Spotlight

in HortTechnology

Landscape Performance of Grasses under Low-input Conditions

Fifteen native and eight nonnative grass species and cultivars, and two grass-like species were evaluated over 3 years at two locations under low-input landscape conditions. Based on quality rating and survival data, Thetford et al. (p. 267) concluded that a majority of the species and cultivars were marginally acceptable for 2 years or more, but only six were rated as excellent or good over all 3 years. Four of these species were native while only two nonnative species demonstrated potential for long-term performance in a low-input landscape at both sites.

Ceanothus Evaluated for Landscapes in Western Oregon

Few of the many species/cultivars of ceanothus are used as landscape shrubs in western Oregon, partly because of concerns about adaptability and cold hardiness. Bell (p. 411) evaluated 38 species, cultivars, and hybrid selections of ceanothus in a landscape trial in Silverton, OR, from 2001 to 2005. Most cultivars grew and flowered well during the evaluation. Only Ceanothus thyrsiflorus var. griseus, C. thyrsiflorus var. griseus ‘Yankee Point’, C. thyrsiflorus ‘Snowflurry’, and C. hearstiorum suffered severe cold damage. Several cultivars were effective drought-tolerant groundcovers, including ‘Wheeler Canyon’, ‘Joyce Coulter’, and ‘Joan Mirov’.

Video Analysis of Olive Damage Improves Canopy Shakers

Fruit injury is a major constraint to the use of mechanical harvesting for table olives. Castro-Garcia et al. (p. 260) used stereo video analysis via two high-speed cameras during operation of a harvester with reconfigured critical components to identify sources of fruit damage from canopy–harvester interactions. Strike-impact by harvester rods was the main source of fruit injury. Canopy acceleration correlated with damage; thus, increasing drum frequency to improve fruit removal efficiency was limited by fruit damage. Use of softer padding materials was effective in mitigating fruit injury caused by the impact of rods and hard surfaces.

Rooting Hardwood Cuttings of ‘Gisela 5’ Cherry Rootstock

Exadaktylou et al. (p. 254) investigated the effects of several external factors in an attempt to improve the rooting of hardwood cuttings of ‘Gisela 5’ cherry rootstock. Improved rooting was achieved using cuttings 9-11 mm diameter and 20 cm long quick-dipped in 1000 mg·L21 indole-3-butryic acid (IBA) solution. Cuttings should be collected at 15 Nov. or 2 Mar. and placed vertically into a 1 perlite:1 peat or perlite rooting substrate. It appeared that ‘Gisela 5’ could be propagated by cuttings with a rooting percentage of about 50%.

High Yields of Organic Sweet Peppers in the Tropics

Juroszek and Tsai (p. 418) collected data on fruit yields of sweet pepper under organic farming conditions in the tropics. They found that total and marketable yields of organically grown pepper were similar to those of conventionally produced pepper. The relatively high yields achieved in tropical Taiwan, which are comparable to those achieved in a study in Brazil, may encourage farmers and agricultural stakeholders to consider organic farming as a viable alternative to conventional farming systems in tropical and subtropical countries worldwide.

Hoop House Construction Provides Students with Practical Skills

To enhance students' horticulture skills, St. Hilaire et al. (p. 445) developed the construction and operation of hoop houses as a laboratory exercise. Students in each of three laboratories constructed a 12 3 15-ft hoop house and equipped them with irrigation systems and data loggers. Students (86%) agreed that they knew the techniques of hoop house construction, and 89% agreed that they understood the practical use of building them. Students observed temperature variations in unvented hoop houses. Because the hoop houses were relatively inexpensive and easy to construct, they potentially will augment students' practical horticulture skills without straining teaching budgets.

Mechanical Pruning Decreases Production Costs in ‘Concord’ Vineyards

In western New York, decreasing grape prices and increasing labor costs have reduced profits for ‘Concord’ grape producers. Bates and Morris (p. 247) compared the effect of four pruning techniques on yield, quality, and production costs in a commercial ‘Concord’ vineyard over 5 years. Mechanical cane pruning with either manual pruning follow-up or mechanical fruit thinning maintained juice quality and decreased production costs compared to traditional hand pruning. The study provides two mechanized grape management options to maintain profitability in the competitive juice grape market.

Do Community Gardens Impact Local Property?

Gorham et al. (p. 291) mapped 11 established Houston, TX community gardens; property crimes from Houston Police Department 2005 crime data; and 2000 demographic data from the U.S. Census Bureau using geographic information system (GIS) software. Community gardens were compared statistically with randomly selected areas that were within a 1-mile area surrounding each garden. There were no differences in numbers of crimes among community garden areas and randomly selected areas. Interviews indicated that community gardens had a positive influence on neighborhoods, with residents reporting neighborhood revitalization and perceived immunity from crime.

