Another issue that can arise from overwatering is edema (also known as oedema). Despite being frequently referred to as a sort of plant disease, it is not a virus, a fungal infection, or a bacterial infection like most other diseases. It’s actually a form of aberrant water retention, which can cause some unattractive symptoms.
WHAT IS EDEMA?
Edema happens when a plant’s roots take in more water than it can use, creating water pressure inside the plant’s cells. This frequently happens after a nightly ritual of watering or right before a sharp decrease in temperature. When this occurs, the plant makes an effort to drain the extra water by opening pores in the leaves. These cells have the capacity to burst, die, and subsequently create plant “blisters.” Blisters eventually erupt, and unsightly growths take their place. You don’t need to be concerned about it spreading from plant to plant because it isn’t fungal or bacterial.
Edema is typically brought on by an excessive amount of water, frequently in conjunction with a lack of light.
SYMPTOMS
Your plant may develop bumps or blisters, which are often yellowish, white, or brown in appearance. While yellow bumps typically appear on the top of leaves, white crystalline pimples typically appear on the bottom of leaves. When the leaf tissue has begun to dry out and die, brownish patches form.
WHAT TO DO NOW
Fortunately, edema is rather simple to manage; all you have to do is wait until the soil of your plant has slightly dried up before giving it another watering. It will have a chance to recover and adjust as a result.
PREVENTION
Try to water your plants a little less in the future. Never let the plant sit in water, and constantly check the soil’s moisture level before adding more water. Under the ‘Info’ tab in Planta, you may learn how wet the soil needs to be before adding more water for each individual plant in your collection.
If your plant is in a large pot, it’s possible that the pot is a little too big for it and is thus not draining properly. To assist it dry out more quickly, you might think about repotting it or moving it to an area with more sunlight (but make sure the plant is compatible for this by first checking its optimal light conditions, also in the “Info” page). In fact, plants with edema may benefit from having more solar exposure overall. Just be careful not to burn them by placing delicate plants in sunlight that is too intense.
Last but not least, instead of watering in the evening or at night, try changing your schedule to water in the morning when the sun has risen. This will aid in preventing the recurrence of edema.
Why does succulent edema develop?
The ailment known as “edema,” which is formally written “oedema,” affects numerous plants, including succulents. No illness or bug is to blame for the situation. Edema, on the other hand, is a sign of unusual water retention. Small, elevated spots on the leaves that resemble papules and are either lighter or darker than the normal color of the succulent’s leaves are the most common signs of edema. These little clusters of welts appear when a succulent consumes too much water. Cells in the leaf burst due to oversaturation, and this is what causes the distinctive welts to appear. The spots won’t spread and won’t harm the plant, but they can change how your succulent appears and are a surefire indication that your plant is receiving too much water.  
Causes of Edema in Succulents
Overwatering or poor drainage are the most frequent causes of a succulent’s excessively wet leaves. Succulents and cacti require well-draining soil, and it’s common for these plants to struggle with edema if their soil isn’t porous. Edema doesn’t, however, always result from inadequate drainage. According to science, a succulent experiences edema when its roots take in water more quickly than the plant can utilize it.  
Plant edema: Will it disappear?
Ever have a day where you feel a little bloated and lethargic? Your plants may experience the same issue since they hold water when the conditions are unfavorable, just like people do. Plant edema is not a serious disease and is not a sign of a bug, bacterial, or viral infestation. Plant edema can be easily treated if discovered early and is frequently brought on by overwatering and ineffective fertilization.
How is leaf edema treated?
Edema, also referred to as oedema, is not a disease and is neither a sign of bacteria, viruses, or insect harm. It is actually a form of aberrant water retention (or disease) that is frequently impacted by environmental problems. Enough water is absorbed by plants to prevent transpiration (water loss from the leaves), which causes edema, than is actually required.
Different plant species exhibit edema in different ways. Young fiddle leaf fig leaves, for instance, develop a scarlet pattern of dots when swollen cells break, while some plants develop a bubbling appearance on top of their leaves or have tiny white “crystals” on the underside of the leaves.
Plants that are only mildly harmed will bounce back, but plants that are significantly harmed may lose their leaves, develop malformed new leaves, or even perish.
Prevention
Use a well-draining soil mixture and water plants uniformly, around the roots rather than the leaves.
Make sure there is room between plants so they can receive adequate light and avoid becoming overly soggy after watering or raining. This will assist ensure they receive enough light. Never leave drained water in saucers or on top of pots.
