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Ferns, the Epic Fruit Tree Mulch (...or am I missing something?)

 
Nicole Alderman
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Last year I discovered, quite by accident, that not much can grow through a layer of fern fronds. I had put a nice layer of them in my potato garden, as I read it would reduce the loss of potassium and nitrogen...only to find the potatoes and even the garlic couldn't grow through them! So, I got no potatoes or garlic, but I did learn something useful!

This year, I'm using the fronds as a mulch around my my fruit trees, layering/weaving the fronds around the base of my trees were I really don't want anything growing. I'm hoping that it will keep the weeds down. For the places that already have grass growing, I'm putting down a layer of duck bedding and then putting the fronds on top of that. I sloppily interweave the fronds in various directions. I assume that the rain and oxygen can still filter through those fronds (unlike with cardboard/newspaper, which can supposedly smother)

I did this a little around one of my cherry trees last year, and there was markedly less weed growth than with my other trees. I have a lot of ferns around me, so I plan on mulching as many of my fruit trees in this way as I can. Below is a picture of one of my cherry trees that I just mulched today (I'd show the other one I mulched, too, but it's covered in snow).

Is there anything that might be wrong with this mulch? If/when I apply the duck bedding, would it be better to put it above or below the ferns?
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Ken W Wilson
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I was hoping someone knowledgeable about ferns would reply. Very few ferns here. It seems unlikely that the ferns physically prevented your plants from growing. Maybe they have some chemical that prevents other plants from growing. Hopefully someone on here will know if that's possible, but my guess is that there was some other problem like it was too cold and wet or too hot and dry. Just a guesses though.
 
allen lumley
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Nicole & Ken : Most ferns are dynamic accumulators -that is they collect heavy metals, its important to not only know where the ferns themselves came from-

( unless you grow them from spores ) but it is also important to know the history of the ground and its historical use before you introduce them from a different

area . As there are two principle types of edible ferns this is twice as important ! For the crafts Big AL
 
Levente Andras
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There is at least one genus of ferns - Bracken (Pteridium) - which should be handled with caution.

Looking at sources available on the web, you can learn that:

- The plant is carcinogenic to animals
- It seems that spores wafting in the air (e.g., in hot, dry weather) are carcinogenic if inhaled
- There may be an association between eating bracken and stomach cancer or cancer of the oesophagus in humans
- If bracken or its spores get into the water supply, it is possible that it would be carcinogenic
 
allen lumley
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- Because of its ubiquitous placement as a early wild green in the Northern U.S., and the ease of learning to make a positive I.D. of the 'Ostrich Fern' This is my

Go-to spring green. Bracken which is an earlier variety found in the same general locations is in my opinion barely edible when well cooked and never otherwise.

See link below :


https://en.wikipedia.org/wiki/Fiddlehead_fern

To restate my earlier point, it appears that all ferns are dynamic accumulators and the history of the soils they are found in AND the upstream land in the same

drainage should be personally known to the picker before using ! For the Good of the Crafts ! Big AL
 
Dillon Nichols
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Only sword fern is present in qtys practical for this use here, but we like the looks of the big banks of it, so it gets spared the sickle.

Instead, we've been transplanting awkwardly located sword ferns to new locations beside apple trees. They don't always make it, but those that do can provide substantial grass-defeating coverage, and no need to chop/transport anything; the dead fronds build up into an excellent weed-barrier that grows with the fern.

It should be possible to propagate sword ferns by digging up a portion from the edge and planting that, but I haven't tried that yet


Interesting point about bracken. We've got some of that too, but it seems to be a transitional species here, fading out over the course of a decade or so.
 
Neil Layton
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Levente Andras wrote:There is at least one genus of ferns - Bracken (Pteridium) - which should be handled with caution.

Looking at sources available on the web, you can learn that:

- The plant is carcinogenic to animals
- It seems that spores wafting in the air (e.g., in hot, dry weather) are carcinogenic if inhaled
- There may be an association between eating bracken and stomach cancer or cancer of the oesophagus in humans
- If bracken or its spores get into the water supply, it is possible that it would be carcinogenic


Bracken (Pteridium aquilinum) is a common wild species around here. It only spores after a hot, dry summer, which isn't common in this country.

That said, the plant does release allelopathic compounds, which do remain in the soil after decomposition, so I would still think twice about using it as a mulch.

It's easy to recognise as this is the only one with divided fronds.
 
