Cordyline problems – pests, diseases and other problems

Last updated on March 23rd, 2023

The Cordyline, sometimes referred to as the Cabbage Palm, is a plant native to south-eastern Asia and Australia and one that grows just as well throughout the UK depending on the variety. Depending on the age it can span between 3 and 10 metres in height, however, you can often spot taller ones further down south where the winter is usually milder. Cordylines prefer full sun but will thrive just as well in light shade.

There is one particularly hardy variety that can be grown outdoors in the UK, and this is the Cordyline australis (common green cordyline). It will tolerate temperatures of -5 degrees if planted in a sheltered position. If you have any other variety beyond this one, you will need to protect it in the winter and take extra steps to prevent pests and diseases by maintaining an environment with temperatures around 15 degrees Celsius.

Most of the Cordyline australis plants will survive over winter as long as they are sheltered but in harsh winters they still need a little more protection. If you have a different variety, you will need to take steps to move it indoors or put it in a greenhouse to give it extra protection against diseases often brought about by winter conditions.

Otherwise, these plants are incredibly easy to grow, and they simply need fertile, well-drained soil, which is truly the key to preventing many diseases. You can keep your Cordyline healthy for years with a well-balanced fertiliser and a keen eye toward pests.

Protecting Cordylines from cold weather

The most common problem with cordylines is damage caused by a hard frost and it can be sudden and even after a plant has been established and been in many years. If you see your plant has yellow and brown patches (in the early spring) on its leaves and some of those leaves have dropped off, your Cordyline plant was likely damaged by the winter weather.

After a particularly severe winter, your plant will come away looking quite battered, especially if your area was subject to strong winds or cold snaps like it was in my town as shown in the picture above. Most of the cordylines in mine town were badly damaged.

This could have been prevented for cordylines by simply tying up the leaves with string to protect the crown. For young plants and those grown in pots, I always recommend pulling the leaves together and covering them with fleece as well because this will help protect the crown. When the weather improves, the plant will naturally perk up, and any damaged growth can be removed. 

Below I cover some of the other likely problems, such as spider mites and thrips which can cause damage to the leaves. I also look at leaf damage caused by water issues as well as some diseases such as leaf spot disease and the more serious Cordyline slime flux.

I start with cordyline pests, and these are also common on cordylines grown in greenhouses too.

Cordyline Pests

Spider mites

Two types of pests might affect your Cordyline. The first is spider mites. This is is more common in varieties grown indoors or in a greenhouse. Spider mites are almost impossible to see with the naked eye if you aren’t looking for them specifically because they are so small. Most people notice the webs before they notice the actual spider mites.

These are tiny insects that suck the plant sap directly out of the leaves, which distorts them. You can knock them off your plants by spraying them with water, but this should be done in the early morning so that the leaves have the opportunity to dry out before the weather gets cooler. 

You can also circumvent the issue entirely by letting loose ladybirds on a regular basis during the growing season. Ladybirds are natural predators of aphids and spider mites alike.

If the issue is particularly problematic, you can invest in a pesticide spray to do away with the spider mites.

Thrips

Of similar concern are thrips. These are also sap-sucking insects as well that will discolour and scar your leaves, however, they can also stunt the growth of your entire Cordyline plant.

If you see an infestation of them you should cut away any affected part of the plant and destroy it immediately, after which you should sterilise the tools you used to do it.

Spray the remaining plant with insecticidal soap. Again, you can also release things like ladybirds or lacewings, both of which will eat the population and help manage it. 

Where to buy Lacewings and Ladybirds

You can actually buy them as larvae online and have them delivered to your door, they are actually known as a biological control as opposed to spraying chemicals.

Buy Lacewings from Amazon.co.uk

Buy Ladybirds from Amazon.co.uk

---

Common Cordyline Problems

Leaves turning brown at the tips

With this particular plant you need to be careful if your water has extra fluoride in it. It is for this reason that any container-grown Cordyline plants should be watered with distilled water. If you notice that the leaves are turning brown on all of the tips it’s indicative of fluoride toxicity. If you use tap water when watering your plant and the water is heavy with fluoride the tips of your leaves will start to turn brown and eventually all of your leaves will become mottled and die. If possible use rainwater or distilled water.

Leaves turning yellow and brown and drooping

If the leaves are turning yellow and brown and drooping, by comparison, this is simply indicating that the plant needs regular, deep watering. The key here is to keep the soil regularly moist but never overwater the soil. With container-grown plants, which are how many gardeners grow their Cordylines, you can water them until such time as you see that water coming out of the drainage holes and then you want to leave the pot until it is almost dry before you water again. 

---

Cordyline Diseases

Leaf spot disease

There are a few diseases that you need to look out for with Cordyline plants. The first is leaf spot. This is a fungal disease that will discolour your leaves and the best way to prevent this is to water the roots of your plant. Most people water the stem or the leaves mistakenly which leaves extra water on the leaves and in colder weather this provides the perfect environment for fungus to thrive.

Preventing leaf spot

It’s also recommended that you water early in the day so that if any water does splash onto the leaves or the stem it has an opportunity to dry out before the evening temperatures drop. It’s always good to check the air circulation around your plants as well as any insufficient air circulation will create a habitat perfect for leaf spot. 

Dealing with leaf spot on infected plants

If you notice your plant is affected, remove any of the affected branches and destroy them. Any tools you use for this process should be disinfected. If your plant is severely affected by leaf spot you might need to turn to a fungicide and this is something you can purchase from most garden centres and nurseries.

Root rot

Fusarium pathogen causes root rot, another concern associated with Cordyline plants. This type of rot is caused by poor drainage or excess watering. It is for this reason that you absolutely must allow your plant to dry in between watering so that the roots never sit in waterlogged soil.

Cordyline slime flux

Cordyline slime flux is a particularly nasty outcome of insufficient protection against winter weather. This is a disease caused by bacteria and the bacteria is only able to get into your Cordyline once it has been damaged by frost. If you live in an area with particularly cold weather, should water remain in the stems, leaves or the roots, the remaining water can actually freeze and causes tissue damage from the inside out. Any areas that are damaged in this way become a gateway for bacteria.

Once the plant is affected by this bacteria you will notice a thick, white fluid on the stem and it might have a particularly foul smell. If not white, there could be black stains directly below the white fluid. If you see any of this, it’s imperative that you cut away the affected stems and destroy it along with any other damaged tissue you can find. Only by destroying the damaged tissue and removing it can you prevent it from spreading.

Preventing slime flux

The best line of defence against this bacteria is to protect your plants against the winter weather. If you have containers or pots, bring them into a greenhouse or inside your home. If that’s not feasible, cover the pot with bubble wrap to protect the roots and tie the rest of the plant up with string and wrap it with fleece to protect it. If your Cordyline is in the ground and you simply can’t move it, wrap it and mulch the ground around the base of the plant.

Overall the best way to protect your Cordyline plants are to be completely mindful of when you water and where you water, and then to provide proper protection in the winter. By watering at correct intervals, allowing the plant to nearly dry out in between and watering at the roots rather than along the leaves, you can prevent many of these diseases and common problems listed above. Protecting your plant over winter will go a long way towards sustaining its overall well-being.

---

Last update on 2024-11-22 / Affiliate links / Images from Amazon Product Advertising API