As I’m planning to get some apple trees on my homestead, I was looking into some of the conditions they can get and how to treat them. One of the most common is yellow leaves. However, there are different reasons apple trees can get yellow leaves, and there’s not a clear explanation for all of the main causes of it. So, I did some research to find out more. Here’s what I found.
Solid yellow leaves on apple trees can commonly be fixed by adjusting the tree’s soil drainage, watering, nutrients, or pH. On the other hand, if the yellowing is spotted, then it’s likely a disease such as cedar apple rust or necrotic leaf blotch. To treat these diseases you can use a homemade spray made of whey.
So, while there are a variety of conditions that can affect apple trees and turn their leaves yellow, what do they look like and what can we do to fix them?
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Why Apple Trees Get Yellow Leaves
Apple trees most commonly get yellow leaves from poor drainage, overwatering, a lack of nutrients, and diseases such as cedar apple rust and necrotic leaf blotch. If the yellowing is solid, the tree is likely stressed. If the yellowing is spotted, it’s likely from disease and the tree can benefit from a spray.
Let’s take a closer look at the specific reasons why apple trees get yellow leaves.
Overwatering or Poor Drainage
Overwatering and a lack of drainage are especially common in areas that have a high clay content in the soil. Clay is a notoriously bad medium for drainage, often holding water for days at a time. This is a problem as the apple tree’s roots can drown and even develop a fungus (commonly called root rot). This causes the apple tree’s leaves to turn yellow and fall off.
Fortunately, there are ways to improve watering and drainage for your apple trees.
When watering apple trees, you should only water when the top 2-4 inches of soil gets dry. Letting the soil slightly dry out will help aerate the roots and prevent mold from developing. However, if the soil isn’t draining well, and it stays wet after several hours or days, there’s likely an issue with its drainage.
To fix your soil’s drainage, first test its current drainage. Start by digging a 1-foot by 1-foot hole outside of the tree’s drip-line (be careful not to damage its shallow roots). Fill the hole with water and see how fast it drains. If the hole drains slower than 2 inches per hour, it has poor drainage.
To amend the soil, if you haven’t yet planted or potted your apple tree, you can mix the soil with equal parts compost or sand to help break up the clay and larger pieces.
On the other hand, if your apple tree is already planted, it can do more harm to dig it up and amend the soil as this can lead to transplant shock. In this case, apply 1-2 inches of compost and sand on top of the soil. The compost and sand will be naturally worked into the soil over time. Make sure the compost stays at least 3 inches from the tree’s trunk to prevent mold from spreading.
Additionally, apple trees should be mulched, regardless of their condition or how you’re growing them. This is because mulch will greatly improve water retention and protect the soil from drying out in the sun. Over time, their waterings will be much more efficient and they’ll need considerably less. Using drip irrigation will improve this as well.
To apply mulch, place 2-3 inches around the drip line of your apple tree. Some good mulches for apple trees are leaves, bark, pine needles, and straw. Like compost, avoid touching the mulch to the trunk, keeping it 3 inches away.
When amending or mulching the soil, it’s a good idea to check the soil’s pH every 2-4 weeks and make sure it’s still balanced for the apple tree’s nutrient needs (more on this later).
A less common reason why apple trees get yellow leaves is due to a sudden change in weather. Typically, this means swings of 20ºF or more, but yellow leaves can also occur when the weather gradually gets too hot or cold.
So, if your weather has had a hot spell recently, and you’ve noticed yellow leaves developing on your apple trees, this is most likely the cause.
With temperatures greater than 95ºF, it’s best to either shade potted apple trees during the hottest part of the day or bring them indoors. For planted apple trees that are smaller, you can shade them with large patio umbrellas or with other trees. For planted apple trees that are full-size, consider planting larger trees to create a bit of natural shade.
Keep in mind that apple trees primarily stay cool by using their roots to send moisture to their leaves. This is why mulching is a best practice—the roots are protected from the sun and more water can be retained in the soil, cooling the tree overall. So, if you commonly get hot weather and your apple trees aren’t mulched, you may want to start!
Lack of Nutrients
A shortage of nutrients can cause leaves to not develop properly. In this case, leaves will gradually yellow and fall off. Like most plants, the main nutrients that apple trees need are nitrogen, phosphorus, and potassium (NPK). However, the primary nutrient that causes leaves to yellow is a lack of nitrogen.
Apple trees are fairly flexible when it comes to fertilizer. They commonly benefit from a balanced NPK, but an NPK higher in nitrogen and potassium works nicely too. In fact, for apple trees with yellow leaves, extra nitrogen can be key in treating it.
