I’ve recently been learning more about pear trees and saw they often lose their leaves from several possible issues. To find out more, I did some digging. Here’s what I found causes leaf drop on pear trees.
Pear trees commonly drop their leaves early due to a stressful change in watering, nutrients, or environment. Additionally, pests and diseases such as aphids, scab, and fire blight cause pear trees to lose their leaves early. After resolving the issue, the tree should regrow its leaves.
So, while pear trees lose their leaves from multiple issues, how can we tell which one is causing it, and what can we do about it? Let’s take a closer look.
1. Seasonal
Like many other temperate fruit trees, pear trees are deciduous, so they normally lose their leaves in the fall. Usually, the leaves turn yellow and brown before they drop.
The reason why pear and other deciduous trees drop their leaves in the fall is for survival. By shedding their leaves, they’re preserving resources so they can go dormant, waking when spring arrives (similar to a bear hibernating).
Pear trees also require about 200-800 chill hours (every hour under 45ºF) per year. This cool temperature allows them to maintain their hibernation, or dormancy. If the winter temperature gets above 45ºF, the pear trees start to come out of dormancy and can face issues.
The most notable issue is if they wake and start blossoming, only to have a frost kill the vulnerable flowers. This can prevent them from fruiting successfully until the next spring.
On the other hand, many evergreen trees (like citrus trees) commonly don’t experience much frost, so they keep their leaves year-round. The evergreen trees that do experience frost (like pine trees) have adapted to have other ways of surviving the winters.
For example, in his book, The Hidden Life of Trees, professional forester Peter Wohlleben found that pine trees have a type of anti-freeze in their needles, allowing the tree to keep them during the winter.
So, if your pear tree’s leaves are turning yellow and red and dropping in the autumn, know that this is normal and they’ll regrow their leaves in the springtime.
However, what happens if your pear tree is dropping its leaves earlier in the year (spring and summer)? What could be causing it then?
2. Under or Over-Watering
Under and over-watering causes pear trees to lose their leaves quickly. Typically, under-watering symptoms include leaves curling, drooping, drying, and browning before they fall off.
On the other hand, over-watering symptoms are dropping green leaves and swampy-smelling soil. Over time, this leads to root rot, a water mold, which decays the roots and can kill the pear tree.
So, what’s the best way to water and prevent both under and over-watering?
Ideally, only water pear trees when the first 2-4 inches of soil are dry. You can check this by pushing a finger into the soil. This is the best way to prevent both under and over-watering while promoting the tree’s water independence.
However, there are times when the soil has poor drainage. In this case, the soil likely needs to be amended before continuing a regular watering practice.
If you have a potted pear tree, the best way to amend its soil is by repotting the tree with fresh potting soil. It’s also a best practice to repot the tree into a larger pot every 3-5 years to prevent root binding.
But, if you have a pear tree planted in the ground, it can be difficult to amend its soil. For this issue, add organic amendments such as compost to improve the richness and drainage of the soil.
For pear trees that have not yet been planted in the ground, and you have heavy clay soil, it’s often best to plant them in mounds of soil. For more information about planting in clay soil and why mounds are the best way to plant, check out my other post: Can Fruit Trees Grow in Clay Soil (& How To Plant Them)?.
Once your pear tree’s soil is well-draining, apply 2 inches of compost and 4 inches of mulch to promote better water management.
Compost is great at not only providing sufficient nutrients (more on this later) but increasing the soil’s richness—every 1% increase in the soil’s richness holds an additional 20,000 gallons of water per acre (source).
Mulch brings benefits such as regulation of soil (and root) temperature, reduced evaporation, and added nutrients once the mulch breaks down.
Remember to keep the compost and mulch at least 3 inches from the tree’s trunk to prevent moisture build-up (which can lead to mold on the trunk).
