Hoya Has White / Black/ Brown / Red / Yellow Spots

A hoya is a tropical plant that grows all over the world in various climatic conditions. There are around 200-300 species of this plant, most of which are native to Asian countries. Hoyas are popular houseplants, and people love them for their attractive flowers, which vary across each species. However, hoya plants can develop specks or spots on their leaves for various reasons.

Hoyas that have white, black, brown, red, and yellow spots or specks are usually caused by mineral deposits on leaves, white scale or mealybug infestations, shore flies, bacterial leaf spot disease, overwatering, under watering, sunburn, and nitrogen deficiency respectively. 

In this article, we will focus on the causes of the various spots and what measures you can take to remove and prevent them from affecting your hoya plant again. Let’s dive in!

Hoya Has White Spots

Mineral Deposits

Hoya leaves might develop white spots on their surface over a period of time, which is actually just a buildup of mineral salts. If you’re using hard water to water your hoya, there’s a high chance of these deposits accumulating more often. Though this isn’t really dangerous to the plant, it can affect its looks and appear like an infection.

How to Cure

  1. Take a few tablespoons of vinegar or lemon juice and dilute it with water. 
  2. Using a clean, soft cloth, gently wipe the leaves with this solution.
  3. Avoid rubbing it hard as it might damage the leaves.
  4. Also, remember to only clean the upper portion of the leaf as that is where the deposits are found.
  5. The underneath of the leaves contain pores and the stomata, so make sure the vinegar or lemon juice does not touch it as it may adversely affect the plant.

How to Prevent

Instead of using hard water, use distilled or rainwater to water your hoya. This will prevent the accumulation of mineral salts on the surface of the leaves.

White Scale and Mealybug Infestation

White scales are plant bugs that latch onto hoya leaves and spread all over the plant as they multiply. They generally give the leaf a whitish layer and can spread across the entire plant if left unchecked.

How to Cure

  1. The Missouri Botanical Garden suggests mixing a tablespoon of insecticidal soap and 1 cup isopropyl alcohol with 1 quart (945 ml) of water to create a solution that can be applied on the leaves.
  2. Spray the affected area of the hoya with this mixture once in 3 days for 2 weeks. 
  3. If the infestation is not widespread yet, you can simply dab the affected area with cotton swabs soaked in alcohol.

Mealybugs are plant bugs too, but are a little more different in appearance. Though they’re white as well, they have a fuzzy texture and live in small colonies all over the plant, making it look like small white bumps on the plant’s leaves. 

These are extremely dangerous as they can spread like wildfire. You may even lose the plant if you fail to get rid of them quickly and efficiently. 

If you’d like to know more about mealybug infestations and what they look like, I recommend giving this video below a watch:

How to Cure

  1. Mealybugs can be removed by cleaning the leaves of the hoya plant with water and a soft cloth. 
  2. To prevent them from returning, you may have to spray the plant with a pesticide like Natria Neem Oil Pest Control, which can be used on many insects that affect indoor plants.
  3. If the infestation is on a larger scale and has affected the entire plant, it is better to get rid of the plant before it spreads to the other plants in your garden or home.

In addition to this, if you’d prefer using a homemade organic pesticide, I recommend checking out this video that demonstrates how mealybugs can be destroyed using a solution of rice and water:

How to Prevent

Using pesticides and organic sprays can help get rid of white scales and mealybugs immediately. However, if you want to make sure the pests don’t make a comeback, follow these instructions given below:

  1. Don’t over-fertilize the hoya plant as these bugs tend to thrive in nitrogen-rich soil.
  2. Be sure to remove all the insects thoroughly when getting rid of them.
  3. Clean the plant every now and then for a few consecutive weeks following the infestation, as this will help you get rid of any insect that may have escaped earlier.
  4. If the plant is heavily infested, it is best to get rid of it for good.

Hoya Has Black Spots

Shore Flies

Shore flies are tiny insects that lay eggs on the soil of plants. The larvae of shore flies look like small worms with clear bodies. However, the feces of these pests are what cause black spots on hoyas and other indoor plants. 

