The weeds love my mulch

[Orkine]

So I started mulching some of my trees late last year.
I still have several bare.  What I have noticed recently is this explosion of weed (or ground cover) on the mulched plants.  On one the density was such you could not see the mulch.  On the others I pick the weed once I see it. 
I took a 3 day trip a couple of weeks ago and when I returned I had to spend a good amount of time freeing my trees from what I see as competition.  Am I missing something?

Should I be removing these weeds?  Does it matter what they are?
If I had all my trees mulched it will be a full time job keeping the weeds off, is there a product to knock them back without harming the roots near the surface.
I am not doing organic and will use chemicals if i have to, but will like to keep the use of chemicals to a minimum.

Should I just bury the weeds under even more mulch?

I need all the information on mulching I can get because I am thinking this is the way to go with the other trees (no trunk damage from edger on my mulched trees  ) so please share your experience.


Modified to add pictures:



The weed is on the edge of the mulch, waiting to invade!



On the move



Close up view of a few I pulled.



Complete take over.  I mulched this little tree and didn't keep it up.  The weed has taken over what used to be mulch, mostly soil now.



Trying to get back my territory.  I pulled half of this mulch bed.  You can see the dying weeds on the pulled half.  They have nice white roots, very happy looking roots.  Just on the wrong plants.



I also have this weed which is also pretty aggressive.  It crawls along crowding out just about anything else.


One last fact in case it matters.  I get my mulch from a local nursery for free.  It is wood shavings or chips used for stable bedding.  It slightly aged but you can still see the dried horse business (#2).  Could this be seed source for importing new weeds.

[pineislander]

Sounds like you have applied mulch over the roots of perennial weeds or grass. This is a common problem. The plants are able to regrow through the mulch because they have enough energy or are adapted to passing through.

I've seen folks plant trees directly into well established bermuda grass  or possibly worse torpedo grass sod and when they mulch the grass quickly recolonizes the mulch growing even faster since it now has cool roots, irrigation water, and fertilizer. Few resources on planting trees explain that before planting the tree you MUST provide a weed-free area well outside the hole. 

This video from Lowes, for example, shows a neatly cored hole cut right out of the sod with absolutely no removal of anything.
Doing this in the presence of deeply rooted perennial grasses will guarantee failure.

https://www.youtube.com/watch?v=0VVeeWT3AAc

So, back to Orkine's problem. Take a good closeup picture of the weeds you are seeing and let's try to identify what you have to deal with. Is it a grass or a broadleaved plant? It might help to also show a picture of the roots.

[Orkine]

I did add mulch onto an established plant with some grass in the area mulched.  This weed though is not grass and was either not present or was out competed by the grass before mulching.  It starts at the edge of the mulch and grass and sends a strand or two over the mulch.  The it sends down root and the mulch and its off to the races. 
I will add photos or a mulch bed where I am winning, where it is about to start and where it has won (for now).

[pineislander]

My first guess is Commelina, but it could be anything. If it has flowers get that in the pic. If it is elsewhere in the yard you may find it flowering.

Just a guess, and I don't know all the worst weeds yet here in Florida.
Give us a pic when you get a chance.

Most likely you can use Roundup or another generic with active ingredient Glyphosate. Spray a ring around the outer edge of the mulch to avoid re-entry of plants into the root zone.
Avoid using in wind and understand it kills by contact with leaf surface of any plant. It may affect exposed roots of your tree. You can put a garbage bag over a small tree with bottom taped onto the trunk, larger trees just wrap the trunk/root flare and be careful.
If you have certain weeds in the grass a mower can spray chopped weeds onto the mulch and re-plant it. Best to mow by circling the mulched tree counterclockwise or whatever direction doesn't throw weeds onto the mulch.

[Orkine]

One last "pestilence".   
I also have old world climbing fern, lygodiumhttps://plants.ifas.ufl.edu/plant-directory/lygodium-microphyllum/.  Its not bothering my fruit trees right now but it is on the lot.  I have been battling it for 10 years and is re-sprouts every-time.  Nothing truly kills it.  If a few leaves or pieces drop in areas I have cleared, it will come back.  Hope someone knows of something that I don't to eradicate this invasive.
I have been able to keep it at bay but it always reminds me it is there and waiting to take over.

Can you imagine if this were a great fruit tree that you can re-sprout from its leaves.  Too bad, nothing good comes that easy 

[Dangermouse01]

I'v got that same stuff growing in my yard. Tough to get rid of by pulling, it is segmented and will easily break at the segment, leaving a piece rooted in the ground which will just start to regrow.
And I think mowing over it just makes a bunch more cuttings that are easily rooted and spreads it.

[Bush2Beach]

sheet mulching with cardboard will work better. re apply and keep growing your soil.
remember to remove all plastic tape and labels from the cardboard first.

[Cookie Monster]

Ah yes, the two worst weeds in south florida (besides torpedo grass that is): dayflower and dollarweed. Both thrive in moist soil conditions -- which mulch is expert at providing. The easiest way to control those is to install plastic edging around all of your mulch circles. Dig them into the soil a couple of inches and make sure they stick up above the soil by a few inches. Digging the edging into the soil stops the rhizomes of dollar weed, and the barrier above the ground does a good job of stopping the progression of spreading dayflower.

