News » 21.04.2025 - Looking at some unexpected fertilizer injector problems

This Boston fern crop (Nephrolepis exaltata 'Bostoniensis') wasn't looking right. In looking at the foliage, the chlorosis clearly indicated something wasn't right with the crop. In reviewing the environmental data, the air temperatures and light intensities were all within normal ranges and meeting the target setpoints, which ruled out problems with the growing environment. Nothing had been sprayed on the crop, so phytotoxicity from a plant insecticide, fungicide, or plant growth regulator could also be ruled out.

With the greenhouse environment and chemical applications ruled out as causes of the chlorosis, the other "usual suspect" remaining as a causal factor was fertilization. To determine what may be causing this, there are several steps to be taken to see if sufficient fertilizer was being applied to the crop, including testing the substrate electrical conductivity (EC), reviewing recent changes in fertilizer stock solutions, and inspecting the injector for correct functioning—and this is how the grower proceeded.

The first thing the grower did was measure the substrate (EC). To do this, they used the PourThru method, which is a non-invasive and simple method of measuring substrate pH and EC. When the leachate of several different baskets was measured, it was clear the EC was low, likely causing the chlorosis on the Boston fern foliage. This crop is fed regularly with each irrigation Monday through Friday, with clear water applied on weekends, so it seemed surprising that the substrate EC was low. This meant there were problems with the fertilizer stock solution or the fertilizer injector.

 

Source: www.floraldaily.com

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