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  • Author or Editor: F. Harper x
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Experiments at two commercial farms in Bermuda tested the effectiveness of solarization of narrow beds alone and together with metam sodium (MS) to enhance in-field production of broccoli (Brassica oleracea L. var. botrytis L.) and kale (B. oleracea L. var. acephala DC.) transplants. Soil treatments of clear, low-density polyethylene (LDPE) mulch (25 μm), white LDPE mulch (25 μm) plus MS (702 L·ha-1), and clear mulch plus MS were compared to bare soil. Mulches were applied and MS incorporated through rototiller cultivation 20 cm deep into 1.2-m-wide, flat seed-beds in the last week of June 1995. Mulches were maintained for 8 weeks. Either Broccoli `Pirate' or kale `Blue Curled Scotch' were seeded into transplant beds in Warwick and Devonshire parishes, respectively. Stand data was obtained for broccoli and kale 25 and 35 days, respectively, after seeding. Transplants were rated for root infection and biomass at 11 days (broccoli) or 31 days (kale) after seeding. In general, solarization was as effective as MS in suppression of soilborne pathogens of broccoli and kale plants. An additive effect on plant biomass was observed when solarization and MS were combined. All treatments significantly increased the establishment of broccoli plants and decreased root infection by Rhizoctonia solani in both crops. The incidence of Fusarium sp. was significantly decreased by all treatments in kale roots, and in broccoli by MS alone and in combination with solarization. Shoot fresh weight was significantly increased in kale by all treatments and in broccoli by solarization plus MS.

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The combination of concrete and asphalt surfaces, large buildings, lack of surface water, and anthropogenic heat inputs result in urban temperatures warmer than surrounding rural areas. This effect is often most pronounced with winter minimum temperatures and may cause changes in local plant hardiness zones. Local minimum temperatures were obtained for the years 1974-96 from the National Climatic Data Center and the Office of the State Climatologist of Texas for all recording stations within the Dallas-Fort Worth, Texas metropolitan area. Data were averaged and analyzed in two groups: 1974-86 and 1987-96. Contour maps were created using Surfer software. The 1974-86 local map had only one major difference from the 1990 USDA Plant Hardiness Zone map, which was the inclusion of 8a temperatures in more western portions of the metroplex. The inclusion of the years 1987-96 resulted in the westward expansion of 8a and a new 8b zone near downtown Dallas. These changes mimic the expansion of suburban development and increased urbanization over the last decade. We propose an updated plant hardiness zone map for this metropolitan area, which should more accurately reflect changes that have occurred since publication of the USDA Plant Hardiness Zone map.

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