seaweed like fungus taking over driveway

Lummi Island, WA

This fungus began as a small patch in our driveway a year ago. Since then it has begun to take over. It looks and feels like seaweed. No smell but is slimy dark green. When there is moisture in the air, it grows. When dry, it shrivels up and seems to disappear but only until the moisture returns. Now that it's the rainy season here, it's rapidly spreading. So far it is only growing in the gravel and not the flower beds. It's really alien looking. Do not know how to get rid of it, nor do I know what it is? Is it harmful if it reaches the flower beds? In the picture the fungus is all the dark spots.

Thumbnail by lummigirl
Calgary, AB(Zone 3b)

It's not clear to me, from your photo, what you are referring to... is it the small dark patches among the gray gravel?

Bridgewater, MA(Zone 6b)

From what you've written about it (I can't really tell much from the picture either), it sounds like an algae. You could try getting a potassium soap (found in many commercial algae killers) and see if you can control the outbreaks with that.

Carson City, NV(Zone 6b)

There was a thread about this a while ago. I'm not sure if this is the same stuff but maybe it's related.

mid central, FL(Zone 9a)

baking soda and water sprayed on may kill it but you might have to apply it a couple of times.

Saraland, AL(Zone 8b)

Yep, looks like a slimy algea substance. Not sure if it's fungus or algea but I would think that a solution of bleach in a garden sprayer would work.

Sarasota, FL

Better to use copper sulfate. Bleach will harm plants and mess with soil p.h.

Danville, IN

I see this algae growth at one of the wholesale nurseries I use. They get huge slimy mats of the stuff, but that's mainly in the places that don't drain completely. Since they water twice daily, it can be a problem. If you can't get rid of it, I can check at the nursery to see what they do to try to control it. Copper sulfate should work.

Garland, TX(Zone 8a)

Copper sulfate will give concrete (and possibly certain gravels) a lovely aqua-green stain, too.

This message was edited Dec 4, 2010 5:52 PM

mid central, FL(Zone 9a)

that's why i suggested baking soda. personally i love the aqua stain but not just in one spot. baking soda won't discolor anything although it might make it cleaner looking for a short time.

mid central, FL(Zone 9a)

meant to add that this person's driveway looks remarkably similar to mine...what they call a "tar & chip". this photo was taken the day the workmen finished this section. thankfully, the oily tar on the sides was worse than it looked. it dries almost instantly and after a couple of mowings, it was gone.

This message was edited Dec 4, 2010 8:36 PM

Thumbnail by trackinsand
Sarasota, FL

I can't say about the tar and chip drive; I've sprayed a tile patio with no problem except the odor. That disappeared after a few days.
If copper sulfate liquid has petrolium distillates, the you definately do not want to spray this on a driveway made from tar.

hi i have this problem and have been out ther hrs tryin to scrape it all up,its growing like mad at moment.i find if i rake it it just spreads the stuff everywer and grows faster in damp conditions,ive tried bleach ,worked for a bit.
did u solve it lummigirl?

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