Magnolias have remained desirable trees in many gardens over the years. This article will answer the most common questions related to the problems of growing this tree.
QUICK ANSWER: Drought stress is one of the leading causes of magnolia leaves turning brown. Root rot, pests, mineral deficiency, and scorching sun can cause magnolia leaves to turn brown.
Drought stress
Potted and newly planted magnolias are most prone to drought stress. This usually happens during the hot summer months.
Symptoms include browning of the leaves. This can start from either the edge or the middle of the leaf. Magnolias with soft leaves may droop during drought stress.
How to fix
During the hot summer, check the soil around the magnolia roots several times a week. If it is more than 2 inches dry, water with at least 1 gallon.
This is especially true for potted magnolias and magnolias that were planted less than a year ago. You can stop watering once the magnolia is established (2-3 years old). As for potted magnolias, you should not keep them in a container for many years.
Be sure to mulch the root zone. Use only organic materials such as pine bark or compost.
Read more: Planting And Caring For Magnolia
Black Twig Borer
Black Twig Borer is an insect that lays eggs inside branches. When the larvae hatch, they begin to eat the branch from the inside.
The symptoms of this pest are the browning of leaves on just one branch. If only one cluster of leaves is brown and the rest are green, it may be a Black Twig Borer infestation.
Also, many different sucking insects can cause a change in the color of magnolia leaves. Usually, the leaves will slowly become pale and discolored. After a while, they turn brown.
How to fix
If you see symptoms of Black Twig Borer, cut off the branch with the brown leaves where they attach to a healthy branch or to the trunk. Throw the damaged branch as far away from your yard as possible.
If you see an insect colony on the leaves, spray them with horticultural oil. If the insects are still active after a week, spray the magnolia tree with a systemic insecticide.
Read also: How do I keep bugs from eating my magnolia leaves?
Lack of nutrients
Nutrient deficiencies usually occur in very poor soils. It can also happen if the pH of the soil is too high because the roots are then unable to absorb minerals.
Depending on the weather, this can cause the leaves to discolor first and then turn yellow or brown. If the weather is hot and dry, the yellowing of the leaves will soon turn brown.
How to fix
The first thing to do is to check the pH. To do this, buy a kit designed to measure this parameter. You can easily find these kits at your local home improvement center.
If the soil around the magnolia tree has a pH much higher than 7.0, you need to lower it. Use soil acidifiers to do this.
Next, apply a slow-release fertilizer. Make sure the nitrogen number is no more than 15. Phosphorus and potassium should be less than nitrogen. The product must have magnesium and iron.
Fertilize once a year in early spring. Avoid fertilizing in late summer or fall.
Leaf Scorch
During periods of extreme heat, hosta leaves can get scorched. This usually happens during the summer months in the southern part of the country.
This happens because the sun is too intense on the leaves, and they evaporate moisture very quickly. The tree does not have time to deliver water to the leaves, and they turn brown around the edge.
How to fix
Water the magnolia once with 1-2 gallons of water.
If the tree is up to 7 feet tall, try to shade it. Use a garden umbrella or something similar for this purpose.
Mulch the root zone with organic material to prevent the soil from drying quickly and overheating.
Natural aging
Natural aging is one possible cause of leaf discoloration. It happens to both evergreens and deciduous magnolias.
The leaves of deciduous magnolias change color in the fall. The leaves stay on the tree for a while but eventually fall off.
With evergreen magnolias, it’s a little different. Not all of their leaves age simultaneously, but only some do. This happens mainly in the spring.
How to fix
You don’t need to do anything to the old leaves. It’s all a natural process that repeats every year.
Root rot
Root rot is a severe disease in which the roots lose their ability to absorb water. The supply of water to the leaves stops, and they turn brown.
This is similar to drought stress because the leaves start to dry in both cases. Usually, the edge and then the whole leaf blade turn brown first.
How to fix
Only water the magnolia when the soil is 2 inches dry. Do this in the first 1-2 years after planting.
If your magnolia is growing too close to where water collects or flows, try to divert the water to the side. Next spring, transplant the magnolia to a less wet location with well-drained soil.
Frost damage
Frost can turn magnolia leaves brown in two cases. The first is when late spring frosts damage young leaves.
In this case, the leaves become watery and turn brown if the weather is sunny. This can happen to both evergreens and deciduous magnolias throughout the spring.
Frosty draughts damage the second case during the winter. This only applies to evergreen magnolias.
How to fix
If possible, cover the magnolia with protective material for the duration of the frost. The magnolia usually recovers quickly after such damage.
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