Q How do courgette fruits rot?
A The fruits start to develop normally and then, when still quite small, start to discolour and rot at the flower end. The rot then spreads back along the fruit towards the stem. This invariably starts when the petals of the fading flower start to deteriorate and the rot then spreads into the fruit. The petals rot fairly easily and very rapidly during wet weather.
Q What should I do if courgette fruits are rotting?
A Remove any rotting fruit promptly.
Q How can I prevent courgette fruits rotting?
A Always apply water direct to the base of the plants and avoid wetting the flowers, never water from overhead. In wet weather remove the flowers as soon as the fruit has started to form and that way the problem cannot start.