9 Reasons Your Maple Tree Leaves Are Turning Brown

You planted a maple tree in your landscape because of the shade it provides, and the beautiful fall colors. Possibly it was there when you bought the house, but now your maple’s leaves are turning brown. Assuming it’s not the autumn season, you want to know why the leaves have started turning that nasty shade of mud and what to do about it. 

When maple tree leaves turn brown, it could be because of scorch, too much watering, or not enough watering.

More specifically, there could be root damage, fungus, or problems with the soil that’s causing your maple tree’s leaves to turn brown. Assessing the issue and fixing it soon could save the tree before permanent damage occurs. 

There are several reasons your maple tree leaves could turn brown. A thorough inspection of the tree itself and the surrounding ground can help you understand what is causing the problem. If you can’t figure out what the problem is, you may need to consult with an arborist who can help save your trees. 

There are many varieties of maple trees found around the globe. Most of these varieties are hardy plants that rarely have problems with fungus or pests. When they get planted in non-native areas, though, the conditions can become difficult to deal with.

Most maple trees native to North America are cooler weather trees that don’t like too much heat. The red maple is one species that can handle harsher weather, and they are found as far south as Florida. 

No matter what kind of maple tree you have, when the leaves are turning brown before they should naturally, there’s a problem that needs to be addressed. These are the reasons your maple’s leaves are turning brown. 

1. The Leaves Are Scorched

While this can happen nearly any time during the growing season, it typically happens during the heat of summer. Scorch happens when the moisture in the leaves is removed faster than it can be replaced. 

Extreme heat can cause the leaves to dry out before the tree can pump more water into them, which will cause dried and brown outer edges, while the rest of the leaf turns yellow. As the problem continues to get worse, eventually the entire leaf can turn brown, and then it will fall off. 

High winds can cause the same damage, though it’s not typically as devastating as extreme heat combined with drought. Wind scorch happens when dry air hits the leaves with damaging gusts, causing the moisture in the leaves to evaporate out. 

Scorch can also happen if there is enough damage to tree roots or the tree trunk. When the tree cannot send water from the roots up to the leaves, the environment can dry out the leaves, leaving them susceptible to damage, which will cause them to turn brown. 

Once leaves have been damaged by scorch, they won’t repair themselves. Dried out, brown leaves will never turn green again, so don’t worry about making them look healthy again. 

What you can do is water your tree with a deep drenching. You want the water to penetrate up to two feet into the ground so the roots can get plenty of hydration. Be sure not to over-water the tree, because this can be as bad as the tree getting no water. 

Watering a tree about once a month to once every three weeks is sufficient during dry months as long as the water truly goes deep into the ground. Keep in mind tree roots surpass the canopy. Sometimes they grow several times as large as the top of the tree, so water these areas as well. 

2. Fungus Can Cause Brown Leaves

There are a few fungal infections that can cause a tree’s leaves to turn brown and unsightly. Some of these are not life-threatening to the tree and will clean up on their own, while others may need expert help. 

Anthracnose Fungus

Anthracnose is one fungus that causes maple tree leaves to brown prematurely. It can also make the leaves curl up, become distorted, have brown patches across the leaves, and make them drop early. 

This fungus typically shows itself in the lower and inner areas of the tree, but it can work its way farther into the higher branches. Wind or splashing water containing anthracnose spores can spread the fungus. 

If your maple tree is showing symptoms of this fungus, there’s not much you need to do unless it has infected your tree for a few years in a row, and shows significant leaf damage. When your tree has a prolonged experience with severe anthracnose and shows no signs of getting better, call a tree expert to treat it.

Follow these steps when treating this tree malady; water your trees sufficiently during the growing season, but keep water from splashing onto the leaves. Prune affected branches and leaves, and trim to allow more light to penetrate from the canopy. Then destroy any infected fallen leaves, as well as the trimmed leaves, to prevent the issue from reappearing.

Keep your tree as healthy as possible through this time and it should get better on its own. Just be sure to limit fertilization unless soil tests find the ground lacking in key minerals. 

Tar Spot

Tar spot is another fungus that can cause leaves to turn brown, in small circular spots, and then fall off early. This is another non-lethal leaf affliction, especially in larger, established trees. 

The spots may start about ⅛ of an inch in diameter, and look yellow or brown, but they can grow a little bitter as it spreads. Aside from giving the leaves an ugly appearance and causing them to fall early, this fungus doesn’t do lasting harm to the tree. 

To prevent the spread in the next growing season, rake the leaves up and dispose of them. They can be burned—assuming where you live allows for the burning of leaves—buried, or composted. The compost needs to be warm enough to eradicate the spores if you choose this method. 

