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Thesis (M.S.)--Michigan State University. Dept. of Forestry, 2008. / "Major professor, Dr. Pascal Nzokou"--Acknowledgements. Title from PDF t.p. (viewed on July 30, 2009) Includes bibliographical references. Also issued in print.

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Thesis (M.S. - Renewable Natural Resources)--University of Arizona, 1981. / Includes bibliographical references.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 73-77). Also available via the Internet.

Three studies were conducted with Fraser fir Christmas trees to determine the variation in foliar nitrogen (N) , phosphorus (P) , potassium (K), calcium (Ca), and magnesium (Mg) levels among plantation ages, sample locations within the crown, and effects due to seasonal changes. Extensive variation in nutrient concentrations existed with age of tissue collected, sample location with respect to aspect and vertical position, and normal seasonal fluctuation. Tree to tree nutrient variation indicated that greater sampling intensities are required for younger (under four years) plantations as opposed to older (over four years) plantations to achieve comparable confidence and precision levels. The data clearly illustrated that comparisons of foliar nutrient levels without regard to these sampling variables could cause erroneous diagnoses. Recommended foliar sampling practices involved sampling current-year's tissue from 2- or 3-year-old south-facing branches in October or November for routine foliar diagnoses. Another study developed a DRIS application to evaluate N, P, K, Ca, and Mg nutrition on seventy-nine trees in a 3-year-old Fraser fir Christmas tree plantation. DRIS norms and index equations from premium grade Christmas tree were developed. In contrast to most crops where growth and yield are assessed, Fraser fir Christmas tree performance was evaluated by conventional grading procedures based on tree quality. A classification model utilizing several measured growth characteristics to predict Christmas tree grade was also investigated to objectively evaluate tree performance. Satisfactory grade-prediction results using a discriminant model were obtained yielding overall correct classification rates of 80 percent. Preliminary evaluation of DRIS performance suggested that assessments of nutritional balance, rather than examination of individual nutrient concentrations, may be more useful for prescribing fertilizer to improve Christmas tree quality. / M.S.

The shake and wash technique (samples placed in a jar with alcohol added and shaken to remove the mites) was effective in removing 100% of the predator mites, and adult spruce spider mites from Douglas-fir foliage and 98% of the spruce spider mite nymphs. Eighty-eight percent of the spruce spider mite eggs was removed. This technique was considered efficient for removal of spruce spider mite and its predators from Douglas-fir foliage. Sodium hypochlorite (0.84%) added to the alcohol did not increase the number of spruce spider mites or phytoseiid mites removed from the foliage. The intracanopy distribution of spruce spider mite and its predator mites was studied on Douglas-fir Christmas trees in the Willamette Valley, Oregon. When overwintering spruce spider mite egg densities populations were low (<5 eggs/19 cm of stem), significantly more eggs were found on the current season's growth. No significant differences were found between top and bottom halves of the tree or between compass directions. Differences between current and previous season's growth were not found when egg densities were high (>40 eggs/19 cm of stem), but significant differences were found between levels for current season's growth with more eggs found in the upper portion of the canopy. Quadri-directional differences did not exist with either low or high mite populations. Sampling tip or basal stem-halves with low overwintering egg populations did not bias population estimates. Heavy spring rainfall appeared to reduce mite populations as has been reported elsewhere by washing them off the tree and causing increased mortality. Spruce spider mite disperse to the current season's growth shortly after budbreak. Population density rapidly increased in late May and then abruptly declined in mid-July. / Graduation date: 1991

Fraser fir [Abies fraseri (Pursh) Poir.] is an important Christmas tree species in Virginia. Because it is responsive to fertilization, and because most Fraser fir growers fertilize their crop, a scientifically-based nutrient diagnosis and fertilizer recommendation system is needed. The objective of this study was to develop and test DRIS norms for Fraser fir Christmas trees grown in Virginia for the ultimate purpose of establishing a nutrition diagnosis and fertilizer prescription system. A total of 107 Fraser fir plantations were sampled for foliage, soil, and diameter measurements. These plantations represented the range in site conditions and management practices for Fraser fir Christmas trees grown in Virginia. Foliage was analyzed for N, P, K, Ca, Mg, Zn, Mn, Fe, Cu, and B. Soil was analyzed for extractable macro- and micronutrients. DRIS norms were developed from these data using standard DRIS procedures. A total of 42 nutrient ratios were significant discriminators of tree performance as measured by variation in ground line diameter. The norms were tested using sixth year data from a factorial fertilizer trial. Nutrient limitations due to both deficiencies and imbalance were detected and correctly diagnosed using the newly-derived norms. A complete validation is required, but this preliminary test showed that these norms are useable and useful in their present form. In the process of developing and testing the norms, modifications to traditional DRIS methods were used to meet the special conditions of this crop. DRIS symmetry was maintained by including non-significant ratios, but setting their standardization functions equal to zero. This reduced the influence of the non-discriminating nutrient ratios on the DRIS analysis. Norm ranges as opposed to discrete norms (ratio means) were used to correct for the influence of extremely variable micronutrient ratios on the DRIS analysis. Soil norms did not enhance diagnoses over and above using foliar norms alone. This is due to soil sampling variation, poor correlations of extractable nutrients with tree performance, and an incomplete understanding of fertilizer reactions and uptake chemistry in a variety of soils. Each crop presents unique challenges in the application of DRIS. DRIS should not be naively applied without investigating these problems. The DRIS norms established in this study, and the modifications to standard DRIS methods, provide a sound scientific basis upon which to build a nutrient diagnosis and fertilizer recommendation system for Fraser fir Christmas trees grown in Virginia. / Master of Science

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