Abstract
Fruit splitting is a physiological disorder that produces surface cracks that promote disease and insect damage. Moreover, the spotted-wing drosophila (SWD), Drosophila suzukii (Matsumura), is a species of vinegar fly that attacks various berry crops and reduces fruit quality and yield; this includes grape crops worldwide. In this study, we tested the susceptibility of various hybrid bunch grapes and muscadines to berry splitting and SWD attack. Ten grape cultivars were harvested in 2016 and 2017 and ‘Thompson Seedless’ (Vitis vinifera) was purchased locally. Fruit quality traits examined included Brix (soluble solids), total acidity (TA), pH, fruit firmness, and skin break force. ‘Villard blanc’ and OK392 were the least susceptible to berry splitting (0%). Although the muscadines showed the highest fruit firmness, they were also susceptible to splitting, especially ‘Fry Seedless’ (88% splitting incidence). No significant correlations existed among soluble solids, firmness and splitting; however, there was a negative correlation between splitting and TA. Pierce’s disease (PD)-resistant and tolerant grapes also mostly appear resistant or highly tolerant of SWD infestation. SWD females do not seem capable of ovipositing in fruit hosts that have a fruit firmness exceeding 300 g/mm. Wounds or splits in the grape epidermis increased reproductive success of SWD by 400%, suggesting that a well-managed vineyard will not host large SWD populations. Vineyards suffering severe berry damage might provide SWD with a summer fruit host. Overall, PD-resistant hybrids and muscadines are crops highly adaptive to subtropical climates and tolerant of this new invasive vinegar fly.
- Received December 2017.
- Revision received February 2018.
- Revision received March 2018.
- Revision received March 2018.
- Accepted March 2018.
- Published online April 2018
- ©2018 by the American Society for Enology and Viticulture
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