EVALUATION OF VACCINIUM ANGUSTIFOLIUM AIT. COPPER AND IRON LEAF STANDARDS
The standard leaf concentrations for Cu and Fe were reported by Trevett (1972) to be 7 and 50 ppm, respectively. In a commercial lowbush blueberry field with low leaf Cu and Fe concentrations, nine 1.8×15 m treatment plots were established in a randomized complete block design with 6 blocks. To raise leaf Cu, Copper Keylate® (Stoller Enterprises, Inc.) was applied to foliage at 0.6 kg/ha on June 19, 2002 in a volume of 626 L.ha-1. In a similar volume, the Stoller Enterprises Inc. product Fe Keylate®, was applied at 0.6 kg/ha to provide Fe. For each solution, ammonium sulfate (0.7%) was added to enhance uptake. Treatments included a 19 June prune- or crop-year application of Cu, Fe, or Cu+Fe, a prune and crop-year Cu+Fe, and a 7 June and 19 June prune-year Cu+Fe application. A plot receiving no treatment served as a control. Leaf Cu and Fe concentrations were raised to above satisfactory leaf concentrations (Cu >7 ppm, Fe >50 ppm) by their respective treatments. Leaf concentrations were significantly higher for each element when they were applied together. This was true for both prune-year and crop-year applications. No benefits of raising either leaf Cu or Fe concentrations were found, however, with regard to stem characteristics, such as length or branching, or potential yield (flower bud formation). Berry yield was not increased by prune-year, crop-year, or prune plus crop-year applications of Cu and Fe. It appears that the standards for Cu and Fe are too high.
Smagula, J.M. (2008). EVALUATION OF VACCINIUM ANGUSTIFOLIUM AIT. COPPER AND IRON LEAF STANDARDS. Acta Hortic. 772, 351-354
foliar feed, fertilization, lowbush blueberry