The disease rots the stems from the inside out, making them fall apart, and it’s the most common problem you’ll encounter. Stem rot frequently occurs in plumeria cuttings, but if it hits a mature plant, it can leave it weak and vulnerable to other pests and diseases.
Root rot, often caused by overwatering and soil-borne fungi, is the main culprit behind plumeria stem rot. Warning signs include leaf drop and black spots on the stem, followed by squishy, blackened stems with hollow insides. To fix this issue, you should:
- Prune affected roots, stems, and foliage. Cut the cutting from the bottom until the bark is green and stem core is white and healthy.
- Let the cutting form callus.
- Transplant the the cutting or plant in pot afresh.
Contents
What Does Plumeria Stem Rot Mean?
Plumeria stem rot is exactly what it sounds like: a fungal disease that causes the inner layers of the stems to decay. As a result, it has squishy, soft, and weak stems that are black.If it feels slightly soft, there might still be some hope. If it’s mushy, though, it’s likely rotten.
You can compare it to an overripe melon, like a muskmelon that you’ve taken too much care of and it’s become overripe. It will have that kind of feel.If it’s no good, the bark will have some firmness but will feel weirdly loose.
If you don’t treat stem rot, it can be fatal to your plumeria. In most situations, the affected stems become hollow and mushy in the center. This is a serious problem for several reasons:
- The weight of the plant may make the stems collapse.
- The rot blocks nutrients and water from getting to the leaves and other parts of the plant, leading to dehydration and nutrient deficiencies.
- The rot can disrupt your plant’s rigidity, making your plumeria look floppy or limp.
- It can lead to black spots, leaf drops, and other symptoms of a severe fungal infection.
Factors that Contribute to Plumeria Stem Rot
Overwatering
Overwatering often triggers stem rot in mature plumerias, starting in the root system. When there’s too much water in the potting soil, or when drainage is poor, water can become stagnant, creating an anaerobic (without oxygen) condition that encourages fungal growth.
Without enough oxygen, the plumeria’s fine root fibers can’t breathe, and they start to die. This is when the fungus seizes the opportunity to jumpstart the rotting process, which then spreads to the main root and stem.
Here are some clear signs of overwatering leading to root rot:
- A foul rotting smell coming from the soil at the plant’s base.
- Leaves turning yellow.
- Slowed growth and distorted leaves.
- Mushy roots that look black or dark brown.
- Soil that has stayed wet for an extended period (consider using measurements in inches [or centimeters] to determine how wet the soil is; for example, you might say that the soil stays wet to a depth of 2 inches [5 centimeters]).
Improper propagation
In cuttings, rot disease begins as an infection at the cut end. This is frequently the case when the wound is not given enough time to callous and heal before propagation and transplanting.
Overwintering
Your plumeria is most susceptible to stem rot during storage overwintering. In addition, as you may be aware, these tropical trees shed their foliage when the cold winter weather arrives.
Age or Growth Stage
Old and newly-rooted plumerias are prone to rot. It also infects during the flowering or vegetative stages.
Poor growing conditions
It is often seen on stressed plants from not getting enough light, being too dry, or frozen. Aside from wet soil, cool temperatures and poor aeration contribute to or exacerbate plumeria stem rot.
Pests and disease
Pests such as spider mites, nematodes, and caterpillars can hollow out the insides of stems, allowing fungi to infect your plumeria easily.
Fusarium, Rhizoctonia, and the Pythium are the most common fungi that cause rot infection.
Pathogens typically live in soil or dead plant matter, from which they infect your plumeria, particularly during the cuttings stage.
Spots on the lower part or base of the stem are symptoms that indicate their presence.
These fungi can weaken plumerias and cause stem dieback, wilting, and root rot.
Identifying Stem Rot on Mature Plumeria Plants
Overwatering is the leading cause of stem rot in mature plumeria plants. The pathogens that cause stem decay thrive in wet soil, damp air, or both.
Over-humidification is challenging to avoid, especially if your plumerias are houseplants or grown in a greenhouse.
Fortunately, mature plants are adept at expressing their displeasure. In mature plumeria plants, look for the following early warning signs of stem rot:
Shedding of leaves
Overwatering is the leading cause of stem rot in mature plumeria plants. The pathogens that cause stem decay thrive in wet soil, damp air, or both.
Over-humidification is challenging to avoid, especially if your plumerias are houseplants or grown in a greenhouse.
Fortunately, mature plants are adept at expressing their displeasure. In mature plumeria plants, look for the following early warning signs of stem rot:
Black Spots on Plumeria Leaves
Pests cause the majority of cases of stem rot. Among them are aphids, mites, and other sap-suckers that bore holes into the stems.
Pest damage points are easy to spot because they appear as black spots on the foliage and stems of your plumeria. These are the first symptoms of plumeria stem rot.
Black Stains Outside of Stems
Black stains on the main stem are another sign of stem rot.
They usually indicate that the branch has been internally damaged by root rot progressing upwards or pests/parasites.
Soft, Squishy Blackened Stems
By this point, your plumeria is barely surviving. The rot disease will eventually turn the stems completely black, squishy, and hollow on the inside.
If you don’t want to risk infecting other healthy houseplants, you should get rid of your plumeria.
If you still have a chance to save your plumeria after the stems have become squishy and hollow in the center, drastic measures such as fungicides are your best bet.
Consider trimming diseased stems back to clean areas if your plumeria still has several stems and some are not affected.
Expect new growth to emerge from the rot points (more ahead on this).
Identifying Stem Rot on Cuttings of Plumeria
Plumeria plants are more susceptible to stem rot when younger, newly rooted, or in the cuttings stage than mature specimens.