Make sure your compost pile gets at least 140℉ and you turn the pile frequently to make sure all the leaves get “cooked.”

Fungicides don’t need to be used to treat most cases of tar spot. 

Verticillium Wilt

Verticillium wilt is something that can permanently damage a tree as there is very little that can be done about it. This is a soil fungus that enters through the tree’s roots, then prevents water and nutrients from flowing up through the tree to the leaves. 

Another problem with this affliction is that it can mimic other less destructive symptoms like scorch. Verticillium wilt can occur at any time during the growing season. It also can show up one year, then lay dormant the next year, but it won’t go away on its own.

Unfortunately, no current fungicides work against verticillium either.

Other symptoms of this fungus include loss of foliage on a single branch, which then stops living. It may infect a whole side of the tree. It can also cause stunted growth, and leaf wilting. 

Once it enters the plant, there is no real cure. If the tree is small and new, it is best to remove it and not plant anything in that area until the soil is treated. If the tree is sturdy and established, you can give the tree the best care you can to help it be able to fend the fungus off. 

Keep the tree watered well, but not over-watered, fertilize it with a high-phosphorus content fertilizer and remove any branches that are no longer showing signs of life. 

You may be able to treat the soil by a process that is called soil solarization. Soil solarization heats the soil using the sun’s heat to burn off bacteria, fungi, insects, nematodes, and other soil pests.

First, remove any grass or plants from the area. Then water the ground well. You want the water to create steam from the hot sun. The heat from the steam is what will rid the soil of the fungus.

Next, cover the area with a thick, preferably clear, plastic. Then bury the perimeter to keep it from blowing off and to keep the humidity and heat inside. Leave the plastic to “bake” for at least four weeks during the hottest days, then remove the plastic.

3. Drought Leads To Thirsty Leaves

Trees going through an extended drought can cause leaves to brown and eventually fall off. While trees are more tolerant than grasses and flowers, they can still succumb to the drying effects of a long dry summer. 

Usually, the leaves will wilt when water becomes scarce, followed by a yellowing. If the lack of water continues, then the leaves will brown and eventually fall off. 

Some species of maples are more tolerant of drought than others. The sugar maple is one tree that doesn’t do well in either dry or hot environments and will require more watering. 

If your area is experiencing less than normal rainfall and the soil is becoming hard and dry, you probably need to water your trees to keep them from dropping their leaves. Watering your trees when the leaves have started wilting can bring them back, but once they turn brown, the leaves won’t get green again. 

For more details on the subject, check out our article about why maple trees need so much water.

4. Too Much Water Can Cause Browning

Just as too little water can flip your green leaves to crusty brown, so can too much water. It can be difficult to overwater your trees, especially if you are watering your grass, but in times of extreme rains or floods, this can happen. 

If the environment is to blame for dumping too much water onto your trees, there’s not much you can do. You might be able to go out and implore the clouds to move on to other, drier areas, but I doubt they’ll listen. 

Too much water from rain most likely won’t permanently ruin your trees. Unless root rot sets in which a strong, established tree can usually overcome in the next season. All you can do is wait for the next growing season to see if the tree comes back or if it needs to be removed. 

5. Your Maple Tree Could Be Iron Deficient

Yes, iron is needed for healthy trees too. In fact, iron is an essential block in the formation of chlorophyll. Since chlorophyll gives plants their green color, when there is a distinct deficiency of iron, the leaves can become discolored. 

A mild lack of iron could cause the leaves to turn yellow or white, but if the nutrient is absent for an extended period, then the leaves will transition to bland brown. Since other issues can cause the leaves to change color, the only surefire way to tell if your soil is lacking iron is to do a soil test. 

To get extensive soil results such as pH levels, and several nutrients including iron, try out this MySoil – Soil Test Kit. 

A severe iron deficiency in your tree could become expensive to treat. If it’s caught in time, you can probably treat it with an iron supplement such as Southern Ag Chelated Liquid Iron. When a tree, especially a large tree, is severely lacking in iron, you may have to get a professional arborist out to treat it. 

They may do a deep iron soak by tapping into the soil about two feet and pumping in a liquid supplement, or they might add the mineral directly into the tree. After you rule out insects, water problems, leaf scorch, or fungus, then you might have to resort to iron supplements. 

If you’re looking for a maple tree fertilizer, take a look at our guide on when to fertilize your maple tree for some more helpful tips!

6. Overfeeding Can Lead To Brown Leaves

This happens to me at the dinner table and buffets, but you can also overfeed your trees, which can lead to several problems, including discolored and brown leaves. We want our trees to do well, that’s why we water them, prune branches, and add fertilizers. 

