We have several fruit trees (tangerine, avocado, lime, fig, and more) and we occasionally see them get brown leaves. While we had an idea of what was causing it, we wanted to do more research. Here’s what we found.
Fruit trees commonly get brown leaves from improper watering, climate and nutrients as well as pests and diseases. To fix brown leaves, only water when the soil is dry, grow in the proper USDA hardiness zone, and provide organic fertilizer or compost. Regularly monitor the leaves for signs of pests or diseases.
So, while fruit trees get brown leaves for several reasons, how can we tell which issue is causing it, and from there—how can we fix it? Let’s take a closer look.
In this article:
- Improper Watering
- Weather Stress
- Transplant Shock
- Improper Nutrients
1. Improper Watering
The best way to water fruit trees is to only water when the top 2-4 inches of soil gets dry. You can check this by pushing a finger into the soil (also called “the finger test”). Watering in this way prevents both under and over-watering.
Fruit trees that lack water usually show symptoms such as:
- Dried leaves
- Curled leaves
- Brown leaves
- Dropped leaves
During hot weather and drought, these issues are made worse. On a hot and dry enough day, some fruit trees can lose their leaves within a single day.
You can tell if your fruit tree is under-watered if the soil is bone dry. Again, this happens faster in hot weather. For this reason, composting and mulching your fruit trees are essential.
Compost not only provides your fruit tree with valuable nutrients, but it significantly retains water. Every 1% increase in the soil’s organic matter leads to an additional 20,000 gallons of water held. Compost also improves the soil by feeding beneficial soil life.
Mulch dramatically reduces evaporation, regulates soil temperature, and prevents erosion. It also breaks down into nutrients for the tree (and soil life) as well as preventing weeds. Mulching your fruit trees is a great practice in general, but it’s especially important to protect your fruit tree’s soil from drying out.
Tip: Remember, fruit trees evolved as understory plants in forests. They’re used to plenty of mulch and decaying matter. So, use those fallen leaves! As permaculture guru Geoff Lawton says, a forest grows on a fallen forest.
For best results, apply 2 inches of compost every 1-2 months and 4-12 inches of mulch every 3-6 months. Good mulches for fruit trees include leaves, bark, pine needles, and straw. Place them both in a ring around the fruit tree, with the mulch on top.
To avoid mold buildup, keep the compost and mulch at least 3 inches from the trunk of your fruit tree.
While over-watering fruit trees can lead to brown leaves, it’s more likely to lead to green or yellow leaves being shed. Under-watering (drought stress) is a far more likely cause of brown leaves on fruit trees.
You can tell if your fruit tree is over-watered by:
- Brown leaves
- Yellow leaves
- Dropped leaves
Over-watering can be caused by many factors but it’s the most common with clay soils or those with poor drainage.
For example, clay soils have tightly packed particles, preventing the soil from draining well. This leads the fruit tree’s soil to hold water for days at a time. This causes other issues such as root rot (a fungal disease that typically requires replanting the tree).
The most common reasons why fruit trees get over-watered are:
- Watering too frequently
- Clay soil
- Poor drainage
- Watering during rainstorms
To prevent over-watering fruit trees, use loamy, well-draining soil and only water when the top 2-4 inches of soil gets dry. By using compost and mulch, you can water your fruit trees every 1-2 weeks. Again, the compost helps hold the moisture and the mulch prevents evaporation.
If you check your fruit tree’s soil 2 or more hours after watering it, and it’s still sopping wet, it likely has poor drainage and is getting over-watered.
You can also test your soil’s drainage by digging a 1-foot by 1-foot hole near your fruit tree and filling it with water (percolation test). If the hole drains slower than 2 inches per hour, it has poor drainage.
Just make sure to dig outside of the drip line of the tree to avoid damaging its roots.
Compost, sand, and perlite are some good amendments to use with poorly draining soils. Over time, these materials will work their way into the soil and promote aeration.
Tip: Compost can fix both poorly draining and fast-draining soil as it breaks up the larger clumps of clay as well as retaining the right amount of water.
