As I’m doing research for my new Fuji apple tree, I saw that some apple trees can get red leaves. I wanted to learn more, but it turns out there’s not much information out there. So, I did some digging to find out more about red leaves on apple trees and how this condition can be fixed. Here’s what I found.
Apple trees typically get red leaves from improper soil aeration, poor nutrients, or a genetic mutation. Even though the red leaves can resemble autumn foliage, they can signal an issue if found in the spring and summer months. However, red leaves normally aren’t a concern and won’t cause harm to the apple tree.
So, while red leaves on apple trees might not be a bad sign, when should we be worried, and what can we do to fix it?
Apple trees are deciduous trees, so they’ll typically lose their leaves in the autumn and regrow them in the spring. As part of this process, the leaves can turn different shades of yellow, orange, and sometimes red before falling off. The exact shade depends on the variety of apple trees.
You can typically tell that apple trees with red leaves are just going through a seasonal shedding if it occurs in the fall and if the leaves are a solid red color.
However, if the apple tree’s leaves are changing colors in the spring or summer months, or have small, discolored spots, it can indicate there’s an issue—such as a pest or disease (more on this later).
Poor Soil Aeration
Sometimes apple trees will get red leaves if they have a lack of air in the soil. This is because their roots need some oxygen and space to grow. If the soil is too compact, it can suffocate the roots and even hold too much water—drowning them. For best results, use loose, loamy soil for your apple trees.
So, poor aeration in the soil can stress the apple tree and sometimes cause it to develop red leaves. But how do you check for this (and fix it)?
How to Fix It
You can tell if your apple tree has poor soil aeration if the soil is holding too much water. To check if your soil is well-draining, simply dig a 1-foot by 1-foot hole outside of the drip line of your apple tree, fill it with water, and wait 1 hour. If the hole is still holding water, the soil should be amended with sand or compost.
Compost and sand are more porous, and over time, will be naturally worked into the soil—breaking up the clumps. This is especially useful if you have heavy clay soil.
On the other hand, if you find that you need to urgently fix your apple tree’s soil, transplanting it or repotting it will help. For example, when my potted Kaffir lime tree had poor drainage and developed root rot, repotting it with fresh soil saved it.
However, know that transplanting or repotting the apple tree can create transplant shock and stress the tree even more. So, try to only do it as a last resort.
A Lack of Nutrients
Apple trees get can red leaves from a lack of nutrients—especially nitrogen. Typically, apple trees prefer a balanced NPK (nitrogen, phosphorus, and potassium), but there are times when it needs a different ratio. For example, younger apple trees can benefit from more nitrogen, while mature apple trees can use less.
Normally, younger apple trees are more focused on foliage growth over fruiting. The opposite is true of mature apple trees. Since nitrogen is a primary nutrient in branch and leaf growth, young apple trees could benefit from more nitrogen.
On the other hand, there are times when you don’t want to use high nitrogen fertilizers. This is especially true if your apple tree has a disease.
The reason for this is because the bacteria or fungus from the disease can often feed off of the extra nitrogen, and grow more quickly. An example of a disease that does this is the bacterial disease called fire blight.
How to Fix It
If your apple tree doesn’t have a disease, and you’re looking for a good fertilizer to use, Down to Earth’s Organic Fruit Tree Mix on Amazon is a good choice (I use them for most of my trees).
On the other hand, compost is typically a balanced fertilizer and is often the best source of nutrition for apple trees.
You can also make your own apple tree fertilizer at home. If you’re interested in learning more about this, make sure to check out my recent post: Create an Amazing Homemade Fertilizer for Your Fruit Trees.
Lastly, keep in mind that while apple trees could have plenty of nutrients in the soil, it won’t matter if the soil pH is imbalanced. If the soil is either too acidic or too alkaline, the apple tree’s roots will be unable to use the nutrients in the soil, leading to deficiencies and conditions such as red leaves.
So, for best results, keep the apple tree’s soil pH between 5.8-7.0.
It’s also a good idea to measure the soil’s pH whenever you’re adding amendments, such as compost or sand.
To measure the soil’s pH, you can use a pH strip or meter. I personally prefer using a pH meter since it’s affordable and easy to use. To see which pH meter I use for my plants, you can check out my recommended tools page.
Cedar Apple Rust
Apple cedar rust is a fungus that creates red spots on apple tree leaves. It 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 apple cedar rust is a common recurring issue, it can be treated by reducing nearby juniper trees and by using sprays.
How to Fix It
This disease can be greatly reduced if you remove any juniper trees within a 1,000-foot radius of your apple trees. Additionally, clearing weeds within a 6-foot radius of your apple trees will also help.
Regarding sprays to treat cedar apple rust, it turns out there aren’t many commercial options for truly organic products. However, many growers are finding success in using homemade sprays to treat this disease, along with other apple tree diseases.
For more information on homemade sprays for fruit trees, check out the video below by Stefan Sobkowiak – The Permaculture Orchard.
Wild Apple Trees and Genetics
Red leaves can naturally occur in wild apple trees, those with a recessive gene, or those with a genetic mutation. It’s thought that red leaves are more insect-resistant than other leaf colors, but were bred out of apple trees in favor of sweeter fruit. While rare, certain varieties can get red leaves more often.
Some scientists believe the red leaves on apple trees are more pest-resistant than other leaf colors. The thought behind this is that the red pigment has certain chemical compounds that protect the leaf from being eaten.
An example of a tree defending itself with chemicals can be seen with caffeine. Caffeine is a natural defensive mechanism that was developed by trees to repel insects. This is why coffee grounds can be used as a natural insecticide (and also great to use as apple tree fertilizer).
Red leaves on trees are also sometimes compared to other brightly-colored organisms—especially the more poisonous species.
“[Red leaves are] a warning signal, like the bright colors of a [toxic] frog or butterfly.”Marco Archetti, an evolutionary biologist at Harvard University
So, if you find that your apple tree’s soil aeration and nutrients are fine, its red leaves could simply be because it’s a wild or genetic variant (and could have increased pest resistance because of it).
If your apple tree has solid red leaves, make sure to check its soil aeration, nutrients, and leaves for any sign of disease. If all of these look okay, then it’s entirely possible that your apple tree is a wild variety or has a different gene (kind of like how some animals are born albino).
Overall, red leaves on apple trees usually aren’t a cause for concern. Sometimes the bark, branches, and even the apple fruit’s flesh can be tinted red. Some growers even find these traits unique and desirable. However, if the leaves are mostly green or yellow with small, red spots, it could be a sign of a disease such as Apple Cedar Rust.
Other concerning conditions include brown leaves that are scorched-looking (caused by fire blight, a highly infectious bacterial disease that affects apple and pear trees).
If you’d like more information about apple trees and the different conditions they can get, feel free to check out some of my recent posts below: