Downy Mildew

Garden Problems

Downy mildew typically appears as greyish white downy patches on the undersides of leaves and dark patches on upper surfaces.

Identify the problem
Typically downy mildew appear as greyish white downy patches on the undersides of leaves and dark patches on upper surfaces. Other symptoms of downy mildew are distorted growth and dead leaves and shrivelled leaves. Downy mildew causes blight in seedlings. Downy mildew can cause rapid loss of leaves and consequent stress to affected plants.
Common hosts for downy mildew include roses, brassicas, grape vines, hebes, lettuces, peas, and roses.
Powdery mildew has similar symptoms but the grey powdery patches will tend be on the upper surfaces of leaves.
How to solve the problem
- Downy mildew cannot infect plants if their leaves are dry. Where possible grow plants in areas with good ventilation and sunshine to prevent water from resting for long periods on to the foliage. Water plants around roots and avoid applying irrigation to foliage.
- Remove and destroy infected plant parts. Apply PLANThealth Buxus Blight Buster or PLANThealth Copper Fungicide regularly every 14 days to treat diseased plants.
- Once infestation is under control, use PLANThealth Spectrum to provide ongoing protection for your plant. During damp weather, protect young seedlings and other susceptible plants by spraying regularly.
- Disease is often carried between plants by sap sucking insects. Use Organic Super Spraying Oil to control these insects before they can spread disease.
Did you know?
- Downy mildew is caused by several types of oomycete fungi. There are specific species for many plants.