Yellow spots in Plumeria (Frangipani) leaves are unsightly. Plumeria is tough, beautiful plants that generally thrive indoors. Unhealthy plants develop diseases causing yellow spots on leaves, rust, or yellow wilted growth tips.
Yellow Spots on Plumeria or Frangipani leaves can be caused by too much or too little light, temperatures below 60°F (15°C). Rust and other fungal infections, insect and mite damage, poor inappropriate soils, overwatering, over fertilizing and in some cases human factors.
I’ll walk you through the steps of treating the problems that can cause yellow spots on Plumeria leaves.
What Causes Yellow Spots on Plumeria Leaves?
Excessive Direct Sunlight Exposure
Like all plants, plumeria turn light into energy. Too little light and your plant will starve. Too much light and it will burn. Too much or little light makes your plumeria susceptible to factors that cause yellow spots on leaves.
In winter, days are generally shorter, and light is weaker – i.e. plant starves. In summer days are longer, and light is more intense – i.e. plants can get burnt and can develop Yellow spots.
How to Fix
Yellow spots on plumeria leaves caused by scorching in summer can be eliminated by using a screen to reduce light intensity. Just make sure the plant is not exposed to direct sunlight.
In winter, when light is insufficient, LED or a similar light supplement can help to increase your plant’s day length and amount of light available for photosynthesis. Generally, try to give your plant at least 6-7 hours of light per day.
Plumeria Rust
Plumeria rust is caused by the Coleosporium plumeriae fungus. The fungus produces pustules under the leaves. The rust eventually turns into yellow spots on leaves.
These bursts and spores blow or fall onto the surfaces of other leaves. Moisture on the leaf germinates the spore.
The fungus then grows inside the leaf, eventually killing that leaf, and if it spreads, all the other leaves on the plant.
How to Fix
When Yellow spots on Plumeria leaves are caused by the Coleosporium plumeriae rust fungus this, in turn, creates a toxic mess. That causes Yellow spots on your plumeria leaves. Leaves with higher latex (healthy leaves) are resistant.
Prevention is the best way to keep your plant from yellow spots. Ideally buy a rust-resistant cultivar of Frangipani (ex. san germain plumeria). If your plant leaves already affected by rust then consider removing the leaves.
Spray your plumeria with a fungicide containing Bayleton or Copper oxychloride which is more widely available globally. (Source: Researchgate)
For the treatment of fungal diseases. Here are the fungicides I recommend:
| Name of The Fungicide | Amount | Amount of Water |
| Bonide 811 Copper 4E Fungicide | 1-4 tablespoons (.05-2.0 fl oz) | 1 gallon of water |
| Garden Safe Brand Fungicide3 | 2 tablespoons (1 fl oz) | 1 gallon of water |
| Southern Ag – Liquid Copper Fungicide | 3-4 tablespoons | 1 gallon of water |
Yellow Tip Fungus
Temperatures below 60°F (15°C) weaken the plant’s ability to fight fungi. Colletotrichum and Gloeosporium are fungi that cause anthracnose which results in yellow tips on leaves.
Be advised that water issues can also cause this issue. If underwatering causing this issue then the leaf tips will turn yellow and crispy.
How to Fix
Get rid of the affected leaves to prevent further spreading and infestation. Also, avoid misting your plumeria leaves or keeping the leaves wet. Wet leaves are the breeding ground for fungus.
If temperatures drop below 60°F (15°C) your Plumeria plant’s ability to fight fungi declines and it will get Yellow tip fungus on its growth shoots.
In the optimal temperature range, this will not be a problem. A grow light can also help provide localized heat to the plant.
Generally, this is a symptom of bad weather conditions, and if you correct the conditions your plant will survive.
Root Rot Fungus
Root rot is a fatal fungal disease of the plumeria plant. Root rot infects the root system and causes damage by rotting. As a result, the root can not function normally by intaking the nutrients and water.
Now, it surprises you that how root rot can cause yellow spots on leaves at the top? Well, here is how, as you already know root rot damages the healthy root system, so it can not supply the essential nutrients to the upper portion of the plant.
So, the leaves do not get the nutrients like magnesium to produce chlorophyll and continue their food production system. Due to less chlorophyll production, the leaves lose the greeny look and eventually show yellow spots.
