Popular as a houseplant for its dark and shiny, large leaves, the rubber plant or Ficus elastica, add a touch of glamour and greenery to any house. Also known as Indian rubber figs or rubber trees, rubber plants are easy to care for and maintain. If all the ideal conditions are met, your rubber plant can reach its maturity without suffering from any serious diseases or issues.
If the conditions are not ideal and some of the elements are lacking, like proper sunlight or nutrition, you can observe your rubber plant showing signs of distress in different ways. One of the few troubles that your rubber plant may encounter is the appearance of white spots.
When your rubber plant is exquisitely dark and glossy, white spots can be easily visible depending on where they appear. Most white spots appear as small dots on the undersides of leaves, making it difficult to notice till they spread further to different parts. White spots present on the glossy leaves can give the plant a dull and unappealing countenance.
What are the Causes for White Spots on Rubber Plants?
There can be numerous reasons for the appearance of white spots on your Indian rubber figs, ranging from completely harmless signs to some more serious ones. Very often the white spots simply turn out to be dust that has settled on the leaves, pointing to the lack of regular dusting and wiping of your rubber plant. It could also be the harmless crystals of calcium carbonate known as lithocysts or cystoliths, which are basically a part of the cell wall structure, and is completely normal for such crystals to appear at one point or the other on your rubber plant. If serious, the white spots could be due to pest infestations, powdery mildew, edema, or other reasons. The following are the major causes for your rubber plant exhibiting white spots and what you can do to treat each of them.
Lithocysts or Cystoliths
Cystoliths are part of the natural process of the rubber plants, that can appear at any point in the plant’s life. These calcium carbonate crystals can be white to yellow in color appearing as regularly spaced on your rubber plant leaves. Cystoliths are calcified bodies attached to the specialized outer cell walls of Ficus plants as well as a few other plant families. You may also find these white crystals are referred to as lithocysts. When we say cystoliths, it is in reference to the crystals themselves, whereas lithocysts is the name given to the cells that contain these crystals.
While they may appear to be bug-like, cystoliths pose no danger to your rubber plant. In fact, there are some studies that showcase their presence actually benefits the plant. The crystals help your rubber plant to perform photosynthesis by aiding light redistribution in the leaves. If you notice the appearance of such white crystals, there is no need for any action at all.
The imbalance in the water absorption and transpiration process by your rubber plant can lead to a condition known as Edema. If the rubber plant has been frequently fed water and the roots have generously absorbed them. However, the plant may not be able to perform the transpiration at the same rate. When the rate of transpiration becomes slower, there is too much water pressure developing in the leaves. These can cause a blister-like appearance as the cells in the leaves swell due to the excess water. Eventually, these cells burst and can cause brown or white spots on your rubber plant’s leaves.
Related: Rubber Plant Leaves Turning Brown
Solution and Treatment:
- The first thing to do is reduce the amount of watering so that there is no more supply of excess water.
- During the winter months, you can provide a low humidity condition which will help your rubber plant to transpire better.
- Another way to get more airflow and increase transpiration is by giving the rubber plant a bit of pruning.
- Keep humidity in the area where you have placed your rubber plant below 70 percent.
- Keep a check on your watering to prevent edema by not overwatering.
- Also, let there be sufficient light and better air circulation.
Powdery Mildew Fungal Disease
White spots can also be due to a fungal disease known as powdery mildew. When the rubber plant is kept in low light and shaded areas, coupled with high humidity conditions, the environment is perfect for the powdery mildew pathogens to germinate and start infecting the plant. It is observed that powdery mildew can also be present on your rubber plants during warm days that are followed by cold nights, especially in spring or autumn.
The signs of powdery mildew disease on your rubber plant:
- Firstly, you will see a silvery-gray layer appearing at the base of the plant and slowly spreading upwards.
- Secondly, when not treated at the first stage, the disease then progresses and infects the new growths.
- Thirdly, if untreated in the earlier cases, then sadly there is no saving the plant as even the roots may completely get dried
Solution and Treatment:
- Trim or get rid of parts of the plant that have been infected or damaged by burning or other methods but never by composting.
- Using neem oil can help treat the powdery mildew disease. Make your neem solution by following the instructions on the package and spray on the plant.
- You can also use horticultural oils and biological fungicides.