Nicole Alderman
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Neil Layton wrote:

Bracken (Pteridium aquilinum) is a common wild species around here. It only spores after a hot, dry summer, which isn't common in this country.

That said, the plant does release allelopathic compounds, which do remain in the soil after decomposition, so I would still think twice about using it as a mulch.

It's easy to recognise as this is the only one with divided fronds.


That's really fascinating about it only spores after a hot, dry summer. That would explain why it seems to be a transitional plant, as Dillon said. Right after a disturbance, the land is usually hotter and drier, as it does not have the tree cover anymore. But, as the forest develops, it becomes more moist and less dry. I also noticed that the places that I've seen it were usually dryer and hotter than other areas (under big power lines). The only place I have brackens on my property is at the very top, where it is also hotter and drier than elsewhere.

I had not known that the allelopatic compounds, nor about the fronds being carcinogenic when the spores are breathed in. I recall reading that some people thought that it's fiddleheads were perfectly edible, while other's were saying to never eat it. I have no desire to risk it, so I won't be using those for mulches (I also have no desire to hike to the top of the hill to harvest them even if they were useful).

The only use I ever had for bracken ferns was throwing them like spears. This was one of my brother and my favorite past times (my mom happily encouraged it, because she considered them weeds, and we were pulling them for her!). Maybe I won't be throwing them as spears anymore, or letting my kid(s) do so... Or, if nothing else, we won't throw them when their spores are developed.

The ferns I used here, by the way, are Western Sword Fern, which--while do not have edible fronds--do not seem to be carcinogenic. The natives here used to use them as drying racks for their food, etc. We've got a lot of them growing in our forests, often infringing on our paths, so I just hack off 1/3 to 1/2 the plant in the winter (I recall some people hack the whole thing down each winter, and it sprouts back from its roots). So far, the ones I harvested from last year seem to be doing well. They were not as bushy as the unharvested ferns, but had filled in all the way around. I like the look of ferns, too, but really hate having to constantly weed grass out!

That's really interesting, Allen, about them being dynamic accumulators. I hope that means they'll also accumulate things my trees need. I don't think we have any toxic heavy metals here. As far as I know, this land was only used for 15 years by it's previous owner, and before that it was just used for timber. I will avoid harvesting from areas where the previous owner was active. The guy was a strange man, and I really have no idea what he might have done and hidden here. We keep thinking we'll find a bunker burred somewhere...

I was hoping someone knowledgeable about ferns would reply. Very few ferns here. It seems unlikely that the ferns physically prevented your plants from growing. Maybe they have some chemical that prevents other plants from growing. Hopefully someone on here will know if that's possible, but my guess is that there was some other problem like it was too cold and wet or too hot and dry. Just a guesses though.


I sure hope they don't have allelopathic properties like the bracken ferns! But, the overlapping ferns do seem to create a physical barrier, too. When I realized little was growing in my potato patch, I investigated and found some garlic and potatoes that were trying to push up through the ferns. But, those ferns are stiff, don't like to decompose quickly, and overlap really well! Even a year later, when I went through and dug up what few potatoes there were, the ferns were still mostly intact. and forming a barrier.
 
Dillon Nichols
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Nicole, that pretty much matches the bracken location here, high and dry. Not much like the behavior of most of the other ferns.

My family bought this property about 20 years ago; the former owners had been there for many decades, establishing an orchard and garden with great effort on the devastated land. At some point before them, it had cattle on it, peat was sold from the one tiny spot of rich soil, and all the topsoil was scraped off and sold. Must have been rough going in the first years...

In any case, in their later years the upper portion had become very overgrown, until shortly before we bought it a great push was made to hack back and burn out the himalayan blackberry and scrub that was taking over the orchard and grassy areas at the top of the land. This was just what the bracken wanted, apparently, and great swaths sprang up in short order.

Carcinogenic spores or not, when green in the early summer it makes lovely hiding spots suitable for sundry horizontal activities, but a high dry sunny spot alone doesn't seem to be enough for it, even in the parts we keep clear of larger plants it gradually gets replaced. Even burning out the competition again doesn't cause much regrowth of the bracken, nor have the last couple long hot summers. A puzzlement.



I definitely agree that sword ferns are well able to handle some trimming for mulch... but I am overruled on this one! In any case I like planting once better than chop/drop many times.


