Sensibilità di isolati di Venturia inaequalis ai principali fungicidi utilizzati su melo in Lombardia

Venturia inaequalis strains were isolated from Northern Italian orchards (Lombardy) in order to evaluate the sensitivity levels to the most common fungicide classes used to control apple scab. The mycelium growth at increasing concentration of several fungicides (myclobutanil, trifloxystrobin, dodine, cyprodinil and boscalid) was evaluated. The EC50 values of the isolates were compared to those described in the literature and to the values of three sensitive strains to calculate the resistance factors. Fifty-six isolates were tested, 75% were resistant to trifloxystrobin, 67% to myclobutanil, 25% to dodine, 14% to cyprodinil and 7% to boscalid. Some strains were characterized by multidrug resistance, usually to trifloxystrobin and myclobutanil. These results highlight the need of an accurate monitoring activity to avoid field resistance problems.