Green driveway

[Feltwell]

Our not very old tarmac driveway is turning green - primarily on an area that has a large silver birch overhanging it. The bits that are driven on stay clear, as do the bits under where the gates sit when open, it seems to be the areas that get the most sunlight that are going green. It's not moss - it's an even, thin staining, more like algae.

We've not seen this before - the old (also tarmac) driveway never did this.

Any ideas? It's getting a bit unsightly now. I could leave it until summer and see if the drier & warmer weather stops it, but it's not been very wet lately and the driveway has a good slope on it. A wash over with Jeyes Fluid and a stiff broom perhaps? I don't really want to pressure wash it all as it tends to make the driveway go stripey for a few months!

 

[worms]

Jeyes fluid at the right dilution might do it, although summer might save you the effort.

Personally I'd look for something with sodium dichlorophen as the active ingredient.

 

[Flyfisher]

Our not very old tarmac driveway is turning green - primarily on an area that has a large silver birch overhanging it. The bits that are driven on stay clear, as do the bits under where the gates sit when open, it seems to be the areas that get the most sunlight that are going green. It's not moss - it's an even, thin staining, more like algae.

We've not seen this before - the old (also tarmac) driveway never did this.

No real ideas but we have some old tarmac with a similar effect as shown in the photo below. The tarmac is at least 20-30 years old but the gate has only been in place for about 4-5 years. I'm quite surprised about the effect the gate has had. I find it hard to believe it shades such a narrow strip as the sun moves across the sky and it can't really provide much protection from rain as the ground slopes slightly anyway so rain flows across the bare strip.

It doesn't bother me - well, not enough to do anything about it - but your post has made me curious about the effect now.

 

[LadyArowana]

Is the gate oak? and could it be the effect of the tannins leaching out that is preventing moss/ algae growth?

 

[tobydog]

I had a similar thought along the lines that the rain might be washing out the preservative that was dripping on the drive live a herbicide.

 

[Feltwell]

My gates are softwood painted in linseed paint, no preservative.

I think I'll leave it a bit, see what some sun does. Jeyes fluid is expensive! £30 for 5 litres, I had no idea it was that much. I've got a bottle of fungicide, meant for treating growth on masonry prior to painting - I may dilute that down, try an inconspicuous patch and see what happens. It's odd this green stuff - FF's looks more mossy, mine looks like green food dye has been sprayed over the drive, it's like a very thin coating.

 

[LadyArowana]

My gates are softwood painted in linseed paint, no preservative.

I think I'll leave it a bit, see what some sun does. Jeyes fluid is expensive! £30 for 5 litres, I had no idea it was that much. I've got a bottle of fungicide, meant for treating growth on masonry prior to painting - I may dilute that down, try an inconspicuous patch and see what happens. It's odd this green stuff - FF's looks more mossy, mine looks like green food dye has been sprayed over the drive, it's like a very thin coating.

My guess would be that it is some sort of algae, we get something similar in our warm home and there is plenty of sun there, so hoping the Summer makes it go away might be a tad optimistic ( for more than one reason ). I would be tempted to tip a kettle of boiling water on it!

 

[Flyfisher]

Good thinking Milady, but tobydog just pipped you - and I'm now kicking myself for not thinking along those lines.

It's a softwood gate but treated with some no-doubt lethal chemical cocktail (not by me though) - at least it looks lethal to the green stuff. I'm still a bit unsure why the bare patch is so defined, especially as the rainwater runs under the gate, but I reckon that must be the answer.

 

[LadyArowana]

Good thinking Milady, but tobydog just pipped you - and I'm now kicking myself for not thinking along those lines.

It's a softwood gate but treated with some no-doubt lethal chemical cocktail (not by me though) - at least it looks lethal to the green stuff. I'm still a bit unsure why the bare patch is so defined, especially as the rainwater runs under the gate, but I reckon that must be the answer.

