Cordyline: Problems, Pests, Diseases and Solutions

Cordyline Australis, or simply cabbage palm, is a plant popularly grown in many gardens across the United Kingdom and across America. It is usually grown usually due to its evergreen nature and its resemblance to palm trees. Depending on the varieties, the sun loving plants attains a height that ranges from 3- 20m (10ft – 66ft).

In addition to the heights that they achieve, they also thrive well in sheltered regions.

Early spring is usually the best time to plant these evergreen shrubs. To plant Cordyline, a reasonably deep hole must be dug and the soil amended to fit the requirements of the plant. Next, the Cordyline would be gently removed from the container it was grown in, loosening the root knots in the process.

The plant is then gradually placed into the hole and backfilled to the top edge of the rootball. Lastly, a 1 inch layer of wood mulch can be spread around the plant to suppress weed growth and retain moisture, right after deep watering the plant.

Like most plants, Cordyline require a fertile, well-drained and slightly alkaline soil for growth. Luckily, Cordyline do not feed much, however it would be nice to give the plant an organic boost by applying a slow release fertiliser at the beginning of the planting season, only dropping by every month of the growing season to apply liquid fertilisers.

Furthermore, frequently water the plant as soon as you suspect drying. Over watering may result in root rot, and using tap water frequently may cause fluorine overbalance. Hence, you have to learn to moderately water the plants. You may prune after a while to remove the old and dead leaves that make the plants appear unattractive.

 

Cordyline: Problems, Pests, Diseases and Solutions

 

Though Cordyline are so easy to grow and require little work to maintain, pests and diseases may frustrate the hard work of the gardener. To help you avoid paying the hefty price of ignorance, we gathered some information that may help you prevent and control future frustrations.

Pests, Prevention And Control

The pests that are widely known to affect Cordyline are fungus gnats, mealy bugs, scales, spider mites, thrips and weevil. Most of these insects are introduced to an uninfected plant through contact with infected plants, with the exception of thrips that lands on any susceptible Corydyline during flight.

Mealy Bugs

Mealy bugs are small, white, cottony and wingless insects that cause a great deal of damage on Cordyline. Due to their wingless nature, they cannot invade your plants, unless introduced. They cause damage by eating the stems and leaves of the plant, hereby leading to stunted growth, presence of honeydew and sooty mould and in severe cases, death.

Prevention and Control

To prevent mealy bugs infestation, care must be taken to remove all infected plant as soon as insecticides as possible. Introduction of their natural enemies has always been a good method of controlling pests.

Chemical control, on the other hand is barely a good control method for mealy bugs, due to the chemical immunity provided by their waxy coats. Though, they are insensitive to chemicals, they are awfully heat-sensitive, putting the plant under direct sunshine for few hours may effectively kill some.

Spider Mites

These tiny, web-spinning animals usually go unnoticed until damage caused by them is noticeable. They infect plants through direct contact with an infected plant and slowly destroys the newly infected plant by sucking the sap of leaves and inherently damaging the foliage of the plant.

In instances where you have a high population of spider mites, it may lead to total death of the plant.

Preventing Infestation

Avoiding contact with infested plants is naturally the best way to prevent mites infestation. Spraying the plant with high pressure water can help to manage their population. Use of natural enemies such as ladybeetles and lace wing larvea, usually yield a positive result in reducing the population of mites.

 

 

Cordyline: Problems, Pests, Diseases and Solutions

 

Prior to introducing pesticides, questions must be asked from a certified agronomist on the type of pesticide to get and how to apply it. This step must be taken because some gardeners reported an increase in mites’ population after using pesticides.

Scales

Cottony cushion scale, commonly called scales, infest target plants through contact with infected plants. They slowly diminish the vigour of host plants by sucking phloem sap from the leaves, twigs, branches, and trunk.

As a result of this feeding, defoliation and death of branches and twigs may occur. Like mealy bugs, symptoms of infestation includes presence of honeydew and sooty mould growth.

Control

Control of scales is achievable by the use of natural enemies, Rodolia cardinalis (Vedelia beetle) and Cryptochaetum iceryae, being a worthy mention, due to their specificity and short life cycle.

Chemical control has no effects on adult scales, so it is of no use pursuing the method. Since the animals are sedentary, they can only infest a plant through direct contact with an infected plant.

