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"This post refers to trees that are passed establishment and into the period of growth, often established and or neglected into their 'problems'. For the basic idea skip to the last five or six sentences. You got it JD3000, Maples can have plenty of codominant stems, especially the now popular and wonderful 'freemanii'. And that is why I often reduce the reduction cut diameter, cutting 6-8 feet off at times instead of 12-15. (Or appropriately smaller lengths in a smaller tree).
Reduction cuts remove the larger stem, so they never have collars. And thinning cuts aren't always enough on their own. (But enough in a sugar maple) Often, a maple crotch with a 3" and 2" inch stem has no collar on either side, as you mentioned. To mitigate between reduction and thinning, you can make a reduction cut at a node or two above one of these points leaving the option (necessary or not) of cutting at the lower crotch once the ratio improves. (The reduced side will gain diameter slower than the stem left to dominate). A good prescription involves progression.
It also depends on the reason for reduction. Major decay requires those bigger, uglier, more damaging reduction cuts. (Damaging cut traded for reducing the likelihood of even bigger storm damage, or equally sized but uncontrolled 'hit the car' storm damage) Narrow crotches, codominant stems and minor decay only require small and medium reduction cuts. And I think the amount of wind load reduction achieved with the removal of small cuts (lengths up to 8 feet, diameters up to 1.5 inches) is majorly underestimated. Actually freemanii is a great species to debunk the common practice and ideology around codominant stems, narrow crotches, and stem ratio correction. The first problem is correction. The term ignores progression. To try to correct a tree instantly may ruin it. To improve a tree progressively may in time correct it.
When a freemanii has so many stems, a progressive approach is really the only approach I see working out. The other approach is only a disaster for the tree. You can't significantly reduce or remove all the codominant stems when a tree is mostly codominant stems, and mostly narrow crotches. You also can't have any immediate goals of correcting a one to one to one to one to one ratio. He goal should be to slowly move away from even ratios, among for at least some difference, not major difference.
Part of what I'm trying to say is that we think in terms of cutting at crotches instead of in terms of nodes more often. We do need both. Further to that once the cut diameter falls below 1.5 inches, the diameter of the remaining stem does not matter much. A 1 inch cut leaving just a bud or leaving a 1/8 inch stem is fine. It looks funny and breaks the one third rule, but a year or two later, that bud will be a 1/2 inch stem at a 1" cut. All sapwood too.
So the one third rule is partly or largely useless as well, certainly in cuts under 1 inch. In tightly branched, narrowly crotched trees like maples, look at the terminal of a codominant and come down several nodes. This other habit we arborists have of coming down to a major crotch is archaic and often impossible given the texture of maples. And maples, particularly soft maples, are becoming more important every day. Not that we should plant many of them but we should take care of them, including norways and Manitobas."
