PATTERNS OF WOUNDWOOD ONE YEAR FOLLOWING PRUNING
A doughnut of callus will have differentiated to become woundwood about the cut after the next growing season if done correctly [1 to 2] (See Diagram A on left. When too close and cutís remove the collar [3 to 4] the tree will only form callus to the sides (flush cut). When cuts have been made too close below you will have [1 to 4]. When cuts are too close above, you will have [3 to 2] (broken rings of callus). A treatment that is harmful to trees but can be good for wildlife is to make cuts from 1 to 4. A cavity will form fast. (If cavities are wanted for birds or small animals.) Remember not to leave stubs. If callus does not form, then woundwood will not develop.
Note: Some branches have a sunken cambium zone beneath the branch. In this case the best you can do is a [1 to 4]. See Tulip Poplar sample below. Arrow [A] is sunken area where callus will not form if done correctly.
Below is a Tulip Poplar sample which the the symplast of the branch died and as you can see, the tree is not forming a round doughnut due to the sunken cambial zone. Also you may count the growth increments around the symplastless branch. I count 3 plus the current increment (black arrows). Also note that not only have I removed the symplastless branch, I have also severely wounded the trunk tissues.
The targets were achieved here (round doughnuts) yet this tree still formed sprouts. Two reasons. One, is that the sycamore is a prolific sprouter. Two, very well could be due to the dose - amount removed may have triggered the sprouting. Sprouts are at the black arrows.
Suggested book on "Pruning".
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