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

One of the issues here is the energy requirement to respond to infection. A facultative parasite is one that invades under certain conditions, usually those that adversely affect the tree. In our terms, it is often considered a secondary invader, to the stress factors.

So we have a situation where the tree is under stress, meaning that it does not have sufficient energy reserve to maintain all life functions at optimum levels. Now we add to this the parasite. The tree must respond with the phytoalexins and other defenses. if the parasite is invading over a wide front, the tre simply does not have the resources available to respond well enough to compartmentalize the infection. Parasite wins.

If the tree does have sufficient energy capacity, or the primary stress factor or facultative condition is neither severe nor prolonged, or if the invasion front is limited in scope, then the tree may isolate the infection. Decline is prevented or reversed, tree wins (this round).

So what do we do? Rotate your tires, change the oil, wax the body, and keep the fuel tank full. A well maintained tree will have less trouble with the parasite. Now if we only knew how to do all that for the trees.....

Reply to post by Russ Carlson, on February 19, 1999 at 00:15:09:

Sometimes I wonder if the tune-up should include a cessation to pruning. All those wounds... .
I don't believe that pruning off dead branches reduces decay to the tree proper. I don't believe that pruning off diseased branches stops decay- except for certain pests.
I prune trees, but usually for hazard reduction, and for aesthetics, and for third purposes, including light, view, releasing competing vegetation, safety, access, and so on.

Reply to post by Peter Torres , on February 19, 1999 at 00:15:09:

I agree with you on pruning of live wood. It is simply compounding a decline problem by creating more active fronts of infection pressure.

Removal of dead wood that has been shed seems intuitively counterproductive. Safety is of course an overiding issue. Beyond that the reasons should be carefully weighed.