Alleopathic leaves for weed control?

This idea came off of a response in another thread Making Leaf Mould that I would like to examine more in depth.

The comment is on doing damage to a garden using alleopathic leaves as mulch. On my property I have a lot of black walnut trees, I also have Johnson grass, and locust trees. I'm wondering if I cut the Johnson grass to the dirt, then covered it with walnut leaves, then put a cover over it, like a piece of plywood, what are the odds the walnut leaves have enough toxins to take out the grass? Anyone ever tried this?

And if it might work, what about on the locusts? I have them cut, and I'll try to pull the rootball out when I can, but the little rootlings are all going to try to sprout. Think if I covered the area in walnut leaves it would kill them? I was planning to use fresh chicken poop or dog poop to scorch the ground there, but walnut leaves is an interesting concept.

Thanks for any advice :)

My parents have two big walnuts in their front yard. Most years the leaves don't get raked until late next spring. The lawn is fine. My mum's flower beds never get cleared of the leaves and they, too, are fine. The shade from the trees seems to be more of a limiting factor than anything else.

In case anyone thinks she's planting special juglone resistant plants...
English ivy
hostas
bleeding heart
Daylilies
lilacs
periwinkle

I know there's some other stuff in there but I can't picture it right now.

Would leaves + plywood not just smother the grass anyway?

Jan White wrote:Would leaves + plywood not just smother the grass anyway?

No, Johnson grass is a seriously rowdy invasive here. I had plywood on some sections, and it didn't slow it down much. Tilling it, or breaking it up, spreads it. PITA plant. I'm trying to think of a good way to not fight with it. Had some behind the barn that was 12 feet tall. Whee.

While fresh pine and eucalypt is toxic to many lifeforms, especially if you don't like being in a fire. Both are good after composting.

Jan White wrote:My parents have two big walnuts in their front yard. Most years the leaves don't get raked until late next spring. The lawn is fine. My mum's flower beds never get cleared of the leaves and they, too, are fine. The shade from the trees seems to be more of a limiting factor than anything else.

In case anyone thinks she's planting special juglone resistant plants...
English ivy
hostas
bleeding heart
Daylilies
lilacs
periwinkle

I know there's some other stuff in there but I can't picture it right now.

A good article I came across when researching allelopathy... some plants are naturally resistant to the chemical!  
"Many plants can be grown under a walnut tree. Those that are not sensitive are various beans, corn, beets, onions, and raspberries. Ornamentals tolerant of walnut trees include forsythia, hawthorn, oaks, wild rose, daylilies, iris, phlox, Shasta daisy, and Virginia creeper." But it also says lilacs are sensitive, so who knows! There is a lot of conflicting information on the web.

Link to the article:
https://aces.nmsu.edu/ces/yard/2004/100904.html

Sandy

We use old camphor laurel leaves as an allelopathic mulch for established fruit trees and passionfruit vines.
You can see the allelopathic effect as even aggressive grasses struggle to grow through it for a long time, but it's vastly better than the no-mulch-at-all and lasts longer than lawn clippings.

The allelopathy can be removed by crushing it finer/bagging it & waiting longer/keeping it moist or fermenting it.

I've read of people using allelopathic leaves on their garden beds as part of their annual weed-suppression/fallowing season cycle.
Given the type of trees used in industry and urban plantings, I think this idea could potentially have a vast application.

Sandy Smithsson: Thank you for the link! :) I moved to Missouri from Southern New Mexico, and WOW is it different here. High learning curve!!

I have in my notes, a list off a web page I can't find any more, if anyone can find this again, I'd appreciate it, looks like I have a section I missed when I copied it. The section "Tolerant Vines, Ground Covers and Flowers" starts with G in alphabetical order, would love to know if there was stuff before that.
My notes say : Black Walnut (Juglans nigra) and Allelopathy  by  Richard E. Bir  North Carolina State University
and I hit a 404 here Black walnut companions  

Tolerant Trees and Shrubs
arborvitae, American
ash, white
barberry
beech, American
birch, black: 'Heritage' river
boxelder
buckeye, Ohio
catalpa
cherry, black
crabapple
daphne
dogwood, flowering
elderberry
elm, American
forsythia
fringetree
goldenraintree
globeflower
gum, black
hawthorn
hemlock, Canadian
hibiscus
hickory
holly, American
honey locust
honeysuckle, amur; tatarian
hydrangea
lilac
locust, black
maple, red; sugar; black; Japanese
ninebark
oak, white; red; scarlet
pawpaw
pear, callery
pine, Virginia
privet
red cedar, eastern
redbud, eastern
sassafras
serviceberry
silverbell, Carolina
spruce, Norway
sumac
sweetgum
sycamore
tulip tree
viburnums (some species)
witchhazel

