| Baseline Sensitivity to Mandipropamid Among Isolates of Phytophthora capsici Causing Phytophthora Blight on Pepper |
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Ho Sun Jang, Soo Min Lee, Sun Bo Kim, Joo Hyung Kim, Susan Knight, Kwee Doo Park, Duncan Mckenzie, Heung Tae Kim |
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| Abstract |
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Sensitivity to the new carboxylic acid amide fungicide, mandipropamid, of Phytophthora capsici causing pepper Phytophthora blight was determined on 187 isolates collected in Korea over 3 years, from 2005 to 2007. All isolates were sensitive to mandipropamid, with EC50 values for growth of mycelia ranging from 0.001 to 0.037 μg/ml. Among the isolates, 147 (79.0%) isolates were sensitive to metalaxyl, whereas others were resistant to this fungicide. Mandipropamid had the same effect on mycelium growth of both metalaxyl-sensitive and metalaxyl-resistant isolates, indicating an absence of cross-resistance between these two fungicides. Comparison of the sensitivities of P. capsici isolates showed a positive correlation between sensitivity to mandipropamid and dimethomorph (r2=0.8533). The results of this study indicate that there is no evidence for development of resistance to mandipropamid in this population of P. capsici isolates collected in Korea. |
| Key Words:
dimethomorph, fungicide resistance, mandipropamid, metalaxyl, Phytophthora capsici |
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