Azalea leaves turn brown typically due to overwatering. Azalea leaves also turn brown when the plant is infested by Lacebugs. Brown leaves are seen on Azaleas due to Fungal leaf spot disease and cold wind damage.
Azalea plants belong to the colorful genus Rhododendron. Azaleas are grown for their beautiful blossoms.
There are a variety of Azaleas known to man. Some can be grown as ground covers, while some can even be grown indoors.
It is not that hard to grow Azaleas. Many people, however, complain to me of the browning foliage. Let’s see why the leaves turn brown and how to fix it.
Azalea leaves turning reddish-brown?
Azalea leaves turn reddish-brown/brown if the plant has been sitting in soggy soil for too long. Waterlogged conditions suffocate Azalea roots.
Either overwatering or poorly draining soil can cause waterlogged conditions around your Azaleas. Soggy soils rot the roots.
Phytophthora thrives in waterlogged conditions. Phytophthora fungi cause both crown rot and root rot in Azaleas.
Check the soil with bare fingers. Dig 4-6 inches beside the roots and check the soil for moisture(with a moisture meter, if you have one).
If the soil is too wet and the leaves are wilting, then your Azaleas have been overwatered.
What does an Overwatered Azalea look like?
The leaf tips/leaves of Azaleas turn brown in the case of root rot/crown rot. Leaves of the affected Azalea wilt and become droopy.
The roots become brown and mushy if your Azalea is infected by Phytophthora. Healthy roots are white in color.
In case of crown rot, the part of the stem that touches the ground turns brown.
What happens if Azaleas get too much water?
Azaleas are attacked by Phytophthora root rot if they get too much water. Crown rot is also seen in later stages.
Leaf browning is the primary sign of overwatered Azaleas. If you don’t respond quickly, root rot kicks in.
How to deal with root rot in Azaleas?
- Even in the warmer seasons, Azaleas can thrive on just 3/4th-1 inch of water fortnightly. So, water consciously.
- Improve the soil drainage by adding Perlite or sand.
- Stop watering immediately if you diagnose root rot/overwatering.
- Uproot your Azalea and check the roots closely. Are the roots brown and mushy? Are they white and healthy?
- Even if some of the roots are brown and mushy, there’s still a chance. Wash the infected roots under running water and replant your Azalea in fresh soil.
- You are better off using drip irrigation to prevent such situations.
Lacebugs on Azalea
Severe lace bug infestation causes foliage browning in Azaleas. Lace bugs feed on the undersides of the foliage.
Such feeding habit of the lace bugs is the reason for the mottled appearance of the leaves.
White/Yellow stippling is seen on the leaves. As lace bugs feed on Azalea, your plant’s growth gets stunted.
Plant vigor is reduced and the appearance of the plant is affected. Eventually, you’ll see brown spots on the affected plant’s leaves.
Will Lace Bugs kill my Azaleas?
No, Lace bug infestation doesn’t kill Azaleas. Lace bug infestations damage the appearance of your Azaleas.
Even in the case of severe infestations, defoliation occurs.
How do you get rid of Lace Bugs on Azaleas?
- Don’t use broad-spectrum insecticides that kill natural predators. Use specific insecticides.
- Neem oil, Insecticidal soap, and Horticulture oil are great alternatives to chemical insecticides. You won’t be harming the beneficial insects either.
- Spray Acephate on the affected Azalea to control lace bug populations. It’s a foliar spray that is quite efficient in controlling Lace bugs. Do this only if the infestation is severe.
When Should I Spray My Azalea Lace Bug?
Apply organic insecticides on your Azalea as soon as you see lace bugs on it. Apply again in a week or 10 days.
Control the population properly in March-May to prevent future infestations.
Azalea lace bug Neem oil
Yes, you can eliminate Lace bugs on your Azaleas by spraying Neem oil on the undersides of the leaves.
You will eliminate those bugs that are present on the plant at the time of spraying. Dilute the Neem oil in water and fill it in a spray can.
Azalea leaves turning brown in winter
Azalea leaves turn brown in the winter, thanks to the cold winds. Cold winds damage the edges of the Azalea foliage.
