grand fir beetle?

[snowman]

 Ive been doing some research on bark beetles and they supposidly go after doug fir, On my land they are killing my biggest grand fir, these are like 3 ft on the butt and the ones id like to keep around. The thousands of smaller doug fir around them, 12 inch dbh on average, arnt being touched. What the hecks going on here?

[Frank_Pender]

Just a guess, Snowman, but I have found that Grand Fir in my area that have reached the size you describe have topped out, so to speak.   They seem to be at the end of their lifespan and begin to  not produce natural imune defences, therefore decline.  I have had a number of them reach that point here, on my Tree Farm.  However, I am not a certified forester.   All of the above is speculation via observation.

[Riles]

That's a fact. As trees reach old age, their growth slows and they produce less resin. Resin is the main defence against bark beetles. The best way to fight an infestation is to have healthy, vigorously growing trees. If all you have is a single tree infested, you're OK. If they start to spread to adjoining trees, it's time to start cutting.

[Tillaway]

Snowman
The most common I have seen is Fir Engraver beetles (Scolytus ventralis LeConte).  It is common in Northern California and in parts of Oregon.  Also Indian Paint Fungus is a real problem in older Grand Fir.  There are also numerous root rots that attack as well.

Check out the link.

http://www.fs.fed.us/r1-r4/spf/fhp/field_guide/64frngrvr.htm

[Stephen_Wiley]

Snowman,

Bark beetle presence is usually secondary, and will not always result in tree fatality based upon tree vigor and age. 

Beetles that act as the primary causal agent are usually in endemic numbers for a given area. Healthy trees may show evidence of attack, but may not succumb to it.

The size, shape of the exit/entrance holes will help to determine if the beetle is a bark or engraver beetle.

Bark beetles are usually found with root, sap and heart rots as the primary cause of decline. Tillaway mentioned one 'rooot rot' which is more common east of the Cascades. Depending upon your location other factors such as lack of nutrients can also result in decline. Further (as Frank mentioned) 'tree decline'  is when a species reaches an age of maturity in which it no longer takes up nutrients or responds to aids postively.

Concerning your tree, you should find an experienced forest/arborist pathologist and endomologist to examine if the damage is being defensively thwarted by tree defenses and determine any other primary factor for decline.

[Frank_Pender]

I knew this topic would get to your sharing.  Thanks.  Stephen and I spent a couple days trying to decide what was getting the top 30 to 40 of some of my Douglas Firs.  Upon very close examinations of the two trees, after I fell them.  We discovered that it was wood rats eating the cambiam layer.  It took almost three years for them to completely girddle the tree at the 8" diam.  area of the tree top.  I have since discovered a couple more with the same problems.   I now use a 410 single shot to shoot the buggers nests and them from the tree limbs.

[snowman]

Good info in here, thanks for your help. Tillaway site was informtive, its on my fav list now. I can follow the dead grand fir like dominoes falling, this spring when i can get in there, (have to snow shoe in right now) Im going to try to get ahead of these buggers, i'ts killin me watching these beautiful trees die. I know proper forestry would be to cut them all as they are definately over ripe but this land will be my home too not just timber land, I get all sentimental over trees, kinda weird since iv'e spent my entire adult life cutting trees down, hope i'm not turning into a tree hugger :-\

[Riles]

Proper forestry is doing what the owner of the trees asks. The best economic use of the trees might be to harvest them (a whole separate anaylsis), but if the owner says the tree fits into his plans right where it is, the proper forester says "I agree!"

You don't have to cut them all down in order to stop the spread. You just need to get a tree length or two ahead of the front and cut in a horseshoe shape around them. Drop the trees back towards the infestation.

[Stephen_Wiley]

............. I can follow the dead grand fir like dominoes falling, this spring when i can get in there, (have to snow shoe in right now) Im going to try to get ahead of these buggers, i'ts killin me watching these beautiful trees die.

I know proper forestry would be to cut them all as they are definately over ripe but this land will be my home too not just timber land, I get all sentimental over trees, kinda weird since iv'e spent my entire adult life cutting trees down, hope i'm not turning into a tree hugger :-\

Snowman, the first part of your previous post gives me suspicion that you are indeed dealing with a 'Root Rotting Pathogen'. There are no known cures for root rots...however, a site study could determine the causal agent and rate of disease progression. Further, measures may be possible to prevent further root to root spread in order to  preserve remaining uninfected trees.

Proper Forestry = the collection of all known data concerning environment, micro-climate, available sunlight, available nutrients, identification of pathogens, parasites, and abiotic (non-living) influences to overall forest health.