Sensitivity to the Demethylation Inhibitor Difenoconazole Among Baseline Populations of Various <i>Penicillium</i> spp. Causing Blue Mold of Apples and Pears
Difenoconazole (DIF), a demethylation inhibitor fungicide, was registered in 2016 for the control of postharvest diseases of pome fruits. In this study, 162 isolates from <i>P. expansum</i> (<i>n</i> = 31) and 13 other “non-<i>expansum</i>” <i>Penicillium<...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-01-01
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| Series: | Journal of Fungi |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2309-608X/11/1/61 |
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| Summary: | Difenoconazole (DIF), a demethylation inhibitor fungicide, was registered in 2016 for the control of postharvest diseases of pome fruits. In this study, 162 isolates from <i>P. expansum</i> (<i>n</i> = 31) and 13 other “non-<i>expansum</i>” <i>Penicillium</i> spp., i.e., <i>P. solitum</i> (<i>n</i> = 52), <i>P. roqueforti</i> (<i>n</i> = 32), <i>P. commune</i> (<i>n</i> = 15), <i>P. paneum</i> (<i>n</i> = 9), <i>P. psychrosexuale</i> (<i>n</i> = 8), <i>P. crustosum</i> (<i>n</i> = 5), <i>P. carneum</i> (<i>n</i> = 3), <i>P. palitans</i> (<i>n</i> = 2), along with one isolate each of <i>P. citrinum</i>, <i>P. griseofulvum</i>, <i>P. raistrickii</i>, <i>P. ribium</i>, and <i>P. viridicatum</i>, were collected from multiple packinghouses in the U.S. Pacific Northwest. In vitro sensitivity assays showed similar sensitivities of spores and mycelia across species with the mean EC<sub>50</sub> values ranging from 0.01 for <i>P. psychrosexuale</i> (<i>n</i> = 8) to 1.33 μg mL<sup>−1</sup> for <i>P. palitans</i> (<i>n</i> = 2), whereas the mean EC<sub>50s</sub> were 0.03, 0.12, 0.19, and 0.51 μg mL<sup>−1</sup> for <i>P. expansum</i> (<i>n</i> = 31), <i>P. paneum</i> (<i>n</i> = 9), <i>P. solitum</i> (<i>n</i> = 52), and <i>P. crustosum</i> (<i>n</i> = 5), respectively. The recommended rate of DIF controlled <i>P. expansum</i> and <i>P. roqueforti</i> isolates but not all isolates of four other <i>Penicillium</i> spp. on Fuji apples after five months at 1.5 °C. The mixture of DIF + fludioxonil (FDL) (Academy<sup>TM</sup>) controlled all the dual-sensitive isolates (DIF<sup>S</sup>FDL<sup>S</sup>) and DIF single-resistant (DIF<sup>R</sup>) isolates among the six species tested but not the FDL<sup>R</sup> and dual DIF<sup>R</sup>FDL<sup>R</sup> isolates. Notable polymorphism was detected in the <i>CYP51</i> gene of the “non-<i>expansum</i>” species with four mutations located at four residues. Although the isolates analyzed in this study had not previously been exposed to DIF, the findings indicate variable sensitivity levels among the <i>Penicillium</i> spp. |
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| ISSN: | 2309-608X |