Shore flies don’t directly affect plants, but they can spread diseases when humans come in contact with the infected, unhygienic leaves.

How to Cure

  1. Use a damp, soft cloth to gently wipe the surface of the leaves that contain black spots.
  2. Make sure to wash your hands after you’re done as flies tend to carry diseases.

How to Prevent

Shore flies are generally attracted to areas with a lot of algae, as this is their staple food. So if a hoya plant is algae free, there is a high chance that it will no longer seem attractive to a shore fly. Watering your plant only when necessary will effectively reduce the growth of algae, so that is one way to prevent shore flies from returning to your hoya plant.

However, you’ll still need to deal with the larvae in the soil of your hoya plant. There will most probably be more than 500 eggs due to breeding habits of shore flies, so ignoring it can lead to more shore flies developing in the near future. 

To prevent this from happening, mix one part of hydrogen peroxide with four parts of water and pour it in the soil. This will effectively kill the larvae and won’t harm the hoya in any way. 

Leaf Spot

Leaf spot is a disease that is caused by bacteria and fungi. This usually looks like small, circular black dots that spot your leaves and slowly spread across the plant if left unchecked. Leaf spots generally occur when fungal spores in the air find a plant they can grow on. 

Leaf spots may look small, but it can spread and severely damage the plant in no time, which makes it essential to get rid of and deal with it as soon as it is noticed.

How to Cure

  1. Use a copper fungicide to spray the affected leaves of the hoya plant. Copper is a safe option for indoor plants, and you can also find organic fungicides that are safer still.
  2. Mix the solution with water and spray it on the leaves. Repeat the process according to the instructions given on the label of the product.

If you’ve never bought a copper fungicide before, I recommend checking out Bonide Chemical Copper Spray, as it is specifically designed for bacterial and fungal black leaf spots and is also organic and safe.

How to Prevent

  1. Keep the leaves dry as much as possible. 
  2. If the plant has been infected, make sure you remove all the infected leaves along with applying the copper fungicide treatment.
  3. Inspect the surrounding plants for any signs of infection as the disease is highly contagious.

Hoya Has Brown Spots

Over Watering

If a hoya plant has brown spots or specks on it, it is most likely a result of overwatering or under-watering. Most of the time, brown spots appear due to overwatering, as these plants require only a limited amount of water to thrive. So when they receive an excess of water, it leads to root rot, which causes the plant to slowly wither and die if left unchecked.

Root rot is when the plant receives too much water or if the water is stagnant inside the pot due to the lack of a drainage hole. Root rot in plants eventually leads to root loss, which can slowly kill the plant. 

Under Watering

On the other hand, the plant can also wither if it receives little to no water for a long period of time. This will result in the drying up of leaves, which usually begins with brown spots appearing on all the leaves.

In both cases, brown spots usually indicate a deficiency or excess of hydration and can lead to the drying up of the entire plant if it is not dealt with immediately.

How to Cure

  1. Make sure you do not overwater the plant, especially if the plant is kept indoors where it does not receive direct sunlight.
  2. Reduce the amount of water during winter or rainy seasons.
  3. Water the plant only once a week during summer and spring.
  4. Make sure the plant has a drainage hole so excess water can escape.
  5. Conduct a touch test of the soil if you are unsure about watering the plant.
  6. If the soil is hard and dry, and if the leaves look lifeless and withered, water the plant immediately and closely monitor it for the following weeks.
  7. If root rot has already taken place, transplant the plant after getting rid of the rotted roots.

How to Prevent

Brown spots on hoya plants can be avoided by making sure the plant receives the right amount of water. Do not over or under water hoya plants, as both can result in the eventual death of the plant. 

Water it once a week during hot seasons and once in two weeks during winter, after checking the moisture content of the soil with the help of a touch test.

Hoya Has Red Spots

Sunburn

Hoyas don’t require too much sunlight to survive as they are indoor plants. Receiving an excess of sunlight can sometimes result in a mild sunburn. Red spots appearing on the leaves is usually an effect of this sunburn. Though it isn’t life-threatening to the plant, over time, it can affect the health and appearance of the plant.