Ken, they really can make for a substantial barrier as the fronds don't decay fast, and interwoven will form fairly secure matting. I haven't observed anything that looks like allelopathic behavior where a fern is thriving in an orchard setting near other plants, beyond the direct physical barrier that the fronds provide. Granted the big stands of fern don't tend to have other plants in them, but I chalked this up to lack of competition in the low-light areas they are located in... Hmm. I'll try and remember to take a more critical look at the ferns in the orchard later in the year with this possibility in mind.


Allen, I have heard that ferns are dynamic accumulators, but haven't seen a source with detailed specifics... All ferns? Accumulators of what exactly? I hear 'dynamic accumulator' and generally think 'oh good!', but is there a possibility of this being a detrimental feature, on land that has not been contaminated by human activity? How about if the ferns in question will not be consumed by people?

 
Juan Sebastian Estrada
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This is really a bummer for me. In the following pictures you can see that my property has quite a lot of Bracken growing. It is one of the few things that seem to grow unaffected by all the rampant grass, along with some variety of boneset (which you can also see in the first pic) and other small plants.

To me this has been an indicator of acid and poor soil (even though there is a fairly good amount of organic matter) and I was until now under the impression that the Bracken was here helping to restore balance and bring the pH back up, so I have been chopping and dropping it under my fruit trees as mulch and adding it to my weed teas in the hope that it will release some potassium, but now I'm afraid that I've been doing more bad than good? I'd really like more info and confirmation on its allelopathic (it certainly is not making the grass unhappy) and carcinogenig properties.

Is there any way that the carcinogenic compounds will transfer to my trees or are they only in the spores?

Is it possible that what I have may not be bracken?
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Bracken and Boneset. Lots of bracken uphill.
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Bracken (top right corner) behind some banana plants
 
Neil Layton
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Juan Sebastian Estrada wrote:This is really a bummer for me. In the following pictures you can see that my property has quite a lot of Bracken growing. It is one of the few things that seem to grow unaffected by all the rampant grass, along with some variety of boneset (which you can also see in the first pic) and other small plants.

To me this has been an indicator of acid and poor soil (even though there is a fairly good amount of organic matter) and I was until now under the impression that the Bracken was here helping to restore balance and bring the pH back up, so I have been chopping and dropping it under my fruit trees as mulch and adding it to my weed teas in the hope that it will release some potassium, but now I'm afraid that I've been doing more bad than good? I'd really like more info and confirmation on its allelopathic (it certainly is not making the grass unhappy) and carcinogenig properties.

Is there any way that the carcinogenic compounds will transfer to my trees or are they only in the spores?

Is it possible that what I have may not be bracken?


Yes, that is definitely bracken. Given where you are it might be a different species of Pteridium, and as far as I can see all the studies have been conducted on Pteridium aquilinum, but it's most definitely bracken. All other ferns have undivided fronds.

There have been several studies on bracken's allelopathic properties, which you will find with a web search.

As far as I can see, the allelopathic properties do not affect other plants universally, and some species, such as Digitalis (foxglove) do not appear to be affected, but I'm not finding any evidence of systematic research to find out which plants are affected and which are not. It should not, as far as we know, massively affect established plants significantly, but there is too little research to be sure.

Also, as far as I can see, the carcinogenic properties would be a problem only if you ate the bracken or inhaled the spores.

 
Levente Andras
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Juan Sebastian Estrada wrote:This is really a bummer for me. In the following pictures you can see that my property has quite a lot of Bracken growing. It is one of the few things that seem to grow unaffected by all the rampant grass, along with some variety of boneset (which you can also see in the first pic) and other small plants.

To me this has been an indicator of acid and poor soil (even though there is a fairly good amount of organic matter) and I was until now under the impression that the Bracken was here helping to restore balance and bring the pH back up, so I have been chopping and dropping it under my fruit trees as mulch and adding it to my weed teas in the hope that it will release some potassium, but now I'm afraid that I've been doing more bad than good? I'd really like more info and confirmation on its allelopathic (it certainly is not making the grass unhappy) and carcinogenig properties.

Is there any way that the carcinogenic compounds will transfer to my trees or are they only in the spores?

Is it possible that what I have may not be bracken?


Thankfully, I have never had bracken in my gardens, but there was a lot of it in places where I went on long trips in the summer. So I read up on bracken (on the Web) - hence my knowledge on the subject is only 'second-hand'.

Based on what I've read so far, I suspect that bracken (or its spores) will NOT affect your trees per se.

What is more concerning is Bracken's potential for contaminating water sources where bracken is present in great quantities), and its toxicity to animals that eat it. You can find info on the Web on these issues.
 
Juan Sebastian Estrada
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Thanks Neil and Levente.