Treatment
There are several techniques to treat edema, depending on the etiology. Maintain the ‘dry side’ of watering for the affected plants, especially if they are indoor plants. For plants to have greater ventilation and lower humidity levels, some pruning may be necessary.
Feed impacted outdoor plants once every four weeks with Aquaticus Organic Garden Booster, and once every four to six weeks with Kings Houseplant Food, for indoor plants.
Edema won’t be reversible in extreme cases when the majority of the leaves has fallen, therefore it’s best to attempt to avoid it if you can.
What causes plant edema?
Oedema is a physiological condition that happens when roots absorb water more quickly than the plant can utilise it or evaporate it through the leaves. The inside leaf cells develop a water pressure that causes them to burst, leaving behind dead cells that are apparent as a blister, mostly on the undersides of leaves.
What does edema on plant leaves look like?
A plant with oedema may exhibit a variety of symptoms, including: On the leaves, water spots initially surface. These develop into elevated, warty, or pimple-like growths. The growths may burst and appear white and powdery, or they may turn rust-colored and take the form of scaly patches.
What is TranspirationTranspiration is the process of water movement through plant… More?
Plant edema is a problem brought on by an imbalance in the transpiration process, not a disease. So let’s first look closely at transpiration.
Transpiration is the term used to explain how water moves through plants. Every cell in the plant receives moisture from the soil through the stems and leaves, which is subsequently discharged through the leaves and stem. All of a plant’s tissues receive water, oxygen, and nutrients through transpiration. A plant needs to go through this procedure to survive.
A plant’s leaves exude water in imperceptibly little droplets. Take a sizable zip-lock bag and place it over the branch of a plant that is in direct sunlight to get an idea of how much water plants transpire during the day. Pick a branch with a bunch of leaves that the baggie can fit around. To keep the air out, string should be wrapped around the baggie’s neck. Check the amount of water that has accumulated in the baggie after leaving it in place for 30 minutes. It is the end consequence of transpiration within the plant. Really nice, no? To survive and thrive, plants need to transpire.
What is Plant Edema?
Plant edema, pronounced “eh-DEE-muh,” is a malfunction in the transpiration system that causes tiny scars on the leaves of the plant. The scars are often elevated like a blister and have a cork-like texture. They are frequently tiny and atypically formed, although they can also take the form of white, yellow, reddish, or black patches. Succulents are among the many types of plants that can develop edema.
When a plant absorbs water through its roots more quickly than it can digest and expel through its leaves, it experiences plant edema (also written oedema). Succulent edema develops when healthy roots absorb water more quickly than the leaves can expel it into the atmosphere, in contrast to root rot, which occurs when roots drown and decompose as a result of too much water in the soil. Furthermore, edema only affects a small number of cell walls close to the epidermis, unlike severely overwatered succulents, whose internal cell walls collapse due to excessive water. Before the circumstances that cause edema were present, it’s possible that these cells were already frail or perhaps injured.
In contrast to other plants, succulents retain extra water for when they eventually need it. They have developed the capacity to absorb more water than the plant can utilize. Succulent edema symptoms appear when the system that controls transpiration and water storage is out of balance. This causes uneven lumps or blisters on the skin of a leaf because the pressure from the extra water stretches and collapses the cell walls. Small, rough, and uneven brown spots on succulents are most often caused by edema.
Conditions that Lead to Succulent Edema
Plant edema happens when the roots absorb water more quickly than the leaves can expel it into the environment. But under what circumstances does this occur?
The pace, effectiveness, and balance of transpiration are influenced by external factors like as air and soil temperature, humidity, and air circulation:
- Usually, warm soil and/or water facilitate faster water absorption by plant roots.
- Healthy roots must absorb water more quickly when there is too much water in the soil.
- The capacity of leaves to release water into the air is slowed by high humidity or fog.
- The plant releases water into the air more slowly when the air is cold.
- The ability of the leaves to release water into the air is slowed by poor air circulation.
- Additionally, improper fertilization might cause edema.
The combination of too much water in the soil and a chilly or humid environment is the most typical cause of succulent edema.
Diagnosing Succulent Edema
Brown patches on succulents can have a variety of reasons, most notably sunburn, insects or insect damage, and plant edema. So how can you distinguish between the two?
