Recognizing and Controlling a Tree Burl

Finding, Identifying, and Selling Tree Burls

Trees with burls
 dennwaf/Flickr/Public Domain

Apparently, little research has been done to confirm the cause or causes of burls. Available sources suggest that a burl could be caused by many environmental factors, but the biology of burls on trees is not well known. To be sure, burls and galls may serve as secondary infection avenues for insects and diseases, but as a rule, they do not appear to be harmful to most trees and maintain protective bark.

Burl-Like Symptoms

These tree trunk infections called "burls" look like bumps or warty growths probably caused as a result of environmental injury. Cambial growth is hyper-stimulated as a way for the tree to isolate and contain the injury. Almost all burl wood is covered by bark, even when underground.

Often, a tree that has developed burl wood is still generally healthy. In fact, many trees with burl wood will go on to live for many years. Still, burl wood in vulnerable spots or with off-shooting growth can become so large and heavy that they create additional stress on a tree and can cause the tree to break apart.

Preventing Burls

Even though not much is know about the cause of burls, it should be assumed that proper tree management that improves tree health can help reduce the occurrence of burls or make the presence of a burl less of a problem. Burls certainly should not be removed from a living tree bole since that would expose a large decay-producing wound or completely kill the tree. Boles can be removed if located on prune-able branches or limbs using proper pruning methods.

Not All Burls Are Bad

Burls can yield a very peculiar and highly figured wood, one prized for its beauty by many and sought after by people such as furniture makers, artists, and wood sculptors. There are a number of well-known types of burls. Quality burl wood often comes from redwood, walnut, buckeye, maple, baldcypress, teak, and other species. The famous birdseye maple superficially resembles the wood of a burl but is something else entirely.

Burls Are a Valuable Wood Product

As mentioned, trees can carry a tumor-like growth and still look healthy above and below the growth. It is more than likely a sound burl can be a valuable sawn wood in the specialty market, Many loggers are getting smart to burl value and have connections with millers and turners.

Cherry and ash trees are popular burl-producing species often with remarkable grain. Oak trees, on the other hand, tend to mill out with defective rot and holes and are usually rejected. Depending on quality and size you will find the best on walnut, redwood, and maples but most tree species can offer rare gems.

If you have a large burl on a tree you might want to sell, measure its size and take photos from several angles. It would help if you include a yardstick in the photo for perspective. The burl must be covered with sound bark with no major rot and its value is significantly increased with increased size.

The best market and prices paid for burls come through a local woodturner. Google search makes this easy by using the keyword "woodturner" along with your location. You will find a listing for woodturners and woodcrafters who buy burls or know who would be interested. Another great source would be the Americah Association of Woodturners.