What species of fungus grows on my coffee grounds?

patty4150(SoCal)October 25, 2007

I am trying to find out what sort of mold spores I am accidentally inhaling when I take the moldy espresso pucks out to the compost.

The mold grows on the pucks in a couple days. It starts white, somewhat powdery looking, and turns green as it starts to sporulate. I don't recall if it will then have a black stage as well, I think it does.

I think it might be Rhizopus, but I wonder if it might be something of more concern like Aspergillus.

Does anyone know the common molds that grow on coffee grounds?

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Guess I really never looked at the mold on coffee grounds as anything other than the initial stage of the breakdown process. Anyone with mold allergies might regard it in a different light.

Aspergillus mold is white and gray and appears fluffy or feathery and I've seen that mentioned in conjunction with the breakdown of moist coffee grounds.

Rhizopus is the common bread mold.

Although some people could make an educated guess, molds can only be positively identified with a microscope.
Bluish-green to green molds are usually Penicillium or Aspergillus. Black to brown-black molds can be Aspergillus niger, Alternaria alternata, Cladosporium herbarum, Cladosporium sphaerospermum, or Stachybotrys chartarum (a highly toxic mold). Reddish or pink molds are usually species of Fusarium.

    Bookmark   October 26, 2007 at 1:09AM
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I don't know which molds grow on coffee grounds, but if you're concerned, you could always wear a mask while adding them to the compost.

    Bookmark   October 26, 2007 at 1:49AM
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The mold described in the first post is called "Trichoderma" or "the forest green mold". Completely harmless and, if tested, would be found contaminating everyone's home in North America.

It also tends to be the bane of small-scale, home-grower mushroom farmers because it is parasitic to other mycelium (the "root system" of fungus) and can ruin crops.

Nothing to worry about but as I happen to be allergic to that and several other types of molds, I tend to air dry/sun dry my UCG unless I plan on using them immediately.

    Bookmark   October 26, 2007 at 7:38AM
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gardenfanatic(MO zone5b)

I've been wondering about that too, because I was concerned it was the kind that causes crown rot in hostas. Anyone know what kind of fungus that is?


    Bookmark   October 26, 2007 at 3:53PM
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claireplymouth z6b coastal MA

This timing is perfect - I went to my local coffee shop this morning for grounds and they asked me if I'd take the espresso pucks with orange mold. I said sure.

She said that only their espresso grounds produced the orange growth - she didn't know why.

This mold is a soft peach color.


    Bookmark   October 26, 2007 at 4:11PM
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I am not sure what the mold that forms on spent coffee grounds is but it is not harmful to your garden. Since it is part of the process that will digest those grounds it is not a plant disease any more than the penecilin mold on bread is.

    Bookmark   October 27, 2007 at 7:05AM
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I've been getting coffee grounds for the compost and garden for a couple years now. I've seen white, gray, yellow, orange, etc. I usually don't see it on grounds that I get and use right away but stuff I leave in the bags or put in a bucket for a while before using always get some type of mold. Mold is everywhere and so long as I can't smell it in the house or see it on food I'm about to eat, I'm usually fine with it.

    Bookmark   October 27, 2007 at 9:46AM
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Crown rot of hostas is attributed to Sclerotium rolfsii, aka southern blight. This is a pathogenic fungi rather than the harmless fungal organisms associated with decomposition, which is what is present on the UCG's. Incorporating UCG's or any other OM into the soil may very well build up sufficient populations of beneficial soil organisms to keep hosta crown rot at bay.

    Bookmark   October 27, 2007 at 10:13AM
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claireplymouth z6b coastal MA

I haven't been concerned about the mold on coffee grounds; I figured the grounds were just raring to compost.

My only concern was putting the moldy bucket in the trunk of my car. Luckily it's too heavy to fall over.


    Bookmark   October 27, 2007 at 12:21PM
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Thanks for the feedback -

FWIW I don't worry about the garden or the plants. The more fungi the merrier. Except for powdery mildew.

But I have had a sore throat for ten months and the doctors (4 different specialties) are all stumped. I have been wondering for three months or more, if it could be some exotic mild fungal infection, but since I don't have anything life threatening the doctors have simply told me to go home and eat right and eventually maybe it will get better. Or maybe it wouldn't. So I've been following that advice for a while now.