Based on some internet searches I can say that it is most likely Pteridium aquilinum. People here use it a lot for burning off the hair of slaughtered pigs (it does make great kindling when dry).

I guess I'll just stop using it for mulch and try to get rid of it by consistently pulling and cutting it over time, and hope that as the system progresses it will recede.

I've been thinking of spreading some wood ash around to mitigate the soil's acidity, maybe that will also make the bracken unhappy.

What if I burn it? do you think that will eliminate the allelopathic compounds but leave the potassium and trace minerals available in the ash?
 
AleŇ° Fister
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In my country (Slovenia) they traditionally used bracken for bedding (Slovenian wiki here). Which was very likely brought back to the fields for fertility next year, so I don't think the allelopathic compounds are an issue in this case.
Some even say bracken has a detterent effect on slugs and mulching with bracken keeps slugs away.

So personally I think no harm should come from moving around bracken once in a while. Or mulching fruit trees with it. I'm not sure it is appropriate for the garden, but some shred it and use it like that for mulch.
 
Wendy Howard
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Anything can be carcinogenic in sufficient quantity. Bracken gets such a bad rap! Hot and dry isn't quite the story - it will appear after land is burnt to rebalance the potassium levels in the soil. It grows all over places like the Scottish Highlands where 'hot' and 'dry' occur about 5 days out of 365, but again it appears in response to burning - the practice of burning heather, the natural groundcover, to keep it to a manageable size has encouraged the bracken to take over. So they burn the bracken. Which just encourages more bracken ...

It will also grow on ground that pretty much nothing else will. Here on mountain slopes where bedrock is very close to the surface, it's the bracken that helps form soils with its extensive root mass. Once climax vegetation is established, it will die back.

There's a lot of bracken here. Regular devastating forest fires (on account of pine and eucalyptus monocultures) make sure of that. It's a valuable plant which I use a lot. Early in the season before the fronds have hardened, I cut it for the compost heaps because it's so rich in potassium. Then I let it grow. Its dense cover helps keep the ground cool and trap moisture through our long hot summers. Tree plantings will survive without irrigation surrounded by bracken. They're far less likely to if the bracken is removed. I pull up fronds and stick them in the soil to shade young plants in the vegetable beds from the afternoon sun. I use it for mulch both around trees and (chopped more finely) in the vegetable beds. I haven't noticed any allelopathic effect going on. I also use it for thatching things like the poultry houses.
 
Erwin Decoene
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Over here, ferns have the reputation to repel insects and to be unedible. The insect repellant quality is named as the reason why dried ferns are good bedding. I also believe some species were used medicinally. If i'm not mistaken bracken is also a traditional animal fodder in Scotland.

I can't say for now, where i picked this up. Must by thirty years ago in my youth holliday camp days. No digital source material.
 
Liz Green
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Hi. Have a look at the Braken (sic) Fern thread on the cascadia forum. www.permies.com/+/679/cascadia/Braken-Fern - some useful information there.
 
Roberto pokachinni
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A lot of the talk in this thread has to do with Bracken Fern, and that is all good, as it may be related to how toxic the sword ferns are, but it should be put into the context that there is no science (and no websites indicating even pseudo science) that I have found that would indicate that sword fern fronds would be detrimental to use as mulch. I spent an hour looking and speed reading on quite a few pages.

Here's the way I see it: There is every indication that a healthy soil will not be adversely affected by toxic alkaloids that are biologically based (and even many that are petrochemical or heavy metal based), unless those biological alkaloids or terpenes or whatever are actually alellopathic in their local ecosystem to desired plants. The SOM (soil organic matter) included in a proper soil food web, especially including fungi, has a way of sequestering toxins, chelating heavy metals, and thus neutralizing most problems, essentially locking them into the soil in ways that are not clearly understood, but do have some documentation for you to explore.

There may be an alellopathic nature to some species of plant giving off exudates when they grow, but I've never heard of sword fern being an issue in this regard. I planted it as a landscaper in mixed groupings in Vancouver, B.C., quite a few times, with no adverse effects (we had long term maintenance contracts, and my boss would never plant things that would be an issue).

