Articles
Fungicide resistance in Botrytis species: lessons from strawberry fields
Article number
1465_54
Pages
355 – 362
Language
English
Abstract
Botrytis fruit rot has been a major disease affecting strawberry production worldwide, which often drives the need for frequent fungicide applications.
Multi-year resistance monitoring has shown the continued resistance selection, despite the implementation of rotation or alternation of chemical classes of fungicides.
High and stable frequencies of resistance were detected to thiophanate-methyl and pyraclostrobin, and lower but increasing frequencies of resistance were found to newer fungicides such as succinate dehydrogenase inhibitors (SDHIs). Botrytis isolates from California strawberry fields seemed to have greater resistance frequencies than those from the eastern states.
In contrast, isolates from New York exhibited the lowest levels of resistance among all the states tested.
While resistance was typically found to be caused by specific nucleotide mutations in target genes, resistance to phenylpyrroles fludioxonil was attributed to atrB overexpression.
Individual isolates were also commonly found to harbor resistant mutations in different target genes, displaying multiple chemical class resistance (CCR). The presence of those multi-resistant phenotypes may accelerate the resistance selection due to ‘selection by association’. Further analysis showed significantly higher CCR associated with isolates collected from plasticulture strawberries than matted-row strawberries, with 5CCR and 3CCR as the most common phenotypes, respectively.
Moreover, phenotypic and genotypic analysis of Botrytis isolates revealed two prevalent Botrytis species, including B. cinerea and B. fragariae. Although their resistance mechanisms are largely the same, the latter population appeared to have a higher level and frequency of resistance to fludioxonil but resistance to SDHIs has been undetected in B. fragariae so far.
Avoiding unnecessary sprays with high-risk fungicides and routine resistance monitoring are critical to the sustainability of disease management.
Multi-year resistance monitoring has shown the continued resistance selection, despite the implementation of rotation or alternation of chemical classes of fungicides.
High and stable frequencies of resistance were detected to thiophanate-methyl and pyraclostrobin, and lower but increasing frequencies of resistance were found to newer fungicides such as succinate dehydrogenase inhibitors (SDHIs). Botrytis isolates from California strawberry fields seemed to have greater resistance frequencies than those from the eastern states.
In contrast, isolates from New York exhibited the lowest levels of resistance among all the states tested.
While resistance was typically found to be caused by specific nucleotide mutations in target genes, resistance to phenylpyrroles fludioxonil was attributed to atrB overexpression.
Individual isolates were also commonly found to harbor resistant mutations in different target genes, displaying multiple chemical class resistance (CCR). The presence of those multi-resistant phenotypes may accelerate the resistance selection due to ‘selection by association’. Further analysis showed significantly higher CCR associated with isolates collected from plasticulture strawberries than matted-row strawberries, with 5CCR and 3CCR as the most common phenotypes, respectively.
Moreover, phenotypic and genotypic analysis of Botrytis isolates revealed two prevalent Botrytis species, including B. cinerea and B. fragariae. Although their resistance mechanisms are largely the same, the latter population appeared to have a higher level and frequency of resistance to fludioxonil but resistance to SDHIs has been undetected in B. fragariae so far.
Avoiding unnecessary sprays with high-risk fungicides and routine resistance monitoring are critical to the sustainability of disease management.
Publication
Authors
M. Hu, H. Lu
Keywords
strawberry, gray mold, Botrytis species, chemical control, fungicide resistance, selection by association, resistance management
Groups involved
- Division Vine and Berry Fruits
- Working Group Strawberry Culture and Management
- Division Sustaining Horticulture in a Changing World
- Division Horticulture for Human Health
- Division Plant Genetic Resources, Breeding and Biotechnology
- Division Greenhouse and Indoor Production Horticulture
- Division Precision Horticulture and Engineering
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