Dying bottle brush trees

Treating Sick Bottlebrush Plants: Learn About Diseases Of Bottlebrush

Few plants fit their common names better than bottlebrush shrubs. The spikes of flowers, so attractive to hummingbirds and butterflies, look exactly like the brushes you might use to clean a baby’s bottle or narrow vase. These eye-catching plants are generally vital, healthy shrubs, but occasionally bottlebrush diseases strike. If you have sick bottlebrush plants, read on for helpful information about bottlebrush disease treatment.

About Sick Bottlebrush Plants

Gardeners love bottlebrush plants (Callisteman spp.) for their brilliant blood-red flowers, evergreen foliage and easy-care ways. These shrubs are so vital that they can become invasive if left to their own devices. But that doesn’t mean that you won’t have to deal with a few diseases that attack these bushes. If you know the signs of different bottlebrush diseases, you’ll be able to jump right into bottlebrush disease treatment.

Diseases of Bottlebrush

The most common bottlebrush diseases include both easy-to-remedy problems, like twig gall or mildew, and serious issues like root rot and verticillium wilt. Many of the issues are caused by excessive moisture in the soil or on the foliage of the plants.

For example, wet soil is the direct cause of twig gall, a fungal disease. If you see many new twigs growing from the tree and branches that bloat, the shrub may have twig gall, one of the most common bottlebrush diseases. Cut off the unhealthy growth and dispose of it, then correct the overly wet soil.

Powdery mildew is also one of the diseases of bottle brush caused by too much water. But the main cause of powdery mildew is water on the foliage. Bottlebrush disease treatment for powdery mildew is fungicide spray, but you can prevent a reappearance by watering the shrub from below, not above.

Both root rot and verticillium wilt are serious bottlebrush diseases that are difficult or impossible to treat. Both are caused by fungus.

Root rot results from too much water in the soil. Bottlebrushes need well drained soil, not wet soil. When the soil is too moist, the root rot fungus can attack the shrub’s roots as well as the plant’s neighbors. You’ll see the branches dying back, leaves yellowing and falling, and the trunk turning strange colors. Bottlebrush disease treatment here is applying fungicides, but it’s much easier to prevent this disease than to cure it.

Verticillium wilt is another of the diseases of bottlebrush that causes yellowing leaves and branch dieback. It is not likely to kill bottlebrush plants, but it is hard to rid the soil of the fungus. Your best bet is to treat the area with fungicides and move the tree to another location.

Diseases That Affect a Bottlebrush And Measures to Control Them

Bottlebrush trees are considerably small tress which bear deep red, and sometimes pink flowers. As is the case with every living creature, these beautiful trees too, are susceptible to a few harmful diseases and fungal infections that can kill it, or at least severely affect its life and growth. Read the following article to find out more about these diseases.

Bottlebrushes, which go by the botanical name Callistemon, can inspire artists looking for inspiration from nature. Such is their beauty. As far as trees go, they are not really big, with most varieties of bottlebrushes growing to a modest height of around 14 – 16 feet. There is a particularly adorable variety of bottlebrush that grows only up to 3 feet, and is normally used as a flowering shrub! The flowers of this tree are blood red, and when in full bloom the beauty of this tree can steal your breath. The four main species/ varieties that are commonly used, are – Dwarf Bottlebrush, Weeping Bottlebrush, Red Cluster Bottlebrush and Upright Bottlebrush. These trees flower mainly during summer and spring, but they do have some flowers throughout the year, and are not totally barren. It is necessary to care for these lovely trees to prevent them from contracting any diseases, since they are susceptible to a few.

Bottlebrush trees need just the right amount of moisture, in the soil in which they grow. Too little means that they will not grow well, whereas too much means that the soil becomes the perfect breeding ground for various fungi that attack it. This tree is more susceptible to attacks by fungi than by any other pathogens. So care has to be taken to keep the soil adequately moist as per the requirements of this tree, so that it remains disease free and lives out its life completely. The diseases that affect this evergreen tree are given below, along with some information about the preventive measures to be adopted to keep these diseases at bay.

Root Rot


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Bottlebrushes grow well in moist but well drained soil. When the soil is kept too moist, or the tree is over watered, then the conditions become conducive for the fungus that causes root rot, to breed in the soil. This is a rapidly growing fungus and attacks its roots, as well as the surrounding plants. This fungus can cause dieback, and if the attack is severe, it may even kill the tree.


Discoloration of trunk, dieback of branches, brittle reddish brown roots, leaves turning yellow, and premature defoliation.