So I did a search looking for uses of Bracken since it is the one with known toxicity in some cases. I found this link (the underlining and bold is mine)which contains these quotes:

Considered so valuable during the Middle Ages it was used to pay rents.
Used as roofing thatch and as fuel when a quick hot fire was desired.
The ash was used as a source of potash in the soap and glass industry until 1860 and for making soap and bleach. The rhizomes were used in tanning leathers and to dye wool yellow.
Bracken still used for winter livestock bedding in parts of Wales since it is more absorbent, warmer, and easier to handle than straw.
Also used as a green mulch and compost


Toxicity: Known to be poisonous to livestock throughout the US, Canada, and Europe. Simple stomach animals like horses, pigs, and rats develop a thiamine deficiency within a month. Acute bracken poisoning affects the bone marrow of both cattle and sheep, causing anemia and hemorrhaging which is often fatal. Blindness and tumors of the jaws, rumen, intestine, and liver are found in sheep feeding on bracken fern.
Toxicity: All parts of brackenfern, including rootstocks, fresh or dry leaves, fiddleheads and spores, contain toxic compounds, and are poisonous to livestock and humans. Consumption of brackenfern causes vitamin B1 deficiency in horses, and toxins can pass into the milk of cattle. Young leaves of brackenfern have been used as a human food source, especially in Japan, and may be linked to increased incidence of stomach cancer. Humans working outdoors near abundant stands of the plant may be at risk from cancer-causing compounds in the spores.


Conclusion: Considering the Bracken was used as a green mulch and compost, even though it was known to kill livestock, while also considering that Sword Fern does not have such toxic associations, I would make the conclusion (not empirical or authoritative or even well researched-this was a quick search) that it would be safe to use Sword Fern for mulch.


 
Neil Layton
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I agree we need to be separating out the two ferns.

User Nicole Alderman is using sword fern (Polystichum munitum, I think) native to western North America. There is no evidence of this plant releasing toxic or allelopathic compounds, but no evidence does not equal it does not. Her observations that potatoes, which will normally grow through just about anything, will not grow through sword fern mulch suggest further observations may be useful. I doubt it will harm her trees.

User Juan Sebastian Estrada is using bracken (most probably Pteridium aquilinum, with a cosmopolitan distribution, but possibly P. arachnoideum or P. caudatum, native to Central and South America), readily distinguished by its divided fronds. There is evidence of the release of allelopathic compounds which may inhibit the growth of some plants but not others: this may make it a highly useful mulch if we can further identify which plants are and are not affected. Again, I suggest field trials. It does reduce losses of potassium and nitrogen, and lowers soil pH. Eating the plant may be carcinogenic, and caution is advised when feeding it to livestock over the long term. Hot composting this plant should metabolise any toxins, or I suppose you could use pyrolysis and use it as biochar. Where I come from bracken is recognised as highly opportunistic, and the reasons for this may be complicated.

 
Hans Quistorff
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Juan Sebastian Estrada wrote:Thanks Neil and Levente.

Based on some internet searches I can say that it is most likely Pteridium aquilinum. People here use it a lot for burning off the hair of slaughtered pigs (it does make great kindling when dry).

I guess I'll just stop using it for mulch and try to get rid of it by consistently pulling and cutting it over time, and hope that as the system progresses it will recede.

I've been thinking of spreading some wood ash around to mitigate the soil's acidity, maybe that will also make the bracken unhappy.

What if I burn it? do you think that will eliminate the allelopathic compounds but leave the potassium and trace minerals available in the ash?


I have considerable experience with bracken fern. It was the bane of my youth because I had to take the scythe and cut it during the full moon every month during the spring and summer.

According to local lore it could only be starved out by cutting it when tender to make it bleed sap to starve the root. It was my fathers opinion that it grew all night during the full moon; thus my assignment.

When you pull it, as described earlier, you get a black tip which makes it like an arrow and it will work for that purpose when mature and the fronts cut back. but you do not cause much damage to the plant by pulling it because it just breaks at that sacrificial point that it dies back to in the winter. If you dig it up, which I have done inadvertently while excavating a large hole, The plant is actually a web of root one to three feet down at the interface between the soil and subsoil. Therefore plowing would not remove it and would often make it grow more vigorously. Whenever the ferns can open their fronds long enough the roots prepare fresh buds to send up then store energy to send them up. Therefor regular mowing when they are in high fiddlehead stage is the only way to starve them out.

If when digging you find a black crusty root that you might think is just a dead tree root check carefully if it has a moist thread in the center it could be a bracken fern root and they are almost as persistent as Himalayan blackberry roots.
 
Levente Andras
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Neil Layton wrote:I agree we need to be separating out the two ferns.

