Alocasia is considered one of the most beautiful houseplants that bring a pleasant view to the indoor space. But if this plant’s needs are neglected, it can show various signs of illness that you might not like. Due to improper care, you might notice yellow spots on your Alocasia.
Extreme light exposure, improper watering, fertilization issues, low humidity, and pests are the main causes of yellow spots in alocasia. Providing your alocasia with proper care, including correct watering, the right dosage of fertilizer, and appropriate light, can help it recover.
But first, you should understand every possible reason behind yellow spots to treat the Alocasia and save the plant from it. You will fail to fix your Alocasia without knowing the reasons, and the plant can even die.
In this article, I will help you understand every possible cause along with its solution.
Table Of Contents
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What causes yellow spots on alocasias leaves?
There are various causes behind yellow spots on your Alocasia.
Some of these include:
- Incorrect lighting
- Improper watering
- Fertilization issues
- Low humidity
- Fungal diseases
- Leaf diseases
- Pests problems
Now let us discuss each point in detail.
Alocasia requires 6-8 hours of bright and indirect light, and if your plant is not receiving that, it starts to show unwanted symptoms like yellow spots.
Exposing the plant to extreme intense sunlight makes them dehydrated.
If you keep your Alocasia near intense heat sources, direct sunlight, vents, and heaters, the leaves can develop yellow spots.
The chlorophyll destroys because of excessive light, leading to faded yellow spots on the leaves.
As time passes, these yellow spots turn into brown spots, and then the whole leaves get brittle, crisp, and fall off.
If the light is low, chlorophyll completely stops working in this situation.
Because of this, the leaves start to fade slowly from specific points and lead to yellow spots.
This needs to be treated quickly.
Otherwise, it can lead to various other health problems.
Depending on the soil’s moisture level, Alocasia needs to be watered once a week.
But if the plant is not meeting its proper watering requirements, it can suffer from various illnesses, one of which is yellow spots.
This plant likes to grow in moist soil.
Both underwatering and overwatering can cause yellow spots on the leaves.
If your Alocasia stays without water for too long, it makes them completely dry, weak, and pale.
This leads to brown and yellow spots in Alocasia.
If the plant is overwatered, the oxygen supply inside the soil reduces, and the roots fail to breathe.
Because of suffocation, the roots can’t function, leading to weakness in Alocasia and causing yellow spots in the leaves.
Overwatering is more injurious and difficult to fix as compared to underwatering.
The best way to avoid these is to avoid frequent watering of your Alocasia, but don’t stop watering entirely.
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Alocasia needs fertilizers once a month during its growing season.
This plant can develop yellow spots if fertilized incorrectly.
Various nutrient deficiencies can make your plant develop yellow spots such as Manganese, Nitrogen, Iron, and Phosphorus.
Nutrients deficiencies slowly make specific parts of the leaves yellow and eventually spread to the entire leaf.
You will see yellow or brown spots, brown tips, pale leaves, weak stems that indicate fertilization problems.
Even overfertilizing your Alocasia can harm your plant.
Stronger doses and frequent fertilization causes extreme harm to the roots.
This causes weakness and leggy growth in the plant, and you will see yellow spots as a sign.
Low humidity can affect the health of Alocasia plants as they need at least 50-60% of the humidity level inside the house.
Humidity is not considered the major reason for yellow spots.
But if your Alocasia is getting proper water, adequate light, enough fertilizer, and still the leaves are developing yellow spots, and low humidity can be a possible reason.
If you have kept your Alocasia near heating objects like heaters, radiators, or vents, the plant can suffer from low humidity at frequent levels.
When the humidity is low, the leaves lose all the moisture through transpiration, making them completely dry, and because of this reason, the leaves can start to develop yellow spots.
Leaf diseases are caused by fungus.
The most common leaf disease is leaf blight caused by a fungus called helminthosporium turcicum pass.
All these leaf diseases mostly develop in a humid environment and cause yellow and brown spots all over the leaves.
When leaf diseases are left untreated, all the fungus start to develop spores in the form of bacteria that destroys the leaf tissue.
When the leaf tissue is destroyed, the leaves slowly develop huge blotches like brown and yellow spots.
If this is still not treated on time, the leaves can turn entirely brown, pale and fall off.
Leaf diseases are mostly caused due to poor air circulation, overwatering, low humidity, tight soil, damp roots.
Keeping your plant outdoors can also lead to leaf diseases, so you should avoid that.
Pests are one of the most common reasons for yellow spots.
If your Alocasia is attacked by one, it can suffer from various health problems.
Many pests can attack Alocasia, such as aphids, mealybugs, spider mites, scales, etc.
Alocasias can become prone to pests when they suffer from low light, overwatering, low temperatures, poor aeration, high humidity, poor soil drainage, and overfertilization.
When this pest remains in the plant for too long, it becomes a homely environment.
Pests feed on the leaf’s tissues and suck out necessary nutrients from the leaves.
Continuous feeding makes the stems and leaves weak, leading to yellow spots, discoloration, and brown edges in the foliage.
If pests are left untreated, the entire Alocasia can even die, so try to fix it without any delay as soon as you notice anything.
Different kinds of fungal diseases can attack Alocasia and can make them weak.
Fungal diseases like anthracnose, root rot, powdery mildew, and leaf spot can be responsible for yellow spots on your Alocasia.
At first, all these fungal diseases develop black dot-like spots on the leaves, and then with time, those black spots can turn pale and yellow.
Some fungi can even develop inside the plant’s tissue, creating fungal spores.
Due to fungal spores, the leaves can develop small yellow spots.
Fungal diseases can develop due to various reasons.
Overwatering is the most common cause.
A damp condition creates a perfect environment for the fungus to develop.
