Diagnosis and Recommendation Integrated System (DRIS) Nutrient Norms for Fraser Fir Christmas Trees

Abstract

Abstract Fraser fir (Abies fraseri [Pursh] Poir.) is an important Christmas tree species in Virginia and North Carolina. 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 Diagnosis and Recommendation Integrated System (DRIS) norms for Fraser fir Christmas trees 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 and soil were analyzed for 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 groundline 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 more thorough validation will be made with time, but this preliminary test showed that these norms are a reasonable first approximation. For. Sci. 37(4):998-1010.