Also known as oedema, edema is not a disease, nor a symptom of a virus, insect damage or of bacteria. Instead, it is a type of abnormal water retention (or disorder) that is usually influenced by environmental issues. Basically, edema occurs when plants take up more water than needed for transpiration (water loss) from the leaves.
Edema presents differently in different kinds of plants. For example, when bloated cells burst on young fiddle leaf fig leaves they create a reddish pattern of spots over the leaf, while other plants will have a bubbling effect on top of their leaves, or have small white ‘crystals’ on the underside of the leaves.
Mildly affected plants will recover, while severely affected plants may drop leaves and grow distorted new leaves, or even die.
Water plants evenly, around the roots, not the leaves, and use a well-draining soil mix.
Make sure there is space between plants, which helps ensure they receive enough light so they don’t stay damp for too long after watering or rain. Do not let drained water sit in saucers or cover pots.
Depending on the cause, there are different ways to treat edema. Keep affected plants on the ‘dry side’ of watering, especially if they are houseplants. Reduce humidity levels and offer better airflow for plants, which may need a little pruning to achieve this.
Feed affected outdoor plants with Aquaticus Organic Garden Booster once every four weeks, and indoor plants once every four to six weeks with Kings Houseplant Food.
In severe cases, where most of the foliage has dropped, edema will not be reversible, so it best to try and prevent it if possible.
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