The color change occurs due to a pigment in the leaf called anthocyanins, which responds to varying light levels. These pigments protect the photolabile molecules in the plant from degradation, making them an essential part of a plant’s well-being.

In short, this is not a disease but a reaction to light, so you needn’t worry about it being a parasite or infection which can destroy your hoya.

How to Cure

  1. If the plant is outdoors, try moving it to the shade and see if there is a reduction in the red spots.
  2. If the hoya is indoors near a window where it receives a lot of sunlight, try shifting it away from direct sunlight.

How to Prevent

  1. If you notice a sudden climatic change, it is better to keep the plant indoors where the environment would be more stable.
  2. Make sure the plant receives a sufficient amount of water during summer, as the plant will dry up sooner than usual. Brownish red spots may also be indicative of under hydration in a plant.

Hoya Has Yellow Spots

Nitrogen Deficiency

Nitrogen is one of the nutrients required for the healthy growth of a plant. Nitrogen deficiency in plants occurs when the soil lacks nitrogen or has been mixed with some other components like sawdust. 

One of the symptoms of nitrogen deficiency in plants is the yellowing of leaves. This yellowing usually begins with yellow spots appearing on the leaves of the plant. If noticed at this stage, the plant can still be saved from further damage.

How to Cure

  1. You can use nitrogen-rich fertilizers or liquids to balance out the nitrogen levels in the soil.
  2. You can also use fish fertilizer mixed with lukewarm water as a fertilizer.
  3. If you prefer homemade fertilizers, you can add used coffee grounds to the soil, as this promotes nitrogen production.
  4. Also, remember to closely follow the instructions given on the product if you’re using store-bought fertilizers.
  5. Avoid over-fertilization as this can cause the leaves to turn brown and fall.
  6. Additionally, avoid using fertilizers during winter.

How to Prevent

The only way to prevent nitrogen deficiency in hoya plants is by using good quality soil that is rich in nutrients. You can do this by making sure you only use soil that has not been mixed with other components. 

Additionally, inspect your hoya every so often for the first signs of nutrient deficiency. This helps you tackle the problem in its beginning stage and prevent the deficiency from becoming severe. 

General Instructions to Prevent Spots on Hoyas

As the old saying goes, prevention is better than cure, and there are a few general instructions that you can follow to ensure your hoya does not get any spots. Let us look at this list below!

  • Use distilled or rainwater to water your hoya, as tap water may contain additives. Distilled water also prevents minerals from accumulating on the leaves of the hoya.
  • Inspect your plants regularly for any signs of an infestation. Also, make sure that you immediately deal with an insect infestation to prevent them from spreading all over the plant. Use pesticides over the surface of the plants for the following weeks to completely eliminate any parasitic trace.
  • Make sure the soil of your hoya plant does not have algae as that will attract shore flies, which are hard to get rid of. Also, make sure to treat your soil to kill shore fly larvae if they do infest your plant.
  • Make sure the leaves are not wet after watering as that can cause leaf spot and other diseases.
  • Water your plant the right amount of water to prevent root rot, root loss, and under hydration in your hoya plant.
  • Move the hoya away from direct sunlight, especially if there is a sudden surge in temperature.
  • Make sure your hoya receives enough nitrogen from the soil. If not, add extra nutrients like ground coffee to balance the nitrogen level in the soil.

Final Thoughts

This article summarizes the various causes for a hoya plant to develop spots of varied colors on their leaves. Here’s a short recap of this topic.

  • White spots: It could be a result of mineral deposits on the leaves. It could also be a white scale or mealybug infestation.
  • Black spots: It is usually a result of shore flies living and breeding near your hoya plant. The black spots could be the feces of the shore flies.
  • Brown spots: This could be a result of over or under watering the hoya plant.
  • Red spots: This is typically caused due to sunburn when the hoya plant receives an excess of sunlight.
  • Yellow spots: This is caused by nitrogen deficiency.

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