Actually, the pixies live by one gatepost and work opposite, so it's all the little pixie feet running backwards and forwards that wears the moss away, but you wouldn't have believed that if I had told you!

 

[Flyfisher]

. . . you wouldn't have believed that if I had told you!

Ah, but I'd have so wanted to . . . faeries at the bottom of the garden is a lovely thought.

 

[worms]

It's a softwood gate but treated with some no-doubt lethal chemical cocktail (not by me though) - at least it looks lethal to the green stuff. I'm still a bit unsure why the bare patch is so defined, especially as the rainwater runs under the gate, but I reckon that must be the answer.

Very well defined indeed, which is strange. What are the nails made of?

Jeyes fluid is expensive! £30 for 5 litres

How long is the drive way? At a dilution of something like 1:60 and something like a litre per square metre, then a 5 litre can would do a 150m driveway. A blast of hot air from a weed wand/flamethrower might do the trick, or perhaps I could post you all the snails from my garden and you could train them to graze it down!

 

[Feltwell]

At a dilution of something like 1:60

Ahh - that makes a big difference! I didn't know that you watered the stuff down to that degree.

 

[Flyfisher]

Very well defined indeed, which is strange. What are the nails made of?

Nuts and bolts actually and I think they're just basic galvanised ones. Are you thinking 'zinc poisoning' ?

 

[Feltwell]

My guess would be that it is some sort of algae, we get something similar in our warm home and there is plenty of sun there, so hoping the Summer makes it go away might be a tad optimistic ( for more than one reason ). I would be tempted to tip a kettle of boiling water on it!

Hmm - I hadn't thought of algae, it would make sense of why it only appears where it gets lots of light. I'll try a kettle of boiling water - should be enough to finally convince the neighbours that I do need certifying if nothing else. It would take a lot of kettle-fulls to do the whole drive though.....

 

[LadyArowana]

Hmm - I hadn't thought of algae, it would make sense of why it only appears where it gets lots of light. I'll try a kettle of boiling water - should be enough to finally convince the neighbours that I do need certifying if nothing else. It would take a lot of kettle-fulls to do the whole drive though.....

This stuff claims to do 100 sq m with one bottle http://www.gardenhealth.com/hero/he...centrate.php?gclid=CPOH4s3j5a4CFUZa3wodT3_MvA

 

[eezageeza]

Jeyes fluid is expensive, but you don't have to buy a 5 lt can! I've never used Jeyes for that sort of cleaning, but imagine it would work. I'd recommend Armillatox, which is very similar, and which i know will work. Dilute it at around 1:300, water on with a fine rosed watering can, and leave it. Nothing will appear to happen, but over the next few weeks the green stuff will gradually disappear (that's assuming we get some rain to wash it away!).

Armillatox is also expensive (last time I looked about £60 for 5 litres) but the smallest bottle you can find will be plenty.

There are chemicals available only to professional users which will also do the job very evffectively, but you'd obviously have to employ someoneto do that, and I'm guessing its not that important!

Oh, and worms is right - something containing sodium dichlorfen will also work. This used to be the active ingredient in garden mosskiller, but I'm not sure that it hasn't been banned - go and peruse the shelves in the local garden centre!

 

[Feltwell]

Thank you everyone - I shall give one of those, or LadyA's "Hero" product a try - although I am a little concerned that if using that I may be required to wear my underpants outside my trousers! You're right, a green driveway is not that important at all - just rather annoying to see a new & expensive tarmac driveway go "green & mouldy" within 2 years.

 

[worms]

I'll try a kettle of boiling water - should be enough to finally convince the neighbours that I do need certifying if nothing else. It would take a lot of kettle-fulls to do the whole drive though.....

You don't have a wallpaper removal steamer do you? I've used mine for all sorts of alternative steam uses and it might do the driveway?

Yes Sodium Dichlorophen was removed from domestic sale in its most useful formulations but you can still get products with it as the active ingredient, it is active at very low concentrations (probably down to about 0.004% w/v), so a little goes a long way.