[Willow Hill]

As a new member, I am trying to use this site most efficiently for all, so, after searching the archives (which would be more useful if they were searchable by key word--don't know how feasible this is) I have a question that I haven't found an answer to:

I need to remove a lawn under oaks, on a slope, after lots of rain (in Pacific NW). It is sparse, so cutting sod will probably not work. I don't want to spray Roundup. Would suffocation under newspaper, cardboard, plastic, old leaves in any combination (all are available; would require varying amounts of labor) kill the grasses without causing erosion by April, so that new soil can be blown on and new landscaping proceed at that time? The site is not too large for me to do this and the client is not concerned about appearances for that amount of time. I need to know if it sounds feasible in that amount of time. Thanks!

[trees]

Newspaper, etc. would work. I'd use Roundup, personally. One time use of that product won't cause any long-term effects, or even short term (save for the death of the offending grass).

One thing sticks out at me, though. You mention "new soil" being blown in. What's that? The last thing you want to do under established trees is bring in any substantial changes to the grade. Depending on tree species, even as much as a 2" grade change can lead to decline, and eventual death of the tree. You can bring in light organic matter, but that's about it. Care needs to be taken when landscaping around established stands of trees. Use the soil that's there, add organic matter and pit-plant everything (no tilling). Choose only plant material that will thrive under those conditions. Don't do anything that will alter the pH of the soil and go easy on the fertilizer. And mulch lightly, no more than 2".

Hope that helps...

[Willow Hill]

Thank you, trees, for the quick reply (I'm liking this forum!).

I will consider the Roundup. I am still not totally convinced that there is no spread of this herbicide beyond its application point, especially in such rain-saturated soils as we have here right now.

Your points about changing soil levels under trees are well-taken, and I'm aware of the potential problems. I am working with others on this job, and intend to make sure that when they come in to do further work, they don't change soil levels.

There are several companies here that provide a number of different mulch, soil and compost mixtures made from forest and landscape debris and manures that are composted. It is new to me (I just moved to Oregon from Iowa) and I think it is a great way to recycle. We haul trimmings in and they make good soil and mulch out of it. They will sell from their yard or bring truckloads of it to the site. This client has opted to have them blow soil and compost onto his yard for new landscaping.

[sleepy]

Round up is not going to hurt unsprayed areas . If it rains it will dilute the product and run off at the soil level. Round up only works on the leaves. It would probably take 2 aplications in the north west due to cold and slow growing conditions under trees.
Plastic or cardboard will also work in the amount of time your talking about but the seeds will soon sprout in spring!
Welcome to the north west where we have the most hellish perennial weed problem that you will grow either to love or hate !

[GLAN]

First

You will not be applying any Roundup if you are being paid for this service and you DO NOT have a Pesticide Applicators License

[Willow Hill]

Yup, it's a different ball game here in Oregon. Much less dormancy, and that at the opposite time (summer due to dry vs. winter due to cold). But so much green! Makes for a big "green" industry, with more reg's. I don't apply herbicides and would rather not, so haven't got that license (point taken, GLAN).

I am thinking I'll smother the grass. There are piles of leaves for the taking from the city. In Iowa a 4" layer of leaves would kill grass pretty well, but here it seems that leaves on lawns actually fertilize them, breaking down in the wet winter in time for spring growth. Newspaper and plastic would probably work better, I'm thinking.

No tilling, I presume, until the ground dries out, to prevent compaction. I read recently that tilling is not recommended up to 10' from the base of trees. That seems like a large radius to me. It depends on what kind of tree (depth of roots), and Oaks usually don't have lots of surface roots. Thinking of tilling anything that sprouts before the new soil goes on--or just good ole' digging on hands and knees . . .

Thanks, I appreciate any input.

[trees]

Don't till under established trees at all. The feeder roots are in the top layer of soil (depth depends on soil type). The "surface roots" you're referring to are structural roots and anchor the tree. Some species have these roots running very shallow, some not so much, but ALL species have the vast majority of their water and nutrient collection system in a fairly shallow feeder root system. Large-scale tilling can disrupt this system to the detriment of the trees.

When advising for tree preservation on construction sites, it is recommended that a fence be constructed at 1.5 times the drip line radius of the tree and nothing goes inside. Not piles of materials, debris, port-a-johns, machinery, nothing. While rarely followed (and possibly not overly realistic), this preserves this feeder root system and ensures the health of the tree.

Trees with compromised root systems may not show stress right away. In fact, in fatal root damage it may sometimes take several YEARS for the tree to die. This is how developers and builders can advertise "large, wooded lots", sell them for a premium, take little care for the long-term health of the trees and walk away before large-scale die-offs happen, instantly devaluing the property.

Bottom line on all of this is: pit planting only for extensive planting under established and valuable trees.

Sorry if this seems like a lecture, but I guess it is, kind of . I have an article I wrote for the Memphis Business Journal's contractor's edition last year on tree preservation that I can email to you, if you'd like to read more of that particular rant...

[Willow Hill]

Hey, trees, you named yourself well. I'm glad you're out there, educating people about keeping trees healthy. The "lecture" is what I am here for; if you people don't mind fielding questions about things I'm clueless about, I'm going to keep asking and thank you very much. You can't see how sheepish I look when I get your answers, anyway. I just hope I can contribute in my turn.

[trees]

"I am the Lorax. I speak for the trees, for the trees have no tongues..."

Hey, no problem. This forum is great and we all have learned from each others' experiences. I've learned a tremendous amount from the pros on this site and appreciate it every day. I give my insight when I can and hope it is received well.

You'll undoubtedly learn too, then give back as your confidence in the field increases. In the meantime, keep asking questions. You undoubtedly have a good handle on where you want to go in this business and want to do the right things. We're here to help each other. It's a beautiful thing, indeed.

[sleepy]

Trees did you know that book is banned in Oregon?