but my courgettes were so good last year...

Hello all, have a couple of questions re courgettes. I've had 4 fruits set and grow only to turn yellow, go soft and stop growing. Generally the plant looks well (large and robust) but the leaves are covered in silvery white coating and the courgettes themselves are as said. Does this sound like powdery mildew and does anyone know if this can lead to the rotting fruit?

but the yellowing fruit sounds like a pollination problem. They should sort themselves out though