Prevention/ Control

Applying fungicides may help, but this disease is very difficult to treat once the fungus has attacked the tree. So to prevent this disease, ensure that the soil is kept adequately moist, not wet and soggy all the time.

Leaf Blotch/ Leaf Spot

This is a fungal disease that spreads due to the water being too soggy. It affects the beauty and appearance of the tree, and although it does not kill it, the tree looks infected and ill.

Premature defoliation is a good indication that the bottlebrush may be suffering from leaf spot, but since this symptom can also be confused with root rot disease, the other, more telling symptom to look out for, is spots on its leaves. These spots are small when they begin to show, but they increase rapidly in size. They are brown in the center, with a yellowish border around it.

When the leaves fall off, there is still fungus on them, so instead of letting them stay where they fall, it is advisable to rake them and burn them off. This will help prevent the fungus from re-attacking the tree. Spray the tree with liquid copper fungicide. Keep the soil slightly moist instead of wet, and do not over water the tree.

Verticillium Wilt

All bottlebrush buckeye trees can be hit by this fungal disease. The fungus that is responsible for this disease, breeds in the soil and attacks the wood. This disease is notorious for killing other plants if the attack is severe, but strangely, the bottlebrush is spared this fate. At the most, this disease succeeds in killing a few branches of this tree.

Yellowing or discoloration of the leaves, along with early defoliation.

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This fungus is very resilient towards fungicides, so even after the soil has been properly and thoroughly sprayed with the fungicide, this fungus will still stay alive. The affected branches should be cut off, and sterilized or sprayed with fungicides. Even this is no guarantee that the tree is safe from this fungus, since it is still present in the soil. So the safest bet, is to uproot the tree and move it to another place, where the soil is healthy.

Twig Gall

Sphaeropsis tumefaciens is the pathogen that causes this fungal disease. It loves attacking the bottlebrush, since this tree is ‘woody’. Warm and moist conditions aid the breeding of this fungus, hence, soggy soil around this tree will cause an attack of twig gall.

In this disease, an abnormally large number of shoots spring from the tree, and the branches of the bottlebrush seem to bloat and become bulky. Over time, these symptoms exaggerate and severely harm the tree.

This disease can be prevented, by not allowing the soil in which the tree is growing, to be soggy and water logged. Cut off the swollen branches of the bottlebrush immediately after the symptoms become visible, to stop the fungus from spreading to other parts or plants that it comes in contact with. After cutting off the swollen and unhealthy branches, make sure to sterilize them, in order to destroy the fungus present on them. Fertilize the tree as and when required, to prevent re-occurrence.

Powdery Mildew

Incorrect watering practice causes this disease. When the tree is watered from above, it causes the water to collect on the leaves. The fungus that causes this disease breeds in such collected water. Even rainwater collecting on the leaves after a shower, will cause this fungus to breed. This disease does not kill the tree, but it does affect the blooming of the tree, making it look dull and unattractive.

Powdered mildew has the appearance of a fine whitish powder, in keeping with its name. This powder appears on the leaves of the tree. Early defoliation, withered buds, discolored or yellowed leaves, are symptoms of this disease.

Let your tree remain as dry as possible. Plant it where it receives plenty of sunlight, and where it is not cluttered or closely surrounded by other plants. Spray it with fungicide, and allow the tree to breathe. Mainly, do not water the tree from the top.


Fungus is the cause of this disease too, since this tree is extremely susceptible to fungal infections. Once again, the cause is extremely wet and soggy soil, and improper fertilization. This disease spreads very rapidly, gravely affecting the growth of the tree. Bottlebrushes affected by this disease suffer stunted growth, and look dead and lifeless. If the infection is grave, the tree will eventually die.

The tree becomes disfigured, and the branches become uneven, with pits and swollen areas. This is visible on the branches, and more so on the trunk of the bottlebrush.

Regular and timely fertilization, and proper spraying of the tree with fungicides, should help prevent this disease from affecting the tree. As mentioned earlier, make sure the soil is not too wet. As soon as the symptoms start showing, cut off the affected areas, and spray them with fungicides and sterilize them.

From all the above prevention techniques, it must be pretty clear by now, that the bottlebrush tree cannot tolerate extremely wet and soggy soil. If taken care of properly, this tree can add a lot of beauty to any garden or backyard. Maintaining this tree is actually not a herculean task. It requires fertilization approximately 4 times a year. This tree is often short lived because of its susceptibility to fungal diseases and infections, but proper maintenance will let you enjoy its blooms all year round.

