Strawberry transplants in Florida are traditionally bare-root short-day cultivars produced in the north and planted in early October for November harvesting. Bare-root transplants are field harvested in such a way that leaves are removed, wounds created that pathogens may enter, and size and flowering patterns may vary. When they are transplanted into the field, they require a period of continuous irrigation to keep the air cool and the leaves functioning until they establish.
A potential alternative to bare-root plants is Florida produced plug transplants. Plugs are created by cutting the runners with two to three expanded leaves from the mother plants and transplanting them into trays. Trays vary by their cell number, with fewer cells in a tray providing a larger rooting volume and vice versa. Optimization of plug production requires making the smallest plants that will still perform well in the shortest time.
University of Florida researchers wanted to determine the best length of time in the nursery and tray size to produce strawberry plugs that would provide the best yield, and to compare the plug performance to traditional bare-root transplants.
‘Strawberry Festival’ runners were collected for plug production in August. The runners were grown in 50-cell trays for either 4 or 6 weeks and half were treated with IBA rooting hormone applied to the roots. The five treatments tested in the field were: bare-root transplants, plugs grown for 4 weeks, 6 weeks, 4 weeks +IBA, and 6 weeks +IBA. Transplants were planted in early October and harvested twice per week starting 8 or 9 weeks after transplanting. Early marketable yield was the weight of all harvests until December 15, while total marketable yield was the cumulative weight harvested until mid-February. Marketable fruit were greater than 0.4 ounces without visible blemishes and at least 75% external red color. The experiment was repeated over two years.
In another experiment, tray size was tested, using 30- 40-, 50-, and 72-cell trays to produce plugs with ‘Strawberry Festival’ and ‘Florida Radiance’. Similar measurements were made on yields from plants over two years.
There were no differences in plant growth between plugs grown for 4 or 6 weeks, or with or without IBA. Bare-root plants produced a significantly higher early yield because of greater fruit numbers. However, the total yields were similar for all treatments.
There were no differences in early or total yield from the transplants from the various cell tray sizes compared, although in one experiment the 72-cell trays produced less total yield than 50-cell trays for one cultivar.
Four seasons of data resulted in bare-root transplants producing higher early yield than plugs, but no differences in total yield. Bare-root plants probably produced earlier fruit because they had been treated to chilling hours in the north during nursery production and so were planted with more initiated flower buds than the plugs. If floral induction in the plugs could be improved to increase the profitable early crop, they could be a better alternative to bare-root plants. However, bare-root plants provided steadier production and earlier yields than plugs in these experiments.
Plugs produced in 50-cell trays in four weeks of growth in the nursery were adequate for production. Although plug plants did not have as large an early yield as bare-root, they have the potential to save water during establishment. Eighty percent less water was needed to establish the plugs compared to the bare-root plants. Potentially 820,800 gallons/acre per season could be saved by using plugs.
- A. Torres-Quezada, L. Zotarelli, V. M. Whitaker, R. L. Darnell, K. Morgan, and B. M. Santos. 2020. Production Techniques for Strawberry Plugs in West-central Florida. HortTechnology April 2020 30(2):238-247.