- If the infection is severe, commercial fungicides can also be used.
- Keep your rubber plant in bright, indirect sunlight.
- Reduce the humidity level by pruning your rubber plant to increase air circulation.
- If you have placed your rubber plant in close proximity with other plants, spacing them further apart will also help decrease humidity.
- Watering early at sunrise allows time for the plant to dry.
Presence of Excessive Salt in Water
When using water that has too much salt in it to water your rubber plant, this will lead to the accumulation of excess salt in the soil. Too much salt allows for root rot conditions and thus providing a favorable environment for fungus growth. The fungal infection can cause white spots to appear.
Solution and Prevention:
- If it is available to you, using water harvested from rain is ideal for your plant. If not, you can use distilled water.
- In case you don’t have access to both, letting the water rest overnight can help get rid of chlorine or fluoride and you can then use the water the following day.
Related: Rubber Plants Water Requirements
Harsh direct sunlight can harm your rubber plant. Such exposure leads to the development of white spots on the leaves, which is the result of sunburn. The best lighting conditions for your rubber plant are bright yet indirect light. Sunburn can also result when you suddenly change the location of your rubber plant from a shadier place to a bright directly lit area.
Solution and Treatment:
- Move your plant to a lower light intensity area to avoid further damage to the plant.
- In case leaves are damaged, remove them and reduce the amount of watering for your plant.
- Choose a bright, indirectly lit location to place your rubber plant.
- If keeping next to a window, adding a filter like a curtain or a screen is recommended.
- Choose a window that gets the morning sunlight and not the harsh afternoon light.
Inadequate Nutrition Supply
Lack of proper nutrition can present itself as white spots on your rubber plant. Without adequate nutrition the plant is unable to produce major molecular components in the right way, resulting in underdeveloped growth. This improper growth can further cause infections and other serious conditions. The following is a look at some of the major nutrients and how to combat their deficiencies in your rubber plant:
Related: Why Is My Rubber Plant Not Growing?
a. Iron deficiency shows itself as yellowing of the young leaf veins at first and then progressing to white color.
- You can buy Iron chelate and combine them with water to form a water solution that can be sprayed into the soil. These can also be placed directly on the soil.
- Seaweed fertilizer can also help in supplying iron to your rubber plant.
b. Calcium deficiency results in the leaves growing oddly shaped and showing signs of necrosis.
- Lime is a good way to get the calcium level up.
- Another easy source is the use of crushed eggshells, which can also help in aerating the soil.
c. Magnesium deficiency manifests itself by turning the leaves yellow around the edges and turning the plant lighter in shade.
- Using dolomite fertilizer is a good way to provide magnesium to your plant.
- There are also Epsom salts that need to be mixed with water at a ratio of 2 tablespoons to a gallon. Use the resulting solution to spray on the plant.
d. Copper deficiency can result in your rubber plant not growing anymore and starting to wilt.
- Copper sulfate or oxide in your fertilizer will do wonders for rubber plants suffering copper deficiency.
e. Manganese deficiency shows the same signs as when there is a lack of iron nutrients, in addition to exhibiting smaller than normal growth.
- The use of zinc chelates which can be easily bought will increase manganese content.
- This can also be achieved by using fertilizers having zinc sulfate.
Preventing Deficiency of Nutrients in Rubber Plants
- Make it a point to keep a tab on the pH level of your rubber plant’s soil because most often it is due to negligence of the soil that nutrient deficiencies occur.
- Another thing you can do is to get your soil tested in a lab to check if there are any nutrients that are lacking in the soil.
- The addition of organic matter is also a helpful way to increase the supply of nutrients to the soil.
When you see white spots on your rubber plants, another reason could be a possible issue with fertilization. The leaves get damaged and show signs of visible white spots. Overfertilization also causes excess salt to gather in the soil. The new roots of your rubber plant can get burned by excess fertilizers, which then hampers proper absorption of water and essential nutrients. Thus resulting in the plant not receiving proper supply to grow healthily.
Solution and Treatment:
- If you notice excess fertilizer at the base of the plant, on top of the soil, get rid of these.
- You can also trim or cut off the portions of the plants which are damaged.
- If the soil is overfertilized then it needs to be drained multiple times at once in order to remove any trace of the fertilizers in the soil.