Measuring Tissue Nitrate in Leafy Green Vegetables

Rapid, inexpensive methods that accurately measure plant tissue nitrate levels could be useful in the laboratory and field. Ott-Borrelli et al. (p. 439) measured tissue nitrate concentrations with a portable ion selective electrode (ISE) for fresh sap, and benchtop ISE and colorimetric methods for dry tissue extracts. Comparisons showed a strong relationship between the benchtop ISE and colorimetric methods, and a poor relationships among the portable ISE and other methods. Due to tissue processing and/or instrument differences, the portable ISE was not recommended as a substitute for benchtop ISE or colorimetric methods for tissue nitrate analysis.

Traffic Tolerance of Seashore Paspalum Cultivars

Brosnan and Deputy (p. 423) evaluated the tolerance of ‘Tifway’ hybrid bermudagrass and ‘Sea Isle 2000’, ‘Salam’, ‘Sea Dwarf’, and ‘Sea Isle 1’ seashore paspalum turf to simulated athletic field traffic. ‘Salam’, Sea Dwarf’, and ‘Sea Isle 1’ seashore paspalum exhibited greater traffic tolerance than ‘Tifway’ hybrid bermudagrass. Thus, some seashore paspalum cultivars may be suitable alternatives to hybrid bermudagrass for use on athletic fields in warm-season climates.

Citric Acid and Sucrose Suppress Defoliation of Hibiscus

Zhang et al. (p. 305) report that when potted young hibiscus plants were incubated in a room under low-illumination conditions and treated with a mineral solution, all the leaves were lost after 3 months. Incorporation of citric acid into the mineral solution considerably suppressed the defoliation. Treatment with sucrose instead of citric acid also considerably suppressed the defoliation. Treatment with the mineral solution containing both citric acid and sucrose was highly effective in suppressing defoliation. The proton concentration of the organic solution was found to be a critical factor.

Microbial Inoculants Applied at Transplanting Do Not Enhance Palm Growth

Soil inoculants containing arbuscular mycorrhizal fungi alone or in combination with other microbial components or fertilizers have been promoted as a means of enhancing the growth of palms transplanted from containers into a landscape or field nursery. Broschat and Elliott (p. 324) found that mexican fan palm and queen palm inoculated with four such products at transplanting grew no better than non-inoculated palms receiving fertilizer equivalent to the nitrogen content of the fertilizer-containing products, even in phosphorus-deficient soils where mycorrhizae are considered to be most beneficial.

Alternative Methods for Roadside Weed Control

Barker and Prostak (p. 346) studied use of naturally based herbicides, mulching, and burning as alternatives to conventional, synthetic herbicides on roadside sites. A single burning or application of alternative herbicides (acetic-citric acid, pelargonic acid, or clove oil) gave short-term, sometimes weak suppression of vegetation. Repeated applications of these alternatives were necessary for extended efficacy. No suppression of roadside vegetation occurred with corn gluten meal. Bark or woodchip mulches were suppressive against emerging vegetation for 2 years. The costs of materials and labor for the alternative practices were substantially more than for use of the conventional herbicides.

Houseplants Reduce Indoor Ozone Air Pollution

Papinchak et al. (p. 286) evaluated three common indoor houseplants for their effectiveness in reducing ozone concentrations in a simulated indoor environment. Ozone was injected into treatment chambers until concentrations of 200 ppb were achieved. Then ozone concentrations were recorded over time until <5 ppb was measured in the chamber. On average, ozone depletion time ranged from 38 to 120 min per evaluation. Ozone depletion rates were higher within chambers that contained plants than within control chambers without plants, but there were no differences among plant species.

Ophiopogon Species Cultivated in the Southeastern United States

Ophiopogon species are prominent landscape plants in the southeastern United States. Misidentifications are common with plants often marketed under other species names. A taxonomic study by Fantz (p. 385) reports eight species currently available in the green industry, plus six additional species names being used. Each species was given a quantitative morphological description, and observational notes. Taxonomic terms used in morphological descriptions were defined. A key is presented for delineation of these 14 species' names.

Germinating Seeds of an Endangered Species from Yunnan, China

The use of plant growth regulators (PGRs) and moist chilling to breaking seed dormancy of huagaimu (Manglietiastrum sinicum) was reported by Zheng and Sun (p. 427). Gibberel-lic acid (GA3) at 300-500 mg·L21 and moist chilling at 4 °C for 3 weeks were effective. After 30 days of incubation, the germination of combined treatments of PGRs followed by moist chilling was significantly higher than that of PGRs treatments alone. However, the highest overall percentages of germination were observed in seeds treated only with moist chilling.

