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

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

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.

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.

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?

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?

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.

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?

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.

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

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.

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

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.

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.

Nicole Alderman wrote: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?

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