3. Lack of Nutrients
| Nutrient Deficiency | Leaf Symptom |
|---|---|
| Nitrogen | Entire leaf is pale or yellow |
| Iron | Dark green veins, rest of the leaf is yellowing |
| Zinc | Yellow blotches |
| Manganese | Broadly pale leaves, foliage color looks mottled or smeared |
A lack of nutrients can cause pear trees to drop their leaves. This is typically from a nitrogen deficiency, although, other deficiencies can also cause it. For best results, provide the pear tree with a quality 10-10-10 fertilizer, or compost. These materials provide sufficient amounts of main and trace nutrients.
If your pear tree’s leaves fit any of the above descriptions in the table, it can be a good indicator one of those nutrients is lacking in the soil. While nitrogen is the primary nutrient plants need, iron, zinc, and manganese are important trace, or secondary nutrients.
However, this table is not black and white as sometimes there’s a combination or range of issues and symptoms. If you’d like a more definitive nutrient profile of your soil, consider reaching out to your local cooperative extension as they commonly have soil tests available for your area.
How To Fertilize Pear Trees
While chemical fertilizers have nutrients in quantity, many growers are finding they are lacking in quality and lead to issues such as poor water retention, declining soil health, and increased pests and disease.
As a result, many are learning that compost and manure not only have nutrients in both quantity and quality, but they can even replace fertilizers.
“Approximately 70-80% of nitrogen (N), 60-85% of phosphorus (P), and 80-90% of potassium (K) found in feeds is excreted in the manure. These nutrients can replace fertilizer needed for pasture or crop growth, eliminating the need to purchase fertilizers.”
University of Massachusetts Amherst
While it may be hard to believe, chemical fertilizers were only invented in 1903 and plants have been thriving without them for many hundreds of thousands of years.
If you’d like to see which pear tree fertilizers I do recommend, check out my recommended fertilizer page.
However, nutrients aren’t the entire picture.
Imbalanced Soil pH
Without a proper pH, the soil is either too acidic or too alkaline for pear trees, resulting in them not absorbing nutrients from the soil.
Pear trees prefer a soil pH of 6.0-6.5.
The reason why pear trees (and most plants) prefer a slightly acidic pH is because it dissolves the solid nutrients to be absorbed by the plant’s finer roots (source). Without a sufficient pH, even if the soil has nutrients, the pear tree can’t absorb them and develops issues such as leaves dropping early.
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 pear 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 pear tree’s soil is too acidic, 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 pear tree will either be slightly dormant during the cold or too stressed in wet soils.
4. Extreme Weather
Generally, pear trees can handle temperatures between -30ºF and 90ºF but get stressed when there’s an early frost, extreme heat, or a swing in weather. This stress causes the tree’s leaves, blossoms, and fruit to brown and drop. To prevent this, monitor swings in weather and shelter the tree if possible.
For best results, keep your pear trees between 45ºF and 80ºF during the spring and summer.
When pear trees get too hot, their leaves start to burn and the soil will likely dry. Dry soil makes the issue even worse as the tree’s roots can’t send moisture to its leaves and help cool them.
On the other hand, pear trees can tolerate cold temperatures fairly well due to them being deciduous trees. As deciduous trees, they shed their leaves in the fall and enter dormancy to survive through the cold winters (much like how bears hibernate).
Because of this, pear trees do best in USDA hardiness zones 4-8, but most varieties can survive in zones 3. Also, like other deciduous trees, pear trees require a certain amount of chill hours per year to grow and fruit properly—about 200-800 hours.
However, too much cold will kill pear trees. Typically, pear trees will be dormant for the winter and have a good chance of surviving it, but an unexpected frost outside of dormancy can damage the tree.
For example, pear trees that are woken from dormancy mid-winter will start growing again, only to suffer from a later frost. This can stunt the tree for a season or kill it if severe enough. Pear trees will have their dormancy broken if temperatures reach 45ºF or higher.
