Potato downy mildew

Potato mildew is a disease that attacks both the stem and leaves as well as the tuber and is capable of partially or totally destroying the crop. It has some symptoms to recognize it and solutions to alleviate it.

Do you want to know how to treat mildew on potatoes?


  • 1 Mildew characteristics
  • 2 Conditions of fungus formation
  • 3 How to avoid mildew

Characteristics of mildew

When the disease occurs on the leaf, necrotic spots are formed that can be recognized with the naked eye, since they have whitish mold in the areas where the disease progresses. The most serious damage occurs when the plant is younger and is not as protected by the leaves.

The spots are brown, similar to leaves, and can affect the entire stem causing it to rot. If the conditions by which the mildew forms are favourable, it will be able to produce more sporangia and germinate, colonizing all the healthier tissue. When this happens, the disease inevitably progresses.

When the spores are carried by the water, the tubers are also infected, acquiring a more corky texture and a light brown color. If we look at the tuber from the outside, we can see the accumulations of white mycelium.

Fungus formation conditions

The fungus requires temperatures above 10 degrees and humidity greater than 90%. When the temperature rises above 30 degrees , its growth stops. Thanks to these conditions, it has been possible to make prediction models for the appearance of mildew.

How to avoid mildew

affected potato

This is a disease that causes more losses worldwide in crops and therefore, it is necessary to have greater control over it. What is currently being done to prevent mildew is to combine disease prediction systems with the development of fungicides capable of eliminating or minimizing damage.

The fungicides that have the most effects are those that are translaminar and systemic. In this way they can act in different stages of potato cultivation.

Potato downy mildew

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