‘Mrs. G.G. Gerbing’ azaleas were grown for 1 year in a pine bark:Canadian peat:builders' sand (2:1:1 by vol) medium amended with 3 kg/m3 (5 lb/yd3) of dolomitic limestone and fertilized with 4 Woodace 14N-l.5P-2K (14-3-3) briquettes placed either below the root ball, 4 briquettes placed in the growth medium surface or 2 briquettes in the surface and 2 below the root ball. After one year, shoot and root dry weights were greatest for the surface placement and these plants were less chlorotic than for the other placements. The 460 ml (l in) per irrigation rate resulted in the smallest plants with more chlorosis than the 150 or 230 ml (0.3 and 0.5 in) rates. Leaf tissue, N, P and K levels were generally lower than optimal levels for azaleas. Data from this experiment indicate Woodace briquettes should be placed in the growth medium surface and the medium should be amended with supplemental micronutrients even though the briquettes contain micronutrients.
Florida Agricultural Experiment Stations Journal Series No. 6487. The authors gratefully acknowledge Claudia Larsen and Jan Weinbrecht for their excellent technical assistance, and Estech Inc., Chicago, IL for financial assistance.
2Associate professors of Horticulture, resp.