Poor air circulation around the plant’s atmosphere and inside the soil is another reason that helps fungus to grow.
How to treat yellow spots on Alocasia?
You know everything about what is wrong with your Alocasia, but it is not enough.
After identifying the problem, you have to treat the plant immediately before the situation gets out of control.
Before treating the problem, remove the entire damaged leaves as they cannot get back to normal again, and then wash the plant with water.
Find out the causes behind yellow spots in Alocasia and then provide them with proper care.
After the recovery, don’t stop looking after your plant.
You should keep checking it after every 3 days to monitor its health.
Now, let us discuss all the possible solutions to cure this issue before the situation gets worse.
Provide sufficient indirect light
Alocasia needs 6-8 hours of indirect sunlight every day.
Too much light or low light can upset your plant.
- To fix the lighting problem, place your Alocasia near a location where they will get indirect sunlight the whole day.
- East-facing windows or north-facing windows are the best locations for your Alocasia. In this area, the light is neither harsh nor too low.
- While keeping the plant near a south-facing window, shade it with any shield to filter the direct sunlight. You can use sheer curtains or a net to filter the light.
- Artificial light is also a great option to use as an alternative to natural light. It works as well as natural light.
- If you don’t want to see yellow spots again in your plant, always check your Alocasia to see whether it is getting proper light or not.
Improvise a correct watering method
Sometimes people become too casual about watering their plant, due to which the plant either undergoes underwatering or overwatering.
But it’s never too late to recover your plant from any issue.
If you start taking care of the watering schedule now, your Alocasia can easily get back to its healthy state again.
Always check the moisture of the soil before watering your Alocasia.
This plant needs water only when the soil is 25-50% dry.
Check the moisture level by inserting your index finger or a moisture meter into the soil.
If the soil feels moist, wait until it gets a little dry.
You can also use a moisture meter to check the moisture level.
Watering also differs with the changing season.
Like in summer, your plant needs frequent watering because of the intense heat, but the plant does not need much water in winter because of its dormancy.
To recover underwatering, water your Alocasia thoroughly to make the soil moist.
Continue this for a few days until the plant is hydrated again.
To recover overwatering, stop watering Alocasia immediately and keep it in the area where they will get bright sunlight and good aeration.
Also, change the pot if it has poor drainage.
Raise the humidity if it is too low
Alocasia is a tropical plant.
That’s why it prefers high humidity to thrive.
Don’t keep your plant near vents, radiators, heaters, or other heating objects, as in those areas, the humidity is very low.
You can keep bowls filled with water around your Alocasia.
Evaporation will increase humidity around the plant.
Using a pebble tray is good for increasing humidity.
Take a tray and fill it with pebbles and rocks.
Then pour water into the tray and keep the plant in it. Make sure the drainage holes are not touching the water.
You can also use a humidifier to increase the humidity inside the house.
Set the humidity level according to the plant’s needs.
Keep other moisture-loving houseplants together with Alocasia.
This will increase the humidity around the atmosphere whenever you water your houseplants.
Mist your Alocasia after every 3-4 days by using a spray.
Ensure the water is not sitting on the leaves whenever you are misting.
Treat fungal disease
Fungal diseases can even kill your Alocasia, so it needs to be treated as soon as you notice.
Remove all the infected leaves to avoid spreading to the other healthy parts.
After that, wash your entire plant with water.
Then spray Alocasia with a solution.
Use a copper-based fungicide as a solution to treat your plant.
You can also use horticulture oil and spray it all over the Alocasia.
Do this at least 3 to 4 times.
Wait for 1 week to see the results.
If the fungal disease is still there, then spray again.
Applying cinnamon on the soil surface can also help you get rid of the fungus in a large amount.
Treat leaf disease
Leaf diseases can make your plant extremely unhealthy and mostly develops when they get poor air circulation and too much moisture.
Put the solution in a spray bottle and spray all over the Alocasia until the diseases vanish.
You can also use baking soda.
First, take half a teaspoon of baking soda, mix it with one gallon of water, and then spray it.
If these don’t work, you can use a commercial fungicide.
You can easily get this from the market.
To get rid of the pests, you need to isolate your plant.
- First, remove all the infected leaves, then wash your entire plant with water.
- After washing your plant, wipe the infected parts with wet cotton balls by dipping them into the isopropyl alcohol.
- Spray Neem oil by mixing it in 1 liter of water and little drops of dish wash soap.
- Rubbing alcohol is also very effective in eliminating all kinds of pests.
- You can also use pyrethrum spray. This is a natural pesticide and comes in the form of powder. Mix the powder with water, and a few drops of dish wash soap, then spray the solution on the entire plant.
- After spraying, wait for 2 days to see the results. If the situation still doesn’t improve, spray the mixture again.
- Try not to provide too much humidity to your Alocasia when it recovers. Otherwise, the pests will spread even more.
Adopt correct fertilization techniques
Alocasia needs to be fertilized to promote proper and healthy growth.
This plant needs fertilizer that is overall rich in nutrients.
Alocasia requires balanced liquid fertilizer in the ratio of 20:20:20.
First, mix the fertilizer with water and apply it every month during summer and spring.
If the plant is overfertilized, you have to wash the entire soil to remove excess fertilizers.
At first, remove the top 2 inches of the soil and then wash the entire soil by watering the plant.
Do this for a few minutes so that the water will drain out from the holes.
Make sure you don’t water again till the soil gets dry.
If the situation is serious, you need to change the whole soil by repotting it in a new pot.
Cut all the injured roots and wash them off.
Then choose a larger pot and repot it using a fresh soil mix.
Reference: Science Direct, Propagation of Alocasia, The University of Arkansas Division of Agriculture, Alocasia sanderiana, Alocasia micholitziana.