I’m considering adding apple trees to my orchard, but I heard they can often get leaf curl. Before buying a pair of them, I wanted to know more about curling leaves on apple trees and how I can treat it if I ever run into it. After a bit of research, I found some answers.
Apple trees most commonly get leaf curl from underwatering, poor nutrients, and aphids. The best way to prevent leaf curl is to only water your apple tree when the first 2-4 inches of soil gets dry. For nutrients, apple trees prefer a loamy soil with a pH of 5.8-7.0. For aphids, use water, neem oil, or ladybugs.
So, while apple trees usually get curling leaves from improper watering, a lack of nutrients, and an abundance of aphids, what can be done to treat these conditions and reverse the curling leaves?
Pro-tip: Compared to planting in the ground, raised garden beds have fewer weeds, more drainage, and better water retention. If you want to make gardening easier and maximize your garden space, check out the best raised garden beds on Amazon.
During warmer and drier weather, apple trees will need more moisture as they can run out quickly trying to stay cool. However, if there’s not enough moisture in the soil, the apple tree’s roots can’t sufficiently cool the leaves and they’ll begin to dry and curl.
To check if your apple tree is underwatered, use a finger and check the first 2-4 inches of soil. If the soil is wetter than a wrung-out sponge, avoid watering it until dry. On the other hand, if the soil is bone dry, then you should consider either increasing the frequency or amount of water you provide.
Generally, apple trees do best when they’re mulched and deep watered. These practices can not only help treat leaf curl but also leaves that are yellowing or browning.
For more information about apple trees with yellow leaves, check out my recent post: How to Fix Yellow Leaves on Apple Trees.
Mulching and deep watering mimic fallen leaves in a forest along with heavy rainfall. This is what apple trees (and most other trees) are used to and prefer. Mulching apple trees prevents the soil’s moisture from evaporating too fast and drying out, especially on hotter days.
For best results, provide 2-3 inches of mulch around the drip line of the apple tree and only water when the soil gets dry. Avoid touching the mulch to the trunk, keeping it at least 3 inches away.
Additionally, while watering with a sprinkler or watering can work well, drip irrigation will reduce evaporation and the slow trickle will help the soil absorb more water.
While leaves curling from overwatering is less likely than underwatering, it’s still a possibility for apple trees. Many times, overwatering isn’t caused by providing too much water, but because the soil has a lack of drainage. This is especially true for potted apple trees.
To check if your apple tree is overwatered, you can use the same method as above—use a finger to check the top 2-4 inches of soil. If it’s sopping wet, especially if it’s been several hours after watering, consider improving its drainage.
Keep in mind that clay soil is well-known for having poor drainage due to the compactness of its soil particles. Water simply can’t pass through these dense particles effectively. So, if your apple tree’s leaves are curling, and you have clay soil, consider performing the above drainage test to confirm it.
An easy way to test if your apple tree’s soil drains well is to dig a 1-foot hole in the nearby, similar soil and fill it with water. If the water hasn’t completely drained after 1 hour, the soil should be amended.
A good way to amend the soil and improve its drainage is to provide 1-2 inches of compost 1-2 times per month during the growing season (this can also replace fertilizer! More on this later). Eventually, the compost will be worked into the soil, and will also help build the beneficial life in it.
Generally, avoid composting or fertilizing apple trees during the winter months as the trees are more dormant and won’t need as many nutrients. If too many nutrients sit in the soil, it can chemically burn the tree’s roots. For best results, compost during the winter and apply during early spring (after the last frost).
For potted apple trees, overwatering can be easy to do since the potting soil can become collapsed or not have enough drainage holes. If your potted apple tree is overwatered, try drilling more holes in the pot. If that doesn’t help, you’ll likely have to repot it with fresh soil (I had to do this with my Kaffir lime tree after it developed root rot from overwatering).
