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Jeanine M. Davis

In recent years there has been an increase in the incidence of “gold flecking,” which develops on the surface of ripe tomato fruit. Gold flecking looks like a light sprinkling of gold on the skin of the fruit. There are no lesions and the interior of the fruit is not affected. Usually, gold flecking is barely noticeable. In 1998, however, gold flecking was severe enough in some cases to cause economic losses. It has been suggested that gold flecking is due to use of the insecticide Asana or it may be a genetic disorder. The objective here was to determine if gold flecking is caused by Asana and/or is cultivar-dependent. Treatments consisted of three cultivars (Mountain Fresh, Celebrity, and Mountain Pride) and four insecticides (Asana XL, Karate 1 EC, Thiodan 50 WP, and a water control). There were two plantings. Only red fruit was harvested. For both plantings, there was more gold flecking in the control than any of the insecticide treatments. There were no differences among the insecticides. For the early planting, `Mountain Fresh' had more gold fleck than the other cultivars. In the late planting, there were no differences between cultivars. This study demonstrates that Asana was not responsible for gold flecking and actually reduced it compared to the control. These results also suggest that insects may play a role in gold flecking.

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Jeanine M. Davis

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Jeanine M. Davis

Goldenseal (Hydrastis canadensis L.) is a widely used medicinal herb that is commonly collected from forests in North America. An increasing demand for goldenseal has put intense pressures on wild populations and increased the interest in cultivation. Cultural information on goldenseal, however, is limited and contradictory. A 3-year study was initiated to examine the effects of soil pH (4.5, 5.5, 6.5, and 7.5) and four rates of P and N (0, 0.1, 0.2, and 0.3 kg P or N/m3 of soil) on growth and development of goldenseal. In Spring 1993, small rhizome pieces were planted in pots of forest soil and grown under a wood-lath structure. Plant growth, flowering, and fruiting are monitored throughout each growing season. The plants are brought into an underground storage facility for overwintering. In late winter, roots are weighed, evaluated, and replanted. After one season of growth, root weights were highest with pH 5.5 and 6.5 and no additional P or N. During the second season of growth, the greatest plant growth and fruiting were obtained with pH 5.5 and 6.5 and with the two highest rates of phosphorus.

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Jeanine M. Davis

In 1991, a four year study was initiated in which staked tomatoes and snap beans are rotated annually and grown with three cover crop treatments (wheat, crimson clover, and bareground) and three N rates (0, 60, and 120 kg N/ha) in a RCB with four replications. Crop growth, yield, nutrient status, N cycling, and pest populations are being studied. The first year there was no response to cover crop. The next two years, crimson clover reduced bean yields due, in part, to high levels of disease. Mexican bean beetle populations were also highest with clover and increased with increasing N rate. In 1992, wheat increased tomato fruit crack, but there was no effect on yields. In 1993, wheat reduced early season tomato yields but had no effect on total season yields. Aphid populations were highest on tomatoes grown with crimson clover. The study reveals that cover crop systems are dynamic and long-term studies are required before dependable grower recommendations can be made. This study is part of the Tri-State Vegetable Project, a cooperative research project with N.C., S.C. and Ga.

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Jeanine M. Davis

Farmers are looking for new crops to grow to diversify their farms and increase profitability. Medicinal herbs are often of interest because they are generally perceived as being easy to grow, in high demand, return good prices, and serve as useful rotational crops. In reality, most farmers who have not previously grown medicinal herbs do not understand the global herb market. They do not know how to find a buyer or which herbs to grow. To help growers produce and market medicinal herbs, we initiated the Medicinal Herbs for Commerce Project. We also conducted studies on production problems for a variety of herbs. An issue that should be addressed is that there are hundreds of medicinal herbs in commerce and it is impossible for a small number of research programs to independently answer all the questions that are being asked by the industry. Developing a consortium of researchers around the world to coordinate efforts on how best to grow and process medicinal herbs and to create a database of information for farmers and agricultural advisors would be a great service for this industry.

