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  • Author or Editor: Bryan Brunner x
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While much research has been conducted in organic farming, little has focused on tropical systems. Tropical, versus temperate, systems present additional challenges for organic producers, including differences in soils, temperature, daylength, rainfall, and humidity. Pest management in tropical organic systems can be particularly demanding due to the year-round pest pressure and optimal environment for pest proliferation. Weed management is essential for the production of high-quality watermelons, but can be difficult when herbicides are not permitted. Weeds also serve as a source of inoculum for disease organisms and a habitat for insects, both beneficial and detrimental. Many products have been advertised for pest control in organic farming systems, most of which have not been adequately evaluated in independent, replicated trials. Here we investigated alternatives to pesticides for the control of weeds, insects, and diseases in `Crimson Sweet' watermelons. A split plot on a RCBD with four replications per treatment was used, with weed treatment (± paper-grass mulch) as the main plot and 12 insect and disease control alternatives as subplots. The alternatives for insect and disease control included traditional copper-based fungicides, biological control agents, potassium bicarbonate, hydrogen dioxide, milk, and commercial formulations of essential oils. Weed abundance (percentage cover), disease severity (percentage disease), and insect damage (percentage foliar damage) were evaluated weekly using a modified Horsfall-Barratt scale. Yield and quality were measured at harvest on five plants from each replication. While none of the products should be relied upon as the sole means of managing pests, those with efficacy could be integrated into organic management programs.

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Abstract

A study was conducted in Puerto Rico to estimate the outcrossing rate of six common bean (Phaseolus vulgaris L.) genotypes when planted in December or May. Two experiments were conducted for each date, one using indeterminate and the other determinate genotypes. In each experiment, homozygous dominant and recessive genotypes were planted in alternate rows to permit natural cross-pollination. Percent outcrossing was calculated based on the number of heterozygous individuals observed in the progeny of the homozygous recessive rows. Significant differences in the rate of outcrossing were observed between genotypes and between planting dates. The dwarf outcrossing (do) genotype had rates of 15.9% and 39.3% for the December and May planting dates, respectively. Outcrossing rates of stipelless lanceolate leaf (sl) and dark green savoy (dgs) genotypes did not differ significantly from the white-flowered (p) genotype, which was < 1% for both dates. Outcrossing rates < 1% were also observed for both planting dates for the determinate genotypes.

Open Access

Consumption of staminate (male) flowers of squash and pumpkin (Cucurbita sp.) has generally been limited to summer squash (Cucurbita pepo), a species of temperate regions or highland tropical environments. In the lowland tropics of the Caribbean Basin, tropical pumpkin (Cucurbita moschata) is better adapted and more widely grown. We evaluated flower production in Lajas, Puerto Rico, and postharvest attributes (shelf life, chemical and nutritional properties, sensory quality) of flowers of four tropical pumpkin and two summer squash cultivars. Tested cultivars varied slightly among experiments. Passive and active modified atmosphere packaging (MAP) were compared. For passive MAP, packages were sealed without further intervention. Under active MAP, packages were adjusted to 6% to 7% oxygen (O2) and 12% to 13% carbon dioxide (CO2) during sealing. Sensory quality of fresh and canned tropical pumpkin flowers was evaluated by panelists. Production ranged from 1.8 to 4.0 flowers/plant per day. Flower weight and length were up to 50% greater in tropical pumpkin compared with summer squash. Packaged flowers turned more orange but with less color saturation as they aged. In active MAP packages, decreases in O2, and increases in CO2 observed after 5 days were small or not significant compared with initially established atmospheres at day 0. Storage temperature generally had no effect on changes in O2 and CO2. Packaged flowers lost about 27% of their initial weight after 5 days. Type of MAP had no consistent effect on the appearance of packaged flowers. Storing flowers at 5 °C often improved appearance compared with storage at 10 °C. The rate of deterioration was slower in packaged flowers of tropical pumpkin compared with summer squash, but by day 6 the poor appearance of flowers of all cultivars made them unmarketable. Compared with fresh flowers, packaged flowers stored for 5 days exhibited a decrease in soluble solids, total acidity, ascorbic acid, antioxidant capacity, and total phenolics, and generally an increase in pH. Beta-carotene often increased in stored flowers although this varied by cultivar. Storage temperature and type of MAP had inconsistent effects on chemical attributes of stored flowers. Panelists rated fresh flowers as “like moderately” to “like very much” for texture, taste, and overall acceptability, whereas canned flowers were rated as “like moderately” for overall acceptability. Male flowers of tropical pumpkin are suitable for human consumption but deterioration after 5 days of storage limits their market potential unless better packaging methods are developed. Canned tropical pumpkin flowers may be an alternative to packaged flowers.

Open Access

There is increasing interest in red raspberry (Rubus idaeus) production worldwide due to increased demand for both fresh and processed fruit. Although the United States is the third largest raspberry producer in the world, domestic demand exceeds supply, and the shortage in fresh market raspberries is filled by imported fruit from Canada during July and August, and from Mexico and Chile during November through May. The raspberry harvest season is well defined and the perishability of the fruit limits postharvest storage. Winter production of raspberry in tropical and subtropical climates could extend the harvest season and allow off-season fruit production during periods of high market prices. The objective of the current study was to examine growth and yield of red raspberry cultivars grown in an annual winter production system in Florida and Puerto Rico. Long cane cultivars were purchased from a nursery in the Pacific northwestern U.S. in 2002 (`Heritage' and `Tulameen'), 2003 (`Tulameen' and `Willamette'), and 2004 (`Tulameen' and `Cascade Delight') and planted in raised beds in polyethylene tunnels in December (Florida) or under an open-sided polyethylene structure in January-March (Puerto Rico). In Florida, harvest occurred from ∼mid-March through the end of May, while in Puerto Rico, harvest occurred from the end of March through early June (except in 2002, when canes were planted in March). Yields per cane varied with cultivar, but ranged from ∼80 to 600 g/cane for `Tulameen', 170 to 290 g/cane for `Heritage', 135 to 350 g/cane for `Willamette', and ∼470 g/cane for `Cascade Delight'. Economic analysis suggests that, at this point, returns on this system would be marginal. However, increasing cane number per unit area and increasing pollination efficiency may increase yields, while planting earlier would increase the return per unit. The key to success may hinge on developing a system where multi-year production is feasible in a warm winter climate.

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