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Cause Both Dracaena deremensis and D. fragrans (corn plant) are very sensitive to fluoride toxicity. Although there are many natural sources or fluoride in water, many municipal water sources inject fluorine (at 1ppm) as an additive to prevent tooth decay. Use of this water for irrigation can result in toxicity symptoms on sensitive plants. Fluoride is an accumulative poison in plant foliage. Accumulation may be gradual over time. Fluoride strongly inhibits photosynthesis and other processes. It will move in the transpiration stream from roots or through stomata and accumulate in leaf margins. Excessive drying between waterings also can lead to brown tips and margins, especially if fertilized too much.
A wide variety of plants are sensitive to fluoride toxicity. Typical indoor foliage plants include Dracaena, Tahitian Bridal Veil (Gibasis pellucida) and the spider plant (Chlorophytum comosum). Sensitive flowering plants include gladiolus, lily, tulip and yucca.
Symptoms Tips or margins of leaves turn brown and necrotic.
Cultural control
- Keep high calcium levels in soil, with a pH of 6.5 to 7.
- Fertilize sparingly.
- Water D. deremensis so that soil is evenly moist. Allow D. fragrans to dry out; it is easily overwatered.
- Avoid fluoridated water or treat water by reverse osmosis, condensation or remove fluorine with charcoal.
Reference Powell, C.C. and Rossetti, R. 1992. The Healthy Indoor Plant. Columbia, OH: Rosewell Publishing.