- Use water that is distilled or filtered to remove fertilizers present in the soil, repeating the process for at least four times.
- In case there has been excessive fertilization, thorough rinsing of the plant’s root system and repotting using new soil is recommended.
- While the rubber plant is in recovery, avoid using any fertilizer for a couple of months.
- Like most other houseplants, the winter months are a dormant period for rubber plants and need less or no fertilization at all.
- During the growth months in spring and summer, regular fertilization is needed to boost new growth and keep your rubber plant healthy.
- A water-soluble fertilizer can be used for easy application into the soil that directly reaches the roots.
- The package will come with recommended dosage which needs to be diluted at a 50:50 ratio with water before feeding it to the plant.
- Feeding this diluted fertilizer once a month is enough to meet your rubber plant’s nutrient requirement. This can be eased during winter dormancy.
Cold or Frost Damage
When your rubber plant is exposed to freezing or frosty conditions, it can cause harm which can be visible as white spots on the surfaces of leaves. What frost does is, causes the water in the cells to freeze, which can lead to the cells themselves exploding as the water molecules solidify. As the temperature warms up with the changing season, your rubber plant can also suffer from dehydration issues.
Solution and Treatment:
- If the plant is being kept in a location with too much sunlight, it is best to relocate to a more subdued lighting area to prevent further damage.
- Even if you feel tempted to cut away portions of the plants damaged by frost, resist and let the plant recuperate well first.
- Ensure that the soil is in moist and well-drained condition without any excess water accumulation.
- Also stop the use of any fertilizer at the moment, till you notice that the rubber plant has recovered and growing healthily.
- Whenever there are cold drafts or freezing temperatures, safeguarding your rubber plant is crucial to avoid frost damage, by using cloths or plastic to cover the plant.
- If you are covering the plant, ensure that the material isn’t in contact with the rubber plant leaves by using stakes or sticks.
- Once the temperature is back to normal, these can be removed.
- If covering your plant isn’t feasible or cumbersome, investing in artificial lights, like a 100-watt lamp, is a good way to keep your plants warm and safe from any cold or frost.
Pest Infestation Problems
Pest infestation is an issue that most houseplant owners have to deal with at some point or the other. Since less than ideal growing conditions can trigger your rubber plant to become prone to pests, it is important to ensure all the basic requirements of the plant are fulfilled. Most pests give an appearance like white spots on your rubber plants. Dealing with pests is best done as soon as they are spotted. If they are overlooked for long, without any treatment, pest infestations can lead to the death of the plants.
Solution and Treatment:
- For infestation by spider mites, simple use of a watering hose can get rid of these pests. When they are too many of them, neem oil or soapy insecticide solutions can be of great help.
- Scale insects are tough and can withstand the use of pesticides. To remove scale insects, use cotton that has been soaked in an alcohol solution and then using these to wipe the stubborn pests off.
- If you notice aphids targeting the plant, they can be easily removed by hand, or if you prefer you can trim these damaged parts of the plant. The liquid soapy solution also proves effective against aphids.
- In case of mealybugs attacking your rubber plant, these can be easily removed by spraying them off underwater.
- No matter how reputed the place is from where you bought your rubber plant, always inspect any new plant thoroughly, checking each and every part, before it is brought inside the house.
- Even after it passes the naked eye inspection for pests, keep the new plant isolated from other houseplants you may have in your house to contain any spread of infection or disease.
- Keeping the plant away from others for at least a month is recommended.
- Fighting pest infestations can be a winning fight if you regularly monitor your rubber plant and give them a thorough health checkup.
Any healthy relationship thrives on giving careful and much-needed attention. So, is the same with your houseplants. A routine check is the key to overcome any issue that your rubber plant might be facing. This will help you notice any troubling signs that the plant is exhibiting and giving you enough time to remedy the situation. When there are white spots on your rubber plant and they are not something harmless as lithocysts or cystoliths, timely intervention can save your rubber plant from further damage and possible death.
Ranjan Singh Moirangthem is a media professional based in India, currently working as a freelance copywriter. Growing up in a hill station and now living in a concrete jungle, he finds solace in the green corners of the city, be it parks or his housing society garden. He’s even passionate about plants and gardening and shares his experience by writing in-depth and well-researched articles for our readers.