Description

Downy mildew is a foliage disease caused by several types of oomycete microbes. They spread between plants especially during wind-blown rain periods.

Warm and wet weather increases the dispersal of the disease. In these favourable conditions, prevention measures are mandatory.

Info

Plants Affected

Grapevines

Brassicas

Cucurbits

Lettuces

Main Symptoms

Discolouration on leaf surfaces

Fungal growth

Abnormal leaf fall

Necrotic areas

There are various species of downy mildews, each one affecting its own group of plants. However, the prevention and control methods are mainly the same.

How to Prevent

Allow enough space for good air circulation between plants.

Irrigate in the morning to promote shorter periods of leaf wetness.

Water from below, e.g. as a drip system.

When possible choose cultivars that are resistant to downy mildew.

In greenhouses control humidity.

 

Control Measures

Remove and destroy affected leaves and if necessary all the plant

Use Bordeaux mixture especially when disease-favourable conditions are expected

Nettle Slurry

Horsetail decoction

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