The Forestry Forum

General Forestry => Urban and Community Forestry => Topic started by: bedlam on August 17, 2007, 04:32:48 PM

Title: oak trees and woodpeckers??
Post by: bedlam on August 17, 2007, 04:32:48 PM
I was wondeirng if anyone knows why I find many dead oak trees this year.I have three alone that are about 20 incehs across, and upon dropping them, I find thet in the upper limbs, there are holes into the tree deeper than the bark. They are so well spaced, i thnk maybe a pecker has made them, as an ant would be so well spaced.
I have another really big one that has no leaves this time, but Im gonna let it stay a year and se what happens. Im just not sure that they will survive without the leaves on them for another year.
And thougths on this would be greatly appreciated.
thanks Al
Title: Re: oak trees and woodpeckers??
Post by: Riles on August 17, 2007, 04:44:19 PM
Where are your trees located, bedlam?

The drought in the southeast is wreaking havoc on trees, the gypsy moth is a problem in the northeast, and oak wilt is moving eastward.

It's tough to be a tree.
Title: Re: oak trees and woodpeckers??
Post by: WDH on August 17, 2007, 10:54:55 PM
Once the tree get under a great deal of stress as it begins to die, it attracts insects that bore in wood.  The wood peckers come after the insects.  I suspect that all this is happening after the tree is long gone.  Drought is killing the oaks around here.
Title: Re: oak trees and woodpeckers??
Post by: Dodgy Loner on August 18, 2007, 12:26:38 PM
Yellow-bellied sapsuckers (a type of woodpecker) bore holes into the bark of living trees and consume the sap that runs out.  They also feed on the insects that are attracted to the sap.  They make regularly spaced holes that don't generally penetrate beyond the phloem (inner bark).  After all, the phloem is where the sap is.  However, I've never seen them feed on oaks.  They mostly feed on pecans, hickories, apples, pears, etc.

If the holes are deeper than the bark, they were almost certainly created after the tree was dead.  Perhaps by another species of woodpecker looking for insects, as WDH suggested.
Title: Re: oak trees and woodpeckers??
Post by: rebocardo on August 18, 2007, 04:11:08 PM
I have cut a few like that. I think it is the woodpeckers after the ants in the tree. When I have cut the trees down I have found them with heart rot and major ant nests in the crotches.
Title: Re: oak trees and woodpeckers??
Post by: jackpine on August 18, 2007, 07:14:39 PM
 Here in central Wi. we have a double whammy of 3 dry years in a row and rampant oak wilt . Small woodpecker holes in an oak that appears to be still healthy is a sure sign that the tree is really dying but has not given any signs yet. In a few weeks the leaves may begin to wilt or if it makes it through this year will not leaf out next spring.
Not sure what the insect is that senses the tree is dying but they appear to attack the lower section of the tree as well as the upper branches.

 The pine sawyer beetle can also sense when a white pine is dying or unhealthy and lay their eggs under the bark in the bad section. Woodpeckers as a sign of unhealthy pines also.

Title: Re: oak trees and woodpeckers??
Post by: Riles on August 19, 2007, 11:28:13 AM
It's not so much the insects sense which trees are stressed, it's that the trees are less able to defend themselves, so the insects are more successful. You see signs of insects in a stressed tree because they're there, if that makes sense.

It's kinda like "trees growing toward the light." Trees don't reach for the light, they grow where the light is and don't where the light isn't. You get weird shaped trees in the understory because that's where the light was when the branch was "passing through."
Title: Re: oak trees and woodpeckers??
Post by: jackpine on August 19, 2007, 03:48:51 PM
Riles, I understand what you're saying but that brings up another question. How does a healthy tree defend itself, say a white pine against the sawyer beetle?

Not having had any classes in forestry I,m learning as I go :)
Title: Re: oak trees and woodpeckers??
Post by: Riles on August 19, 2007, 06:53:45 PM
A healthy pine responds to a puncture by producing resin to plug the hole. A stressed tree won't be able to keep up. Different species have different defenses. Leaves may be toxic if eaten, or dropped if eggs are laid in it. Trees may compartmentalize the invasion by growing additional tissue to surround it or just grow more leaves to compensate for the loss.

This is a classic evolution case study. The insects attack and the trees develop new defenses over time. Then the insects adapt, and the process starts over. What you find is pests and diseases tend to be specific to a host. Dutch elm disease doesn't affect oaks. Southern pine beetles don't affect western pine species. Also, over time the attacker and defender tend to stalemate. If the attacker is too good, his meal becomes extinct and so does he. It's when external factors come into play that the balance is upset (hurricanes and droughts, for example).

Chestnut blight is one of those neat lessons. The pathogen is hosted on a large number of species, but is only lethal to the American chestnut. The pathogen won't go extinct, because of the alternate hosts, but chestnut doesn't have whatever adapted characteristic the others had. On the other hand, chestnut is a vigorous stump sprouter, and the blight doesn't kill the roots. Chestnut is in no danger of extinction, but if either of those two conditions wasn't true, chestnut would be gone now.

You gotta fight for your right to party.