Killing grass for mulching the CRZ

[southsoundtree]

I have a lot of trees that are suffering on a project from lawn in the root zone, and mower damage, particularly.

I want them to mulch over the grass and planed-off roots.

What is the best ways you've found for killing grass under existing trees.

I've used cardboard and mulch. Seems like it wouldn't suffocate the root zone as much as maybe newspaper might. Is a lack of fresh air to the roots an issue with sheet mulching?

Would landscape fabric for a few years work better?

 

[CutHighnLetFly]

Big fat NO on the landscape fabric bud. Unless you feel differently about the product, I've used round up. Wont be absorbed thru the roots or trunk. Spray close to perimeter you want, then edge out the rest so yur not spraying truf you don't want to kill. Let it be taken in by the grass, die, then go grub it out, or better yet, weed wack the snot out of it, that way your not damaging the roots at all grubbing out the grass.

 

[GregManning]

Big fat NO on the landscape fabric bud. Unless you feel differently about the product, I've used round up. Wont be absorbed thru the roots or trunk. Spray close to perimeter you want, then edge out the rest so yur not spraying truf you don't want to kill. Let it be taken in by the grass, die, then go grub it out, or better yet, weed wack the snot out of it, that way your not damaging the roots at all grubbing out the grass.

This same approach was suggested for use on my own trees years ago.
I agree that Round-Up will not hurt.

1. However, do you really need fancy mulch to dress up the project ?
2. Do you need to wack out the dead grass ? I think it will decay pretty quickly under the mulch.
3. Do you really need to use Round-Up ? (Great product)
4. A shallow trench will be necessary to contain the mulch, in any case.

My approach was to just cover the grass with very well composted, fine wood chips.
I used composted chips the first year due to concerns about excessive Nitrogen uptake during the initial application & chip decay.
The grass was smothered & died.
The following years, I just used "green" chips. (The nitrogen from the initial chips will be left behind.)

Granted, my grass was not golf course quality.
But, if you have some grass that pops up, then spot treat with Round-Up.

Note: To use Round-Up effectively, the grass needs to be actively growing.
It is taken up by the grass blades, then translocates to the roots to kill the plant.
This will take a couple weeks for the grass to die out.

 

[southsoundtree]

Seems there are some biodegradable fabrics that wouldn't have to be removed in a year or three.

This is what I'm working with in some areas. Little turf growth. Other areas, its full-on lawn.

BTW, I know that RCX is part 1.



Nice 'pruning', huh? About 100 of those.

 

[guymayor]

Roundup CAN damage trees through lenticels and thin bark; less issues with trees like you show.

re sheet mulching, Depends on type of grass--rhizomatous sp. (wiry-rooted) will often persist or even thrive under mulch.

 

[JontreeHI]

I've had good success with a season's leaves and a good chip layer

 

[southsoundtree]

Roundup CAN damage trees through lenticels and thin bark; less issues with trees like you show.

re sheet mulching, Depends on type of grass--rhizomatous sp. (wiry-rooted) will often persist or even thrive under mulch.

As long as it doesn't break through.

These are thick barked doug-fir, and cherries chock full o' lenticels.

 

[guymayor]

If it thrives it will break through.

Good Luck! Looks like you will be there awhile.

 

[southsoundtree]

I know very little about turf. How does one know?

 

[JSJ]

AS we all know, turf and trees are not friends. I work on both sides of this fence and I concur with the reply above that suggests:
1. Do use a single active ingredient of glyphosate (the a.i. in Round Up. Beware there are many combination herbicides on the market and some of the other a.i.'s will leach into the root zone and can be absorbed by the trees you are trying to help - glyphosate binds to organic matter and does not leach) to kill the turf in the area you want to create into a wood mulch bed. Do NOT allow glyphosate to drift onto your trees especially the thin-braked cherries! Treat on a calm day, and consider using a sheet of cardboard to protect the trunks during application. Also, avoid the open wounds on the 'planed-off' roots you described.

2. Allow the turf to metabolize the herbicide for about a week before you cover it with the wood mulch. If you got good coverage and uptake of the herbicide, the dead turf will decompose under the mulch. - No need to cut it out which may injure your tree's finer, surface roots.
Yeah for you for creating mulch beds for your trees - Absolutely the simplest, cheapest and most beneficial cultural practice we can do for trees!
'Just attended a seminar on mulch (Dr. Bert Cregg) at ArborCon 2016 in MI, and the research presented stated that there is no Nitrogen depletion under fresh mulch. AND, benefits of mulch can last up to 9 years even without reapplying!! Keep it off the trunks and 3" deep.

 

[Mahk_Adams]

CutHighnLetFly wrote:

Big fat NO on the landscape fabric...

Ditto that. Several reasons for not using it, but the main one is that weed seeds will quickly find their way into whatever material covers the fabric, so there will still be weeds.


JSJ wrote:

'Just attended a seminar on mulch (Dr. Bert Cregg) at ArborCon 2016 in MI, and the research presented stated that there is no Nitrogen depletion under fresh mulch.

That's new and interesting. Can you provide a link to any of that research? Did they look at just trees, or other types of landscape plants (annuals, perennials, shrubs, etc.) as well? I have spread cheap, quick release fertilizer on and into chip piles months before they are to be used to help speed up the breakdown process, especially if there is little or no leaf material in the chips.

 

[GregManning]

Previously I have read reports that there was Nitrogen depletion with using "green" wood chips.
Did this research mention those previous conclusions, and the reason for the contradiction ?

 

[DSMc]

There is some tie up of nitrogen when using green mulch but only at seed level as long as the chips are used as a top dressing only. On the other hand if you incorporate any material into the soil that is not fully decomposed, nitrogen will be utilized in its decomposition, thereby tying it up.

 

[Tree_Frog]

Vinegar?

 

[southsoundtree]

Thanks for the point about the damaged roots as uptake surfaces.

I'm getting good buy-in from people higher up the totem pole.
I was introduced to the regional chief of Grounds, today.
He introduced me to two "suits" (middle management), maybe a manager and his assistant.
A 5 minute overview.
5 minutes of Google Imaging for Included/ Excluded bark crotch, Stem Girdling roots, Root Collars, and Cable and Brace.
Walked them around showing them this, that, the other. Filling, mower damage, conks, compaction. Q & A.

It felt promising to that we will be getting them on board with improvements on what I'm guessing is an 800 tree site.