User Nicole Alderman is using sword fern (Polystichum munitum, I think) native to western North America. There is no evidence of this plant releasing toxic or allelopathic compounds, but no evidence does not equal it does not. Her observations that potatoes, which will normally grow through just about anything, will not grow through sword fern mulch suggest further observations may be useful. I doubt it will harm her trees.

User Juan Sebastian Estrada is using bracken (most probably Pteridium aquilinum, with a cosmopolitan distribution, but possibly P. arachnoideum or P. caudatum, native to Central and South America), readily distinguished by its divided fronds. There is evidence of the release of allelopathic compounds which may inhibit the growth of some plants but not others: this may make it a highly useful mulch if we can further identify which plants are and are not affected. Again, I suggest field trials. It does reduce losses of potassium and nitrogen, and lowers soil pH. Eating the plant may be carcinogenic, and caution is advised when feeding it to livestock over the long term. Hot composting this plant should metabolise any toxins, or I suppose you could use pyrolysis and use it as biochar. Where I come from bracken is recognised as highly opportunistic, and the reasons for this may be complicated.



A good summary.

Regarding bracken, we may want to look beyond its effects on plants when used as mulch, or on people/animals when ingested. In places where bracken is growing in large numbers (area, density), contamination of water sources may be a concern. As discussed in this (rather alarmist, I admit) article:

http://www.theguardian.com/society/2004/sep/09/research.science

I'd also be careful when handling large quantities of bracken at the stage when its spores become airborne (e.g., in the process of cutting and transporting it & laying it down as mulch / bedding). As the plant is carcinogenic, it's better to avoid inhaling the spores.
 
Hans Quistorff
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Separate post on the sword ferns. I do like to use them as living mulch. I have successfully transplanted them during the winter to more desirable locations. Mulching with the woven mat of leaves is a great idea; if the spores start a new plant it will be in the correct place.

Interesting comparison between the eastern variety that I experienced and ate in Maine and the western variety that I have here. The fronds of the ones in Maine would almost completely disappear into the soil under the snow during the winter. Here the fronds stay green all winter and the bottom layer on the ground takes several years to decompose. The fiddleheads here have a protective coat as they come up which has an undesirable taste compared to the ones in Maine.
 
Peter Ingot
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A friend of mine researched bracken ash as fertiliser at agricultural college. He found it to be rich in potassium and very effective for potatoes and other crops. He attempted to get it approved as an organic soil amendment but was told that the ash would have to be composted first, which he suspected would cause much of the potassium to be lost. Bracken is the best natural source of potassium that I know of.

I have used bracken and other ferns as mulch and found them to work well. Plants seem to grow well around them.
Bracken is definitely allelopathic. It takes over. I would not expect much to grow through a bracken living mulch. The impression I get is that once allelopathic plants are dead, the allelopathic effects don't last. I have been watching a variety of plants springing up in dead and dying pine forest for instance. Organic compounds tend to break down sooner or later. Allelopathy is a plant continually pumping out natural herbicide into its environment.

A study on lung cancer showed after exhaustive statistical analysis that forestry workers who breathed bracken spores on a daily basis were at a higher risk of lung cancer than average, once factors such as smoking were factored out. Cancer is apparently higher in cows which graze on bracken infested areas and there is even evidence that milk from cows in Costa Rica which ate bracken could be carcinogenic. The very mention of the word "cancer" seems to provoke panic in some people, and the media regularly spouts utter tripe on the subject. What people should be asking is "how big is the risk?" Feed enough of something to enough rats and you can often prove that it causes an increased risk of cancer, but what is less commonly reported is that the increased risk might be 0.0001% I can't find any actual data on the risks from bracken, and until I do, I won't lose much sleep over it. Cancer research UK doesn't think its a big deal compared to food and smoking http://www.cancerresearchuk.org/about-cancer/cancers-in-general/cancer-questions/does-bracken-cause-cancer Animals rarely eat their bedding, and washing root vegetables is a no brainer.

Animals shouldn't graze continuously on land infested by plants they don't want to eat. It's bad pasture management for one thing, it will encourage the plants you don't want. Close cutting and removal of bracken encourages grass to grow at its expense. I would not hesitate to compost the bracken obtained this way unless I suspected the land was contaminated with heavy metals.
 
Juan Sebastian Estrada
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Lots of great info. I agree that the threads should be separated.