Tolerant Vines, Ground Covers and Flowers
goldenrod
grape, wild
hollyhock
hosta
hyacinth, grape; oriental
iris, Siberian
ironweed
jack-in-the-pulpit
lamb's ear
liriope
lobelia
May apple
morning glory
mullein yarrow
phlox
primrose
raspberry, black
rose, wild
rudbeckia
scilla
sedum
speedwell
spiderwort
St. John's wort
sunflower
trillium
tulip
violet
wisteria

Plants Damaged by Juglone
apple
azalea
birch, white
blackberry
blueberry
chrysanthemum
crocus, autumn
forget-me-not
grape, domestic
lily-of-the-valley
linden
mountain laurel
peony
pine
potato
rhododendron
thyme
tomato


What I see when I look at that list is most of the tolerant plants are things that grow naturally in the same area, while the intolerant plants are things that are not native to the area. So Amur Honeysuckle is tolerant, and it's all over out here by the walnuts, but tomatoes, which are native to South America, are not tolerant. Wild grapes are tolerant, domestic are not. This isn't 100% accurate, but an interesting perspective/theory. Maybe what I need to to figure out where Johnson grass came from... Hm....

I hadn't looked close at that list since I have learned a lot about this area, I got it a couple years ago, when I realized black walnuts were going to be part of my life in Missouri. The things I learn when I write posts!!

Edit: thinking about it. Japanese Honeysuckle is NOT on the tolerant list, and it's an invasive here... I think I'm going to try removing it via walnut leaves or wood chips.

Jondo Almondo wrote:
The allelopathy can be removed by crushing it finer/bagging it & waiting longer/keeping it moist or fermenting it.

I've read of people using allelopathic leaves on their garden beds as part of their annual weed-suppression/fallowing season cycle.
Given the type of trees used in industry and urban plantings, I think this idea could potentially have a vast application.

Ah HA!!! Thank you!! That is what I wanted to learn!! Appreciate it! And yeah, I think it could be useful if I can figure out exactly how. Permaculture teaches there are solutions to all problems if you look at it right. Toxic leaves need to be a solution in my life, not a problem

Pearl Sutton wrote:This idea came off of a response in another thread Making Leaf Mould that I would like to examine more in depth.

The comment is on doing damage to a garden using alleopathic leaves as mulch. On my property I have a lot of black walnut trees, I also have Johnson grass, and locust trees. I'm wondering if I cut the Johnson grass to the dirt, then covered it with walnut leaves, then put a cover over it, like a piece of plywood, what are the odds the walnut leaves have enough toxins to take out the grass? Anyone ever tried this?

And if it might work, what about on the locusts? I have them cut, and I'll try to pull the rootball out when I can, but the little rootlings are all going to try to sprout. Think if I covered the area in walnut leaves it would kill them? I was planning to use fresh chicken poop or dog poop to scorch the ground there, but walnut leaves is an interesting concept.

Thanks for any advice :)

Black Walnut is very allopathic so if you used fresh green leaves, you could see some reduction in Johnson grass, but a better approach would be the use of lasagna style mulching with a  first layer being the fresh black walnut leaves.

Black Locust is a very invasive tree, it will put up shoots from the roots, much like Sumac does where a grove is just a bunch of sucker babies from the mother tree.

Scalping Johnson grass only creates a situation where it will start suckering from the roots too, so unless you do a deep, solid cover for at least one full growing season, you aren't going to get rid of Johnson grass (same goes for the nutt grasses).

Pearl Sutton wrote:

Jondo Almondo wrote:
The allelopathy can be removed by crushing it finer/bagging it & waiting longer/keeping it moist or fermenting it.

Ah HA!!! Thank you!! That is what I wanted to learn!! Appreciate it! And yeah, I think it could be useful if I can figure out exactly how. Permaculture teaches there are solutions to all problems if you look at it right. Toxic leaves need to be a solution in my life, not a problem

I've outlined the specifics of how I try to denature the allelopathic components here: Camphor Allelopathic Denaturing
There's information on using alellopathic leaves unprocessed in the garden if you google 'Whole leaf garden mulch [species]'
Hope this helps.

Jondo: Thank you! I'll read it soon!
Edit: read it, cool! I took notes :D