This is often called ‘windburn’. Winter temperatures damage the foliar tissues of Azalea, turning the leaves brown.
Azaleas are called evergreen, but that doesn’t mean they won’t turn brown in the winter.
The affected Azaleas usually recover in the warmer months. Just give the plant some time and proper care, it should revive itself.
Fertilizer burn Azaleas
When you feed your Azaleas more than they need, fertilizer burn is seen. The foliage turns brown on the affected Azaleas.
The leaves look scorched when the plant is overfertilized. The salts from the fertilizer clog up the soil and deter the roots from absorbing adequate water.
This also happens when the fertilizer is applied to wet foliage. The affected foliage not only turns brown but withers.
Tips to prevent fertilizer burn in Azaleas
- Fertilizing according to the instructions. When it comes to fertilizing your plants, less is better almost always.
- Don’t apply fertilizer to the wet foliage of Azaleas.
- I prefer slow-release fertilizers as they eliminate the chance of fertilizer burn. Adding compost is also a great way to feed your hungry plants.
- Water thoroughly after adding fertilizer to the soil.
Note: Get the soil tested to confirm fertilizer burn.
Dieback Azalea
Dieback in Azalea can be caused by two fungal pathogens, viz., Phytophthora and Botryosphaeria. Entire branches die back because of this disease. Leafborers also can cause dieback in Azalea.
Azalea Fungal dieback
Fungal infections can’t be treated. You can, however, prevent infections in the other plants by treating them with fungicides.
Leaves initially discolor and turn yellow. Such leaves eventually turn brown. This is followed by the dieback of the entire branches.
Prune off the infected branches as soon as you see them. Apply some fungicide on the plant and prevent the infection from spreading.
Pests that cause dieback in Azalea
Rhododendron stem borer and Rhododendron borer are the two insects that cause dieback in Azalea plants.
These borers can attack any cultivar of Azalea. The adult lays its eggs in the stem of the Azalea tree.
Cut off the bark of the affected part of Azalea. Split the bark into two pieces, lengthwise. Check the bark for borer larvae.
Chemical treatment is not suitable for these borers as they hide perfectly under the bark. You need to cut off the affected branches as soon as you notice them.
If you can see adult insects feeding on the foliage, spray some Insecticidal soap or Horticulture oil on the leaves.
Underwatered Azaleas
Azalea foliage also turns brown when the plant is given less water than it needs. This usually happens in the warmer months.
Underwatered Azalea’s foliage wilts, curls, and turns brown. The leaves become dry and brittle.
If you think the plant is underwatered, check the soil with bare fingers immediately. Is the soil completely dry or is it somewhat moist?
If it is dry and has been dry for a couple of days in a row, it is probably underwatered. Do this to ensure the plant is underwatered, not overwatered.
Overwatered and underwatered plants show almost the same symptoms. Check the roots closely if needed, for better diagnosis.
Water more frequently if the plant’s been underwatered. Add mulch around your Azalea to lock the moisture in.
Leaf scorch in Azalea
Too much sunlight can scorch the leaves of Azalea. It never happened with my Azaleas but this can happen with these plants.
Leaf scorch is usually seen in the summer months.
Too much sunlight scorches the tissue of the leaves. It leaves yellow/brown-colored lesions on the surface of the leaves.
Observe for a few days, what kind of light your Azalea gets. Is it bright, direct sunlight? Do you think it’s too much for the plant?
If yes, move the plant to a different place where it gets at least some shade for a part of the day.
What are the black spots on Azalea leaves?
The black spots on Azalea leaves could be due to fungal leaf spot disease. Fungal leaf spots are reddish-brown/brown with black centers.
These spots are irregular and often merge together to form blotches. These black spots are the fruiting bodies of the fungal pathogen.
This disease could even kill your Azaleas. Healthy Azaleas can survive this disease after a while.
Prune off the infected leaves using a pair of pruning shears. Disinfect the pruning shears after working on an infected plant.
Dispose of the leaves away from your garden. Water carefully and don’t water your Azaleas overhead.
Apply suitable fungicides after the blooming period. Two or three applications would be adequate to control the disease.
Happy Growing 🙂