considering how many times you sprayed.. and with so many different things... im at a loss to figure out which one damaged the leaves ...

and if we cant rule out spray damage.. its of no use to contemplate media deficiencies ...

if you still have seed.. why not just start a few more ... and if you end up with the same issue.. without the spraying.. we might be able to think it is a media problem ...

what does this mean: mushroom compost of somewhat dubious provenance

ken

Don't think the sprays damaged the leaves, the sprays started after the leaves started showing signs, and the different sprays were over the course of several weeks.

The mushroom compost thing just means there's a local mushroom farm that gives away free compost - some people swear by it, but I can't really speak to what's in it exactly. The compost I used had been aged for at least a year or two though.

If I hadn't mentioned sprays what would you think it might be?

The pictures look like it may be cucumber mosaic virus. The vector is often aphids. Unfortunately there is no cure and it can spread to other cucurbit species. I'd toss the plants and medium.

Appreciate the response - doesn't really look like CMV to me based on what I've seen. Doesn't really have the 'mosaic' pattern where there are gradual shifts from darker to lighter green, these discolorations are very distinct. I was thinking maybe anthracnose or downy mildew at first but not sure why my sprays wouldn't be controlling them if so....