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Q:  Parts of my bottlebrush tree are dying and it appears to be growing leaves and flowers only on one side of the tree.  What would cause this?

Girdling roots

A: I appreciate you bringing me clippings of the tree. It was especially important to bring in limbs with living leaves still attached. It is often difficult to determine the cause of a problem if the only material I see is totally dead. I was unable to locate any disease or insect damage so the next thing to do is look at the root area. In several recent instances I have found the same damage you described and discovered girdling roots at the base of the tree. A girdling root is similar to having a tourniquet wrapped around your arm. What will eventually happen to your hand if the tourniquet is left in place for a long period of time? Your hand would have the blood supply cut off and the limb would be lost. The same thing can happen to a tree branch if a girdling root is allowed to grow around another tree root.

We recently planted fourteen new trees at the James S. Pages Governmental Complex and every one of these new trees had some degree of girdling and circling roots – from mild to severe. It is important to examine the root ball of any tree or shrub you plant. Remove those girdling or circling roots before you plant. Remove the top layer of soil and root mass so you can examine the root structure carefully. In your situation, the plant has been in the ground for several years but it is still important to remove any roots growing into another root. Cut the girdling root just above where it starts to grow over the other root. You may need to use loppers to make a clean cut. Do not add any amendments to the soil – no black cow or fertilizer. Just be sure the plant is well irrigated for a few weeks to help get it through the shock of losing a major source of water. Keep lawn grass as far away from the roots as possible. Be sure the mulch is not too deep – only about 2-3 inches. Never allow mulch to be piled up around the trunk tissue, which can provide the perfect environment for disease. Allow 18 – 24 inches area around the trunk of the tree or shrub which should contain nothing but soil and air.

The above photo demonstrates what can happen if the girdling root is allowed to get too large. Girdling and circling roots are probably one of the more important causes for failure in newly planted trees. For more complete information regarding removal of girdling roots please check out the UF/IFAS Environmental Horticulture website: http://hort.ufl.edu/woody/removecircling.shtml

by kathywarner

Posted: July 11, 2017

Category: Clubs & Volunteers, Home Landscapes

Tags: girdling root, proper tree planting

Dying wax myrtles and bottlebrush tree

Cause could be a number of things and likely more than one. First the single wax myrtle that was replaced with bottlebrush and it is dead.
1. What comes to mind first, is perhaps a soil borne fungal disease – Phymatotrichum omnivorum, that can attack more than 2,000 species of plants is commonly known as cotton root rot. Our plant disease clinic can test plants for this condition. website: plantclinic.tamu.edu
2. Larvae (worms) of Japanese beetle – the occurrence would be in high numbers in the soil, I suspect to kill a large wax myrtle. Timing of the treatment of this pest is critical to control. If the larvae are large as they are at the end of summer, then treatment is much less effective.
The single wax myrtle lost in the larger planting of w.m. – could be due to a number of things, but over the past 5 years or so, we are observing seemingly healthy, well established wax myrtles, just turn up their toes and die. It is reason for concern by a number of horticulturists, especially since this is a native plant. Could be a number of reasons – soil borne fungus, root issues – ie. girdling, water – too little/too much; drainage issue, heat stress. It is just hard to say definitely. In our demonstration garden plantings of wax myrtle, we have lost 2 large specimens in the last 2 years.

The Bottle Brush tree (Callistemon), belongs to the Myrtaceae family. Bottlebrush trees are quite similar (and closest) to the Paperbark melaleucas, who also have flower spikes shaped like a bottlebrush.

Native to Eastern and Southeastern Australia, you’ll find the bottle brush in abundance along Australia’s tropical north up to the temperate south.

Beautiful bright red flowers of the bottlebrush tree

New Caledonia gives us four species and two from the southern part of Western Australia. Located in wet or damp areas within flood-prone areas or along creek beds.

The proliferation of this cheery plant started in 1789 when the Crimson Bottlebrush (Callistemon citrinus) was imported by Joseph Banks into Britain.

This woody shrub/tree, the Callistemon grows from .5 to 18 foot tall. It’s striking; colorful red flowers make them one of Australia’s best species of flora, and a favorite among plant growers.

The Bottle Brush Tree Flowers

The “brush” is a collection of individual blooms; its long filaments are colored by the pollen that forms the tip. The filaments provide the Bottle Brushes’ distinctive shape, and usually, fall into the color range of either red or yellow.

A Bottlebrush plant can have red flower spikes accentuated with bright, yellow pollen.