Like most other fruit trees, apple trees prefer a loamy, slightly acidic soil with a pH between 5.8-7.0. To provide more nutrients for your apple tree, you can either use compost 1-2 times per month or a fertilizer with a balanced NPK. For example, a fertilizer with an NPK of 5-5-5 or 10-10-10 would work well.
A lack of nutrients can not only cause apple tree leaves to curl, but it can also cause other issues such as leaves to yellow, brown, or fall off.
When the pH isn’t in the plant’s preferred range, it will be unable to absorb an adequate amount of nutrients from the soil. If your apple tree is planted in clay soil, not only can it have poor drainage, but the soil is typically more alkaline.
Fortunately, there’s a way you can improve your apple tree’s soil drainage, pH, and nutrients all at once.
While a commercial and balanced fruit tree fertilizer can benefit apple trees, compost is one of the best fixes for curling leaves. Not only will compost amend the soil by improving drainage, pH, and nutrients, but it also dramatically helps the beneficial life in the soil. These microbes assist the apple tree by providing it with nutrients further down in the soil, along with increased disease and pest resistance.
You can apply compost in 1-2 inch layers 1-2 times per month during the growing season. Like mulching, keep the compost at least 3 inches away from the tree’s trunk.
If you’d like to learn more about building the beneficial life in the soil, and improving the health of your plants, a great resource for this is Gabe Brown’s book: Dirt to Soil.
On the other hand, if you do opt for commercial fertilizer, look for one that has a balanced NPK (nitrogen, phosphorus, and potassium). For example, this can include fertilizers with NPKs such as a 5-5-5, or 10-10-10. For the best application, follow the instruction listed on the package. Normally, this means applying a measured amount (based on the apple tree’s size) during the early spring.
Aphids can also cause leaves to curl on apple trees. Typically, they’re difficult to see at first since they either hide within the curled leaf or just underneath it. If you inspect the leaves for aphids and confirm they’re causing the issue, you can use water, neem oil, or ladybugs to remove them.
To confirm if your apple tree has aphids, check inside of the curled leaves and also under them. If you see small black, white, or yellow bumps (they can come in a range of colors), it’s mostly likely aphids causing the leaves to curl.
When I had aphids on my Kaffir lime tree, I found that simply spraying them with a jet of water was enough to knock them off and prevent them from coming back. If you try this, make sure the jet isn’t strong enough to rip through the leaves. I used a hose without a nozzle and fit my thumb over the opening to adjust the pressure.
However, since your apple tree’s leaves are most likely curled at this point, it can be difficult to get the water in there and spray the aphids out. In this case, try neem oil as a natural pesticide. The sprayed oil will render the aphids unable to move and they should die off.
Alternatively, you can purchase ladybugs (an aphid predator) at your local gardening store and release them in your garden.
There are even some companion plants that can help keep aphids away. If you’d like more information about apple tree companion plants, feel free to check out my recent post: The 10 Best Companion Plants for Apple Trees.
More Tips to Care for Apple Trees
- If you find that your apple tree’s leaves are curling due to weather that’s too hot or dry, provide 1-2 hours of shade during the hottest part of the day (along with mulching and deep watering). The hottest hours are typically in the late afternoon from 2-4 pm. You can use a large umbrella for smaller or potted apple trees. For larger and planted apple trees, stick to keeping the soil moist so the tree’s roots can help cool its leaves.
- If you’re mulching your apple tree, some good mulches to use are leaves, bark, or pine needles. However, pine needles can be more acidic than the others, so make sure to check the soil’s pH every month or two.
- For clay soil, you can amend it with sand (along with compost). The sand will not only break up the clumps of clay but also increase the acidity of the soil. Adding compost will help prevent the sand from creating too much drainage and support proper water retention in the soil.
- If you aren’t sure what the pH of your apple tree’s soil is, you can either use pH strips or a pH meter. I prefer a pH meter since it’s easier. To see the pH meter I use, you can check it out below and on my recommended tools page.