Therefore, keep an eye on your plumeria that is less than a year old, especially if it is in a humid and stuffy environment.
When cuttings are grown in water and transferred to potting soil, they are more susceptible to stem rot disease.
In addition, transplanting your cuttings may cause the roots to be shocked, causing them to thin out as they seek water.
These weakened roots in the soil are far more vulnerable to rot-causing fungi.
The rot causes them to become soft, mushy, or spongy, as well as a darker color. Root rot spreads, infecting and killing the stems.
On your plumeria cuttings, look for the following signs of stem rot:
- Stems that have been cut start to rot at the base or cut end before turning brown or black all the way through.
- Dehydration causes the leaves on the affected cuttings to discolor, wilt, and curl up.
- The entire stem cutting will shrivel, revealing a black or brown hollow inside.
- Your plumeria cuttings will resemble the sickly plants you imagined.
Treatment for Plumeria Stem Rot
If there is a chance to fix rotting of cuttings or stem, try withholding water for a few days. If you expose it to sunlight, the stem might firm up. Sometimes, even if it’s not rotten, the stem might feel a bit soft when it has been watered too much. If that doesn’t work, you’ll have to follow the pruning method for cuttings mentioned at the beginning.
Pruning roots serves a dual purpose: treating and preventing stem rot. Getting rid of diseased, dead, or affected roots aids in the establishment of a more robust root system and plant.
- Begin by removing any affected leaves, stems, flowers, or growths. When pruning the roots, you don’t want the pathogens to spread.
- Take your plumeria out of its container. Root rot is indicated by smelly, mushy, or spongy roots.
- Soggy, odoriferous soil should never be reused. Every gardener should avoid reusing old soil if root rot is present.
- Trim off all affected roots with a sharp pair of sterile pruners. Only white, firm, healthy roots should be left.
- To treat the remaining roots, use hydrogen peroxide or a fungicide drench.
- Repot your plumeria with new potting soil and a good, well-draining potting mix. Check that the new pot is well-drained and has plenty of drainage holes.
- If the rot disease has turned all of the roots mushy, you must collect healthy stem cuttings from propagating new plants.
Misdiagnosing Plumeria Stem Rot
Stem rot isn’t the only problem plaguing plumeria plants. For example, black-tip fungus and winter burns have similar symptoms.
Unfortunately, this can lead to incorrect diagnoses and the application of inappropriate solutions. Here’s how to tell the difference.
Winter Burns or Stem Rot?
Plumeria and other cultivars of frangipani typically shed their leaves right before winter’s biting cold. Then, they enter into survival mode to overwinter.
Most gardeners, including me, notice any problems with stems when they’re left bare by dropping foliage.
But, unfortunately, leaf drop is quite aggressive in distressed plumerias, particularly if they’re old or stressed by low-light conditions, drought, or frost.
As with stem rot, winter burns cause the development of brown lesions and dry rot around the stem.
This is usually due to running central heating during winter plus humidity, causing the branches to appear burnt.
The same can happen if you position your plumeria near heating vents, boilers, radiators, or fireplaces – they will dry out so much that they split and allow fungus in.
In most cases, winter burns affect your plant during winter storage while it’s overwintering in the garage.
The most noticeable differences between stem rot and winter burns include:
- Rot caused by winter burn is visibly drier and doesn’t spread.
- Stem rot usually spreads quickly, and fungal infection can engulf the entire plant in weeks.
- Winter burns are usually confined to small areas, often near the tip of the stems.
- Stems affected by winter burns are usually still fleshy and intact inside unless they get infected or become wet during storage.
Winter burns don’t present a severe threat to your plant’s life. However, they can affect its health and are unsightly.
An easy fix is trimming the plant’s burnt parts and redirecting resources to the healthy parts.
Does Plumeria Have Black-Tip Fungus Or Stem Rot?
Stem rot resembles black-tip fungus. An opportunistic fungal infection thrives on insect damage to the stems.
They appear when the damaged areas of the branch absorb moisture and remain wet for an extended period.
The fungal disease typically feeds on stressed plumeria plants caused by light, drought, or frost. Another critical factor is old age.
The fungus kills off the tip growths, while stem rot usually begins at the base of the stalks. Evergreen and deciduous plumeria varieties are frequently affected by black-tip.
Spider mite infestations usually cause plumeria stem rot because they eat the cellulose in the leaves, petioles, and stems.
They make hollow nooks and crannies that are perfect for fungi to grow when they get wet.
On the other hand, black-tip fungus typically thrives in outdoor plumeria plants impacted by the beetle and fruit-spotting bug feeding activity.
These bugs feed on the plumeria tips, predisposing your plant to fungal infection.
Black-tip fungus is usually easier to treat than plumeria stem rot. The black-tip fungus typically focuses its damage on the growth tips.
It can be treated by removing the “black” tips and applying a fungal spray (Amazon link).
Trimming diseased plumeria growths infected with the black-tip fungus ensures that you prune back to clean, healthy tissue. Shoots will regrow just below the stem’s damaged area.
If the black tip of your plumeria is unsightly, or you are concerned that the infection will spread downwards, use a sterile pair of sharp pruning shears to trim back and clean the cuts.
To prevent pathogen transfer, disinfect the cutting tool with rubbing alcohol or a bleach solution after each cut.
How To Defend Against Plumeria Stem Rot?
The following ways can help you keep plumeria stem rot at bay:
- Garden soil should be amended with compost or a well-draining potting mix.
- Remove Any Debris You Come Across.
- Keep Your Environment Clean And Healthy.