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Effect of Cultural Practices in Controlling Southern Blight of Potato in the Mid-Atlantic Region.

Jose Garcia Gonzalez: Virginia Tech - Eastern Shore AREC

<div><span>Over the past decade, the incidence of southern blight caused by <em>Sclerotium rolfsii</em> Sacc. in potato (<em>Solanum tuberosum</em> L.) has increased on the Eastern Shore of Virginia (ESVA) and surrounding production areas. To date, no potato cultivar is resistant to southern blight, and management has been inconsistent using fumigants and fungicides. This research evaluated the effect of planting date and cultivar selection on reducing potato loss due to southern blight. A factorial design of four planting dates and ten cultivars was evaluated in 2017 and planned for 2018. The field trials were inoculated between 56 and 73 days post-planting with virulent strains of <em>S. rolfsii</em> isolated from ESVA potato fields in 2016. In 2017, earlier planting dates (Mar 7 and 24) produced lower disease incidence (6-60%), whereas incidence increased (66-100%) for the later planting dates (Apr 14 and May 10). Total yield and tuber quality (% marketable) were significantly reduced in the last two planting dates. There were differences in stem and tuber susceptibility between cultivars. ‘Accumulator’ and ‘Atlantic’ were identified as cultivars with lower susceptibility in the first two planting dates (10-17%), and only ‘Accumulator’ significantly displayed the lowest disease incidence (71-66%) in the last two planting dates, compared to the other nine cultivars examined (89-100%). In general, the two early plantings presented a lower incidence of disease, higher yield, and quality; therefore, early planting dates coupled with cultivar choice are recommended as strategies to suppress potato southern blight.</span></div>