The flower’s nectar are favorites among nectar-feeding insects and birds like the hummingbird. They make nice additions from butterfly gardening.

The red bottlebrush flowers aren’t just for show – they produce tiny fruits that contain hundreds of seeds inside. The woody fruits form along the stem in clusters. The seeds aren’t immediately released and only fall when the fruits open up after one year.

New Bottle Brush bush leaves make excellent ornamental accessories, colored brightly and covered with fine, felt-like hair.

There are different weeping bottlebrush tree and red Bottlebrush plant varieties:

  • Willow
  • Alpine
  • Lemon Bottlebrush Tree
  • Kingaroy
  • Crimson
  • Prickly Bottlebrush – the dwarf

Bottle Brush Plant Care

The Bottle Brush plant rewards its owners when properly cared for with full, healthy growth and very bright red, colorful blooms.

The evergreen Callistemon can grow in containers, as a stand-alone small tree like a hibiscus or as bottlebrush hedges, a large shrub or as border plants.

It’s a resilient plant growing in USDA hardiness zone maps of 9 to 11. It’s popular for homeowners gardening in Florida. The Bottle Brush flower resists most types of plant diseases and pests.

To get the most beautiful blooms, Callistemons need the power of the full sun.

As for the soil, bottle brush trees and shrubs need a well-drained soil that maintains a consistently damp condition. Bottle Brush can tolerate occasional periods of drought. Make sure your potting soil doesn’t have high levels of alkaline.

When using Bottle Brush as a hedge leave 3′ to 4′ feet of breathing space between each plant.

Allow 4′ to 6′ feet of space if planting right outside the house. From the driveway or walkway design, allow 5 feet to keep the nectar-hunting bees from making contact with visitors.

Fertilizer with a low-phosphorous, granular fertilizer in the autumn, summer, and spring. Mulching helps keep away unwanted garden weeds and assist in retaining soil moisture.

Add a supplemental feeding if your Bottle Brush shrub is behind on growth and produces pale flowers. Liquid fertilizer or some bone meal will promote better, more colorful blooms in season.

Related Reading:

  • The New Zealand Christmas Tree
  • Another Australian tree: Grevillea robusta – Silk Oak Tree
  • The Wax Flower (Chamaelaucium)

Pruning Bottlebrush

To keep Bottle Brush plants in great shape prune plants lightly after flowering. Prune, young plants after each flowering period, to remove the spent flower spikes. Cut back interior branches where less foliage exists.

During spring, prune old woody parts, and apply a general purpose complete fertilizer to encourage growth.

To encourage growth, tip prune just behind the blooms before the winter season arrives to minimize the frost damage on the new flowers.

You might ask if pruning is needed. Would you need to sacrifice the first growth of flowers for the sake of shaping them according to your preference?

The short answer is yes, for a number of reasons.

The Bottlebrush tree benefits from early pruning, especially in the establishment stage. It encourages regenerative growth from basal pruning as it revitalizes the plant from the ground up.

Basal pruning eliminates all branches from ground level and adding fertilizer will encourage vigorous growth.

Propagating The Bottlebrush Tree

Bottle Brush propagates easily from seed. Take one of its unopened fruit and put it in a dry paper bag.

Keep the paper bag in a warm place, until seeds release. Sow seed into a freely draining seed-mix during spring and summer.

To propagate bottle brush from cuttings using clean, sterilized pruners to take 6-inch cuttings of semi-mature wood in summer.

On the lower half of the cuttings pinch off the green leaves and also remove any flower buds.

Dip the cutting into a rooting hormone powder and stick the cutting into the rooting soil. Cuttings root better when placed in a mini-greenhouse using a plastic bag or plastic box.

How fast do bottlebrush trees grow?

Roots form in about 10-12 weeks and can then be potted and moved outdoors in the spring.

Callistemon In Closing

The bottle brush is an evergreen tree or shrub with light drooping grace, height to twenty feet.

Tiny creamy white flowers are borne on drooping spikes to eight inches long, composed of rich, dense tufts of red stamens. Flowers at branch ends resemble a bottle brush. Blooms periodically but heaviest in the spring. Fruit is capsular.

An excellent tree as a specimen in the yard or patio, suitable for near a water feature or background object.

Not particular as to soil and has fair salt tolerance. Grows moderately fast in a frost-free area, full sun.

Prune (check out our favorite pruners and the review here!) to shape. Propagated by seeds or cuttings.

A hardy tree that withstands heavy winds and one of our best evergreen flowering trees with a weeping habit.

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