Prevention is Better Than Cure 

Good cultivation is as much a part of fighting diseases as recognizing and treating them, and with few fungicides now available to the amateur, preventative measures are essential.

Plants require a ready supply of nutrients and water to sustain healthy growth, so add plenty of organic matter to the soil to release nutrients and help retain moisture. Additional watering may also be needed, particularly in hot weather. It is important not to forget plants under cover and in containers, which rely on regular watering and feeding to sustain them. Damp conditions and poor air circulation can encourage fungal problems, such as damping-off of seedlings, so use free-draining potting mix and provide good ventilation when sowing indoors.