Both of these weeds are very hard to remove. Dollar weed has an extensive system of underground rhizomes which must be completely removed. Even a small piece left over will regrow. Same goes for spreading dayflower -- leave just a tiny piece, and it will quickly return. But dayflower has an extra trick up its sleeve: it produces microscopic seeds that quickly sprout and cause the problem to return. Thus, in areas which previously had dayflower, it's important to examine the area for new sprouts every few days -- sometimes for months. You can use roundup on dayflower, but you still have to worry about seeds that were left behind (unless you mulch over them, thus depriving the seeds of sun).

I've eradicated both from my entire orchard, but I think that's only possible because I don't have any grass left. In your case, you can achieve good control with plastic edging. But you'll still get sprouts now and again, especially if you use a weed whacker around the edges, which will kick up tiny pieces of rhizome and fling it into your mulch circles. You just need to be vigilant in removing the small sprouts. A quick inspection once every couple of weeks is sufficient.

[pineislander]

I guessed right. It is Commelina, AKA Dayflower/Asiatic Dayflower, has small blue flowers that last one day.
There is a smaller type which is easier to deal with. The one you have looks like the Indian variety with longer runners.
This one can also have underground flowers as described in this link.
https://www.freshfromflorida.com/Divisions-Offices/Plant-Industry/Bureaus-and-Services/Bureau-of-Entomology-Nematology-Plant-Pathology/Botany/Noxious-Weeds/Commelina-benghalensis-tropical-spiderwort

The second one with yellow flowers is an escaped groundcover called Wedelia.
http://plants.ifas.ufl.edu/plant-directory/sphagneticola-trilobata/
Like CM and I said, it can spread by mowing, I didn't know about the seeds. At this point you can carefully remove any Commellina close to the trunks, use herbicide, and lay cardboard over the existing mulch and mulch again Use edging or herbicide outside the mulch line and keep after it. I've been able to remove and mulch after to get control, but it is hard to get it all.
You are lucky you don't have torpedo grass.....

[KarenRei]

So, I'll tell you the reason you're getting all of these weeds: it's the "horse business" that you refer to.  I use horse manure extensively as a fertilizer on my land. It's great fertilizer, but it's jam-packed with weed seeds.  You weren't just dumping mulch on your plants; you were planting weeds as well.

As for control: I'm an IPM-type, not a pure-organic type. But I wouldn't even consider most herbicides right next to a tree unless I can guarantee that they're extremely selective between the weeds and the trees. You could use foliar systemic herbicides like glyphosphate, but I personally wouldn't want to take the risk.  If I'm seeing in the pictures right it's a mix of broadleaf trees and bananas?  A broadleaf-selective weed killer might work around the bananas but obviously would not be safe around your broadleaf trees.  I think your best option might be pre-emergent herbicides. They kill off seeds / sprouting seeds but have no effect on mature plants (like your trees).  So whatever you (fully) remove (pulling, smothering, burning, etc) won't come back.

In the future: anything that comes from horses, for use where weeds are a concern, you need to hot-compost it.  That is, compost it at a temperature hot enough to kill off all weed seeds in it (it also prevents transmission of nematodes and other soil pests). 

[Orkine]

Thanks, that explains why its aggressive where I mulched.
I do use the bedding in compost, aging it until it all breaks down.  I turn the heap and no weeds grow.
Looks like I will spend time watching and weeding. 
I will try the cardboard layer also but if i am importing seeds, I am thinking "Sisyphus."

[sahai1]

a nice lawn will keep out the weeds, concentrate on growing good grass, remove the weeds from the grass.  Time consuming, but that is the solution.  Make sure you choose a grass that is not a runner, but if you have crab grass, just let it spread up to the tree, and mow it under the tree.  The grass is not going to harm the tree, and the tree will like the fertilizer provided from mown grass.

[pineislander]

So, I'll tell you the reason you're getting all of these weeds: it's the "horse business" that you refer to. 

I'm not so sure. I do know the Wedelia is spread by cuttings. Looking closeup I see the dollar weed and several others mixed in under the trees.

I am starting fresh planting 3 acres. I spent considerable time eradicating perennial weeds and grass before mulching solidly. My next move is to establish selected ground covers. The easiest so far for me to propagate here in Florida are perennial peanut and sunshine mimosa, both are adapted to full sun. In full shade I'm working with Thai pepper leaf and monstera deliciosa.

Believe it or not, some folks let Wedelia dominate as a ground cover. It will become a climber if it gets something to lean against. I've seen this happen within a large Bougainvillea and it is quite a mess.

Weeds have been defined as "Plants out of place". I suppose that is right.

[Orkine]

Pineislander, I don't mind keeping a weed or two, just don't want them competing with my trees especially now that I am fertilizing and taking better care of them.

I started with Bahiagrass (or weed) lawn but have seen some St. Augustinegrass and other grass I didn't plant take residence over the years.  I don't have a sprinkler system and let my lawn go brown in the dry season which kills off some weeds.  What survives is well adapted to our seasons.  Now that I have started irrigating my trees in the dry season, there is a burst of activity close to each tree and within the spray radius of the spray gun I use.

If it is good ground cover, I will let it be.  If it competes with my mango roots, then it is toast , at least I will try to make it so.  I think Wedelia might have something to say about that.