Peronospora malattia delle piante

Downy mildew disease of plants

What is downy mildew? How does it manifest itself? What plants does it attack? What are the causes? How is it treated?

Downy mildew disease of plants

Generalities of downy mildew

To the genre downy mildew belong various species of mushrooms of the Peronosporaceae family.

These mushroom species despite being microscopic microorganisms parasitize various ornamental plants (roses), some horticultural and some fruit plants causing conspicuous aesthetic damage and irreparable physiological damage.

The best known and feared mushroom of the family is undoubtedly the Plasmopara viticola which mainly affects the lives.


Symptoms and manifestations

The plants infested with this fungus present the leaves covered by spots:

  • on the top page they are translucent and similar to oil stains;
  • on the top page I’m yellowish mold spots.

Downy mildew-Plasmopara viticola
Over time the disease spreads by hitting i sprouts and floral buds that dry up And they fall.

Read also: Rosa cultivation

The fungus reproduces by depositing on the leaves of oospores, which remain on the leaves even after the fall and if they are not burned, they spend the winter there, and the following year they repeat their cycle infecting the plants.

Damage caused by late blight

The plants attacked by Downy mildew even if they don’t get to the death, show evident signs of suffering: deterioration of vegetation, poor production of flowers and consequently poor fruit production.

Causes and period of infection treatments of downy mildew

The causes of this disease are mostly attributable to particular physical and environmental factors: high humidity And spring temperatures.

The major ones infections occur in periods presenting the so-called rule of three 10:

  • shoots of 10 cm,
  • rain of 10 mm in 24-48 hours,
  • minimum temperature 10 ° C.

Downy mildew

Treatments of downy mildew

In the presence of the three elements listed above, it is necessary to proceed by resorting to preventive treatments.

  1. The plants attacked they must be sprayed with specific products against downy mildew such as products based on copper salts, zinc or organic compounds as with Bordeaux mixture.
  2. The use of these products helps not only to prevent or contain the infection already in progress but it is essential to prevent the germination of conidia.

Downy mildew-vine

You may be interested in: Climbing roses

Fruit plants that are attacked by downy mildew

There downy mildew it is invasive and without any distinction it attacks almost all plants.

Among the fruit plants we remember:


the vine where it manifests itself on the leaves, the still green shoots and especially the bunches.

Ornamental plants attacked by downy mildew

Among the various ornamental plants, the favorite of this mushroom is the rose.

Downy mildew-pink

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Horticultural plants suffering from downy mildew infection

Among the horticultural crops those that suffer most from the attack of this fungus are:

lettuce salad
the lettuce;




artichoke, chard, all crucifers and tobacco plants.

Vegetables suffering from downy mildew

Among the vegetables the most sensitive to the attack of this fungus are:

Downy mildew-pumpkin

melon, cucumber, watermelon, pumpkins and courgettes,






Cucumber-downy mildew
cucumber, strawberries, onion, garlic, leek and shallot.

Downy mildew photo gallery


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