Compartmentalization of Decay in Trees

With text and Images from Sterns Botany Online Visual Library,Jimmy Walters, S.C. Forestry Commission,

Dr. Tom Smiley, Bartlett Tree Experts and USDA Forest Service Publication by Alex Shigo

CODIT(Compartmentalization Of Decay In Trees)

Four walls of defense against decay & pathogens:

Wall 1: Inhibits movement of decay organisms in a vertical direction (weakest wall).

Wall 2: Inhibits movement of decay organisms inward (second weakest).

Wall 3: Ray cells inhibit movement of decay around the stem (strongest wall at the time of wounding).

Wall 4: New wood formed by cambium after wounding (strongest wall).

From Jimmy Walters, SC Forestry Commission

Wall 1.

After being wounded, the treeresponds in a dynamic way by

plugging the vertical vascular systemabove and below the wound. Theconducting elements-vessels inangiosperms and tracheids inGymnosperms are plugged in

various ways: tyloses, gum depositspit asperations, etc. The pIugged

elements complete the transverse topand bottom walls of the

compartments. Wall 1 is the weakestwall.

From Tree Decay an Expanded Concept, USDA FORESTRY SERVICE publication by Alex Shigo

Wall 2.

The last cells to form in eachgrowth ring make up the tangentialwalls of the compartments. These

walls are CONTINUOUS aroundeach growth ring--except wheresheets of ray cells pass through.

Wall 2 is the second weakest wall.

From Tree Decay an Expanded Concept, USDA FORESTRY SERVICE publication by Alex Shigo

Wall 3.

Sheets of ray cells make upthe radiaI walls. They are,

DISCONTINUOUS walls becausethey vary greatly in length, thickness,and height. Walls 3 are the strongest

walls in the tree at the time ofwounding.

From Tree Decay an Expanded Concept, USDA FORESTRY SERVICE publication by Alex Shigo

Wall 4.

After a tree is wounded. thecambium begins to form a new

protective wall. The wall is both ananatomical and a chemicaI wall. Thiswall separates the tissue present at

the time of wounding & new tissue thatforms after. It is the strongest of the

four walls.

From Tree Decay an Expanded Concept, USDA FORESTRY SERVICE publication by Alex Shigo

1

2

3

4

Wood Decay

From Jimmy Walters, SC Forestry Commission

Wood Response to WoundingCompartmentalizationFour boundries 1. Up/Down -

vessel plugging 2. Inward –

annual rings 3. Around – rays 4. New wood

Dr. Tom Smiley Bartlett Tree Experts

Dr. Tom Smiley Bartlett Tree Experts