What is happening to my cucurbits?!

[GreaterMarrow]

I'm having terrible problems with my courgette, cucumber and cucamelon plants. The issue seems to follow the pattern of a single leaf on the plant turning papery and then the leaf stem becomes ridged, pale and translucent.

On some of the plants more leaves and stems have then followed suit, but on other plants only the one leaf/stem has been affected and the plant otherwise seems healthy. They have been grown indoors (on sunny windowsill) and I have only just started to harden them off.

Any idea what is causing this? Is there any hope for them?!

I have tried to take pictures of an affected leaf and stem.

[WendyC]

Is it like a powdery mildew or does it look like damage from something burrowing between the layers of the leaf?

[roitelet]

Have they only turned like this since you started to harden them off? If so it is the weather, not warm enough and too windy. Give them some more protection and they will recover.

[GreaterMarrow]

My courgettes had powdery mildew last year and it's nothing like that.

The problem started when they were still being kept indoors so I was doubtful that it was a pest problem.

I've looked at all sorts of pest/disease sites online and can't find any explanation that seems to fit :/

I had wondered whether it was related to the plants being overcrowded on the windowsill but I have no idea really!

[Jungle Jane]

Could it be that the leaves were wet & then burnt by the sun? Do you think they should be in bigger pots? I can't see clearly but they look small? Is the new growth coming through green & healthy? I would pot them on,hopefully your news growth will come through fine & you could get rid of those leaves once you have more leaves. Have you been feeding them too much? Overfeeding can cause damage too?

[lottie dolly]

The only thing i can suggest is,give moor room between plants so the air can travel,in the meantime,remove affected leaves,also could they have had water splash on them,then into the sunny window,think back as to what position of rotation they were on your W cill when you first noticed it,try a rescue first,this year is also turning into another funny germinating/growing year.

[muddled]

Did they have a radiator nearby?

I've done that....not realised that my husband was turning the radiator on " just for an hour, to dry some washing" while I was out at work
Couldn't work out why the leaves AWAY from the window were papery and scorched looking!

[Potstubsdustbins]

Have they been in bright sunlight for any length of time, if so that could be sun scold, cucurbits not not like direct sunlight.

[Thelma Sanders]

I agree, bright sunshine can do that to them, if they're not used to it.

[GreaterMarrow]

Thank you all for your suggestions! I can't decide what the problem is most likely to be. They were in 12cm pots and I was taking care not to get water on the leaves. They could have been scorched as the window does get a lot of sun, but I've had other plants alongside them (tomatoes and chillis) that have not been scorched, although I guess they like the sun more!

I decided to plant the courgettes out on the allotment and just see how they go. I've kept the cucumbers in pots at home for now as they are smaller and only recently potted on. Will see how it goes I guess!