2. Weather Stress
When fruit trees are exposed to weather that’s too hot or cold, they can get stressed and begin to show symptoms such as:
- Brown leaves
- Wilting leaves
- Dropped leaves
Every kind of fruit tree has a different tolerance to climate. Because of this, it’s best to know your climate as well as the preferred climate of your fruit tree. This can help you better plan which fruit trees do best in your area, and the type of care to give them.
Tropical vs Temperate Fruit Trees
When it comes to climate, there are two main types of fruit trees:
Tropical fruit trees include citrus, bananas, avocados, mangos, and others. These fruit trees evolved in the tropics and prefer warm, humid weather and little to no frost. As a result, they grow best in USDA hardiness zones 9-11 and generally keep their leaves year-round (evergreen). They also prefer more sandy soil.
Temperate fruit trees are those that evolved in cooler climates. They include apples, cherries, peaches, berries, and others. These plants are used to mild to moderate winters and even prefer some chill hours (hours spent under 45ºF). Because of this, they generally go dormant and shed their leaves in the winter (deciduous) and prefer USDA zones 3-8.
Tip: If you haven’t yet, find your USDA hardiness zone. Once you do, check the preferred zone of your fruit trees and see if they do well in your climate. This will help you plan and provide the right care for your fruit trees.
Tips for Hot Weather
If your fruit tree is commonly exposed to temperatures 90ºF and above, it’s likely causing the brown leaves. This is especially true for temperate fruit trees such as apples and pears.
Before we jump into ways to cool your fruit trees, it’s helpful to know how they cool themselves. Fruit trees cool themselves by:
- Sending moisture from their roots to their leaves
- Transpiring (exhaling moisture from their leaves)
Knowing this, keeping your fruit trees cool becomes a lot easier.
Now, here are some ways to help your fruit tree stay cool:
- Water – Water only when the soil is dry, but don’t let it get bone dry—especially in hot weather. Use the finger test and try to keep the soil moisture similar to a wrung-out sponge.
- Shade – Provide at least 2 hours of afternoon shade (from the western sun). You can use umbrellas, other trees, structures, or shade sails. Don’t over-shade—give your fruit tree at least 6 hours of daily sunlight.
- Compost – As mentioned, compost is great at retaining moisture in the soil. Apply 2 inches of compost every 1-2 months.
- Mulch – Follow up by putting 4-12 inches of mulch on the compost. Reapply the mulch every 3-6 months.
- Density – Using transpiration, planting your fruit trees with other plants increases the humidity around them and keeps them cooler. A great way to do this is by companion planting.
Tips for Cold Weather
If your fruit tree is getting to 45ºF and below (55ºF and below for tropical plants such as banana plants), it’s likely getting brown leaves from the cold.
Tip: It’s completely normal for deciduous fruit trees such as apple, pear, cherry, and peach to have brown and dropped leaves in the winter, as they go into a state of hibernation or dormancy. These trees typically don’t need frost protection and can survive temperatures down to -30ºF.
If your fruit tree is getting exposed to temperatures below its recommended range, here’s how to keep them warmer:
- Cover – Covering your fruit tree’s canopy significantly reduces wind chill and provides a barrier to frost. Bedsheets are an affordable and common material to cover fruit trees.
- Mulch – Insulate your fruit tree’s soil with 4-12 inches of mulch. If you want, you can even add 2-4 feet of mulch. This helps prevent the ground (and roots) from freezing.
- Wrap – While the canopy and roots are protected, you can also protect and insulate the trunk by wrapping cardboard around it.
- South – If you live in the northern hemisphere, the southern sun is the hottest. So, if cold is a concern for your fruit trees, plant on the south side of your property or plant along a south-facing wall to reflect heat onto the plant.
- Potted – Bring your potted fruit tree inside if it gets too cold. Remember temperate fruit trees prefer chill hours to fruit properly in the spring, so avoid bringing them in unless the temperature is beyond their recommended range.
But what if you’ve been watering your fruit tree properly and have had fair weather? What could be the issue then?
3. Transplant Shock
If your fruit tree was recently planted or repotted, and it has brown leaves or is dying, it’s likely due to transplant shock. Transplant shock occurs when a plant is exposed to a new environment and has to establish a new root system.
Avoid transplanting fruit trees unless necessary as it can take up to 1 year for recovery.
