Shrivelling gherkins

and courgettes....

Thought I had that mosaic virus on my courgettes but I see some healthy new leaves, phew! but - few courgettes.. i.e. few female flowers.. how can I encourage these?

Also, have lost one courgette plant I have in a terracotta pot. Two courgettes have formed about 2 inches long but now starting to shrive. Same with some of my gherkins.. form to about .5 inch and then shrivel. Why? I'm watering regularly but perhaps too much... too much feed?

The only things in my garden that are so far thriving this year, turnips and the runners.

 

Its down to pollination.
Often, until the plants get really established, the first female flowers dont set.

 

Thanks Pete