[mdjlucan]

any one no wot doing this to the leaves the brawn Marc on it

[shokkyy]

Actually, I'd like the answer to that too, it's all over my nasturtiums.

[mdjlucan]

all i did was put 2 seeds to a hole  that's how they ore new did not thin them out

[Yorkie]

It's not just sun scorch, is it?  Rain / watering followed by strong sunshine before the water has dried off?

[richyrich7]

I get them too , they are leafminer larvae.  
you get some scorch marks on them too if they get watered in full sun or the sun gets them before the dew lifts, but if it's little tunnels coming off then it's leafminer

[shokkyy]

Then I guess my nasturtium are doing their job as sacrificial companion plants