To help avoid transplant shock, I like to plant with the following steps in mind:
- Have the new ground (or pot) prepared
- Remove as much of the plant’s current topsoil as possible, without damaging the shallow roots
- Grab the base of the plant’s stem and wiggle lightly
- Using your other hand, scoop up and support the rootball
- Lightly place the plant in the new ground (or pot) and fill it in
- Make sure the soil is at the same level on the plant as before
- Apply 2 inches of compost and 4-12 inches of mulch to the top of the soil
- Water generously and add more soil as needed
If you haven’t planted your fruit tree recently, let’s take a look at nutrients next.
4. Improper Nutrients
Lack of Nutrients
|Entire leaf is pale or yellow
|Dark green veins, rest of the leaf is yellowing
|Broadly pale leaves, foliage color looks mottled or smeared
A lack of nutrients in the soil is more likely to cause yellow leaves, but it occasionally causes brown leaves.
Soil can have insufficient nutrients from:
- Over-watering (also called leaching)
- Depleted soil nutrients
- Improper soil pH (more on this later)
Over-watering fruit trees often leach nutrients from the soil—the nutrients seeping too far down into the soil, out of reach of the plant’s roots (beyond about 2-3 feet).
For example, sandy soils are notorious for their leaching properties as their larger particles allow for more space in the soil.
Excess nutrients (over-fertilizing) chemically burn the fruit tree’s roots, causing stress and leading to leaf issues. Other issues include poor growth as well as decreased flowering and fruiting.
Normally, fast-release chemical fertilizers are the cause of over-fertilization as organic fertilizers and compost aren’t potent enough.
Fortunately, most of these issues can be resolved by properly fertilizing fruit trees.
The Best Fertilizer for Fruit Trees
I recommend using both compost and organic fertilizer for fruit trees. Apply 2 inches of compost every 1-2 months and fertilizer 1-2 times per year (in the spring and/or fall).
The three main nutrients for fruit trees (and most plants) are nitrogen, phosphorus, and potassium (NPK). While nitrogen is by far the most important (vital for root and canopy growth), phosphorus is essential for flowering and fruiting.
The two main ways to fertilize your fruit tree are with fertilizer or compost. If you choose a store-bought fertilizer, aim for one that’s organic and has a balanced NPK (nitrogen, phosphorus, and potassium). For example, use a 10-10-10 NPK.
Tip: Citrus and avocado trees require double the nitrogen to phosphorus and potassium. For example, a fertilizer with a 6-3-3 NPK works well.
Keep in mind that while chemical fertilizers have nutrients in quantity, they often don’t have quality nutrients. Chemical fertilizers often kill the beneficial soil life and dry out the soil—turning it into dirt.
On the other hand, organic fertilizers promote healthy soil life such as earthworms and mycorrhizal fungi.
Mycorrhizal fungi promote many aspects of plant life, in particular improved nutrition, better growth, stress tolerance, and disease resistance.Department of Biology, University of Fribourg, Switzerland
Either one you choose—you can see my recommendations for both compost and fertilizer on my recommend fertilizer page.
The majority of fruit trees do best with a soil pH of 6.0 to 7.0.
While nutrients are important, they’re next to useless if the soil does not have a proper pH. This is because a slightly acidic pH is necessary to dissolve the nutrient solids in the soil and make them accessible for the plant’s finer roots.
Fourteen of the seventeen essential plant nutrients are obtained from the soil. Before a nutrient can be used by plants it must be dissolved in the soil solution. Most minerals and nutrients are more soluble or available in acid soils than in neutral or slightly alkaline soils.Donald Bickelhaupt, Instructional Support Specialist, Department of Forest and Natural Resources Management
Two good ways to check your soil’s pH are either by using a pH strip or a pH meter. I prefer using a pH meter since they’re affordable and easy to use. To see which pH meter I use and recommend, check out my recommended tools page.
If you find that your fruit tree’s soil is too alkaline (above 7.0) you can add acidic amendments such as coffee grounds, sand, and peat moss. On the other hand, if your fruit tree’s soil is too acidic (below 6.0), add alkaline materials such as wood ash, charcoal, or lime.
Additionally, cold and/or wet soils are not good at promoting nutrient uptake as the fruit tree will either be dormant during the cold or too stressed in wet soils.
