (Figure 4). In 2006, in 9 of 15 monitored orchards the resistant forms amounted from 0.6 to 18.9% and in the other 6 orchards, they were not detected (Figure 6). In 2007, only in 2 of 14 orchards resistant forms amounted to 57 and 32.9% and in the other 12 orchards the level of resistance was
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Resistance of Venturia inaequalis to strobilurin and dodine

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