Also known as cabbage palm, the Cordyline is a species of plant that looks similar to a palm tree and they can grow up to 20 meters tall. This hardy evergreen plant has over ten varieties, some of which sport different colours and thrive in different climates. To grow a Cordyline successfully, you need to be aware of some of the common problems that can affect it.  

While Cordyline varieties such as the Cordyline Australis are typically easy to grow, various pests and diseases will damage the plants if left unchecked. This article is geared towards unveiling these common problems and possible treatment measures. Read on further to find out more:

Pests that damage cordylines

Common pests that attack Cordylines include:

Scales insects

Scale insects are a common pest affecting various plants, if left untreated they may cause irreparable damage to your plants. Scales are small insects that feed on the plant’s sap, therefore limiting the nutrients supplied to the rest of the plant. These insects not only feed on the plant’s sap but also leave behind honeydew. Honeydew is a sticky residue that attracts other insects like aphids and infections such as sooty mould.

Scale infections need tending to before they cause defoliation, which will then lead to the demise of the plant. To control a scale insect infection, there is a need to recruit their natural enemies such as vedalia beetle, lacewings, parasitic wasps and ladybirds.

Utilising natural predators is more effective than using chemicals because insecticides don’t seem to be effective in the long run.

Mealybugs

If you observe your Cordyline plants and notice tiny white cotton-like insects then it must be mealybugs. These wingless and soft-bodied insects feed on the plant’s sap, just like scale insects do. In small numbers, mealybugs cannot cause significant damage to the plant; however, in large numbers, they weaken the plant. You will see the leaves become yellow and start curling before finally dying off.

Mealybugs do not do well in intense heat; therefore, you can expose them to the hot sun for a few days to chase or kill them off. Alternatively, you can use insecticides containing Beauveria bassiana, a fungus that attacks troublesome pests. Furthermore, the use of natural predators like lacewings and ladybirds always prove beneficial.

Make sure to remove the infected sections before employing a treatment method to avoid re-infestations.

Spider mites

Same as thrips, people usually notice spider mite damage after some time. These tiny web-making insects live and feed on the underside of leaves. They puncture the leaves and consume plant tissue to sustain them. These insects are very small and you will only know of their presence from the discolouration and eventual fall of the leaves.

If your Cordyline plant is infested with a large population of spider mites, you will see fine webbing on the stems and leaves. Managing this infestation includes using natural predators like lady beetles. You can also use a high-pressure hose to dislodge and kill the pests without affecting the plant.

Pesticides are available but confirm from an agronomist which products are effective because some people report an increase in population after the use of pesticides.

A pesticide that kills mealybug, scale insects and red spider mites

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Thrips

Thrips are winged insects that have an estimated 6000 species worldwide. These tiny insects also consume the cellular matter found in plants, therefore, weakening the plant over time. By consuming the cellular matter in the leaves and soft stems they leave behind damaged and discoloured leaves. They might not kill off the Cordyline, but the disfigured leaves will be an eyesore.

To prevent thrips from causing further damage to your plants, find predatory insects such as green lacewings, mites, parasitic wasps or ladybirds to control their population. Using natural predators is the best way of preventing infestations in the future.

Insecticides are not considered superiorly effective on thrips because, by the time you notice the damage, they would have migrated elsewhere.

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Common Cordyline diseases

Root rot

Root rot is typically brought forth by Fusarium fungus. This fungus thrives in wet soil and cold temperatures. It is crucial to plant your Cordyline in well-drained soils to avoid promoting fungus-friendly environments.

This disease is signified by wilting, yellowing of the base leaves and brown roots. If left untreated, the Cordyline stems, roots and leaves will dry out. To prevent root rot make sure the soil completely dries out in between watering sessions.

If the infection is severe, you will have to cut down the plant. If the infestation is mild, a professionally recommended fungicide will do the job.

Slime flux

When winter comes around, the chances of a slime flux infection are high due to frost. This bacterial disease is catalysed by harsh winter conditions that damage the plant’s tissue. The bacterial infection produces a bad-smelling fluid around the stem that is hard to miss. These thick fluids, together with black stains, are the main indications of slime flux and they signal that the infected sections need removal if the plant is to survive.

As of yet, there are no prescribed treatments to deal with slime flux; however, prevention is better than cure. Ensure your Cordyline plants are winter protected by moving them indoors if they are potted or wrapping the plant in warm fleece.

You can learn how to protect cordylines overwinter here

Fungal leaf spot

Fungal leaf spot is a result of Fusarium moniliforme spores finding ideal conditions to thrive in your Cordyline plant. If the temperature is warm and there is water around, then the fungus will take hold in a matter of days. You can identify fungal leaf spots through blotchy patches on the leaves. These leaves eventually die off and then the fungus finds new leaves to take over.

If you notice an infection, remove the affected leaves immediately to prevent further damage. The use of fungicides will also help to mitigate the infection, giving the plant time to recoup.

A suitable preventative measure is to water the base of the plants rather than the leaves. This way the spores will not have a suitable environment to thrive.

Learn how to revive a dying cordyline in my guide here

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Other issues that affect Cordylines

Dull colours

Cordyline plants are known to have vibrant colours whether it is green, purple or pink. If you notice that the plant’s colour is becoming dull, this might indicate that the plant is not receiving adequate sunlight. Expose the plants to intense sunlight and see if the colour changes.

Winter damage

Winter comes with its own set of problems for unprotected plants. If you witness your Cordyline possessing brown or yellow patches in spring, then the plant has been damaged by the winter weather. It is crucial to protect the plant in severe winters to prevent these complications. Wrap the plant in warm fleece until winter passes.

Water composition

Water that contains high levels of fluoride will damage your plants. The tips of the leaves will turn brown or yellow depending on the levels of fluoride. You can use rainwater or distilled water to mitigate this problem. Also, check the fluoride concentration in the fertilisers you use, as they may be a possible cause. If you are not sure how much fluoride the fertiliser has, you can opt to use natural compost. I hope that this article was informative enough to prevent any future issues with your Cordyline. Be proactive and monitor your plants to notice infestations before they intensify. This way, you will enjoy the sight of healthy Cordyline plants.

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Last update on 2024-04-19 / Affiliate links / Images from Amazon Product Advertising API