Courgettes are generally problem free, although prone to powdery mildew late in the season as the nights turn colder and especially if it has been a dry summer. Courgettes are also much effected by the weather and dislike cool conditions which can reduce pollination and so yields. Another problem of all of this family, squashes and cucumbers is they can root off at the stem where it meets the soil. This is much more likely to happen in a colder summer where after rain the wet lies in the soil for longer and newly planted courgettes which are not yet established are the most prone. If happy Courgettes fruit prolifically and two./three plants is usually enough for any courgette loving family.