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Thomas S.C. Li

Siberian ginseng [Eleutherococcus senticosus (Rupr. ex. Maxim.) Maxim] is currently a popular medicinal plant in Eurasia and North America. It has been used by the Chinese for over 2000 years. Recently, imported products of this plant have become available in North America, with a market share of 3.1% of the medicinal herbal industry. Siberian ginseng is harvested from its natural habitat in Russia and northeast China. Overharvesting has resulted in this popular herb approaching endangered species status. Cultivation is the only way to avoid its extinction, and to ensure the correct identity. Siberian ginseng is not a true ginseng (Panax quinquefolium L. or P. ginseng C.A. Meyer), but it has its own bioactive ingredients with unique and proven medicinal values. However, standardization and quality control of the active ingredients in the marketed products, which are mainly imported from China, are needed to avoid mislabeling or adulteration with other herbs.

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Thomas S.C. Li

Echinacea species, a popular medicinal herb throughout the world, have been used by indigenous Americans for hundreds of years as an effective immunostimulant. The cultivated acreage in the United States and Canada is increasing because of the great demand for Echinacea products. Better cultural methods and standardization and quality control of the value-added products are needed to increase the confidence of growers, producers, and consumers in this promising medicinal herb. Echinacea can be propagated from seed, crown division, and root sections. Seed stratification for 4 to 6 weeks at 34 to 40 °F (1 to 4 °C) before planting can improve germination. Echinacea thrives under cultivation in moderately rich and well-drained loam or sandy loam soil with regular irrigation and weed control. Roots are harvested in the fall after 3 to 4 years of cultivation. The best stage to harvest flowers has yet to be determined. Leaves are a source of valuable active ingredients, but no information is available in the literature on leaf harvesting. Active ingredients in Echinacea include polysaccharides, flavonoids, caffeic acid derivatives, essential oils, polyacetylenes, and alkylamides.

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Thomas S.C. Li

The ginseng industry has expanded rapidly in recent years. Asian and American ginseng are cultivated around the world. Ginseng products in various forms are increasingly popular, and its consumers are no longer limited to Asians. More knowledge is needed about the horticultural characteristics, cultural methods, disease control, drying and storage procedures, and technology for value-added products. Once-secretive information about ginseng and its culture is gradually becoming available, especially from the orient. Growers and researchers are eager to know more about Asian and American species of this high-value crop.

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Stephen S. Miller and Thomas Tworkoski

A series of experiments was conducted with apple (Malus ×domestica) and peach [Prunus persica (L.) Batsch] from 2003 to 2008 to evaluate the flower thinning efficacy of eugenol and a eugenol-based essential oil. Flower thinning effects by hand defoliation and alternative chemical agents were compared with eugenol in different years. Eugenol or the eugenol-based contact herbicide Matran 2 EC (or Matratec AG) produced noticeable phytotoxicity to floral parts and exposed leaf tissue within 15 min to 1 h after application and injury was proportional to rate. At the highest rates (8% and 10%), eugenol resulted in complete burning of all exposed tissue except bark tissue, in which there were no visible signs of injury. Within 3 to 4 weeks of application, phytotoxicity was difficult to observe even at the higher rates of eugenol. In companion experiments, hand defoliation of young leaves at bloom resulted in abscission of young fruitlets in apple, but not in peach, indicating that eugenol may cause thinning by multiple mechanisms. Ammonium thiosulfate (ATS) [49 L·ha−1 or 6.0% (v/v)] provided thinning in peach and showed little or no phytotoxicity, but the response was inconsistent. ATS was also inconsistent in thinning apple. The thinning response from monocarbamidedihydrogen sulphate (MCDS; Wilthin) at 3.2% (v/v) was inconsistent in peach. At the rate used, MCDS caused some phytotoxicity on peach. Applications of 1% to 2% eugenol appear promising, but good blossom coverage is critical for thinning. Furthermore, eugenol formulations need improvement to ensure uniform coverage for more predictable thinning.

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Margaret R. Pooler* and Thomas S. Elias

The neotropical shrub Hamelia patens Jacq. has been cultivated as an ornamental in the United States, Great Britain, and South Africa for many years, although only in limited numbers and as a minor element in the trade. In recent years, other taxa of Hamelia have been grown and evaluated as new flowering shrubs. The relatively recent introduction of a superior ornamental species of Hamelia called the “African firebush” has propelled this genus to greater prominence as an excellent small flowering shrub or container plant, especially throughout the southeastern United States and in other countries such as South Africa. Initially, this firebush was sold as an African plant. Data from field studies, herbarium specimens, and from DNA analysis of several taxa and populations of Hamelia show that the African firebush in southern Florida may have originated from populations of Hamelia patens var. glabra native to southern Mexico. The original plants were taken to Europe, southern Africa, and southeastern Asia probably in the mid to late 1800s and then recently re-introduced to New World markets as a new African ornamental plant.

