Every gardener knows that healthy azalea leaves are supposed to be green – but what if they turn some unsightly color instead?
Azalea leaves turning brown can indicate a serious issue. This guide will detail the most common problems associated with browning and dying azalea leaves, as well as what you can do to save your plant.
Why does my azalea look burnt?
Azalea leaves can turn brown for numerous reasons. Overwatering is the leading cause of a browning or dying azalea, but other factors like pest infestation, drought stress, fertilizer burn, and plant diseases may also play a role.
In most cases, azaleas can bounce back to health if the underlying problem is diagnosed and treated at an early stage. However, it might be too late to save your plant if the damage has become extensive.
Azalea leaves turning brown – common reasons
1. Overwatered azalea
Azaleas can die from overwatering. As any grower can attest, houseplants like azaleas do not need constant watering to thrive. In fact, most plants prefer to be left until the soil becomes dry before they are watered again.
Although plant roots are buried deep in the soil, they also need oxygen to survive. Plants breathe the air held in tiny pockets in the soil, known as soil pores. Compacted or waterlogged soil will thus limit the amount of oxygen available for the roots.
Additionally, too much water in the soil can attract fungal pathogens and cause root rot. Instead of having firm white roots, the affected azalea will start to develop brown and mushy roots that emit a strong, unpleasant odor. With compromised roots, the plant will start to struggle with nutrient-uptake issues.
If your azalea’s leaves turn brown and appear droopy, it might be worth investigating the roots for a more accurate diagnosis.
What to do if your azalea is overwatered:
- Check whether the plant still has some healthy, white roots. If so, you can revive your azalea by repotting it in fresh, healthy soil. However, if the entire root system is damaged, there is nothing you can do to save it. It is best to discard both the affected azalea and its potting soil and start over with a new plant.
- Do not water your plant until the top layer of soil becomes dry. Always stay up to date on the weather conditions, too, since your plant’s watering needs will vary according to the climate and the season.
- Use a well-draining pot and soil. Avoid using compacted or dense soil, as this can retain too much moisture for longer periods.
2. Underwatered azalea
Similar to overwatering, an underwatered azalea will also display brown leaves.
Water is an essential requirement for all plants to grow. They need water to carry out important metabolic processes like photosynthesis, and to transport nutrients from the soil into the stems and leaves.
If your azalea has been neglected for several consecutive days, it will start to struggle with dehydration and nutrient absorption. The result is a sad-looking plant with dry and brittle leaves. You might also notice the leaves dropping, wilting, and curling due to the lack of water.
If you suspect your azalea is underwatered, here is what you can do to revive it:
- Soak the plant in a sink or tub filled with water for 30 minutes. Then take the pot from the tub and let it sit for a couple of minutes until all of the excess water has drained.
- Trim any brown or dead leaves you see. Once your plant has recovered, it should start growing fresh green leaves again.
- You might need to increase your watering frequency if the weather is very hot. The summer season tends to dry the soil easily, so make sure to check your plants regularly at this time of year. Remember that you cannot water your azalea according to a fixed schedule – its watering needs will vary depending on the weather conditions.
- Always make it a habit to check the soil so that you can give your plant the right amount of water at the right time. Most growers recommend using the finger test. To do this, you just need to poke the topsoil with your finger to assess whether it is dry to the touch. A quick glance at the soil should also help you tell whether it is moist or dry. Remember that moist soil tends to be a darker color than bone-dry soil.
- Add mulch to the soil to prevent it from drying too quickly, especially during the hotter seasons.
3. Leaf spot disease
Leaf spots on azalea leaves can appear as reddish-brown lesions with a necrotic center. Over time, these irregularly-shaped spots will merge together into larger spots, or blotches. Although fungal spores are often the culprit, leaf spots can also be due to injuries caused by insects, herbicide application, and environmental toxicity.
In general, leaf spot diseases are unlikely to be life-threatening to your azaleas. However, long-term neglect can be detrimental to their health, leading to an untimely demise.
To revive your plant, follow the tips below:
- Isolate the infected plant to prevent the disease from spreading throughout your garden.
- Using a clean pair of pruning shears, cut off the affected leaves and discard them right away. Do not use the leaves as compost for your garden.
- To keep your azaleas’ leaves dry, do not water the plants from above. And, most importantly, avoid misting the leaves. Some gardeners might swear by the benefits of misting, but this can actually encourage the growth of fungal spores. If you need to improve the humidity level indoors, use a humidifier instead.