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Jeanine M. Davis

The objective of 2 years of field studies was to begin development of a luffa sponge gourd (Luffa aegyptiaca Mill.) production system for a cool, temperate climate by studying the effects of planting date, planting method, in-row spacing (30.5, 61, and 91 cm), and pruning techniques on yield and quality of luffa sponge gourds. High yields of mature gourds were obtained when transplants were field-set as soon as the danger of frost had past. Highest marketable yields were obtained when plants were spaced 30.5 cm apart in the row and the first four lateral shoots were removed. Plants spaced 91 cm apart produced gourds with the largest diameter, whereas plants with 30.5-cm in-row spacing produced the highest yields of gourds with bath sponge diameters (5.1-7.6 cm). Plants spaced 91 cm apart and topped at node six obtained high fiber density, strong fibers, and excellent visual appeal, but low yields. Yields were competitive with yields obtained in warmer climates.

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Jeanine M. Davis

Using various mulches for small-scale, commercial basil (Ocimum basilicum L.) production was examined. Sweet basil and bush basil, on raised beds with drip irrigation, were grown on bare ground or mulched with black polyethylene, wheat straw, hardwood bark, or mixed wood chips. Bacterial soft rot (Erwinia spp.) was highest for both basils grown with wheat straw and for sweet basil grown on bare ground or with back polyethylene mulch. Both basils grown with hardwood and pine bark mulches had few soft ret symptoms. All mulches provided acceptable weed control. Yields throughout the growing season were highest with black polyethylene mulch and lowest with hardwood and pine bark mulches.

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Jeanine M. Davis

Goldenseal was grown in pots of forest soil under a wood-lath structure for 3 years. Soil treatments consisted of four pH levels (4.5, 5.5, 6.5, and 7.5) and four rates of P and N (P or N at 0, 0.1, 0.2, and 0.3 kg·m–3 of soil) arranged as a RCB factorial with eight replications. Final root weights were highest with pH 5.5 and 6.5. Although response to N and P rates varied from year to year, final root weights showed no response to P and decreased with increasing N. Increase in fresh weight from initial weight of the planting stock to final total root weight ranged from 5.7× (pH 4.5, P at 0 kg·m–3, and N at 0.3 kg·m–3 treatment) to 28.5× (pH 5.5, P at 0.2 kg·m–3, and 0 N treatment). Flowering, fruit set, plant height, leaf number, and fibrous roots: rhizome ratio were highest at pH 5.5 and 6.5 and not influenced by P or N rates. Preliminary analysis suggest that root alkaloid content was also affected by soil pH.

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Jeanine M. Davis and Wayne H. Loescher

Diurnal fluctuations in soluble carbohydrates and starch were monitored in young (expanding), mature (first fully expanded), and old (nearing senescence) celery (Apium graveolens L.) leaves. In all tissues, mannitol and sucrose were the carbohydrates present in the highest concentrations. In old and young leaflets and their petioles, there was little change in levels of mannitol and sucrose in 26 hours. In mature leaflets, sucrose accumulated in the light and decreased in the dark; mannitol increased slightly in late afternoon. Starch concentration, although quite low, showed definite diurnal fluctuations in mature leaflets, but only small changes in young and old leaflets. Both sucrose and mannitol were present in mature petiole phloem tissues. Mannitol concentrations were high in the adjacent storage parenchyma tissue, but sucrose was almost undetectable. These data support earlier findings that sucrose is produced, translocated, and metabolized throughout the celery plant. Mannitol is also translocated, but also serves as a major storage carbohydrate in leaf tissues, especially petiole parenchyma. Starch serves as a minor short-term storage compound in leaflets.

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Jeanine M. Davis and Edmund A. Estes

Unstable prices and increased competitive market pressures have caused many staked-tomato (Lycopersicon esculentum Mill.) producers to reexamine the costs and benefits of various production practices. In 1988 and 1989, field studies were conducted to determine if changes in plant in-row spacing and pruning could reduce production costs, increase yields, and improve grower net returns of staked `Mountain Pride' tomatoes. In both years, early-season yields were highest using early pruning (when lateral shoots were 5 to 10 cm long) or delayed pruning (when lateral shoots were 30 to 36 cm long) and in-row spacings ≤46 cm. In 1988, total-season yields per hectare of pruned plants increased as in-row spacing decreased. For nonpruned plants, however, total-season yields were high at all spacings. In 1989, total-season yields were lower from delayed-pruned plants than from nonpruned plants and there was little yield difference due to in-row spacing. In both years, nonpruned plants produced low yields of fruit >72 mm in diameter but their total yields were greater than those of pruned plants. Net returns per hectare, calculated from combined data of both years, were highest when 1) plants spaced closely in-row were pruned early and 2) plants were spaced 46 to 76 cm apart and either pruned early or not pruned.