Now I'm still at a loss with the aspect of soil acidity: Even though I haven't tested my soil, there are certain indicators that suggest my soil is acid, e.g. the property was previously planted with conifers, certain trees from the myrtaceae family which like acid soils have been well adapted like psidium cattleianum and eugenia sp, presence of dock (rumex sp) and dandelion, and of course bracken fern. Also the previous owner used to burn cut grass and brush after mowing in a specific spot and there the grass seems to be greener almost all of the time, which I assume has to do with the ash content, but I prefer not to grow anything there because I suspect he might have also burned other types of garbage there.

My question is, why would bracken make acidic soil even more acidic? I thought these transitional species normally would help stabilize soil conditions so that other species could move in and take over in the successional path, thus my initial assumption that bracken would help raise the soil pH. Might this be the reason that allelopathy is assumed? perhaps other plants don't like growing around bracken simply because it makes the soil more acidic instead of actively putting out allelopathic compounds?
 
Chris MacCarlson
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Hey all -

Bracken fern is clearly edible, but may be one of those things that may not be a good idea to eat in large quantities.

Regarding the use of bracken fern as a mulch. Mulches that have a high carbon or lignin content can "lock up" nutrients that would be otherwise available to plants. This isn't necessarily a problem if you have sufficiently high quality soil around a tree, but in some cases could lead to decreased nutrient availability for plants, until the bracken suffiently breaks down.

From a quick search, Bracken fern litter has a high C:N ratio (77:1, compared to 20:1 for grass clipping), and tends to acidify soils where it decomposes.

If you wanted to use bracken fern around trees, but are worried about locking up nitrogen or acidifying, i would chop and drop, or make a pile, and let the bracken decompose for a year, best if mixed with other greenery, before adding around planted trees or shrubs.


Sources:
Impact of litter quality on mineralization processes in managed and abandoned pasture soils in Southern Ecuador https://www.researchgate.net/publication/223336699_Impact_of_litter_quality_on_mineralization_processes_in_managed_and_abandoned_pasture_soils_in_Southern_Ecuador_Soil_Biol_Biochem
Forest Service Fire Information database http://www.fs.fed.us/database/feis/plants/fern/pteaqu/all.html
 
Roberto pokachinni
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Bracken fern is clearly edible, but may be one of those things that may not be a good idea to eat in large quantities.


Hi Chris; This is probably true.

Here's another quote from the link that doesn't seem to be working for me now... I will try again here And it looks like it worked this time. Sorry I didn't test it. This is a GREAT site for ferns and other woodland plants!

Most commonly used today as a food for humans. The newly emerging croziers or fiddleheads are picked in spring and may be consumed fresh or preserved by salting, pickling, or sun drying. Both fronds and rhizomes have been used in brewing beer, and rhizome starch has been used as a substitute for arrowroot. Bread can be made out of dried and powered rhizomes alone or with other flour. American Indians cooked the rhizomes, then peeled and ate them or pounded the starchy fiber into flour. In Japan starch from the rhizomes is used to make confections. Bracken fern is grown commercially for use as a food and herbal remedy in Canada, the United States, Siberia, China, Japan, and Brazil and is often listed as an edible wild plant. Powdered rhizome has been considered particularly effective against parasitic worms. American Indians ate raw rhizomes as a remedy for bronchitis
Bracken fern has been found to be mutagenic and carcinogenic in rats and mice, usually causing stomach or intestinal cancer. It is implicated in some leukemias, bladder cancer, and cancer of the esophagus and stomach in humans. All parts of the plant, including the spores, are carcinogenic, and face masks are recommended for people working in dense bracken. The toxins in bracken fern pass into cow's milk. The growing tips of the fronds are more carcinogenic than the stalks. If young fronds are boiled under alkaline conditions, they will be safer to eat and less bitter.
Bracken fern is a potential source of insecticides and it has potential as a biofuel. Bracken fern increases soil fertility by bringing larger amounts of phosphate, nitrogen, and potassium into circulation through litter leaching and stem flow; its rhizomes also mobilize mineral phosphate. Bracken fern fronds are particularly sensitive to acid rain which also reduces gamete fertilization. Both effects signal the amount of pollutants in rain water making bracken fern a useful indicator.
Fronds may release hydrogen cyanide (HCN) when they are damaged (cyanogenesis), particularly the younger fronds. Herbivores, including sheep, selectively graze young fronds that are acyanogenic (without HCN) Lignin, tannin, and silicate levels tend to increase through the growing season making the plants less palatable. Cyanide (HCN) levels fall during the season as do the levels of a thiaminase which prevents utilization of B vitamins.


