CODIT- Compartmentalization of Decay in Trees- is a useful model, and like all models, limited in scope. I would like to get some conversations going about this model. Please join in, one and all.

1. Trees that are resistant to a given pathogen are able to wall off and isolate the infection.

2. Hardwoods compartmentalize, in general, more successfully than softwoods do.

3. A facultative parasite can be isolated by a tree with vitality, but not by a tree in decline.

4. A saprophyte is automatically walled-off by any living tree.

5. A strong parasite on a susceptible species is not compartmentalized at all, but only slowed in its colonizing activities by defensive reactions including hypersensitive reaction and production of phytoalexins.

These are some of the issues and questions involved in the lumped-together topics of CODIT. It might be a good idea for participants to tacle these and other aspects under different threads.

Reply to post by Peter Torres, on February 18, 1999 at 21:59:18:

I would like to hear more from folks about how specific pathogens affect specific species, and what the presenc eof conks etc tells us about the internal condition of the tree. This would be useful information for developing species profiles.


Julian Dunster

Reply to post by Julian Dunster, on February 18, 1999 at 21:59:18:

What we find in microscopy, in at least the
tylosis response in live oak (Q virginiannaXfusiformis)to the presence of Ceratocystis fagacearum (oak wilt) is the ability of the fungus to develope endohyphea in small branch form to locate and grow beyond small perforations in the vascular cell wall. This adaptive ability of this nasty pathogen is I feel, a mutated response. 20 years ago, compartmentalization was more effective in eliminating further spread.

Reply to post by Reed Holt, on February 18, 1999 at 22:40:02:

Reed,

Would be very interested in how your seeing this with any microscope. I believe that would be quite a breakthrough in itself for diagnosis.
Do you contrast the tissue? What is your marker for the presence of the fungus?

Dennis Brown