By Nancy Penrose

As you appreciate the fully grown leaves on your trees in the summer, you may notice bulges growing on tree trunks. What are those bumps and are they bad for your trees? Well, to answer the first question, those bulges are called burls and the cause of the burls on your specific tree isn?t easy to pinpoint without looking at it. However, they sometimes develop due to bacteria, fungi and insects, while other trees have a genetic predisposition to producing burls.

Are burls bad for my trees?

Normally they pose no threat to trees. Sometimes, although it is rare, a burl can interrupt the vascular system of the tree. We recommend finding the reason why the burls appeared to make sure there isn?t a health threat to the tree.

Can I remove burls from my trees?

Removing burls from trees poses a high risk for your tree. Not only would it leave a wound on your tree?s trunk, it could also lead to an infection. We recommend not removing burls to maintain the health of the tree.

The best thing to do is to find why the burls appeared. Due to the fact that burls are a product of insect or fungi damage, it is important to make sure there aren?t any signs of an insect infection or something similar. If you see small holes in the trunk and branches, give us a call at (866) 313-2333 and we will help!

Nancy Penrose is owner of Big Trees Inc. (, (tree nursery Snohomish, WA), one of the largest Seattle tree nurseries, specializing in large trees for sale and transplant tree service. Learn more about tree preservation at and for more tips on tree care or installation go to See our video at and connect with us on Facebook

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