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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

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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

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

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 (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* and George B. Cox

Weeds are a major concern in the production of many medicinal herbs. Weeds can interfere with the growth of the herb, reducing yields of foliage, flowers, and roots. The presence of weeds in the harvested herb can lessen the value of the herb or render it unmarketable. Weed control on medicinal herbs is difficult because there are few herbicides cleared for use and many herbs are organically grown. In this study, we examined the use of white and black plastic mulches to control weeds in the production of six medicinal herbs in the northern piedmont region of North Carolina. The herbs were grown for 2 years on raised beds with drip-irrigation. The beds were left bare or covered with black plastic mulch or white plastic mulch. The herbs grown were Arnica chamissonis, Echinacea angustifolia, Echinacea purpurea, Leonurus cardiaca, Scutellaria lateriflora, and Spilanthes oleracea. Transplants were field set in May and June. Depending on the particular herb, foliage, and flowers were harvested during both growing seasons and roots were harvested at the end of the second season. Both plastic mulches provided excellent weed control compared to the bare ground treatment. A. chamissonis flower yields were reduced when plants were grown with either plastic mulch. Growth and yield of E. angustifolia, L. cardiaca, and S. lateriflora were unaffected by any mulch treatment. In contrast, total season yields of E. purpurea tops (stems, leaves, and flowers) and roots were higher with both plastic mulches than with the bare ground treatment. Root yields of S. oleracea were higher with the bare ground treatment than with either mulch, but top yields were unaffected by treatment.

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Jeanine M. Davis and Edmund A. Estes

Stable prices and increased competitive market pressures have caused many staked tomato producers to examine the costs and benefits of adopting intensive production practices such as drip irrigation and plastic mulch. Inclusion of these practices with traditional growing practices often results in a total production cost in excess of $10,000 per acre. In 1988 and 1989, field studies were conducted in western North Carolina to determine if changes in plant spacing and pruning could reduce production costs, increase yields of large fruit and improve grower net returns from staked tomatoes (c. Mountain Pride). Combined data indicated that the greatest early season yields were obtained using early pruning (when suckers were 2-4 inches long) and in-row spacings of 18 inches or less. Net returns per acre were greatest when: 1) plants were pruned early and spaced closely in-row, which increased high priced early season yields and 2) plants were spaced 30 inches apart and either pruned early or not pruned, which increased total season yields. Non-pruned plants had lower yields of Jumbo and Extra Large size fruit, but higher total yields than pruned plants.