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Jonathan R. Schultheis and C. Ray Campbell

In the last 3 years, ≤50% of the North Carolina sweetpotato crop has been produced with the variety Hernandez. A brown to black discoloration on the epidermis of the `Hernandez' sweetpotato may develop when maintained in storage for several months. The symptoms resemble blister—blister is caused by a boron deficiency. Preliminary studies in 1994 indicated that boron reduced the discoloration on `Hernandez' but did not eliminate the problem. To help confirm these findings and further define the role of boron in defining skin discoloration, boron was applied in 1995 at several rates (0 to 5.6 kg·ha–1) and stages of plant development using two application methods (foliar or soil). Yields and plant analysis data were obtained. Marketable yields ranged from 18.4 to 29.3 mt/ha. Leaf boron concentration ranged from 50 to 100 mg·kg–1 throughout the production season when 1.1 kg·ha–1 boron was soil applied shortly after planting. Excessive levels of boron (200+ mg·kg–1) were measured in plant tissue when application levels exceeded 2.2 kg·ha–1 regardless of timing. Soil application appeared to be an adequate method for boron application. Roots were examined for symptoms of discoloration after 5 months. Results indicated no affect of boron on incidence or severity of the symptoms.

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Stuart L. Warren, C. Ray Campbell and Walter A. Skroch

Fraser fir [Abies fraseri (Pursh) Poir.] and Norway spruce [Picea abies (L.) Karst.] were grown in seven vegetation management programs ranging from 100% cover of grass-dominated vegetation to bare soil on opposing north and south aspects. Concentrations of 13 nutrients were determined at three growth stages during 2 years: active terminal growth, cessation of terminal expansion, and dormancy. Aspect did not affect nutrient concentrations. Vegetation management programs bad a significant impact on nutrient concentration for both species. Nitrogen, Ca, B, Fe, and Mn concentrations during dormancy were negatively correlated with herbaceous biomass. In contrast, N during active growth and P and Mg concentrations during all stages were positively correlated with herbaceous biomass. Vegetation management only affected the seasonal trend of Mo. Seasonal trends varied by nutrient in both species.

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L. Eric Hinesley, Layne K. Snelling, C. Ray Campbell, D.K. Roten and Jeff Hartzog

Abstract. Abies fraseri (Pursh) Poir. Christmas trees were fertilized for 5 years with four levels of N (0, 56, 113, or 170 kg·ha-1 per year) in spring, fall, or equally split between spring and fall. Nitrogen did not affect leader length, number of leaders, or bud frequency on the upper (distal) portion of the leader. Nitrogen increased bud frequency on the lower (proximal) 20 cm of the leader in only 1 of 3 years of measurement. All application schedules increased the number of apical buds on branches, whereas the number of lateral buds was increased only by spring applications. Nitrogen increased tree fresh weight and retail value as well as weight, length, and surface area of needles. Foliar N concentrations in the fall varied with fertilization schedule, and were higher in November than in October.

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James L. Gibson, Brian E. Whipker, Dharmalingam S. Pitchay, Paul V. Nelson and C. Ray Campbell

Elemental deficiencies of N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, and B were induced in `Osaka White' ornamental cabbage (Brassica oleracea var. acephala L.) plants. Seedlings were planted in 4.7-L plastic containers and fertilized with a complete modified Hoagland's solution or this solution minus the element that was to be investigated. Plants were harvested for tissue analysis as well as dry weight when initial foliar symptoms were expressed and later under advanced deficiency symptoms. Root architecture was also recorded for the plants treated with the solutions. The containers were replicated three times for each of the two harvests and were randomized in a complete-block design. Deficiency symptoms for all treatments were observed within five weeks. The most dramatic expression of foliar symptoms occurred with N (a purplish tinge on underside of lower foliage leading to necrotic margins on the mature leaves), P (elongated internodes and a purplish tinge on underside of mature leaves), K (compact internodes with chlorotic lower foliage leading to necrotic patches on the leaf margins and blade), Fe (bright yellow upper foliage leading to a bleach white appearance), Ca (complete meristem necrosis with lower foliage becoming chlorotic then necrotic), and B (deformed young leaves and fully expanded leaves becoming thick, leathery, and brittle). The dry weight of plants treated with solutions not containing N, P, Ca, Fe, or B was significantly lower when compared to the control. Foliar tissue concentration data will assist plant tissue analysis laboratories in establishing foliar symptom standards for grower samples.

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Dharmalingam S. Pitchay, James L. Gibson, C. Ray Campbell, Paul V. Nelson and Brian E. Whipker

The margin of error in pinpointing the difference in deficiency symptoms between calcium and boron is high. Several experiments were conducted in the greenhouse to induce as well as to differentiate the exact foliar and root symptoms of Ca and B. The experiments were conducted with modified Hoagland nutrient solutions. The treatments were with or without Ca or B salts for inducing total deficiency symptoms. Symptoms were expressed on the upper part including the growing point of the plant. In absence of Ca, marigold and zinnia plant heights were reduced by 58% and 37%, respectively, from the control. However, the reduction in height was only in the 27% and 25% range for B deficiency. Ca deficiency was noted as a blackened region on the leaf blade (early stage symptoms) which progressed into necrotic spots on the newly formed leaves. Severe necrosis, was observed on the growing point with advanced Ca deficiency. B deficiency results in a leathery and gray color in zinnia, needle like and narrow leaflets in marigold. The leaf blades were brittle in all B deficient species. B deficient plants roots were stiff and leathery and lateral roots possessed black nodule like endings at the tips. The Ca deficient roots expressed less side branching and at the advanced stage the roots were shorter and fewer with severe necrotic symptoms. The above initial and advanced deficiency symptoms appeared earlier in treatments without Ca than B. Images of Ca and B deficiency symptoms, as well as tissue concentration values will be presented.

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L. Eric Hinesley, Layne K. Snelling, C. Ray Campbell, D.K. Roten and Jeff Hartzog

Abies fraseri (Pursh) Poir. Christmas trees were fertilized for 5 years with four levels of N (0, 56, 113, or 170 kg·ha–1 per year) in spring, fall, or equally split between spring and fall. Nitrogen did not affect leader length, number of leaders, or bud frequency on the upper (distal) portion of the leader. Nitrogen increased bud frequency on the lower (proximal) 20 cm of the leader in only 1 of 3 years of measurement. All application schedules increased the number of apical buds on branches, whereas the number of lateral buds was increased only by spring applications. Nitrogen increased tree fresh weight and retail value as well as weight, length, and surface area of needles. Foliar N concentrations in the fall varied with fertilization schedule, and were higher in November than in October.