- For fungal leaf spot, we highly recommend fungicides like Patch Pro for early-stage control of the disease. However, for severe cases, it might be best to discard the sick plant to prevent infecting your other plants.
4. Lace bug infestation
Lace bugs are one of the many types of pest that can damage the leaves of your azaleas. They usually appear as white, silvery, or yellow spots on the surface of the leaves. These tiny pests can also be found hiding on the underside of the leaves. If you notice a black, sticky substance on the foliage, it is likely that these unwanted guests are helping themselves to the juices of your plants’ tissues.
As with any pest infestation, lace bugs compete for the plant’s nutrients by sucking the leaf juices, or sap. Eventually, their feeding activity will reduce your plant’s vigor and cause severe damage to the foliage. This is why you will notice browning lesions on certain sections of the leaves.
Thankfully, there are simple and effective ways to get rid of these nuisances and return your azalea to full health. These include the following:
- Using insecticidal soaps – preferably organic – to kill the bugs and their eggs.
- Applying neem oil or horticultural oil on the leaves to get rid of lace bugs and prevent them from coming back.
- Spraying the affected plant with acephate to manage the lace bug population, especially if the infestation is severe.
5. Fertilizer burn
Fertilizer is one of the essential plant care requirements for growing azaleas, especially those that are grown in containers. Not only does it boost your plants’ growth, but also ensures that there is a constant stream of nutrients in the soil to keep your azaleas looking happy.
Sometimes, however, you may accidentally pamper your plants too much by applying an excessive amount of fertilizer. If you have done this at some point, you are not alone – novice gardeners can easily overestimate the nutritional needs of their plants, leading to over-fertilization. And no – adding too much fertilizer will not make your plants grow bigger or healthier! Instead, the excess will accumulate as salts in the soil and cause root burn.
Once the roots are damaged, we all probably have an idea of what happens next – root burn inhibits the roots from absorbing water from the soil. This is why the symptoms of over-fertilizing can be similar to those of underwatering, such as wilting and browning of the leaves, particularly on the tips and along the leaf margins. Another tell-tale sign of an over-fertilized azalea plant is the appearance of white crusts on the surface of the soil.
6. Azalea dieback
Dieback is a disease common in azaleas, characterized by dying branches. Typically, the disease affects single or multiple stems of an otherwise-healthy azalea plant. The leaves also begin to die and turn brown while still attached to the stems or branches of the plant.
Branch dieback in azaleas is commonly caused by Phytophthora and Botryosphaeria. Unfortunately, there are no fungicides available to treat these diseases, but you can still use chemical treatments to prevent them from spreading to other plants.
Rhododendron borer is a plant pest that can also cause branch dieback in azaleas. This tiny insect is a type of clearwing moth, although it looks more similar to a wasp. It is about half an inch long, with a dark head and a pale yellow body. Although it primarily attacks rhododendrons, it can also cause severe damage to azaleas by chewing on the inner bark tunneling into the branches.
Unfortunately, chemical sprays might not be very effective in eradicating these pests, since they hide inside the stems. You will need to prune and destroy the wilted branches. It is also recommended to apply permethrin to protect the trunks from the borer larvae. Thoroughly spray the stems three times at 10-to-14 days intervals. If you notice any borers coming out onto the leaves, you can also use horticultural oil or insecticidal soap to kill them.
7. Leaf scorch
Similar to drought stress, leaf scorch can also cause your azaleas to turn brown due to various unfavorable conditions. For example, if the plant is exposed to too much sunlight, the leaf tissue will begin to develop brown lesions. In this case, you only need to move your plant to a shady area to avoid the damaging rays of the sun.
You will also notice brown discoloration on the tips and margins of the leaves if your plants are exposed to freezing temperatures. Although curled-up leaves will likely bounce back once the spring season arrives, any damaged or browned stems and leaves may never recover. You should cut off these damaged parts so that the plant can focus its resources on new growth.
Azalea leaves that have turned brown are generally a sign that something is not right! You need to figure out the underlying issue as quickly as possible if you want to save your plant. In this guide, we have broken down each possible cause, as well as the appropriate solution. Once you have cleared up the issue, remember to establish preventative measures and proper care routines to keep your azaleas green and healthy!
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