Variation for Fungicide Resistance among Cucurbit Powdery Mildew Populations in the Czech Republic

摘要: A total of 88 cucurbit powdery mildew (CPM) isolates, 52 Golovinomyces cichoracearum (Gc) and 36 Podosphaera xanthii (Px), collected in the period 2005-2007 Czech Republic (CR), were screened for tolerance and/or resistance to three freauentlv used fungicides (fenarimol, dinocap, thiophanate-methyl). Benomvl served as ineffective control. Bv employing benomyl, which be most frequently fungicide CPM protection CR, we could monitor compare development changes variation tolerance/resistance among populations. (21 Gc, 14 Px) isolates from 2007 also tested azoxystrobin resistance. Fungicide sensitivity was determined by a modified leaf-disc bioassay with five concentrations. Significant differences even between years 2005 2006-2007 observed. Occurrence resistant tolerant both species different locations Fenarimol (Rubigan 12 EC) dinocap (Karathane LC) expressed decreasing efficacy year 2005, however these two showed high level effectiveness all CPMs controlled recommended concentration (36 μg a.i./ml fenarimol, 105 dinocap). Benomyl (Fundazol 50 WP) thiophanate-methyl (Topsin M 70 found ineffective, because majority (96%) belonged highly strains, reaction at (250 525 thiophanate-methyl) or higher than (500 a.i./mi benomyl 1050 Some 89% (except only 22% Px on profuse limited sporulation 2× (1000 2100 Azoxystrobin (Ortiva) efficacy, 37% (Gc a.i./ml) concentrations 2000 a.i./ml).