8 Reasons Avocado Leaves Turn Brown and How to Fix it

If you notice a few leaves on your avocado tree turning brown and falling off, it’s not unusual. A regular part of a healthy tree’s life cycle involves shedding some leaves. But, when it’s more than just a few, then there could be a problem, especially if that’s the case for your avocado tree.

Causes And Treatment Of Avocado Leaves Turning Brown

Avocado Leaves

Here are various causes and treatments for avocado leaves turning brown:

1. Inadequate Water

Avocado trees need more water to survive as water helps in the supply of its nutrient. If your avocado tree leaves are turning brown, it could be because there is little or no water.

This likely happens in hot or humid weather. Trees release water to cool off as they go through transpiration. When there is inadequate water, the avocado tree won’t be able to cool itself, and this can cause your avocado tree leaves to turn brown.

Not only will the avocado tree leaves turn brown, but the leaves will also appear and feel very dry, curling around the edges and even falling off.

How to Treat It:

Check the water in the soil around your avocado tree by dipping your finger into it. When the top layer of 2-4 inches is dry, you should only water it. If you overwater, it can also cause problems, so you want to avoid creating a new problem while trying to solve one.

Use a deep watering method so the water can sink to at least 2 feet below the soil surface. Always check on the tree during hot weather; do this more often to ensure it stays dry. Soil should be so well saturated that it holds together like a wet sponge when you squeeze it.

Add a layer of compost or mulch on top of the wetted area. It helps secure water. With a 2-4 inch layer of mulch or compost, the soil around your tree stays moist for longer, and you won’t need to water it often. Compost and mulch add nutrients to the soil, nourishing your avocado tree.

2. Chloride Salt Build Up in The Soil

Sodium chloride is a naturally present salt in water (freshwater or purified water). After the dissolution of water, chloride salt is left behind in the soil.

With much shallow watering rather than deep watering of the avocado tree, sodium chloride can build up in the soil. In very hot conditions, water dissolves faster, which can also cause more chloride buildup.

Avocado trees are highly sensitive to chloride compared to several other plants. The roots take in chloride, gathering within the tree. When the chloride level gets too high, it makes the leaves of your avocado tree turn brown and eventually die.

Avocado tree leaves turn brown because chloride buildup begins with the tips of the leaves turning brown. If not properly examined, the brown will continue to spread over the rest of the leaves, killing the leaves totally so that they fall off the tree.

You can get a soil salinity test from your local extension office if you need help with what to do and have a chloride buildup problem.

How to Treat It

Ensure your avocado tree has good drainage. With that, you can use extra water to wash away excess salt from the soil. Deep water the avocado tree at least twice weekly for several weeks. This is to help the chloride buildup go out of the soil. Once chloride buildup has occurred, this is the only way to remove it.

If your avocado tree needs better drainage, you’ll need to fix that problem first because frequent deep watering can trigger root rot if the water can’t drain properly.

Water your avocado tree always and deeply, which helps flush excess salt frequently to keep chloride from gathering up in the soil.

3. Sun Scorch

Avocado tree leaves rarely have issues with sunshine on the leaves, but there are some occasions where it can happen.

If you’ve planted a young avocado tree and you observe the leaves turning brown, it could be sun-scorched. A young tree in a shady nursery might react differently when planted in a sunny location, especially during summer. After some time, the tree will adapt to being in full sun.

How to Treat It:

For a young tree, provide a bit of shade until the tree gets established. Excessive heat can also cause sun scorch, especially if there are multiple days of excessive in a row. Keeping your tree properly watered helps prevent issues with sun scorch.

4. Very Low Temperatures or Frost

Your avocado tree leaves may turn brown after a frost or string of very low temperatures; it could be a reaction to the cold. If this is the case, the tree will recover when temperatures rise or return to normal.

5. Fungal Disease

If your avocado leaves have brown spots instead of the whole leaves or leaf tips turning brown, it could be a fungal disease such as scab, verticillium wilt, or Alternaria.

Dealing with the disease depends on which disease has infected your tree.

6. Nutrient Deficiency

Avocado trees are commonly in need of zinc, nitrogen, or iron. Deficiency in these nutrients is another potential cause for avocado tree leaves turning brown.

To diagnose a nutrient deficiency, get a soil test, and your local extension office can do it for you. Alternatively, you can get an at-home test from Amazon or Home Depot.

How to Treat It

If your tree has a nutrient deficiency, the best step is to add fertilizer (there are many options, including natural and organic) or organic matter like compost. You’ll know the fertilizer needed after getting the soil test results.

7. Pests

Pests can also be an issue, with avocado tree leaves turning brown. Pests like lace bugs and grasshoppers feed on the leaves of avocado trees, causing them to turn brown or have other issues. If there are holes besides brown on your avocado tree leaves, pests could be behind them.

How to Treat It

Get plant-friendly pesticides to deal with the problem. You can also go to the expert to advise you on the best option to deal with the pest bugging your avocado tree leaves.

8. Humidity Issues

If the air is humid, your avocado tree may take in water faster than it can release through transpiration. This leads to edema, a buildup of water that destroys the plant’s cells.

Signs of edema are brown spots, a crumbly texture, or swollen veins on your avocado tree leaves.

How to Treat It

Allow the soil to dry up before watering it again, after which you can regulate your watering method.

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