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Bumps on the Leaves of Pear Trees — Reasons and Remedies

Bumps on the Leaves of Pear Trees — Reasons and Remedies

Pear trees make a beautiful addition to any home garden. Their dark green, glossy foliage is luscious and full. 

When they are healthy, pear trees provide wonderful shade in which to snack on the sweet, tart pears they produce from August to October. 

Whether your garden boasts the nectar-like green Bartlett pear variety, the tender red and green Anjou variety, or the tan, crunchy Bosc pear, you’ll know just how satisfying it is to pluck a snack right off the branch. 

Unfortunately, bumps on the leaves of pear trees cause their owners concern and detract from the overall appearance of the tree. 

If your pear tree is starting to develop pimple-like lumps on its leaves, read on to learn how to identify the cause of these lumps as well as how to treat them. 

 

What are the Bumps on the Leaves of my Pear Tree?

Bumps on the leaves of pear trees are caused by pear-eriophyid mites which feed on new leaf growth in spring. They may damage fruit and lead to early leaf drop but aren’t life-threatening. Prune off affected leaves and spray the tree with lime sulfur in the fall and spring to rid of the insects.

Bumps on the Leaves of Pear Trees
Bumps on the Leaves of Pear Trees

Pear trees are relatively healthy and sturdy. They can generally cope with low temperatures, weather most storms, and are even a great plant for north-facing gardens.

That said, there is no tree that is immune to the damage caused by insect infestations. 

Pear trees are great plants to grow in your garden as they're sturdy trees, not to mention immune to insect infestation
Pear trees are great plants to grow in your garden as they’re sturdy trees, not to mention immune to insect infestation

Like so many other trees (check out our advice on dealing with bumps on lemon trees and bumps on pecan trees too!), pears can become unwilling hosts to miniscule mites that wreak havoc on their foliage. 

If you notice bumps appearing on your pear tree’s leaves, read on to learn how to identify the cause of bumps on pear leaves, discover why the bumps appear and familiarize yourself with how to treat the problem. 

 

How to Identify Bumps on Pear Tree Leaves

There are several reasons why bumps might appear on the leaves of your pear tree.

However, the most common cause is the presence of pear-eriophyid mites, also known as rust mites or pear leaf blister mites. 

The first tell-tale symptom of a pear leaf blister mite infestation is raised pinkish red or green pimple-like lumps.

Affected leaves will soon begin to turn brown and will then eventually blacken as their tissue dies from the damage caused by mite wounds.

The leaves may then begin to drop from the plants. 

In some cases, the mites will migrate to the pears themselves and begin to feed on their skin. This causes similar brown lumps to appear on the pears. 

 

How Bad Bumps are on Pear Tree Leaves

Bumps on pear tree leaves are largely a cosmetic issue. If preventative measures are taken in the fall and spring to mitigate the infestation, it is possible to eliminate the issue without the tree’s long-term health being affected. 

Since the bumps on the pear leaves are more of a cosmetic issue, you can easily fix the issue if you treat them during the spring and fall seasons
Since the bumps on the pear leaves are more of a cosmetic issue, you can easily fix the issue if you treat them during the spring and fall seasons

However, in the short term, bumps on pear leaves mean your pear harvest may suffer.

Understanding why plants produce fruit can help you care for your pear tree when it is facing difficulty. 

If leaves drop prematurely, not only can your tree not photosynthesize effectively because it has less healthy leaf surface area to take in the sun, but your pears may sunburn because they lose the natural shading provided by the foliage. 

Make sure you follow all treatment recommendations to minimize the adverse effects of mite damage in the current season and to work towards eliminating them before the next growing season.

 

What Pear Rust Mites are

Pear rust mites, also known as pear blister mites, are microscopic insects whose mature females overwinter in the buds of pear trees.

They are a kind of gall mite and at just 0.2mm when fully mature are invisible to the naked eye.

When the buds begin to emerge in the early spring, the mites emerge from the buds and begin to suck the sap out of the new leaves.

While the pear rust mites feed on the pear leaves, they secrete chemicals that cause the formation of bumps
While the pear rust mites feed on the pear leaves, they secrete chemicals that cause the formation of bumps

As they feed, they secrete chemicals that react with the leaf tissue and result in the emergence of raised growths. 

 

How to Treat Bumps on Pear Tree Leaves

Fortunately, pear blister mites don’t have an overly negative impact on pear tree health. 

If there’s only minor damage done, then simply prune off the affected leaves. 

The bad news is that, as with the damage caused by all gall mites, you cannot actually reverse leaf blistering within a single growing season. 

Your best bet is to let your tree see out the current season and then take the preventative measures detailed below to avoid the problem from emerging again next season.  

However, if your tree is very badly affected, you can spray its foliage with a chemical solution such as abamectin, carbaryl, or fenbutatin-oxide.

Spraying the leaves of the pear tree that have bumps with chemical solutions can help  in killing the mites
Spraying the leaves of the pear tree that have bumps with chemical solutions can help in killing the mites

These solutions will kill mites, but they are not great for your tree’s health because they will also eliminate other forms of biodiversity. 

 

How to Prevent Bumps on Pear Tree Leaves

The best thing you can do when you notice pinkish blisters emerging on your pear tree leaves in early spring is resolve to take preventative steps to make sure the problem doesn’t reoccur the following growing season. 

The first thing you should do is to clear regularly the fallen leaves from under your pear tree. 

Bag them up in a light-proof bag and dispose of them as regular waste. This will prevent any mites from overwintering in fallen foliage and then climbing back up the trunk next spring.

Regularly clearing fallen pear leaves help prevent the mites from overwintering on the leaves and climbing back up the tree's trunk
Regularly clearing fallen pear leaves help prevent the mites from overwintering on the leaves and climbing back up the tree’s trunk

Repeat this process until the end part of the growing season arrives. 

The next thing to do is to spray your tree with lime sulfur in the fall and then again in the spring before the new growth emerges. 

In general, try to keep your pear tree in good health by keeping it watered and using one of the best fertilizers for fruit trees to keep it well-nourished and strong.

The healthier a pear tree is, it will have better chances of withstanding pest damage. 

Conclusion on Bumps on the Leaves of a Pear Tree

Bumps on the leaves of pear trees are caused by pear-eriophyid mites. Treat by pruning off affected leaves and spraying the tree with lime sulfur

Author Bio

Daniel Iseli

Taking care of houseplants and gardening are my greatest passions. I am transforming my apartment into an urban jungle and am growing veggies in my indoor and outdoor garden year-round.

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