Edema (or oedema) is yet another problem that can result from overwatering. Although it’s often referred to as a type of plant disease, it’s not viral, fungal or bacterial like the majority of other diseases. Instead, it’s a type of abnormal water retention, which in turn can lead to some unsightly symptoms.
WHAT IS EDEMA?
Edema occurs when a plant’s roots absorb water faster than the plant can use it, causing its internal cells to experience water pressure. This often occurs after a routine of watering in the evening, or just before a significant drop in temperature. When this happens, the plant tries to get rid of the excess water through pores in the leaves. These cells can burst and die, then form plant “blisters.” Eventually the blisters erupt and ugly growths form in their place. As it’s not fungal or bacterial, you don’t have to worry about it spreading from plant to plant.
Edema is usually caused by too much water, often also in combination with insufficient light .
SYMPTOMS
Bumps or blisters on your plant - these can vary in color, often yellowish, white or brown. White crystallized bumps tend to appear on the underside of leaves, whereas the yellow bumps occur on top of the leaf. Brownish spots appear when the leaf tissue has started to dry out and die.
The plant’s leaves may start to curl
Stunted growth
Disfiguring of fruits
WHAT TO DO NOW
Luckily, it’s relatively easy to treat edema - simply put, you just need to allow your plant’s soil to dry up a bit before watering it again. This will give it a chance to recover and re-adjust.
PREVENTION
In the future, try to water a bit less - always check how wet the soil is before giving more water, and never allow the plant to sit in water. You can find information about how wet the soil should be before giving more water for each specific plant in your collection under the ‘Info’ tab in Planta.
If your plant is in a large pot, it could be that it is a bit too big for your plant and is consequently not draining well enough. You may want to consider repotting it, or placing it in a sunnier location to help it dry out faster (just make sure that the type of plant is suitable for this - be sure to check its ideal light conditions first, also in the ‘Info’ tab). In fact, increasing your plant’s exposure to sunlight in general can be helpful to plants with edema. Again, just make sure that you don’t burn them by placing sensitive your plants in too-harsh sunlight.
Finally, if you usually water at night / in the evening, try switching up your routine to water in the morning instead, once the sun has risen. This will help to prevent edema from recurring.