Edema scars might resemble thrips or spider mite damage in appearance. One of the members of my Facebook group for succulent enthusiasts suggested including a jeweler’s loupe in your toolkit for caring for succulents. It’s a great concept! With the help of the strong magnifying lens, you can determine whether the brown patches on succulents are actually legs or just a skin defect, which would suggest succulent edema. (Learn how to treat and avoid succulent pests just in case yours does have legs or you discover pests hiding between the leaves.)
You can tell the difference between edema and sunburn without using a loupe. Sunburn typically affects a larger area and is concentrated in the areas of the plant that receive the most sun. In contrast to edema scars, which are frequently elevated like blisters, sunburns are normally flat and rather smooth. Typically, a scorched leaf will have one area of brown, burned skin. Although several leaves may be scorched, only one burn will be seen on the leaf. With edema, it could be a single, tiny scar or a number of distinct, tiny scars that appear to form randomly. On the underside of the leaf, edema blisters can also form, and a surface facing the sun will always become sunburned.
Treatment for Succulent Edema
The fact that plant edema is not a disease must always be kept in mind. It is not communicable and neither is it bacterial or viral in origin. It is not a disease; it is an injury. It is also a significant indicator of the relative health and growing conditions of your succulent. Edema scars last a lifetime. They cannot be removed other than by removing the leaf, yet they do not stop your succulent from developing into a beautiful, huge plant. If you address the root causes of the edema, your plant will eventually grow out of the scars.
The treatments for succulent edema resemble excellent succulent maintenance:
Always use a quick-draining succulent soil to prevent water ponding.
How do plants prevent edema?
On many different kinds of greenhouse plants in the spring, edema (oedema), a typical physiological ailment, manifests as lumps, blisters, or crystal-like development on the undersides of lower or older leaves. Edema is not contagious from one plant to another and is not caused by a virus or bacteria.
Ivy geraniums frequently get edema, and cultivars differ in how susceptible they are. In addition, it affects greenhouse tomatoes, begonias, cactus, ferns, palms, pansies, cleome, and cole crops like broccoli, cabbage, and cauliflower. However, practically any broad-leaved plant may be impacted. Some succulent plants, such jade and peperomia, are particularly susceptible.
Edema blisters on ivy geraniums, according to research from Kansas State University in 2009, develop when water and solutes accumulate beneath or possibly inside cells, stretching and collapsing the epidermal cells. Contrary to what was previously believed, the cells do not rupture.
Bumps may become corky and turn reddish or tan. Frequently, severely harmed leaves will turn yellow and drop off the plant. Particularly on ivy geraniums, the corky spots can resemble spider mite or thrips damage. Growers are encouraged to use a handlens and carefully inspect the undersides of leaves along midveins for spider mites and in growing points for thrips in order to rule out pest damage.
Plants with mild edema frequently recover and finally produce symptomless new growth in late spring and early summer. However, some plants are seriously impacted, losing a considerable number of leaves and having their remaining leaves significantly warped. Since they won’t recuperate in time to be sold, it is unlikely that these plants are worth rescuing.
In the past, farmers have been instructed to fertilize ivy geraniums with calcium and potassium nitrate once every three feedings in order to strengthen the cell walls and increase the plants’ resistance to edema. According to research from Kansas State University, adding extra calcium had no impact on the edema on ivy geraniums in all of their studies.
Even more surprisingly, their studies revealed that there was no significant difference in the frequency or intensity of edema over a range of root medium water concentrations. This runs counter to earlier research findings about the origin of this illness. In their investigation, edema development on ivy geraniums was unaffected by various transpiration rates caused by dry to ideal to saturated root medium water levels.
Tradition has it that edema on ivy geraniums happens when the growing medium is still warm and damp and the air in the greenhouse is cool and moist. The leaf cells burst because the plant’s roots collect water more quickly than it can be flowed through them. Traditional advice for treating edema included the following:
- using a growth medium with good drainage
- Plant spacing will increase light intensity.
- Avoid overfertilizing, particularly with regard to slow-growing plants.
- Keeping plants “dry” during extended periods of low light and cool weather, and avoiding over-watering
- Ventilating the greenhouse early in the morning to reduce humidity, even if it means increasing the heat
- Using containers with snap-on saucers and delaying applying the saucer until the crop is almost completed
- putting similar-growing cultivars on each irrigation line or portion, once more to prevent overwatering
All of these cultural suggestions are sound, but at this moment, choosing ivy geranium cultivars that are edema-resistant may be the best management strategy.