How to Fix
If your soil is too wet and temperatures are low then you got the perfect condition to develop root rot.
It is not easy to fix root rot infection of plumeria. As this disease develops under the soil, it is often overlooked until it’s too late.
So it is a good practice if you notice any early symptoms like mushy leaves, yellow spots, or droopy signs then you should dig in to check if there any root rot developing under the soil.
If you identify the initial stage of developing root rot then
Using a rooting hormone dip that has an antifungal agent in it can reduce this risk. A soil with beneficial microbes and fungi such as Trichoderma can help.
Low humidity
Red spider mites thrive in dry warm conditions, this can lead to darker areas on the leaves as the mites damage the leaf and spread bacteria, fungi and viruses. Thus low humidity in summer can cause Yellow spots on Plumeria leaves
How to Fix
Plumeria leaves can develop Yellow spots in an area where dryness can occur in summer and Red spider mite is a problem.
Red spider mites can be controlled by spraying the leaves with a jet of water. I find most indoor plants benefit from being sprayed down occasionally, even if it’s just to rinse the leaves.
Move the potted plants to the balcony and give them a blast with a hose pipe. Be careful not to rip leaves but be as vigorous as possible.
Spider mite hates being wet. The predatory Phytoseiulus persimilis mite eats red spider mites.
These mites can be sourced online in most areas of the world. Alternatively, many pesticide sprays exist which will kill spider mite.
Insect Infestation
Insects such as aphids and mealybugs, often farmed by ants, can cause Yellow spots on Plumeria leaves.
These insects damage the plants by making holes in the leaves and sucking liquid out of the plant. This damage causes leaf distortion and yellow spots.
Aphids and mealybugs can also be present without ants being around, but my general experience is ants make the problem worse as they actively farm the pests.
How to Fix
The first line of defense against aphids and mealybugs is always to get rid of the ants that often farm the aphids and mealybugs.
You will often see the ants carrying bugs around to plant them on a leaf. What the ant does is to let the aphid or mealy bug harvest juices out of the plant, and then the ant takes a share of this from the insect.
The plant damage created by the insects is a good growth medium for fungi and bacteria that will slowly infect and destroy your plant.
Generally, an ant bait trap is a good start. These products have a poisoned bait that the workers take to the queen, killing her and the colony.
Remove the aphids and mealybugs themselves with a jet of water, by hand or wipe them off with a damp cloth.
There are many pesticides available, which can be used to kill these as per the instructions on the product.
Alternatively, if, like me, you prefer not to use pesticides, there are numerous bio-controls available. It is best to Google which ones are available in your area.
Soil Problems
Poor soil can cause Yellow spots on Plumeria leaves. Soil is the foundation literally of your plant.
Plumeria needs soil that is well-drained and contains a balance of organic matter and sand ideally with a pH of 6-6.5.
If your soil is wrong, it can cause waterlogging, or the pH can be too high or too low and the plant cannot absorb nutrients.
Or the soil may just be old and dead, and basically, it just sits there and does nothing for the plant at all. Good soil is the start of a good plant.
How to Fix
Plumeria like a well-drained fertile loam. Generally, a good sandy loam, supplemented with pearlite to aid aeration and drainage will see your Plumeria thrive and not develop Yellow spots.
I believe in replacing my potted plant soils every year or two. Remember, good soil has a lot of organic matter in it – this degrades and leaves behind only the sand and pearlite. The sand compacts and impedes drainage.
Use sand mixes, with pearlite and slow decaying organic matter such as pine bark, and a bit of compost. Compost degrades faster.
The pine bark helps to keep the soil ever so slightly acidic in the pH 6 range that allows the Frangipani to absorb nutrients optimally.
Recently, I have discovered that feather meals – typically chicken feathers are a terrible problem at poultry factories.
But ground into a powder and added to your soil they provide a slow-release nitrogen source and help the chicken farmers turn their waste into your win.
Nitrogen is key to plants having the resources to synthesize enzymes that help them both resist and fight diseases.
Watering problems
The Plumeria is a tough plant with waxy leaves and a water-rich stem. It can keep a lot of water stored for dry periods.