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C. Thomas Chao* and Pachanoor S. Devanand

Acreages of `Nules' Clementine and `Afourer' mandarin have increased rapidly in California. One way to produce seedless mandarins is using Navel oranges or Satsuma mandarins as buffer to prevent cross-pollination. In order to determine the number of necessary buffer rows or spacing to prevent cross-pollination, we used AFLP markers to determine the pollen parentages of `Nules' and `Afourer' seedlings from two sites. The AFLP markers were able to identify Clementine as pollen parents of 26.6% (25/94) of the `Afourer' seedlings from one site. The pollen of Clementine was able to travel across minimum of 32 rows to pollinate `Afourer' mandarins. We found 12.73% (14/110) of the `Afourer' seedlings at the east side of the site were progenies of `Minneola' tangelo. Pollen of `Minneola' was able to travel across minimum 94 rows to pollinate `Afourer' mandarins. 12.73% (14/110) of the `Afourer' seedlings at the east end of the site were progenies of Clementine. Pollen of Clementine was able to travel minimum 54 rows to pollinate the `Afourer' mandarin at the east end of the site. The AFLP markers also identified `Afourer' mandarin as pollen parents of almost all `Nules' seedlings (98.63%, 72/73) at a second site. The pollen of `Afourer' was able to travel across minimum of 74 acres of empty ground from the east or minimum of 91 rows of Navel (128 acres) from the north to pollinate `Nules' Clementine. The results showed how far can compatible pollens traveled to cause seeds in mandarins in California. The implication from the results in seedless mandarin production in California is discussed.

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J. Thomas Raese and S. R. Drake

Sprays of calcium materials were applied at high volume rates (620 g Ca/400 liters) with a handgun during early June, late June, and mid-July versus mid-July, early August, and late August for five years, 1985 to 1989. Leaf injury was most severe for the late sprays but no spray injury was observed on the fruit surfaces. Bitter pit was markedly reduced with all sprays except CaSO4. In some years, bitter pit was controlled better with the early sprays. Either early or late sprays improved fruit quality including overall appearance, reduced scald development, improved red color of the skin, increased fruit firmness and reduced incidence of bitter pit in cold air (0°C) storage. Soluble solids and acidity in the fruit was not affected by calcium sprays. Leaf Ca was higher from the late spray applications than from the earlier applications. All calcium chloride spray materials resulted in increased fruit peel and cortex Ca. Calcium nitrate sprays tended to increase fruit nitrogen concentrations leading to undesirable higher N:Ca ratios in the fruit.

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Thomas E. Marler and Hiphil S. Clemente

Trade winds occur throughout the year and drought occurs seasonally in many papaya (Carica papaya L.) production regions. We conducted four studies with `Known You 1' and `Sunrise' papaya seedlings to determine the combined influence of wind and water deficit on growth. We conducted three additional experiments to determine plant response to wind within a continuous dose range of 0 to 2.5 m·s–1. The main effects of wind and irrigation significantly reduced most response variables, such as dry weight components, leaf area, and height. However, the two factors acted independently of each other for every measure of plant growth. Thus, there was no departure from simple effects of an additive model for each main factor. The relationship between plant growth and wind between 0 and 2.5 m·s–1 could be described by a quadratic model. Results indicate that the influence of wind on plant growth cannot be studied without controlling or quantifying soil moisture among treatment groups. Practically, our results indicate that wind protection of young papaya plants may be warranted more so in the dry season than in the wet season or under sufficient irrigation practices.

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Thomas S.C. Li and Doug Wardle

The effect of harvest period on fresh and dry leaf and root weights and ginsenoside contents of 2-, 3-, and 4-year-old american ginseng (Panax quinquefolium) plants was investigated. Ginseng plants harvested once every 4 weeks from the end of June through September had the highest and lowest fresh and dry leaf weights in June and September, respectively. The trend was reversed in roots, except for 3-year-old roots that exhibited maximum weight at the end of August. Total ginsenoside contents in leaves of 3- and 4-year-old plants increased with the growing season until the end of August, but in 2-year-old plants it increased until the end of September. Total ginsenoside contents in roots peaked at the end of June for 3- and 4-year-old plants.

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Thomas S. Brettin and Ken C. Sink

We have used isozyme techniques (SGE) to assess variation and begin construction of a genetic map of the Asparagus officinalis genome. Isozyme extraction buffers, electrophoretic buffer systems, and isozyme stability during storage were evaluated. Isozyme expression under different environmental conditions was also examined. Thirty-four enzymes were evaluated for their usefulness as genetic markers in A. officinalis. Of these 34, 13 had sufficient activity and resolution on the gels for isozyme analysis. Of the 13 enzyme systems resolved, polymorphisms were observed in aconitase, endopeptidase, malate dehydrogenase, phosphoglucomutase, and shikimate dehydrogenase. Segregation of putative alleles is presented for ACON, END, MDH, PGM and SKDH isozymes. Co-segregation data showed linkage between a SKDH locus and a PGM locus. The isozyme analysis also included Asparagus densiflorus `Sprengeri' and revealed that aspartate aminotransaminase, endopeptidase, and triosephosphate isomerase would be potentially useful for verification of cell fusion products between the two species.