So... all of that quoted, I would say that your statement is true, but this sort of information (about it's potential as a carcinogen as well as the thiaminase levels), should be registered in the mind of those who are choosing to partake of picking this edible.

And... all of that now said, I pick it, but do so not as a bulk crop for extended consumption.
 
Nicole Alderman
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When I researched bracken a while back, I saw a lot of the same info as Roberto, and came to a sort of similar decision as his. I rank bracken fiddleheads up there with fast food. It's edible, and my body should be able to handle eating it once or twice a year if I feed my body well the rest of the year. If someone served me some, I'd eat it. But, like with fast food, I also really have no desire to go out of my way to consume it.
 
Peter Ingot
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Chris MacCarlson wrote:

From a quick search, Bracken fern litter has a high C:N ratio (77:1, compared to 20:1 for grass clipping), and tends to acidify soils where it decomposes.



Sources:
Impact of litter quality on mineralization processes in managed and abandoned pasture soils in Southern Ecuador https://www.researchgate.net/publication/223336699_Impact_of_litter_quality_on_mineralization_processes_in_managed_and_abandoned_pasture_soils_in_Southern_Ecuador_Soil_Biol_Biochem
Forest Service Fire Information database http://www.fs.fed.us/database/feis/plants/fern/pteaqu/all.html


I'm guessing that figure would be for brown fern cut at the end of the season (roughly equivalent to straw). If you cut it early in the season it would have a lot more nitrogen (roughly equivalent to grass clippings). High carbon is actually pretty good for surface mulch (straw, bark chippings etc.) to control weeds, provided the soil underneath has enough nitrogen. Acidification is a valid concern though.

BTW in South Korea, Bracken is a protected plant, the government is concerned that it may go extinct from over picking of fiddleheads!
 
Hans Quistorff
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Peter Ingot wrote:

BTW in South Korea, Bracken is a protected plant, the government is concerned that it may go extinct from over picking of fiddleheads!

Which means you can make it a cash crop by picking it at the correct stage and sell it to the Koreans.
 
Jan White
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The property we just bought and are moving to in the spring is a bracken forest, so I did quite a bit of research a while ago on it and decided I'm comfortable using it. The ptaquiloside, the carcinogenic compound, breaks down with composting. If the compost is used at the right time, it's not even acidic. Our soil is very sandy, so I am concerned about PTQ contamination in the water and will have to look into that at some point.

This shows the results of using composted bracken as a planting medium for various species, on its own and in various mixes. http://www.forestry.gov.uk/pdf/fcin3.pdf/$FILE/fcin3.pdf

I didn't bookmark much of what I was reading, but there's one source anyway. Hope it helps someone.
 
Hans Quistorff
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The research paper confirms what I wrote about bracken control. So It is good to know that if you cut it when it has put out its maximum growth and before it starts to harden, it not only stunts regrowth and opens the soil under it to crop growth but it also provides a valuable compost or mulch. My experience with areas that have been in fern forest for a long time is that it will have an excellent soil profile. If cut early summer and again in fall it should be good to plant winter wheat or barley if your climate allows. The shade of the standing grain in the spring should further stunt the emerging ferns.

The medium weight scythe is the one I used back in the 50's to cut the ferns but I would use the heavy brush one if there was saplings in the mix.
 
Abbey Battle
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Neil Layton wrote:
Levente Andras wrote:There is at least one genus of ferns - Bracken (Pteridium) - which should be handled with caution.

Looking at sources available on the web, you can learn that:

- The plant is carcinogenic to animals
- It seems that spores wafting in the air (e.g., in hot, dry weather) are carcinogenic if inhaled
- There may be an association between eating bracken and stomach cancer or cancer of the oesophagus in humans
- If bracken or its spores get into the water supply, it is possible that it would be carcinogenic


Bracken (Pteridium aquilinum) is a common wild species around here. It only spores after a hot, dry summer, which isn't common in this country.

That said, the plant does release allelopathic compounds, which do remain in the soil after decomposition, so I would still think twice about using it as a mulch.

It's easy to recognise as this is the only one with divided fronds.


Oh wow, thanks for that. I never knew the difference. I don't know if I have bracken or not. Have always called it bracken so presume it is. Unfortunately we do have hot dry summers (not this year I admit) in the SE.
I'll have to check what covers my field, I don't think it's allelopathic as I have lots of wild flowers growing where I have cut it down.
I would like to experiment with using it as a weed suppressant. I think it's sold as a compost from Ashdown Forest. Before they reintroduced sheep.
 
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