9 Reasons Your Magnolia Tree is Turning Brown and Dying

Is your magnolia turning brown or dying? There are a number of different reasons this can happen, and there are usually some common ways to treat each issue. In this article, gardening expert Melissa Strauss looks at potential problems that could be impacting your magnolia.

Dying magnolia tree with brown flowers and leaves

Contents

You may have heard that magnolia trees are beautiful trees that are low-maintenance and hardy in a wide range of climates. All of those things are absolutely true of magnolias. They are known for being resistant to many types of damage, both from diseases and from environmental factors. They stand up to heat and cold and drought with exceptional resilience.

Like all plants, though, magnolias are not indestructible. Keen observation and good planting and care practices are the best defense against most of these issues. If you know what to look for, and make a habit of checking on your plants, you will catch those issues early on and be able to mitigate damage.

The best way to help your magnolia bounce back from any damage that is causing parts of the tree to become unhealthy, is to identify the cause of the issue, so that it can be treated accordingly.

While many issues that cause foliage to die are environmental and climate related, and less serious, there are a few issues that can cause problems throughout your garden, so it’s helpful to be able to identify the difference between these issues. Listed here are some of the more common causes of brown leaves and dying tissue in magnolia trees, as well as ways to protect, prevent, and treat the damage.

Phyllosticta Leaf Spot

Tree with leaves that have leaf spot disease infecting them. The leaves are covered in brown spots and are all over the leaves, while some are still green and remain uninfected.
Leaf spot is generally fairly easy to diagnose.

Phyllosticta magnoliae fungus affects the foliage of a magnolia tree by causing small purple or black spots on the leaves. As the disease progresses, the spots my enlarge and develop a white center and a pale halo. The disease is typically not fatal to mature trees, but it can be to young trees that are not yet established.

If you notice leaves dying, examine leaves that are adjacent, but still green. If you can identify these black/purple spots or the canker-like appearance of the progressed spots, you know you have this fungal infection.

The Fix

Removal of affected foliage is helpful. A copper-based fungicide will also help to control the spread but must be used early on as it won’t kill the fungus, but rather will control it’s spread.

Using these two methods in conjunction with one another should do the trick. If the tree is young and the fungal infection is very advanced, it may not be possible to rescue it.

Leaf Blight

Tree leaf with blight infected showing with black spots.
Leaf blight shows up in the form of small black spots on the infected plant.

Blight is caused by the bacterium Pseudomonas syringae and affects several different types of trees. Magnolias happen to be in this group. Blight mainly affects trees that are under stress, so in times of drought or in the absence of proper nutrients blight can step in and wreak havoc.

The bacteria are waterborne, so it usually comes from water splashing from an infected plant onto another. Diagnosis is performed visually. Symptoms include brown or black spots on the leaves. Their flowers can also be affected and will sometimes have dark spots as well. Another symptom of blight is tip dieback.

The Fix

Copper sulfate and hydroxide sprays are typical control methods, but the most effective way to prevent whole plant death is by removing affected foliage.

Once blight moves to the trunk it is fatal. If your magnolia has come to a place where it is untreatable, removing it to keep the infection from spreading is the best course of action.

Leaf Scorch

Leaf scorched tree leaf in garden with black edging around the leaf. The plant is in the garden surrounded by other plants with green foliage.
This particular issue is easy to identify, with brown, scorched leaves being the primary symptom.

Leaf Scorch is the result of excessive evaporation and too little moisture to replenish the water lost. It happens primarily in times of high temperature and low rainfall.

If a magnolia is not getting enough water, the first sign will be the ends of the leaves.  If the tips of the leaves are turning brown and looking dry, the issue is probably leaf scorch. Think of this as a sunburn of the leaves.

The Fix

This one is pretty simple. Your magnolia just needs extra water. Give it a good soak every few days until the rain picks up or the temperature goes down. The damaged leaves will not be salvageable. Pruning off any dead foliage will help the tree focus its resources on healthy growth.

Verticillium Wilt

Verticillium Wilt leaves sitting on grass. There are nine leaves sitting on grass in a circle, all in various states of discoloration.
This fungal disease is often spotted early by leaf discoloration.

This is one of the more serious issues that can affect a magnolia tree. Verticillium wilt is a fungal disease that affects the water conducting tissues of the tree. Symptoms include wilting of foliage, yellow and browning of the leaves and stunted or discolored growth. A soil test can accurately diagnose this issue.

The Fix

There is no cure for this fungal disease. It is typically fatal to smaller, younger trees. A larger more established tree can live with it for several years, or even outgrow the disease, but it will permanently stunt the growth of the tree.

You can manage the disease in larger trees with proper pruning of diseased tissue, watering, and fertilizing. Proper tool sterilization is very important to prevent spread.

The fungus lives in the soil and getting rid of it is time consuming. A plant that has died of this fungal infection should be disposed of properly, away from other plants.

Clearing the land affected for 5 years will starve the fungus. You can also treat it by steaming. Wet and cover the soil with a black plastic tarp and allow the sun to heat and steam the affected area. Only plant resistant varieties of plants in this space in the future.

