Powdery Mildew (Erysiphaceae Species)

Plants/trees Affected

Herbaceous and Woody Plants eg. – Apples, Peaches, Plums, gooseberries, strawberries, Rhododendrons, Roses, Sweet Peas, Honeysuckle, Asters, Peas, Beetroot, Parsnip, Brassicas, Cucumber, Melon, Marrow and Ornamental plants.

                         

Symptoms
 

A dry white powdery substance appears on the leaves, shoots, flowers and fruit.  The plant may also show signs of stunted growth and have distorted leaves.  This disease will cause die back and will destroy fruit/crops.

Causes

The powdery effect is caused by thousands of spores from one of a variety of closely related species of powdery mildew fungi. Each of the species of fungi has a limited host range and the mildew on one type of plant will generally not spread to others from a different family. Powdery Mildew thrives best in dry conditions in densely planted areas with poor air circulation and low light.  The spores are carried by wind and will over winter on infected plants or plant debris.

Prevention

To prevent Powdery Mildew it is important to ensure that plant roots do not dry out, mulch in spring to retain soil moisture and water well when needed.  Keep the air circulation flowing by pruning and thinning bushes, don’t overcrowd smaller plants and thin crops to recommended spacing. In Autumn good hygiene is important gather up and destroy fallen leaves, clean and disinfect greenhouses.  It is also possible to buy resistant varieties of plants if your garden is susceptible to this disease.  

Treatment

    Myclobutinal (Bio Fungus Fighter) for ornamental plants, roses & some fruits
    Penconazole (Fungus Clear) for ornamental plants & roses
    Flutriafol (Roseclear) for ornamental plants & roses
    Sulphur dust (or spray with fatty acids) for vines and certain vegetables

    NB – always refer to manufacturers instructions before use.