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Burr growth on trees

  • 21-04-2014 3:22pm
    #1
    tabby aspreme
    Registered Users, Registered Users 2 Posts: 4,099 ✭✭✭


    Can anybody tell me what causes a burr to grow on a tree, thanks in advance


Comments

  • #2
    periodictable
    Closed Accounts Posts: 931 ✭✭✭periodictable


    Usually stress but it insect/fungal or other injury. Tree reacts by the cambium trying to isolate the injury so you get this strange abnormal growth.


  • #3
    gozunda
    Registered Users, Registered Users 2 Posts: 18,996 ✭✭✭✭gozunda


    It is believed that burrs may be variously caused by bacteria, fungi, insects, stress, or possible genetic factors. Some burrs may form for no obvious reason. It has been suggested that it is a method of 'healing' by the tree developing a thick layer around tree that has been damaged. Some species appear to have a greater propensity to Burr growth than others. Burr removal is not generally recommended - even though some wood turners do remove burrs for carving bowls etc.

    Edit: left out the inverted commas!


  • #4
    Oldtree
    Registered Users, Registered Users 2 Posts: 8,109 ✭✭✭Oldtree


    gozunda wrote: »
    It has been suggested that it is a method of healing by the tree developing a thick layer around tree that has been damaged.

    It is interesting to note that trees do not heal from injuries. They do not repair the damaged tissue by knitting it back together like we do. The cambium in a tree will grow around the damaged area attempting to seal it off in a process called Compartmentalization Of Decay In Trees (CODIT) by Shigo. In essence the tree would build four different walls (in a 3 dimensional sense) over time to seal off the damaged part as it grows out and over the wound to seal the damaged area off.

    It is best to leave the burrs alone as their removal could allow for a large wound and thus a large avenue for decay to progress into the tree. If there are shoots on the burr then these can be removed if necessary.


  • #5
    tabby aspreme
    Registered Users, Registered Users 2 Posts: 4,099 ✭✭✭tabby aspreme


    Burrs would add value to commercial timber , I recently got 16 ft of an elm butt 3 to 4 ft in diameter covered in burr had been dead for years but the timber is sound , was standing up to last summer.

    Cats paw in oak is a type of burr too I suppose.


  • #6
    gozunda
    Registered Users, Registered Users 2 Posts: 18,996 ✭✭✭✭gozunda


    Interesting article on Burrs on apple trees ....

    Notes from an Expert Dr. Turner Sutton, NCSU Apple Specialist:

    http://growingsmallfarms.ces.ncsu.edu/growingsmallfarms-burrknot/

    And

    http://www.extension.org/pages/60605/burr-knots-on-apple-trees#.U1g6UCm9Kc0


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  • #7
    gozunda
    Registered Users, Registered Users 2 Posts: 18,996 ✭✭✭✭gozunda


    tabby aspreme wrote: »
    Burrs would add value to commercial timber , I recently got 16 ft of an elm butt 3 to 4 ft in diameter covered in burr had been dead for years but the timber is sound , was standing up to last summer.

    Cats paw in oak is a type of burr too I suppose.

    Also known as Pippy oak...

    http://www.vastern.co.uk/sawn-timber/english-pippy-oak/

    I have seen furniture made with this and it is quite something else.


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