Noxious and invasive weed management

[bigtrees]

Question about noxious and invasive weed management.

My wife and I have about 60 acres of timberland. Most all of it is timbered with a couple open areas. The open areas are weedy, with both regular nuisance weeds and then some invasive/noxious weeds. The forested areas are mostly clear of weeds but there are some. I am trying to work up a plan to take care of them.

One concept that I have been wrestling with is "threshold". I might not be 100% successful in eradicting weeds from our property (cost too much) but would like to get them down below my "threshold". I am not really sure off hand how bad is too bad.

What are your experiences with weed abatement? How do you go about deciding if the weed population is too high and worth your time/money treating it, or whether it is low enough to be acceptable?

We have spotted knapweed, Canada thistle primarily. Smaller infestations of a lot of other weeds to, including houndstongue, yarrow, and yellow toadflax.

[Onthesauk]

A little farther in the west here our county extension offices are usually the best source of info on this stuff.  Very specific for your area.  Given a chance, talk to some of the DOT guys.  They are able to use more stuff then either the county or even the feds can often use.

[nybhh]

I think it really comes down to what weeds you are trying to get rid of and what is the most effective method to isolate them from desirable species.

For example, Japanese Stilt Grass is becoming a huge problem in our area and since it has a much lower light tolerance than other grasses, it is really taking over our woodlands as well.  It out competes nearly every other ground cover and the deer don't  touch it so it doesn't take long to completely dominate the under story.  

In that case, I've had good success with the glass selective herbicide, Clethodim, which works great in the woods since it is the only grass growing in those areas and since it only affects grasses, it leaves ferns, sedges, tree saplings and other under-story plants completely untouched.  A 4 gallon backpack sprayer can cover a lot of area and trying to combat invasives on acerage without herbicide is like trying to fight sea rise with a 5-gallon bucket, IMHO.

[wisconsitom]

.......and more generally, try to work the big picture, as opposed to a totally incremental approach.  What I'm getting at is, can you eventually shade the site with your new trees?  This alone will do more than all the herbicides in the world at changing the composition of the ground layer.  I hate Canada thistle too, but once in shade, it ain't no thang.  Likewise with the knapweed, it needs full sun.

You may have seen my reply to your other post.  Weeds!  I had a field chock-full of ragweed.  On that first summer post-planting, the field was so full of ragweed that when I drove my truck down the lane in late summer, I couldn't see for all the pollen.  One year later......all gone...100%.  The field with the new baby trees in it (that I couldn't see in all the weed cover) was now totally covered by asters and goldenrods.  Much better stuff, and I had done nothing to make this change happen.

Then, in years 2 and 3, post-planting, the trees grew so much that by and large, they were all above the "weed layer" and now have the place to themselves.  I would recommend relatively modest spot-spraying for Canada thistle patches...and perhaps not much else.  BTW, glyphosate is not a  great choice for Canada thistle.  I recommend Milestone-a restricted-use item...because it is far more effective at killing the thistle (with its large, rhizomatous root system) and is far more selective than glyphosate.  With glyphosate, it looks to be working-the plants appear to wither and die...but soon, the colony is sending up new shoots.  You really want the Milestone for this job.  Note:  Milestone herbicide is mixed (for spot-spraying, which is what you will be doing) at exceedingly low rates......I don't have my chart in front of me since our office suite is being remodeled...but I think 1 fluid ounce of product gets diluted in 3 gallons of water!  Hope this helps.

tom

[pine]

In that case, I've had good success with the glass selective herbicide, Clethodim, which works great in the woods since it is the only grass growing in those areas and since it only affects grasses, it leaves ferns, sedges, tree saplings and other under-story plants completely untouched.

Make sure you are in compliance with the Specimen label for Clethodim.  
Non-compliance with the label is a violation of both federal and state law and can come with some VERY hefty fines (in my state $7500 per instance.)
While it is labeled for use on conifers that is for Christmas tree farms, nurseries and plantations.  Use in the forest is not authorized.  How you define a forest versus a plantation can be a grey area however.
I quote from the specimen label on Clethodim:
CLETHODIM 2 EC HERBICIDE can be used to control labeled grasses in Christmas tree farms,
conifer nurseries, and conifer plantations (but not in forests).