Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 6/2/2017
Publication Date: 12/1/2017
Citation: Naegele, R.P. 2017. Host resistance to Botrytis bunch rot in Vitis spp. and its correlation with Botrytis leaf spot. American Phytopathological Society Abstracts. 107:73.
Technical Abstract: Botrytis cinerea, the causal agent of Botrytis bunch rot, is the number one postharvest disease of fresh grapes in the U.S. Fungicide applications are used to manage the disease, but resistant isolates are common and postharvest losses occur annually. Host resistance is needed for long-term management of the disease as fungicide resistance becomes more prevalent. Sources of resistance in grape have been identified, but often have poor fruit quality. In this study, twenty-five grape genotypes (cultivars, breeding lines, and species) were evaluated for fruit and leaf susceptibility to two isolates of Botrytis cinerea. Significant differences in virulence and disease incidence were detected between the two isolates and among lines, respectively. Isolate 16-23 from apricot was more virulent than isolate 449 collected from grape, but no differences in pathogenicity were observed. Most of the Vitis vinifera cultivars had high disease severity in fruit and leaves, while the complex hybrids, V. aestivalus, and V. arizonica had low to moderate disease severity. Three V. vinifera lines had moderate resistance (<50% diseased) to Botrytis bunch rot when inoculated with either isolate. Only two genotypes, both with V. labrusca in their background, had little to no detectable disease across isolates. Correlations were examined among brix, leaf susceptibility, and fruit susceptibility for each of the cultivars. No correlations between brix and disease susceptibility were detected. Moderate resistance to Botrytis bunch rot and leaf spot were detected in V. vinifera breeding lines, suggesting these may be potential sources for selecting grapes with resistance to B. cinerea and high fruit quality.