Why is There Fungus on Azalea Branches and How to Solve It

Azaleas are a popular spring-flowering shrub you can usually find in landscapes, thanks to its attractive appearance and ease of maintenance. While they are problem-free in general and require minimal care, there may be times it meets pests, fungi, and diseases. But why would there be fungus on azalea branches and what can you do to stop it?

Read on as I talk about fungus on Azalea branches and if there’s a possibility to remedy it.

fungus on azalea branches

Why Is There Fungus on Azalea Branches?

If you have Azalea, you might have had some issues about the branches dying or looking like they have been diseased.

There are various causes behind the branches getting fungus, usually caused by insects or diseases. But why exactly does it happen?

1. Pests

If you see the bushes or branches incurring fungus or even dying, you have to watch out for pests that cause it. It can come from the rhododendron borer or the rhododendron stem borer. While both have a similar name, they are different insects.

Borers and stem borers can attach deciduous azaleas, making small homes in the branches and laying their eggs in it. You will know if you have borer infestations when you cut off a branch that looks like it has suffered from dieback, like dying branch tips or twigs, or cracked branches. Slice this branch lengthwise and check its insides for any small and worm-like larvae.

2. Dieback Diseases

There are two diseases that can cause your azalea branches to have fungus, which are:

a. Phytophthora is a fatal disease, with symptoms including:

  • Leaves turn pale green to yellow to brown
  • Leaves fall prematurely
  • Leaves and branch dieback

The azalea bushes may die within two to three weeks of contracting the disease.

b. Botryosphaeria is another common azalea fungus. The fungi would enter through the branches’ natural openings or wounds, with dark and sunken areas forming around the openings, eventually spreading through the stems.

There are no apparent symptoms other than dying branches now and then on a generally healthy plant. You might see that the leaves on its affected branches would turn dark and roll up, though they won’t fall off.

Can I Remedy This Fungal Issue?

While it’s irritating to see your azaleas suffer from fungal issues, there are solutions behind it. Here are what you should follow:

1. Use Insecticide

Are pests the problem? While borers and stem borers are different, they have the same treatment. There isn’t a conventional insecticide to kill the larvae, since they are protected within the branch already.

What you can do is to cut back all the affected branches during the early spring to late summer. If you do see adult insects on the leaves, then spray its undersides using insecticidal soap or horticultural oil. Make sure to follow proper instructions to prevent injuring your plant.

2. Treating Fungal Diseases

If fungal diseases are the problem, then, unfortunately, this will be a bit difficult to treat. In fact, there are fungal diseases you can’t treat at all, as they are generally fatal.

If you have azalea branches suffering from phytophthora, you will need to remove and dispose of the plant immediately, preventing the disease from spreading. You should also avoid planting and replacing the dead plants with more azaleas, as the disease now lives in the soil.

For plants that have Botryosphaeria, you can still treat your azaleas by pruning out the diseased branches. But to lessen the hassle of battling the disease yearly, you can remove the plant and replace it after mulching and caring for your soil quality. Also, make sure you remove all dropped plant material below the plants to prevent any reinfection from the fungal spores remaining on twigs, branches, and leaves.

Besides treating fungal diseases, you should also learn to resist disease and prevent it from happening in the first place. Do this by providing your azaleas and soil with proper drainage and partial shade. This is because diseases would enter your branches from pruning wounds or injuries from maintaining your landscape.

You may try using cultural practices on azalea stem diseases, but if this doesn’t work, fungicides can help. If your azaleas have Phomopsis dieback, mancozeb controls the growth.

Also, when using a lawnmower, make sure it is away from the plant to prevent it from getting injuries from flying debris, and to avoid damaging the plant when trimming it too close using string trimmers.

Would you like to learn more about fungus on Azalea branches? This informative video can help you out:

Wrapping It Up

While Azaleas are beautiful, hardy, and drought-resistant, making them popular for any gardener who would like to make their garden look beautiful. Since they have been bred to be disease-free, it can get quite frustrating when it suffers from fungal issues every once in a while. Don’t worry, as this is totally normal and there are remedies, depending on the type of issues your azalea branches may have.

Hopefully, all this information regarding fungus on Azalea branches helped you out. Check out the signs of fungal issues mentioned above and see if you can still remedy the fungal diseases your Azalea branches may have now.

1 thought on “Why is There Fungus on Azalea Branches and How to Solve It”

  1. Hi, thank You for this information ,but none of these descriptions matches the Fungus? on My Azalea which is 40/50 Years Old , the Branches are covered with a Green/Grey growth and are Dying back ,It has not Flowered as much as It usually does this Year ,I have to be careful about treating It with any Substance which could be poisonous to Birds or Animals ( Cats ) It used to close and shadowed by an Acer which has sadly now been cut down ,any further information about how to treat It would be welcomed ,thank You.Vivien


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