Thrips

As mentioned earlier, these small winged insects does not need to be introduced to a plant before affecting the plant. Their feeding causes discolouration and distortion of affected leaves, and may even lead to stunted growth.

Though they rarely threaten the life expectancy of the Cordyline plant, they do a great job in disfiguring the external appearance of the plant.

Prevention/Control

They are difficult to control because they are migratory so the easiest way to monitor then is by gently shaking foliages that are suspected of harbouring the pest or simply by branch beating.

Like other cordyline pests, natural enemies performs great wonder in controlling thrips. Lace wings, ladybugs, mites and some wasps are usually the biological controller employed. Pesticides are usually not employed for thrips infestation control.

Do not fret, you do not need to scavenge for pests’ natural enemies. You can sit in the comfort of your home, purchase the specific biological control online and have it delivered at your doorstep.

 

Diseases That Affect Cordyline

Fungal Leaf Spot

As the name indicates, it is a fungal disease .This disease happens when the spores of the causative fungus, Fusarium moniliforme, finds an agreeable wet and warm plant surface to thrive and reproduce on.

The fungus, through sporulation, produces many young ones, and together they form a blotchy patch on the unfortunate leaf. This leaf eventually falls off to the soil, and the spores present on the leaf await another wet, comfortable leaf to call home.

Prevention

Since the fungus usually thrive on moisture, especially in cold weather, the best way to avoid its infestation is by watering the soil directly, instead of the leaves. If you however need to water the leaves, do it early in the morning so the moisture can evaporate, before a temperature drop.

Remove and destroy any infected plants as soon as you spot a fungal leaf spot (see what I did there?).

Multipurpose fungicides is useful in controlling already infected plants. Red the instructions given by the manufacturer, or better still consult a professional agronomist.

Root Rot

This disease is also caused by fungal infestation of Fusarium fungus. This is a different species from the fungus that causes leaf spot. Like most fungus, they thrive in cold and wet soil. Visible symptoms includes brown roots, and wilting and yellowing of lower leaves.

As the disease progresses, the foliage and the stem dies out and eventually the root will follow suit

Control

Avoid the creation of the perfect environment for fungi growth by refusing to irrigate and keeping the soil as dry as possible. Also cut down infected plants as soon as possible.

With the help of a professional, you can decide in the best biological agent and fungicide to use in case of an infestation.

Slime Flux

This nasty bacterial disease is preceded by damages caused by extreme winter temperature. The frost damages affected tissues from inside out and these damaged tissues encourages bacterial infestation.

A thick, white, foul-smelling fluid is usually noticed in the stem as soon as the bacteria resumes its activity. Sometimes, a black stain may be noticed under the white liquid.

 

Cordyline: Problems, Pests, Diseases and Solutions

 

Control & Defence

Sadly, there is no known control for slime flux so the only line of defence you can give your plant against slime flux is by completely protecting your plant against extreme winter weather.

During winter, only water the plant when needed and do so in the early morning. Mulching also helps, as it conserves moisture content.

To avoid spread of the disease, immediately cut off infected plant part and disinfect the tools used.

Problems Associated With Cordyline

Flouride Toxicity

The major indicator of excessive fluoride intake in Cordyline is the prescence of brown tipped foliages. And if care is not taken, the leaves may become mottled and eventually die.

If the fluoride intake proves to be a problem, distilled water or rain water should be used to water the plants. In addition, irrigation and fertilisers with high fluoride content should be avoided.

Poor Colour

Cordylines are infamous for their vibrant colours that ranges from purple to pink and yellow, as well as green of course. This colour bust may sadly fade out or become boringly dull if the light intensity the plant is receiving is too low or if the temperature is high.

Low carbohydrates level may also play a role in giving the plant a dull colour. The simple solution to this problem is improving the light intensity.

Poor Water Management

Your plant needs proper watering if the leaves starts turning brown or yellow and starts drooping.

The aim when watering Cordyline plants is to make sure the soil constantly has a relatively normal moisture content for healthy growth, not for the soil to be completely over watered.

Damage of Vital Growing Point

Application of excessive fertilisers or leaf shining chemicals to plants, especially young plants, usually accumulates to growing points and, this, leads to collapsing and damage of the growing points. Although, the plants regrow, most young leaves do not survive the attack.

This can be avoided by simply keeping fertilisers or ‘leaf shine’ off of young plants and growing tips. If you have to apply them, follow the instructions of a professional.