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
Field trials were conducted in two locations in Spain to determine the effect of methyl bromide (MBr) alternatives on soilborne diseases and nematodes, and strawberry (Fragaria ×ananassa) yields under high-tunnel conditions. Fumigant treatments were applied to the same plots each year. Treatments were MBr + chloropicrin (Pic) (50:50, v/v) at a rate of 400 kg·ha−1; 1,3-dichloropropene (1,3-D) + Pic (65:35, v/v) at 300 kg·ha−1; Pic at 300 kg·ha−1; dimethyl disulfide (DMDS) + Pic (50:50, v/v) at 500 kg·ha−1; propylene oxide at 550 kg·ha−1; dazomet at 400 kg·ha−1; and calcium cyanamide (Ca-cyanamide) at 700 kg·ha−1. A nontreated control was also included. Fumigation with MBr + Pic, 1,3-D + Pic, Pic, and DMDS + Pic consistently improved early and total marketable strawberry yields in both locations. This response was caused by successful soilborne fungus and nematode control, improving strawberry growth and development, which resulted in increased plant canopy diameters and higher strawberry early and total yield.