Rowcovers for `Sparkle' Strawberries

Abstract

Table 1. Effect of clear polyethylene rowcovers on fruit weight, yield, and number of runners on unmulched ‘Sparkle’ strawberry plants. This paper reports on the use of clear polyethylene as a rowcover for strawberries to enhance early ripening. Dormant, virus-indexed ‘Sparkle’ strawberry (Fragaria × ananassa Duchesn.) plants were set in single-row, 4.6-m plots 38 cm apart in rows 90 cm apart in a Narragansett silt loam (coarse-loamy, mixed, mesic Typic Dystrochrepts) in Rhode Island. Four runner plants were allowed to develop on each plant set, two on each side of a row, giving a triple-row system. The runner plants were ≈ 18 cm diagonally from the mother plant. The effects of 0.13-mm-thick clear polyethylene covers on the time of ripening, yield, and fruit weight of ‘Sparkle’ strawberries was studied by varying the time of application and removal. To initiate more flower buds for two treatments, plants were covered in the fall (5 Oct. 1958) before air temperature 7.5 cm above the ground surface reached 0C. All polyethylene rowcovers were supported by 8-gauge (3.3 mm in diameter) wire hoops that were spaced at intervals of ≈ 1.0 m above the plants. The sides were held down with strips of furring stapled to them. The ends of the rowcovers were held in place with rocks. There were four treatments: 1) fall–winter (FWC), removal of rowcover in early spring (26 Mar.); 2) fall–winter–spring (FWSC), removal 22 May; 3) winter-spring (WSC), a set of polyethylene rowcovers was placed over the plants on 3 Dec. after 21 days of minima below 0C and removed 22 May; 4) uncovered plants (NC). There were four replications in a randomized block design using minimums of 20 plants/plot. Fruit was harvested, graded, and weighed every 3 to 4 days, beginning 22 May and continuing until 16 July. Fruit grades were: large (> 8.0 g), marketable (4.0 to 7.9 g), undersize (2.0 to 3.9 g), and culls (< 2.0 g and/or malformed). All plants were maintained as mother and a set of four daughter plants. Additional runners were removed and counted on three dates. Time of covering and removal of rowcover significantly affected fruit count and