[Pete C]

While I was weeding the plot this morning, I noticed sky blue marks on broad
bean leaves. On further inspection, I found the same on French beans and
peas. Some just spots, others about 5p size. It wipes off with a wet finger.
Any ideas as to what this could be?
Ta
Pete

[yorky]

Have you or someone on a nearby plot been spraying against potato blight? It could be overspray from something like Bordeaux mixture.

[Pete C]

Thanks Yorky, good thought, but no.
Pete

[Annen]

You are not under a flight path are you?  Blue ice! 

[Pete C]

You are not under a flight path are you?  Blue ice! 

Actually, plot is almost under the flight path into London Docklands. Elsewhere, someone has suggested aviation fuel. 

[Beetroot queen]

You are not under a flight path are you?  Blue ice! 

Actually, plot is almost under the flight path into London Docklands. Elsewhere, someone has suggested aviation fuel. 

Doesn't sound great does it, would that have any effect on the veg

[Growster...]

You are not under a flight path are you?  Blue ice! 

Actually, plot is almost under the flight path into London Docklands. Elsewhere, someone has suggested aviation fuel. 

Some light coloured buildings show up aviation fuel staining, around Gatwick, but that doesn't really help does it...

[Pete C]

UPDATE
On further inspection today, I found it on swede and strawberries too. It
all washed off with a watering can. I checked half a dozen plots either
side....nothing. Then I realised the affected beds are all adjacent to
paths. Getting paranoid now....who have I upset?
 
Pete

[Annen]

I also found some blue spots on my potato  leaves today, but they are the exact same blue as slug bait pellets, so I think that's what mine are - dissolved slug bait.