Nitrate-ammonium Nitrogen Ratio and Fertilizer Application Method Influence Bract Necrosis and Growth of Poinsettia

Abstract

Abstract ‘Gutbier V-14 Glory’ poinsettia was introduced to the commercial industry in the late 1970s and has been shown to be sensitive to bract necrosis (3). Necrotic spots occasionally develop on the intermediate bracts during the latter parts of the crop cycle. Nell and Barrett (2) found this problem to be worse when plants were provided 300–400 mg/liter Ν at every irrigation and well watered during bract coloration. Symptoms resembled injury due to elemental toxicity or desiccation. Observations in commercial operations suggested that necrosis may be related to fertilizer source or formulation.