Applying Diagnosis and Recommendation Integrated System to Fraser fir Christmas trees.

Fraser fir [Abies fraseri (Pursh) Poir.] is responsive to nutrient additions. Christmas tree growers are attempting to take advantage of this responsiveness in order to produce higher quality and therefore more valuable trees. The Diagnosis and Recommendation Integrated System (DRIS) was applied to this tree crop to assess its usefulness for diagnosing nutrient needs. Of 12 tree attributes, basal diameter at a given age proved to be the best substitute for yield in DRIS calculations. The basal diameter used to separate highand low-quality populations was 30 mm for trees in 3-yr-old plantations. This number corresponded to the 90th percentile commonly used in other DRIS applications. Significantly different variances in both nutrient and dry-matter ratios between high and low basal diameter indicate that nutrient concentration as well as balance among nutrients influence basal-diameter growth. The DRIS technique appears promising for diagnosing the nutrient needs of this crop. View complete article To view this complete article, insert Disc 5 then click button8