Mulched Tree Leaves Reduce Dandelions in Established Turfgrass

Kowalewski et al. (p. 297) observed increased spring green-up of turfgrass, and a reduction in dandelion populations in response to oak and maple leaf mulch applications. Leaf mulch application provided up to 80% dandelion control after the first annual application in 2004, and up to 53% control after the second annual application in 2005.

Analysis of Runoff from Nursery, Citrus, and Avocado Sites

Stormwater runoff was collected from 10 citrus or avocado groves and 7 production nurseries in Ventura County, CA between 2006 and 2008. Some of this runoff contained concentrations of nitrogen, phosphorus, or pesticides that were above water quality benchmarks. Detected pesticides included types that typically bind to sediment particles. Mangiafico et al. (p. 360) suggest that pesticide runoff could be reduced by preventing soil erosion and retaining eroded sediments onsite. They recommend proper nutrient management for crops to reduce the potential of nitrogen and phosphorus leaching.

Pruning and Fruit Thinning of ‘Concord’ and ‘Sunbelt’ Grapes

Morris et al. (p. 368) compared hand pruning to minimal and machine pruning with either no fruit thinning, thinning after bloom, or thinning at veraison on ‘Concord’ and ‘Sunbelt’ grapes. Desired soluble solids were achieved in all treatments without differences in other composition parameters. Minimally pruned vines without thinning had delayed ripening (about 7 days) regardless of cultivar. Minimally pruned vines had lower cluster weights and berry weights compared to hand pruning in both cultivars. Machine and minimal pruning are viable alternatives to hand pruning in areas with a long growing season.

Shank- versus Drip-applied Methyl Bromide Alternatives in Field Nurseries

Production of garden rose plants and fruit/nut trees in open-field nurseries depends on preplant fumigation to control several soilborne pests. Schneider et al. (p. 331) compared pest control with alternative fumigants applied with either conventional shank-injectiotn equipment or through a drip-irrigation system. Shank applications generally controlled nematodes better than drip-applications, especially at deeper soil depths. Combinations of iodomethane and chloropicrin controlled nematodes nearly as well as methyl bromide, and were usually better than 1,3-dichloropropene, the only alternative currently allowed for certified nursery stock production in California.

Performance of Four Carob Cultivars in Northeastern Spain

Tous et al. (p. 465) evaluated four carob cultivars in Catalonia, Spain without irrigation. ‘Rojal’ was the earliest bearing cultivar; however, no differences were observed for cumulative pod production 18 years after budding. ‘Duraio’ had the highest cumulative seed yield. ‘Matalafera’ showed the lowest tree vigor. ‘Rojal’ produced the largest pods and lowest seed content, while ‘Banya de Cabra’ and ‘Duraio’ produced the smallest fruit with the highest seed content. In terms of kernel and pod production, ‘Duraio’ appeared to be the best-performing female cultivar for planting new carob orchards.

Cowpeat as a Peat Substitute for Foliage Plant Propagation

Li et al. (p. 340) formulated 14 substrates using composted dairy manure (cowpeat) in different proportions by volume. Testing of the substrates showed that cowpeat- and peat-based substrates had similar physical and chemical properties and the percentages of rooting and seed germination in cowpeat-based substrates were equal to or better than those of the peat-based controls. Success in using up to 60% cowpeat for plant propagation may make cowpeat a viable alternative to peat.

Georgia Survey of Pecan Nutrient Element Status and Soil Fertility

A survey of commercial pecan orchards was conducted throughout the coastal plain of Georgia. Wells (p. 432) reports that pecan producers in the southeastern United States should monitor orchards closely to ensure sufficient availability of potassium, sulfur, and copper. Orchard soil organic matter and soil nitrate-nitrogen were higher in orchards utilizing clover as a cool-season orchard groundcover than those utilizing a grass sod only. The mean carbon:sulfur (C:S) ratio of pecan orchard soils was 504:1, which may further reduce tree uptake of S from low-S soils of the region.

Can Peel Fluorescence Be Used to Identify Freeze-damaged Oranges?

It is often difficult to accurately identify navel oranges that have been damaged and are no longer marketable immediately after a freeze. Previous research had shown that navel oranges that were freeze-damaged under laboratory conditions have small yellow fluorescent spots on the peel that are visible under ultraviolet light. Obenland et al. (p. 379) evaluated naturally-frozen navel oranges following the 2007 freeze in California for the presence of these spots as well as for measures of internal freeze damage. They found that fluorescent spots were ineffective indicators of the amount of freeze damage.

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