Overwatering the plant will cause it to become vulnerable to fungal diseases and eventually die.
Overwatering kills Plumeria plants as it drowns the roots, and your plant cannot function.
If its roots drown, they rot, fungi enter the plant, and it cannot fight them as it has no nutrients because its roots are dead.
If soil, as mentioned above, is prone to waterlogging, your plant drowns faster. Good soil is more resistant to overwatering.
How to Fix
Overwatering is easy to fix, but the problems already created due to overwatering sometimes can be difficult to reverse.
If your plumeria is infected with fungal diseases like root rot then it is very likely to die eventually if you do not take action in time.
You need to inspect the plant carefully to find out the symptoms of root rot. The roots will be soft and brown, emitting a foul smell of rot. If it is the case, then immediate action is needed.
Trim off the infected part of the root system and let it dry for 1-2 days. Now repot the plant using a new pot and soil media.
You need to use a new soil mix because you do not want your plumeria to be infected again with the fungus growing in old soil and pot.
The soil should not hold too much moisture. A soil moisture probe is an inexpensive solution to allow you to get the soil moisture levels right.
Fertilizer Problems
Fertilizer is really something that you need to add to bad soil. If your soil is good, you won’t need much of it.
Over-fertilizing can cause Yellow spots on Plumeria leaves. Fertilizer is good in moderation but in excess, it can cause the plant to get burnt, and in some cases, the leaves will go yellow and fall off.
How to Fix
You can opt for the slow-release fertilizers because they will not burn of damage the root system. Some liquid fertilizers, like worm teas and fermented seaweed or fish products, have magic in them that can be useful.
Countless organic fertilizers exist around the world, and if you wish to add a conventional fertilizer and cannot get one formulated for Frangipanis.
Try to find a fertilizer where the first number – Nitrogen, is lower than the second number which is Phosphorous. E.g 2:3:2 Fertilizer.
The reason is that phosphorus is far more important to these plants than nitrogen. Add slightly less than they recommend on the label.
Fertilizer is to plants like salt is to a good meal – you can always add more, but you cannot subtract it.
If you have over-fertilized a plant this is one of the few times it can help to overwater it as you try to rinse the fertilizer out of the soil.
As an addendum, refer to our next heading about animals and humans – if you find there is a smell of urea in your soil, chances are a cat/toddler is peeing in it. Adjust your fertilizer addition accordingly.
Generally, animal pee is a great nitrogen fertilizer in small doses, so if there is a urea smell in the soil, don’t add anything that has nitrogen in it. Just phosphorous, which is not plentiful in what your assistant is adding.
Animal/Human Problems
Animals and humans are creative and vexatious to gardeners and can be a complex source of Yellow spots in your Plumeria leaves.
Children can damage plants in many ways. Young children can damage leaves with pins, pens, hitting them with rulers, shooting the plants with toy guns, urinating in pots, pouring detergents on plants, etc.
Cats are also a consideration – a plant can make a nice litter box, and cat pee is a very concentrated source of nitrogen. Then there is the issue of claws and scratching.
How to Fix
For toddlers, it is really just a case of being vigilant. They will stop being toddlers, and then if they are boys, will go through various stages of thinking peeing in your pot plant is clever. This tends to stop at about the age of 21 but can persist too many later stages in life.
Adjust your watering regime accordingly and consider putting a small motion sensor camera and naming and shaming.
With cats, covering the surface of the soil with things that make it difficult to climb in the pot and dig can help.
Flat rocks, shells, and thorny branches work. Place a small garden gnome or sculpture strategically to protect the stem. Invest in a scratching post for the cat.
Final Words
Yellow spots on Plumeria leaves detract from the joy you will get from your potted plant. Your Plumeria is a tough plant.
Give it the conditions, using the technology available to you, that mimic its natural environment – warm soil, 12 hours or more of sunlight, moderate moisture, and nice well-drained tropical soil, and it will be a healthy happy plant.
If you get this a little wrong and need to give it some help, fungicides are a useful tool, as are bio-controls and pesticides.
I hope that this article has helped you understand how to treat Yellow spots on plumeria. This plant really is a piece of paradise to enjoy and cherish.