Desert Rose Root Rot — Identification, Treatment, Prevention

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The desert rose is a succulent plant, but due to its huge caudex and branching habits, it can be trained as a bonsai. 

For bonsai enthusiasts lacking the patience to grow a bonsai tree, the desert rose is a terrific alternative. 

It grows fast, benefits from the same bonsai tree care and training techniques, blooms profusely in summer when temperatures rise, and like any bonsai, it adds character to indoor spaces. 

A beautiful specimen of a potted flowering tree. 

That is… when things go right. They are delicate about watering. Too much water will rot it, weakening every part of the tree… slowly killing it from the bottom up. 

Discover the causes of desert rose root rot, the fixes to try, how to revive a dying Adenium, and prevent root rot from starting again. 

 

Desert rose root rot 

Desert rose root rot happens when the caudex stores too much water. An early symptom is pimples on the caudex and feeling soft when gently pressed. Fungal stem rot can cause yellowing leaves that spread to branches and the roots, causing fungal root rot. The fix is to prune diseased roots off. 

 

How to identify desert rose root rot 

Despite not being a true bonsai, leaves turning yellow is the same sign of root rot on the desert rose. 

Yellowing leaves can be a symptom of fungal stem rot. Like any rot, it is a plant disease and it will spread. Fungal stem rot can travel through the veins of the plant, reach the roots causing root rot. 

Infected branches with yellow leaves should be pruned off to stop the spread. 

 

Inspect the caudex

The caudex is a water storage tank for the desert rose. It can hold an abundance of water. It is how these (and other succulents) are so resistant to drought. They have their own internal water storage systems. 

A healthy desert rose will not need a lot of watering. It only needs water when it is growing, and only when the soil becomes dry. It needs very little watering when it goes into dormancy over the winter. 

Let the plant do its own thing by feeding with the water it stores in the caudex. If you keep on watering, it will keep on drinking. Up to the point that the caudex ruptures. 

A sign of an overwatered desert rose is pimples on the caudex. It looks like water blisters. And it is. The cause is too much water inside the caudex.

When water needs to escape, pimples appear first, then burst to let some water out. 

When you see water trying to burst out of the caudex through pimples, it is a safe bet that there will be damage happening to the root system. 

For confirmation, feel the caudex. If it feels soft and squishy, that is the primary symptom that root rot has set in. 

When you feel that, take the plant from its pot to inspect the root. 

The roots should be white. Any brown spots are root rot. 

Root rot that has been caused by waterlogged soil can cause fungal infections. If there is a fungal disease in the soil, accompanying brown roots will be white webbing around the soil.

 

Treating desert rose root rot 

The only viable treatment for a desert rose with root rot is to cut away the diseased roots. 

Use sterile tools to prevent spreading fungal spores to healthy parts of the rooting system. 

Once root rot starts, it spreads. For that reason, you need to inspect all the roots. Not only the parts where it is clear there is rot disease. 

Use a sterile sharp pruning knife, or for mature desert rose plants, it may be easier to use a bonsai sickle saw to make clean cuts through thick roots. 

Some roots can be completely brown, others may only have a small but deep brown lesion. This is particularly true if the cause of rot is a fungus infection in the soil.

Brown roots need to be pruned off. Brown spots are root rot starting to spread. Given the roots will be soft, you may be able to scoop brown spots out using a spoon. 

Dig or scoop out any brown lesions from diseased roots. The process is like digging out necrotic spots on potatoes. The spots go deeper than the initial spread. 

The only healthy parts of the roots you should be left will be entirely white with no brown spots at all. 

 

Let wounds heal before repotting

Standard practice for root rot treatment on most other plants is to repot the healthy roots straight away. You cannot do that with a desert rose. 

Where the cuts were made on the caudex exposing the white flesh should be treated with a fungicide powder. An organic fungicide is cinnamon powder.

Apply a good coating over the white flesh.  Then leave the plant in the shade for a few days to air dry. 

Wait until the wounds callous over before repotting. It can take 3 days to a week for callouses to cover the wounds. 

 

Repot in a pot with drainage holes with a fast-draining mix 

The most important thing to get right with the desert rose is the potting mix. It must be extremely fast draining. 

The pot does not need to be big. Just enough for the roots to sit within the top inch or two of soil. A wider pot is better than a deep one. 

The best potting soil for houseplants (or any succulent) should have plenty of organic matter, be pH balanced, and drain extremely fast. 

For the desert rose, specific mixes developed for cactus plants are better suited. 

The soil should never be damp. Only slightly moist because the desert rose holds a lot of water in the caudex. When there is too much moisture, that sets the groundwork for root rot to start and spread.

 

How to prevent desert rose root rot 

Like any plant problem, the best practice is to focus on preventing problems from arising. Desert rose bonsai care mostly centers around moisture control. 

The areas to pay the most attention are that the soil consistently drains well, and that water is only added when the soil dries out. 

Contributing factors that can cause soil to waterlog are a lack of sunlight, low temperatures, or adding a fertilizer that is too rich that can make the leaves and branches susceptible to fungal stem rot. 

Yellow leaves are indicative of fungal stem rot. Catch that early and prune back infected branches can stop the fungal spores from spreading to the roots, rotting the plant from the bottom up. 

 

Frequently Asked Questions related to desert rose root rot

 

Why is my desert rose caudex shrinking? 

The caudex on desert roses is what it uses to ‘store’ water. It is normal to see it shrink in size after repotting. When the caudex shrinks months after repotting, it means it is using up its energy reserves faster than it hydrates from soil moisture. Inspect the roots to see if some are rotting. 

 

How do I make the caudex on a desert rose fatter?

The caudex stores more water when it thinks it is under attack. You can mimic those conditions by root pruning, and defoliating branches. Trimming feeder roots and removing leaves forces the plant into survival mode. Be careful with how much water you feed it after root pruning and defoliating.