Adding too much fertilizer can stress the tree and cause more damage than good. In fact, most trees don’t need extra feeding because they get enough nutrients from their vast network of roots. Unless your soil is in terrible condition, tree fertilizers aren’t necessary. 

Mulching your grass and leaves into the ground and adding mulch to the base of your trees gives them plenty of nutrients to stay strong and healthy. Testing your soil will let you know if you truly need to add any extra nutrients to your yard.

If you need to add plant food for your trees, be sure to follow the recommended doses so you don’t accidentally feed it too much and cause problems like root rot, slowed growth, and brown leaves.

7. Root Damage Harms Maple Leaves

As well as the rest of the tree. When the roots get damaged, it prevents nutrients from reaching the leaves, which can cause brown leaves. 

Most trees, especially big, established specimens, can easily withstand a bit of root damage. When large sections get damaged either by digging, insects, or fungus, the tree can become stressed. If too much of the root system is torn up, then the entire tree might cease to live. 

While you will be able to tell while digging if you damaged the roots of a tree, insect damage might be harder to spot. Some insects can bore into a tree and down to its roots, causing damage. This can prevent nutrients and water from reaching the foliage. 

To spot insect damage, especially from boring pests, look for small round or D-shaped holes along the base of the tree or around the trunk. You might even see small piles of sawdust on the ground as well. 

Insects can damage smaller saplings much faster than mature trees, but a large enough infestation can create serious damage to the mightiest of trees. If you notice boring insects and they seem to cause a lot of harm to your tree, seek the advice of a professional tree service. 

You might be able to treat them yourself, but if you don’t get them all, another generation of insects could come back and infect the tree again.

If you do have root damage on your tree, then it may be a good reason to cut down your maple when you have the chance.

8. Girdling A Tree Is Bad Business

When a tree’s bark is removed all the way around, the tree is cut along the entire circumference, or something is wrapped around it and left there, that action is called girdling. This is bad for the tree and can cause fatal, irreversible damage. 

Sometimes this happens when using high-powered trimmers around trees, especially young trees. The strings can hit the tree with such force that it rips away the bark and growth areas of the tree, which prevents it from sending nutrients to the top. If this happens, most times it is fatal to the tree. 

Insects, beavers, deer, mice, or other animals can girdle a tree as they search for food. Alternately, if someone were to tie a tight rope or wire around a tree and leave it for several years, this could cause the same damage. The tree is strangled and starved of nutrition. 

There’s not much you can do to save a tree that has been girdled. Some trees, if the damage isn’t too extensive, might survive it, though most times you’ll have to replace them. 

For many damaged trees, there is still hope! Read our article on what to do to save a tree with stripped bark before you give up!

9. It Could Be Growing In A Non-Hardy Zone

Your maple tree might have been planted in a zone that isn’t conducive to hardy growth. Most maple trees like cooler climes. For instance, sugar maple trees love northern habitats and wouldn’t do well in Texas. 

When purchasing trees at local nurseries, they typically have plant varieties tolerant of local weather. However, with the ability to order nearly anything online, sometimes people get plants that aren’t made for their areas. 

While the trees might do alright during mild seasons, when the extremes hit, the trees will end up suffering. Unless the tree is potted and you’re able to move it inside when the weather outside is frightful, it might not survive more than a few seasons. 

When you are planting trees in your landscape, look for plants tolerant of your zone’s climate. Talk to the people working there as they will be able to tell you which plants and trees will work for your area. Doing so will cut down on the care you will have to provide these trees to keep them strong and healthy. 

When you’re ready to plant, check out our article on where to plant a maple tree to learn where and how to grow a healthy maple!

There You Have It!

When your maple trees start browning before fall, it could be several issues. Some are easy to fix, some need little to no attention, while other problems might require the help of professionals.

Your tree could simply need a good, occasional soaking, some soil supplements, or you might have to call a professional tree expert. Most times the problem can be fixed, and hopefully, by the next season at the latest, your maple trees will be full, lush, and gorgeous once again.

References:

Linzon, S. N., W. D. McIlveen, and R. G. Pearson. “Late-spring leaf scorch of maple and beech trees.” Plant Dis.;(United States) 56.6 (1972).  

Douglas, Sharon M. “Common diseases of maple.” The Connecticut Agricultural Experiment Station (2009).

Horsley, Stephen B., et al. “Factors associated with the decline disease of sugar maple on the Allegheny Plateau.” Canadian Journal of Forest Research 30.9 (2000): 1365-1378.

Lucena, Juan J. “Synthetic iron chelates to correct iron deficiency in plants.” Iron nutrition in plants and rhizospheric microorganisms (2006): 103-128.