Aphids are small bugs that suck the sap from underneath the fruit tree’s leaves. This loss of sugar and moisture causes the leaves to curl, discolor, and drop. Aphids also deposit honeydew, which attracts ants.
If left unchecked, aphids can damage the fruit tree’s health and potentially stunt or kill it.
These bugs come in multiple colors including white, yellow, or black, and usually are found hiding underneath the leaves. Typically, aphids won’t cause damage to the fruit, but because they suck sap from the plant, they can compromise its health and therefore reduce fruit size and yield.
The best ways to get rid of aphids (and mites) on fruit trees is by spraying the infected leaves with water or neem oil, or releasing ladybugs (a natural predator of aphids and mites). Most often, a jet of water is enough to knock them off and kill them, but neem oil is a good second option.
For example, when my potted Kaffir lime tree had aphids, I found that a jet of water was sufficient to blast them off and prevent them from coming back. All I did was remove the hose nozzle and used my thumb to increase the pressure. Just keep in mind that too strong of a blast can damage the leaves.
Spider mites are similar to aphids, except they’re part of the spider family. They also feed on fruit trees and cause stunted growth as well as leaves turning yellow, red, and dropping.
The main differences in appearance between aphids and spider mites are the spider mite’s ability to spin webs. These webs can cause damage to other parts of fruit trees such as the twigs and fruit.
So, if you see small dots on your fruit trees, see if they’re depositing honeydew or webs and you’ll likely identify if they’re aphids or spider mites.
Scab (Venturia inaequalis) is the most common disease apples, pears, and crabapple trees contract. This fungal disease primarily affects the leaves and fruit, but can also infect shoots, buds, and blossoms. Heavily infected leaves turn yellow and then brown and black as the spots grow.
These spores mainly survive and spread from diseased leaves that dropped over the winter.
Scab is most common in the warm, rainy season as water and wind allow the spores to spread. In these conditions, infections can take place as soon as 9 to 17 days. Once the infection takes hold, the fungi shoot more spores into the air. As long as the leaves are wet enough, this reproductive process will repeat.
Leaves that are infected typically drop by mid-summer. Infection over multiple seasons can weaken and kill the fruit tree.
|1/2 inch olive-green round spots. Heavily infected leaves turn yellow, and then brown and black.
|Olive-green spots that turn brown. Young fruit become deformed and cracked.
How to Treat Scab
The best way to manage scab is to plant naturally resistant trees (source). Some fungicides can help manage this disease if applied at key points of infection.
Here are some best practices to treat and manage apple scab:
- Clean up infected leaves in the fall (you can burn, bury, or compost them)
- Prune the tree’s canopy to promote airflow and sunlight, reducing moisture and therefore fungal growth
- Avoid densely planting fruit trees. Keep a spacing of at least the size of a mature tree’s canopy
- Avoid fungicides on resistant or immune varieties or those already infected. Trees already infected with scab will not benefit from fungicides until the following spring. Fungicides don’t cure the tree but protect new leaves from getting infected.
- If using fungicides, apply when green leaf tips emerge, about 1/2 inch
- Keep in mind that fungicides that are labeled organic can still be toxic
Fire blight (Erwinia amylovora) is a highly infectious bacterial disease that affects members of the rose family—including apple, pear, crabapple, rose, cotoneaster, mountain ash, hawthorn, quince, spirea, and pyracantha.
This disease causes browning, blackening, and disfiguring of the leaves and fruit, sometimes killing the tree.
Fire blight is one of the biggest reasons why apple and pear trees get brown and black leaves. An easy way to tell if your fruit tree has fire blight is if the branches have a 180º bend and a scorched appearance (hence its name).
It can be difficult to treat fire blight, but there are both conventional and organic methods that help control it. Mostly, treating fire blight involves pruning the diseased branches and applying a spray while the tree is dormant, as well as blooming.
For more information about fire blight and how to treat it, refer to my recent post: Fire Blight: The Most Effective and Natural Treatments.
If you’re not a fan of using chemical sprays (I don’t blame you), Stefan Sobkowiak – The Permaculture Orchard has a great video on a safe, homemade, and most importantly—effective fungicide (hint: the secret ingredient is whey).