Anyway, I asked y'all what mold might be on the coffee grounds, because we keep our pucks way too long, there are plumes of spores coming out of the puck tray when we finally dump it in the compost, it's pretty bad. I thought if the stuff was aspergillus, that I could tell the doc that and he might be persuaded to give me an antifungal to possibly help with this unending sore throat.

As it turns out, he wrote the prescription anyway - He was not eager to do so, because there was no good reason to assume that this is fungal, but I promised I wouldn't sue him :) and since this sore throat has been such a pain, for so long, it seems like a short trial course might be appropriate. Cross your fingers.

    Bookmark   October 27, 2007 at 9:42PM
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sunshineboy(Z5 MA)

Well Patty,
I just wanted to express some concern with your choice of persuading your physician to prescribe some systemic antifungal drugs. Are you aware of the potentially serious side effects of some of these medications? Depending on the drug, a few of the benign side effects possible are upset stomach, constipation, diarrhea, breathing problems, change in blood pressure, etc. There are also rare episodes of anaphylaxis and even spontaneous death. I feel this is not the right forum for such a discussion, but I suggest you inform yourself before taking any medication for what you might guess ails you.

Just a thought. Safety first. Not trying to upset you or start a debate about antifungal drugs.

My suggestion is, if you suspect the problem stems from the way you handle coffee grounds, modify your handling techniques.

    Bookmark   October 28, 2007 at 6:26AM
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Well, sunshine boy,

I just wanted to express some concern with your choice of being entirely unsupportive.

Just a thought. Think first. You have no idea what I've gone through, my level of education, or the amount of research that I have done on this topic. Not trying to upset you or start a debate about internet etiquette.

My suggestion is that you modify your internet etiquette techniques.

(See how that comes across, son?)

    Bookmark   October 28, 2007 at 10:59AM
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claireplymouth z6b coastal MA

I've had episodes of sore throats associated with a lousy post-nasal drip. Probably related to a chronic sinus infection caused by who knows what organism(s).

I understand your frustration and hope the antifungal medication helps.


    Bookmark   October 28, 2007 at 5:50PM
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sunshineboy(Z5 MA)

Your argumentative tone and condescending manner prove you have superior internet etiquette skills than I.
I apologize for allowing the doctor in me to give recommendations--you obviously are omniscient.
Good luck with your health.

And Im just curious, if you think it might be fungi from your UCG pucks, why not handle them differently? I was not attempting to be flip when I asked. It seems that avoiding behaviors is a more rational choice than polluting your body with potent chemicals. It appears my 2 cents is worth nothing to you.

Again good luck with your health. I had no idea I stepped on a land mine when I replied to your post on an open forum.

    Bookmark   October 29, 2007 at 6:40AM
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Patty, my father had a long term sore throat that would go away when put on antibiotics. It would come back, though, when he was done with the course. After a battery of tests, different specialists, and about a year of pain, the root of the sore throat was found...throat cancer (can't remember the exact one...but it was small and hidden.) Not trying to be the pessimist, but just thought I'd pass that along.

OTOH, mold can do quite a number on our respiratory tracts, too.

Good luck in finding the cause.

    Bookmark   October 29, 2007 at 11:02AM
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kqcrna(z6 SW Oh)

Patty: Another consideration is allergies. Have you seen an allergist and had testing? You could be allergic to mold or dust mites or any type of pollen... The possibilities are endless.

Just a thought.


    Bookmark   October 29, 2007 at 1:57PM
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curtludwig(New England)

Cheez whiz Patty I thought the Sunshineboy was being pretty polite and not condescending at all. Like reminding people to use welding helmets even though the fools on tv go without them all the time. I had no idea anti-fungals were so dangerous.
If you already knew that then good for you but I for one did not and if I'm ever in your position I'll be glad I read this post!

    Bookmark   October 29, 2007 at 4:21PM
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I based the wording of my response to sunshine boy exactly on his post (the one I responded to). If my post was a "land mine," "argumentative," and "condescending," then that makes my point about how his comes across.

Thanks to the supportive responses - Claire, anitamo and kqcrna. I appreciate your well wishes. You probably understand why I didn't bring it up in the OP, but when everyone started talking about fungus in their gardens I realized there had been a misunderstanding, about what I was concerned about! On second thought I should have let sleeping dogs lie.

    Bookmark   October 29, 2007 at 10:48PM
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