PPDL Picture of the Week for
January 2, 2012

High salts and New Guinea impatiens

Christopher J. Currey, Graduate Research Assistant and Roberto G. Lopez, Assistant Professor, Horticulture & Landscape Architecture

With the spring bedding plant season just around the corner, it's a good time to put together a crop monitoring program and recognize nutrient and fertility symptoms before they become severe. Certain crops including New Guinea impatiens are extremely sensitive to high soluble salts in the root zone. Soluble salt levels are measured as the electrical conductivity (EC) of the growing substrate. Cupping of unfolding leaves, stunted growth, death of young leaves, and dieback of the growing tip of New Guinea impatiens are all symptoms of elevated substrate EC (Figs. 1 and 2). The EC of the substrate these plants were growing in was above the desired range for New Guinea impatiens. Target EC levels for New Guinea impatiens are 1.0-2.6, 0.76-2.0, or 0.26-0.75 for the Pour Through, SME, or 1:2 media tests, respectively. To avoid high substrate EC, reduce the fertilizer concentration for constant liquid feed programs and/or increase frequency of clear water leaching.

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Symptoms of high EC on New Guinea impatiens

Figure 1

Symptoms of high EC on New Guinea impatiens

Figure 2

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service