7 Most Common Alocasia Diseases & Pests You Must Know

Alocasia amazonica disease and pest

Alocasia plants can be sensitive to diseases and pests just like other houseplants. There is always the risk that your plants could fall prey to a disease or a pest and you will need to know what the right steps are to make sure that you can cure the disease or remove the pests.

Infectious plant diseases can be caused by a pathogenic organism such as a fungus, bacterium, mycoplasma, virus, viroid, nematode, or parasitic flowering plant. These are not the only risks that can affect your houseplants’ health, but they are the most common culprits for indoor plant health challenges.

If you want to learn more about Alocasia diseases and pests, read on!

Most Common Alocasia Diseases

Crown, Stem, and Root Rot

Crown, stem, and root rot are common ailments for many plants. This can happen to your plant due to a fungus in the soil that leads to damage to the crown, the stem, or the roots of your Alocasia plant. Wet conditions and heavy soil often cause this disease and it will have negative effects on the plant.

Signs: You might only see signs on one side of the plant, or just at the soil line. The rot will progress to engulf the whole plant eventually, but the first signs of problems often happen at the soil line. Your plant might become stunted and stop blooming or putting out new leaves.

If the plant is rotting there could also be a foul odor, a mushy stem, and the plant might droop.

You can easily find out if the stem is rotting by gently grabbing the plant’s stem and very carefully pulling it. If the stem is sturdy and you are not able to wiggle it in the soil, the stem is probably not rotten.

If, however, the stem feels weak and wiggles easily, it’s most probably a sign that the stem is rotten somewhere, and you want to look out for rotting parts.

Treatment: This is a difficult condition to treat because it is often fairly advanced before it is noticed. You will need to make sure that you take the infected plant out of the soil it is in and remove it to improved soil that is not infected with fungus.

You should apply a fungicide and drench the soil with this treatment twice every 30 days at a minimum.

Trim back the foliage that is affected to try and leave only the healthy foliage. Continue to repeat this process until only healthy foliage remains.

Powdery Mildew

This is a common Alocasia fungus that leads to a light grey or white powdery substance on your plant’s leaves. This fungus is happy in warm and dry climates but it can also thrive in locations that do not get enough fresh air.

Signs: This is a very obvious fungus due to the visible white and powdery patches that will show up on your plant’s leaves, stems, and flowers. There are not many other things that look like this condition and the signs are quite evident.

Treatment: Make sure that you have adequate spacing between plants and improve the airflow where your plants are stored. Make sure that there is enough sun on the plants as well. Remove dead or diseased foliage and disinfect shears or other tools after each use.

Use an organic fungicide with sulfur as the main active ingredient. You can use this treatment by coating all affected areas at least once a week for three to four weeks.

Leaf Spot

Leaf spot is caused by a fungus that grows on the leaves of your plants and turns them brown and splotchy. The circles can grow in size as the disease progresses and your plant will eventually lose leaves and start to show signs of ill-health overall.

Signs: Small brown spots will show up on the leaves of your plant at first and then they will spread out. The splotches will eventually cause the leaves to die and fall off the plant. Your plant might also look wilted and stunted.

Treatment: Isolate the plant that is affected so that it cannot infect other plants. You can make an organic treatment or you can buy an over-the-counter treatment. Make sure that your concoction contains sulfur and copper octanoate.

You can also mix baking soda at the rate of ½ teaspoon per gallon into the water and wipe the leaves and spray the stems with it.

Xanthomonas Infection

This is a bacterial infection that can cause small brown spots between the leaf veins and lead to crumpled and wilted-looking leaves on the plant. The bacteria involved causes necrosis, which leads to these spots and wilted leaves.

Signs: Small brown spots along the veins of your plant’s leaves. The leaves will eventually curl up and die. There might also be lesions on the fruit, the stems, and even the roots. In some cases, the spots will be quite large and you can feel them as well.

Treatment: There is no treatment for this plant disease that you can spray onto the plant. You will need to quarantine this plant and then cut off all the dead or dying leaves.

You can use disinfection treatments of hydrogen peroxide to try and stop the spread. You can also install biological antagonists in the soil to help good bacteria fight off bad bacteria.

Most common Alocasia Pests

Spider Mites

This is a very common Alocasia pest. These little mites are small yellow or brown invaders that can bring your houseplants to their knees in a few days.

Signs: You might see signs of the bugs themselves when you look at your plants and you will definitely see their powdery white webs that cover all the leaves of affected plants with a powdery mess.

Treatment: One of the best ways to treat this pest is to spray the plant with water from your garden hose. The invaders do not like water and they will often be defeated quite easily with this simple method. You can also use insecticidal oils or soap to prevent and kill existing spider mites.

Mealybugs

These soft-bodied, wingless insects look like white and cottony masses on the leaves and stems of plants. They feed off the plants and suck out the sap from the leaves and stems. These pests can also help with the development of mold.

Signs: Yellow leaves are a common sign, as well as the white clumps of bugs that are easily visible. Their secretions leave a waxy film on the leaves of your plants as well which is characteristic.

Treatment: Mealybugs are easy to wash off the plants with water from your garden hose and that is often the first line of treatment.

You can also wipe the leaves with isopropyl alcohol. You will need to mix the alcohol with water so that the max amount of isopropyl in the mix is 70%.

Another way to treat this Alocasia pest is by using insecticidal soap or neem oil.

Scale

Scale can appear in many different colors, shapes, and sizes, but most often it shows up as small, brown rounded lumps on the plant’s leaves and stems. This is a bug that comes in a hard and a soft scaled variety.  

Signs: Typically small, brown, and rounded lumps on the plant’s leaves and stems. Their secretions can lead to sooty mold and you might also see that the plant has turned yellow or seems wilted and weathered.

Treatment: You can treat these insects with insecticides but you can also just use a toothbrush dipped in rubbing alcohol to remove them. Rinse your plant in the sink or in the shower to wash away any bugs that you have missed.

Trim out the dead leaves or damaged foliage and then make sure to use an organic or chemical pesticide. Use diluted neem oil weekly until the plant returns to health.

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How to prevent pests & diseases from infecting the Alocasia

While it’s not always possible to avoid your plant from getting a plant disease or being affected by pests, you can create the ideal growing environment to help discourage these pests from infesting the plant.

By making sure that your plant has the optimal growing environment, you can prevent the plant from getting heavily affected by a pest or disease.

Always make sure that you use good potting soil and that you do not water too much or too little. Learn about the needs of each kind of plant you have in your home and make sure that you are providing the right growing environment for it.

Alocasia plants are hardy and easy to care for, but you still need to be sure that you learn about your plant’s ideal growing conditions and that you learn about the right fertilizer schedule and the ideal temperature and watering schedule for your Alocasia plant.

Check out the individual complete growing guides for Alocasia plants below: