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Misshapen fruit represent a significant problem for strawberry (Fragaria ×ananassa Duch.) producers around the world. We investigated the effect of cultivar and different cropping practices on the productivity of strawberry plants growing in tunnels at Huelva (Spain) over three years. In the first experiment, ‘Camarosa’, ‘Ventana’, and ‘Medina’ were planted on 10 or 22 Oct. at standard (30 × 25 cm), wide (35 × 25 cm), or narrow (25 × 25 cm) spacings. In the second experiment, ‘Camarosa’ was grown in macro- or microtunnels with and without bees. There was no effect of plant density. Planting time resulted in higher early yields in ‘Ventana’ and higher misshapen fruit in ‘Camarosa’ with an early compared with a late planting. ‘Camarosa’ had the lowest yields and the highest incidence of misshapen fruit. More of the early crop was misshaped and this was related to low temperatures in the 7 weeks before harvest. Pollination reduced the incidence of misshapen fruit and increased yield. Plants grown in macrotunnels were only more productive than those grown in microtunnels when they were pollinated by bees. These results demonstrate that the productivity of strawberry plants growing in tunnels can be enhanced by the selection of the appropriate cultivar, planting date, tunnel system, and pollination protocol. The use of macrotunnels with supplementary pollination results in better economic returns by increasing yield and decreasing the incidence of misshapen fruit. In addition, in some cultivars this profit can be enhanced by early planting, which enables early arrival of fruits into the markets at better prices for growers.
Tunnel and open field trials were conducted in two locations in Huelva, Spain, and one in Florida to determine the effect of selected methyl bromide (MBr) alternatives on strawberry yield. In Spain, the tunnel treatments were: a) nontreated control, b) MBr + chloropicrin (Pic) 50:50 at a rate of 400 kg·ha–1; c) dazomet at 400 kg·ha–1, d) 1,3-dichloropropene (1,3-D) + Pic 65:35 at 300 kg·ha–1; e) Pic at 300 kg/ha; f) dimethyl disulfide (DMDS) + Pic 50:50 at 250 + 250 kg·ha–1; and f) propylene oxide at 550 kg·ha–1. All treatments were covered with virtually impermeable film (VIF), except the nontreated control, which was covered with low-density polyethylene (LDPE) mulch. Dazomet was rototilled 10 cm deep, whereas the other fumigants were injected with four chisels per bed. In Florida, the open-field treatments were a) nontreated control, b) MBr + Pic 67:33 at a rate of 400 kg/ha with LDPE; c) MBr + Pic 67:33 at 310 kg·ha–1 with VIF; d) 1,3-D + Pic 65:35 at 300 kg·ha–1 with VIF; e) methyl iodide (MI) + Pic 50:50 at 230 kg·ha–1 with VIF; f) Pic at 300 kg·ha–1 with VIF; g) DMDS + Pic 50:50 at 250 + 250 kg·ha–1 with VIF; and g) propylene oxide at 500 kg·ha–1 with VIF. The fumigants were applied with three chisels per bed. In Spain, the results showed that 1,3-D + Pic, DMDS + Pic, and Pic consistently had similar marketable yields as MBr + Pic. Similar results were found in Florida, with the exception of propylene oxide, which also had equal marketable fruit weight as MBr + Pic.
Public and private institutions in Spain are increasing strawberry (Fragaria ×ananassa Duch.) breeding efforts to obtain new strawberry cultivars well-adapted to growing conditions in Huelva and other Spanish areas, such as Valencia on the eastern Spanish coast. The new `Medina' is a short-day cultivar that is remarkable for its high production of first quality fruits, and large fruits. `Medina' has also an appropriate harvest calendar for the economic interest of the Huelva area.
The phase out of methyl bromide (MB) requires effective alternatives for soil disinfestation, particularly in high-elevation strawberry (Fragaria × ananassa Duch.) nurseries. Methyl bromide alternative fumigants were evaluated over a 3-year period for weed control and runner plant yields at strawberry nurseries in Spain. Two types of field trials were carried out: replicated experiments and commercial-scale field demonstrations. In the replicated experiments, eight fumigant treatments were evaluated each year, including the nonfumigated control and commercial standard methyl bromide plus chloropicrin mixture (MB : Pic) (50 : 50 w/w). Among the treatments evaluated were dazomet, chloropicrin (Pic) alone, metam sodium plus chloropicrin (MS + Pic), 1,3-dichloropropene:chloropicrin (1,3-D : Pic) (61 : 35 w/w), DMDS plus chloropicrin (DMDS + Pic), and propylene oxide. The best alternative fumigant treatments from the replicated experiments were carried forward to the demonstration phase of the project. Treatments such as 1,3-D : Pic (300 kg·ha−1), the combination of metam sodium plus chloropicrin (Pic) (400 to 500 + 150 to 250 kg·ha−1), Pic alone (300 kg·ha−1) as well as dazomet (400 kg·ha−1) controlled weeds at the level of MB : Pic (400 kg·ha−1). Runner plant yields, in soils previously fumigated with alternative fumigants varied, among years, locations, and trial scale, i.e., commercial scale, or small plot. By comparison, runner plant yields in MB : Pic-fumigated soils were consistently high among years, location, and trial scale. Chemical names used are: 1,3-D, 1,3-dichloropropene; MB, methyl bromide; Pic, trichloronitromethane; MS, sodium N-methyldithiocarbamate; DMDS, dimethyl disulphide; dazomet, tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione; PO, propylene oxide