What is mildew and how do you combat mildew?

Downy mildew is a disease that can be treated

Image – Wikimedia Commons / Rob Hille

The mildew it is one of the diseases that most attack plants. Although we think that it is caused by a single microorganism, in reality there are several species of fungi responsible for the fact that the leaves from one day to the next begin to have yellow spots and a grayish-whitish powder on the underside.

The worst thing is that if we have them near healthy plants, it is most likely that they will also end up infected. Taking this into account, it is important to take a series of measuresfirst so that the disease does not spread, and second so that those crops that are affected can recover, but which ones?

What is it?

Mildew is a fungal diseaseDowny mildew is a fungal disease

Image – Wikimedia / Thomas Lumpkin / CIMMYT

It is a set of diseases caused by different species of parasitic fungi whose spores hibernate in tubers or rootsand are activated in spring, when the temperature is above 10ºC, which is when they are directed to the leaves and the tender stems through the vessels that are inside the plant.

The most popular (because they are the most frequently seen) are:

  • plasmopara viticola: known as the downy mildew of the vine. It is a fungus that only affects plants of the genus Vitis. It causes the appearance of rounded spots normally on the leaves, on the upper side, and a whitish powder on the underside. The fruits can also be damaged, since the stem of the same is vulnerable to the attack of this microorganism. See file.
  • Phytophthora infestans: known as potato mildew or potato mildew. It causes the appearance of dark spots on the leaves and stems of plants, and rotting of the tubers. See file.
  • Phytophthora capsici: known as pepper mildew. It is a fungus that causes the appearance of irregular spots on the leaves, which gradually spread and acquire a burnt-like appearance. The fruits are covered with a whitish powder, and end up wrinkling and drying.

What is mildew mildew?

When we talk about larvated mildew we refer to vine mildew, which has made the berries of the clusters become the size of a pea. This causes that the spores of the microorganism that are inside the fruits cannot go outside because the skin of the grapes prevents it.

For this to happen, the temperature must be between 10 and 30 degrees Celsius, and there must be high humidity or frequent rain. In addition, it is also important to say that it usually occurs in plants that were already ill with mildew before; Well, in those that never had it is rare.

What are the symptoms and damage it causes?

They are the following:

  • Appearance of a greyish / whitish powder or mold on leaves, stems and fruits
  • Appearance of yellowish spots that turn brown on the leaves
  • Rotting of fruits, as well as roots and / or tubers
  • Leaf fall (not because of the fungus itself, but because they can be so weakened that, if the wind blows with some force, they can be carried away)
  • Growth slowdown
  • General appearance of the plant »sad»
  • Decreased productivity of affected crops

What are the differences between mildew and powdery mildew?

These two diseases are very similar, since they both cause that whitish dust or mold to appear on the leaves. But the main difference is that downy mildew also affects the fruits, while powdery mildew only affects the leaves and stems. You have more information about powdery mildew at this link.

How is it treated?

Home remedies

Control the risks

Watering the flowers with a hoseWatering the flowers with a hose

Avoid wetting the leaves and flowers during watering so that they do not get sick.

Mildew, like all fungi, love humid and warm environments, and they enjoy it even more when the plant is suffering from overwatering. For this, it is very, very important to water only when necessary, and to use substrates or soils that are capable of quickly filtering the water.

In addition, you never have to water from the top, and it is not a good idea to put a plate under them (unless we ALWAYS remember to remove the water that is left over 30 minutes after watering).

Use ecological fungicides in spray

For the warmer season of the year, or when the mildew has begun to cause damage to the aerial part of the plants (leaves, stems, fruits), it is preferable to use ecological spray fungicides, like this one here:

Copper or sulfur

Copper and sulfur are two highly effective natural fungicides, both to prevent and to recover a plant that is sick with fungi. Yes indeed, You just have to pour it on the surface of the substrate or soil in spring and / or autumn; in summer it is not recommended as they could burn the roots when watered.

Isolate diseased plants

In order to prevent the disease from spreading, sick plants need to be kept in a well-ventilated corner and, if possible (that is, if they are plants that want direct light) it is recommended to put them with exposure to the sun, at least until they have improved. In this way, they can recover without causing problems for the rest.

Chemical remedies

If we have very sick plants, or if we prefer to use chemical remedies, we must use systemic fungicidesfollowing the instructions specified on the package to the letter. This for example would be a good option:

And with this we are done. I hope it has been useful to you .

What is mildew and how do you combat mildew?

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