Wood Decay

Wood decay and mushrooms at base of tree growing in garden. There are three mushrooms growing at the base of the tree.
When wood decay sets in, you are likely to notice mushrooms growing at the base of the tree from excess moisture.

Wood rot is caused by the introduction of fungus into the trunk of the tree. This is common in times of excessive rain and humidity. If wood begins to decay from being waterlogged, it makes room for fungus to move in and cause further damage.

Sometimes decay is detectable by the formation of mushrooms around the base of the tree, but often the tree will appear healthy for quite some time if the decay begins in the trunk. Eventually, the limbs and foliage will begin to die off.

The Fix

As with most bacterial and fungal diseases, the best treatment is prevention. I can’t stress enough the importance of using clean, sharp tools when pruning a tree, as these diseases spread by using infected tools without cleaning in between. Removing diseased or dead limbs can mitigate the damage caused by fungus.

Drought Stress

Magnolia flower on tree dying due to drought. The plant is dry, and needs moisture to recover.
Drought stress can cause damage to an entire tree.

Magnolias don’t like to be waterlogged, but they do like their soil to be kept moist. Drought stress can show up in the form of leaf scorch, or as damage to the entire tree. Excessive dryness can cause branches to become brittle and snap more easily, in addition to causing other tissue to dry out and turn brown.

The Fix

While magnolias are relatively drought tolerant when they are mature, they may still need to be watered in times of extreme drought. If you’ve gone more than 2 weeks with no rain, it’s a good idea to give your magnolia some water.

Once per week, a good soaking around the roots should carry your tree through a drought. If you notice signs of wilting leaves or leaf scorch, adjust your watering schedule until the tree appears to be bouncing back.

Harsh Winds

Tree damaged from harsh winds in the garden. The blossoms are crisp at the edge, and the plant appears to be dry. The leaves are also a small bit damaged, with browning on the edges.
Harsh winds in colder climates can cause problems for Magnolias.

Freezing winds can be another issue for magnolias in colder climates. First, harsh, cold winds can batter blooms. In addition, when there is little water to be had, as is common in colder weather, the leaves can become wind burned as they are unable to bring up enough water fast enough to replenish what they transpire.

 If you’ve had a freeze while there are leaves on a deciduous magnolia, or at any time with an evergreen, you may notice that some of the outermost leaves turn brown and begin to fall. The tree should survive this just fine, as magnolias can tolerate a hard freeze, but those leaves will be lost.

The Fix

Planting your magnolia in a spot that has some shelter from winds, such as near a house or other structure, will help protect the tree from harsh winds. Larger, surrounding trees can also act as a windscreen in harsh weather.

If you’re expecting a freeze late in the season, it’s a good idea to cover your magnolia with a sheet if it is size effective. This will protect buds and foliage from being wind and cold burned.

Dieback

Cold damage due to tree having been exposed to poor weather. The blossoms are burned, and the leaves are brown. The branches are also brown and damaged.
This problem is somewhat common in colder climates. Luckily, it is usually reversible.

Dieback is another product of cold damage to a tree, and is more severe than wind burn.  If you’ve recently had a freeze and notice that a particular limb, or the ends of several limbs are turning brown and dying, you could be dealing with cold damage.

The good news is that it is very rare for an entire, mature magnolia to die from cold damage. The tree as a whole should recover from this.

The Fix

If you live in a colder climate, think about giving your magnolia some shelter from harsh winds when you plant it. If it’s not possible to do this, or if that damage has already been done, it’s always a good practice to remove damaged foliage. This gives the tree more energy to apply to new growth and existing, healthy foliage.

Root Rot

Yellow leaves from plant due to root rot. The image is a close up of many leaves, most of which are damaged from root rot to the plant.
Yellowing leaves are usually the first sign of root rot, which can be difficult to treat.

Magnolias like most soil, but they don’t do well in swampy soil, with a very few exceptions. Soil that stays wet all the time will weaken the rather shallow root system of a magnolia and open it up to fungal and bacterial infections. Overwatering can also lead to root rot.

The first sign will generally be leaves turning yellow. The nutrients will be diluted, and therefore, harder for the plant to absorb sufficient amounts of. In progressed cases, entire limbs may be affected by the lack of nutrients, or other infections let in by vulnerable roots, that cause damage to the tree.

The Fix

Be sure to plant your magnolia in a spot that has good drainage. If you are regularly irrigating, you may need to take a break from watering, particularly around that tree.

If the tree is established and moving it to a spot with proper drainage is not possible, mixing in some sand with the soil around the tree will help with your drainage issue, but in the long term, moving the tree to a better spot is the best option.

Final Thoughts

Sometimes high maintenance in the present leads to low maintenance in the long term. The most important keys in maintaining the health of your magnolia are prevention and observation. Learn how and where your magnolia will perform at its peak. Give your trees a look over from time to time, so that you will notice quickly when something is amiss.

If your tree has dead and damaged foliage, it is always bet to remove the damaged parts, making sure to use clean, sterilized tools. Clean cuts heal fastest, and this prevents future infections from infiltrating a vulnerable tree. Pruning away damaged growth will help your tree to redirect energy and nutrients toward new healthy growth, and recovery.

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