If you’d like a good apple tree fertilizer to help treat yellow leaves, check out my recommended apple tree fertilizers. They contain plenty of primary nutrients and secondary nutrients, which help any deficiencies that may be causing the yellow leaves.
However, keep in mind that even if an apple tree has sufficient nutrients in the soil, the apple tree will be unable to absorb the nutrients properly if the pH is not balanced.
Apple trees prefer a soil pH of 5.8-7.0, so if the pH is currently outside of this, it’s a likely cause of the yellow leaves.
It’s a good practice to test the soil’s pH every 2-4 weeks, especially if you’re amending or fertilizing the soil. The two main ways to measure pH are with a strip or meter. I personally prefer to use a pH meter since it’s easier and affordable. To see which pH meter I recommend, you can check out my recommended tools page.
If your apple tree’s leaves aren’t solid yellow, and instead have yellow spots, then it’s most likely a disease causing it. Let’s take a look at the two most common diseases that cause yellowing on apple trees, including what they look like and how to fix them.
Cedar Apple Rust
Apple cedar rust is a fungus that spreads from juniper trees (also called cedars) to apple trees. The spores are carried from one tree to another in the spring when it’s warmer and rainy. While cedar apple rust is a common recurring issue, it can be treated by reducing nearby juniper trees and by using sprays.
This disease is most common in the Northeast US and especially affects more rural areas that have both farmland and forests. It’s not uncommon for apple trees to be severely affected by this fungus and it can even live dormant during the fall and winter.
So, what are some ways you can prevent and treat cedar apple rust?
In apple growing areas, junipers are often cut down for a 2-3 mile radius around the production area, or are treated with fungicides to prevent establishment of the fungus on apple trees.USDA/US Forest Service
While this recommendation comes straight from the USDA, I see two problems with this:
- It’s not practical to both identify and cut down all of the junipers in a 2-3 mile radius, especially if you have a smaller property.
- Spraying with fungicides is not a feasible solution for organic apple growers and can often cause more harm to the soil (and therefore—the tree) than it’s worth.
For these reasons, I did a bit more digging and found that apple trees can still greatly benefit if you remove any juniper trees that are within a 1000 feet radius (that sounds a lot better, doesn’t it?). Also, you can help reduce the fungus from spreading if you clear the weeds in at least a 6-foot radius around the apple trees.
Regarding a safe spray to use, while there are not many truly organic sprays out there, many growers are finding success in treating cedar apple rust and other apple tree diseases with homemade sprays (see the video below).
Necrotic Leaf Blotch
Necrotic leaf blotch is a disease that can turn apple tree’s leaves yellow, but the main difference is that this disease usually only affects golden delicious apples. Like most diseases, necrotic leaf blotch most commonly spreads in the warmer and wetter months of June and July.
If you have golden delicious apple trees and believe they’re affected by this disease, check out this helpful resource by the Ohio State University.
If your apple tree has solid yellow leaves, it’s likely stressed. In this case, it’s best to check its drainage, watering, temperature, nutrients, and pH.
On the other hand, if your apple tree has spotted yellow leaves, it’s likely a disease. In this case, refer to the above information and see if you can identify which disease it is.
If your apple tree has been recently planted or potted, keep in mind that apple trees can also get stressed from transplant shock and develop yellow leaves. This is because when transplanted, the tree redirects nutrients from its leaves to form a stronger root structure. Over the next several months, the apple tree should have an established root structure and it will then send more nutrients to the rest of the tree, resulting in green leaves and more fruit yields.
After working through the relevant solutions, if all goes well, your apple tree’s yellow leaves should fall off and grow new, shiny green leaves.
Take a Permaculture Approach
Many growers are finding out that most (if not all) pests and diseases with crops, orchards, livestock are actually manmade. This is why permaculture is becoming such a huge and valuable industry.
We’re relearning that the best plant defense against pests and disease is a permaculture approach, and natural predators are a big part of this. Have snails eating your fruit trees? Get some ducks. Birds eating your fruit? Build some hawk nest boxes.
If you’d like to learn more about a safe and effective spray for cedar apple rust and other orchard diseases, check out this video by Stefan Sobkowiak – The Permaculture Orchard.
If you’ve tried all of the above, and you still don’t have a solution, I wrote a post on how to revive an apple tree in 3 steps, so make sure to check it out.
Alternatively, if your apple tree is also getting curling leaves or early leaf drop, consider: How to Fix Curling Leaves on Apple Trees and Why Apple Trees Drop Leaves Early (and How To Fix It).
If all else fails, I recommend reaching out to your local cooperative extension service. They should be able to help identify the specific issue and suggest a treatment.