Getting to know Powdery Mildew

As with rust, powdery mildew is also a fungal disease.  It loves humid conditions, some warmth, and a bit of shade.  As the name suggests, it shows itself as white powdery patches, usually on the leaf surface, and quickly spreads, sometimes causing leaves to pucker and sometimes to yellow off and eventually die.

Powdery mildew spores are spread with air movement. It doesn’t need wet surfaces for its spores to germinate but germination is favoured when humidity is high.  This is why evening watering should be avoided as it creates night time humidity.  Similarly, good air flow around plants is always helpful in reducing fungal problems, and water root zone rather than the leaves.

Some of the most commonly affected plants include roses, strawberries, pawpaw, cucumber, pumpkin, plants in the shade and many ornamentals.  Infected fallen leaves should be picked up and disposed of.  Removing some infected leaves from the plant may also assist with increasing the air flow to the plant.

A seaweed based plant tonic, available from Tanby Garden Centre, used regularly will increase the strength and resistance of your plants.  There is also apparently some evidence that when applied to the soil it will discourage many fungal problems.  Don’t forget the eco seaweed can be mixed with eco fungicide for an all in one treatment.

Sources: NSW Dept of Primary Industries Pests, Diseases, Disorders and Beneficials in Ornamentals: Field Identification Guide; Sustainable Gardening Australia; Organic Crop Protectants.