After a few readers reached out to me about pear trees, I’ve been looking into them more and discovered a common issue they develop is yellow leaves. While there is some information out there, a lot of it wasn’t too helpful. So, I did some more digging. Here’s what I found.
Pear trees normally get yellow leaves in the autumn, but if they’re yellowing early it’s usually due to a lack of water, insufficient nutrients, or infection from pests and disease. For best results, only water when the soil is dry, provide quality fertilizer, and inspect the leaves for any signs of infection.
So, while pear trees get yellow leaves from a few different causes, how can we tell which issue it is, and how can we fix it? Let’s take a closer look.
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 (source). 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 yellowing and dropping in the fall, know that this is normal and they’ll regrow their leaves in the springtime.
However, what happens if your pear tree is getting yellow leaves earlier in the year (spring and summer)? What could be causing it then?
One of the most common issues with any plant that we grow is under or over-watering. It’s one of the simplest, yet trickiest garden practices to get down.
When pear trees are under-watered their leaves typically start to curl and yellow before turning brown and falling off. The browning usually starts at the tip of the leaves before moving down the rest of the leaf.
If not watered sufficiently for an extended period, the pear tree’s leaves will continue yellowing and dropping, before getting to a point where it can’t photosynthesis. While the tree can still grow new leaves from stored energy, it will soon run out, at which point the tree begins to die. During this process, the tree also becomes more vulnerable to pests and disease.
So, what’s the optimal way to water pear trees?
The best way to water pear trees is by only watering when the top 2-4 inches of soil is dry. You can use a finger to test the soil’s moisture. This prevents both under and over-watering. When watering, make sure the ground gets soaked to about 2 feet down (the depth of the majority of the roots).
If your pear tree’s soil has good drainage, providing compost and mulch are two practices that are a must-have.
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).
If you haven’t yet planted your pear tree in the ground, and your soil has poor drainage, it’s usually best to plant them in a mound of soil. For more information about planting in mounds (and why this is best in clay soils), check out my post: Can Fruit Trees Grow in Clay Soil (& How To Plant Them)?.
For potted pear trees with poor drainage, it’s usually best to repot them with fresh potting soil. Due to being confined to a pot, they typically experience much less transplant shock.
So, if your pear tree’s leaves are curling, drying, and browning, under-watering is the more likely issue.
Although stress from over-watering can induce yellow leaves at times, its symptoms typically include dropping green leaves. Either way, checking the soil’s moisture before watering is the best way to prevent both under and over-watering.
Lack of Nutrients
|Nutrient Deficiency||Leaf Symptom|
|Nitrogen||Entire leaf is pale or yellow|
|Iron||Dark green veins, rest of the leaf is yellowing|
|Manganese||Broadly pale leaves, foliage color looks mottled or smeared|
A lack of nutrients can cause pear trees to get yellow 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. Plants do not distinguish between sources of nutrients. However, compared to commercial fertilizer, manure contains organic carbon which is the key to maintaining soil health, including the characteristics of cation exchange capacity, soil tilth, and water holding capacity.”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 learn more about how compost can sufficiently replace and even outperform fertilizers in the long run, feel free to view my other post: Can Compost Replace Fertilizer? Here’s What the Experts Say.
However, nutrients aren’t the entire picture. Without a proper pH, the soil is either too acidic or too alkaline for pear trees, resulting in them not being able to absorb 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 yellow leaves.
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.
If you’d like to see which pear tree fertilizers I recommend, check out my recommended fertilizer page.
Pests or Disease
While not as common as the other issues on this list, pests and diseases also lead to yellow leaves on pear trees.
Pests and diseases such as aphids, mites, rust, and Fabraea leaf spot can cause pear trees to get yellow leaves. Most pests can be repelled with water, oils, or sprays, while diseases can be treated with organic sprays or fungicides. Some pests and diseases such as aphids can be deterred with companion plants like garlic.
Generally, you can tell if your pear tree has a disease by inspecting the leaves for any yellow or brown spots as well as deformities.
You can also typically tell if pests are infecting the tree if you see them gathering on the underside of the leaves (like aphids) or holes in the tree (like borers).
On the other hand, if you notice your pear tree getting dark green, brown, or black spots, it could be caused by other diseases such as pear scab, sooty blotch, and fire blight.
For more information about pear tree pests, check out this resource by the University of Maryland Cooperative Extension. For pear tree diseases, try this resource by The Connecticut Agriculture Experiment Station.
Again, you can also reach out to your local cooperative extension for more details about the specific issues pear trees get in your area.
A Note on Pesticides, Herbicides, and Fungicides
My parents recently had an issue with caterpillars eating their basil plants in Ventura, CA, and they were about FED UP. Every time they’d plant basil, the caterpillars ate it. Fortunately, instead of giving into chemical sprays, they found an organic spray at their local nursery that’s made from fermented rum. The day after spraying, they’d find dead caterpillars on the soil.
If you’d like to find out more about this organic spray, you can find it here on Amazon.
So, what’s my point here?
Even though chemical sprays and fertilizers are an easy way out, like all easy and convenient things, there are usually long-term costs. Namely to the plants, soil, and surrounding beneficial life. Before using conventional sprays, weigh the pros and cons and consider using organic or permaculture-based treatments first.
To give you a head start, Stefan Sobkowiak – The Permaculture Orchard has a great video on a safe, homemade, and most importantly—effective fungicide (hint: the secret ingredient is whey).