Powdery Mildew is a common fungal disease and infected plants will have a greyish/white, powdery coating on their leaves and the edges may start dying back. 

• It often occurs in humid conditions and typically affects plants during the late summer months, although once it takes hold it can continue to grow in even dry conditions.
• The disease affects cucumbers, and other vegetables such as beans, courgettes, pumpkins, tomatoes etc. 
• Strawberries and apples and even ornamental plants like dahlias can get infected, and of course any plants in the affected area. 
• Cut off any affected leaves and dispose of them away from your property. 
• It's important to maintain good garden hygiene by removing any other dead plant debris lying around. Do not put any infected plant matter into your compost bin.
• To prevent powdery mildew, regularly spray with a copper compound. Ideally, it is best used just before the plant matures and before the powdery mildew has arrived, but do treat it when you spot it. 
• Keep your plants well-watered as dry, heat-stressed plants are more susceptible to disease. Remember to water at the base of the plant and avoid getting water on the leaves. Another tip is to feed your plants with Garden Time Seafeed which Improves plant resistance to stress from drought, heat, frost and disease.