2019 ASHS Annual Conference

Increased yields in November and December, when prices are highest, have the potential to enhance the profitability and stability of the Florida strawberry industry. Transplanting earlier may be a feasible option for generating earlier season yields. However, earlier planting will expose transplants to heat stress. An additional concern for the Florida industry is the large volume of sprinkler irrigation required for bare-root transplant establishment, which could be exacerbated by earlier planting dates. Because Florida-bred strawberry cultivars are not heat stress-resistant, the objective of this study was to determine whether strawberry cultivars in current use in Florida respond in a similar manner to heat stress mitigation with white-on-black plastic (white) mulch plus foliar applications of kaolin. Plug transplants were used to address the secondary concern of water usage for establishment as they can be established with only drip irrigation. Plug transplants are more expensive than bare-root transplants, but higher profit from early yields can offset their higher cost. A split-split plot experimental design was used with planting date as the main plot factor, type of mulch as the subplot factor, and cultivar as the sub-subplot factor. The strawberry cultivars- Florida Beauty, Florida Radiance, and Sweet Sensation^® Florida 127- were evaluated at four planting dates spaced two weeks apart across September and October in 2017 and 2018. White mulch plus two applications of kaolin at 0 and 7 days after transplanting was compared to black mulch with no kaolin applications. September planting dates resulted in increased leaf number, crown diameter and number of crowns for both ‘Florida Radiance’ and Florida 127 when comparing early September dates to October dates. White mulch resulted in higher early season yields than black plastic mulch for the September 6 planting dates, with no difference observed among other planting dates. Early season yield of ‘Florida Radiance’ was highest when planted on October 4, unlike ‘Florida Beauty’ and ‘Florida 127’, which recorded their highest early season yields with the September 6 planting date. Season total marketable yield was lower for all planting dates with ‘Florida Beauty’ than with the other two cultivars. Although season total marketable yields of ‘Florida 127’ and ‘Florida Beauty’ were unaffected by planting date, ‘Florida Radiance’ produced lower yields when planted in late October. The results indicate that heat mitigation was beneficial only for the September 6 planting date, which enhanced early yields of ‘Florida 127’ and ‘Florida Beauty’, but not ‘Florida Radiance’.