If your climate gets too hot or cold for your variety of pear trees (typically outside of -30ºF to 90ºF), there are some steps you can use to help protect your tree.
Hot Weather Tips
- Provide 2 inches of compost and 4 inches of mulch. Compost provides valuable nutrients and increases the water retention of the soil (source), while mulch regulates soil temperature and reduces evaporation. Reapply compost every 1-2 months and mulch every 3-6 months.
- Shade pear trees from the afternoon sun. Since the western, afternoon sun is much hotter than the eastern, morning sun, shade the tree for a least a few hours from its west side. Some ideas to shade are large umbrellas, shade sails, or other trees.
- Move potted pear trees indoors during heat waves. Try to move them gradually over two weeks as to not stress them out from the swing in temperature. If you can move them to a patio with shade, that’s even better.
Generally, while hot weather more commonly leads to brown leaves, extremely cold weather can also cause it.
Cold Weather Tips
- Insulate the tree’s canopy with bedsheets or the trunk with cardboard during times of frost. Plastic tarps also work well, especially at preventing ice build-up.
- Bury the pot or provide a mound for planted trees. Potted pear trees can be buried outside in the ground for more insulation. You can also place the pot in a box and pack in the remaining space with mulch. Planted pear trees can benefit from a 1-2 foot high mound of mulch such as leaves during the winter.
- Place pear trees along a southern-facing wall for maximum sunlight and warmth. Generally, facing south allows for the most sunlight (as it receives both the sunrise and sunset). Also, as night falls, some warmth will continue radiating from the wall onto the tree.
- Avoid bringing potted pear trees indoors during the winter as they require chill hours. Indoor temperatures, including basements, rarely fall and stay below 45ºF necessary for chilling.
5. Transplant Shock
If a pear tree was recently planted or repotted, and it’s starting to die, it’s likely due to transplant shock. Transplant shock occurs when the plant is exposed to a new environment and has to establish a new root system. Avoid transplanting 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 tree’s current topsoil as possible, without damaging the shallow roots
- Grab the base of the tree’s trunk and wiggle lightly
- Using your other hand, scoop up and support the rootball
- Lightly place the tree in the new ground (or pot) and fill it in
- Make sure the soil is at the same level on the trunk as before
- Apply 2 inches of compost and 4 inches of mulch to the top of the soil
- Water generously and add more soil as needed
6. Pests and Diseases
Aphids and Mites
The best ways to get rid of aphids and mites on pear trees are by spraying the infected leaves with water or neem oil, or releasing ladybugs. Most often, a jet of water is enough to get rid of them, but neem oil is a good second option. Additionally, ladybugs are a natural predator and can reduce these pests’ numbers.
When my Kaffir lime tree had aphids, I found that a jet of water was enough 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. Keep in mind that too strong of a blast will damage the leaves.
Scab
Pear scab is a fungus that creates dark lesions on the leaves and fruit of pear and apple trees. The infected leaves can fall off in the summer. Like other diseases, apple scab normally appears in the spring. The best way to prevent and manage apple scab is to prune and pick up any infected leaves and fruit.
A little-known secret is that some companion plants can help prevent apple and pear scab. Specifically, interplant chives around these trees to help control scab disease (source).
If you’d like to see more companion plants for pear trees, check out my other post: The 10 Best Companion Plants for Pear Trees.
Fire Blight
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. Fire blight causes browning and disfiguring of the leaves and fruit, sometimes killing the tree.
Unfortunately, there is no cure for fire blight. However, there are still many things you can do to prevent and manage this pear tree disease.
The best organic solutions to treat fire blight are vinegar and essential oils. Research from Washington State University has shown that oregano, thyme, and cinnamon essential oils are a viable treatment for fire blight. Simply use a spray of 23% thyme oil or 60% cinnamon oil on the tree a few times per year.
If you’d like to see more about treating fire blight, see my other post: Fire Blight Treatment: Non-Organic & Organic Solutions.
