What are your opinions on this?

[kevinjohnsonmbe]

Just going on what's available in the picture, it doesn't look like it would be possible to get a text book 3 part cut back to the collar as per 3998 without impacting that other leader and possibly opening up an even larger wound.

 

Maybe that's why it's spec'd out as it is. Trying to make the best of a situation that doesn't sit perfectly in the text book model?

[skyhuck]

"Pollarding" large limbs rather than removing back to collar has been considered good practice for a long time by many. We have all seen huge cavities where large limbs have been removed, far better to have the decay in a large "peg" than into the stem.

 

I'm not sure the size of this limb justifies this though.

[silky fox]

Good point Mr Huck.

[Andymacp]

This is interesting as I'm away to do the same to large Beech limb. The decision is based on the fact the tree will struggle to heal the wound cause it's so old and the wound will be so large, so it will be left at 4ft to prevent a large cavity forming at the trunk

[jaime bray]

I have seen examples of stub cut on large limbs, and there is certain cases where the branch collar begins to form around the decaying stub. What it APPEARS to do is that at the time of pruning the large wound, the exposed cambial area are offered an element of protection from atmospheric fungal spores. Consequently, at the point at which the decaying/dead stub falls off, (that's if it doesn't put on reactive shoot growth) the occluding wound wood has been afforded some protection from said spores. Admittedly a column of decay still can form into the main trunk, but sapwood exposed fungal spores do not have as larger window of opportunity to colonize the open cambium

[kevinjohnsonmbe]

I have seen examples of stub cut on large limbs, and there is certain cases where the branch collar begins to form around the decaying stub. What it APPEARS to do is that at the time of pruning the large wound, the exposed cambial area are offered an element of protection from atmospheric fungal spores. Consequently, at the point at which the decaying/dead stub falls off, (that's if it doesn't put on reactive shoot growth) the occluding wound wood has been afforded some protection from said spores. Admittedly a column of decay still can form into the main trunk, but sapwood exposed fungal spores do not have as larger window of opportunity to colonize the open cambium

 

This and post 23 seem to make sense in certain circumstances where text book approach might not be possible (like the picture indicates.) Horses for courses?

[Kveldssanger]

Not pushing an agenda here; simply quoting Shigo's A New Tree Biology (p419):

 

"Flush cuts and cuts that leave stubs are major starting points for many tree problems: discoloured wood, decayed wood, cavities, resin pockets that do not accept preservatives in wood products, circumferential cracks (ring shakes), radial cracks and seams (frost and sun cracks), wetwood, a host of different cankers, energy depletion about the wound that invites insects, and dead strips on the trunk that may continue downward to roots."

 

Of course, wound size also plays a factor. It's ultimately a case of assessing which is the lesser of two evils.

[kevinjohnsonmbe]

 

Not great pictures (shooting from dark to light on iPhone this afternoon) but here's a Beech with several major limb failure stubs, perhaps a coronet style cut would present better options for natural recovery rather than a flush cut?