What is mildew and how to control it

Hello! In this week’s article we return to topics related to the field. I warn you that from now on we will talk to you more about other aspects related to wine and oil, but they have nothing to do with the countryside. Today I am going to talk to you about what mildew is and how to control it in order to obtain quality grapes and optimal harvest production.

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What is mildew?

If this is the first time you’ve heard this word, or you haven’t been told about it, I’ll quickly tell you that mildew is a disease that affects vines, among other crops. More specifically, it is a fungus that causes great damage to the strain. From loss of foliage (leaves) to partial or total loss of fruit.

When does this disease occur?

This disease is most dangerous when the vine vegetation is in its beginnings, generally before fruit set. In this area, this is usually from mid-April to mid-May, which is when the fruit of the vine begins to set.

Weather conditions greatly influence, since for this fungus to spread easily there must be certain humidity and temperatures. The optimal conditions for this fungus to appear are:

Vine shoots longer than 10 cm
Rain greater than 10 l/m
Average temperature greater than 12 degrees Celsius

It also has a lot of influence if after it rains we have carried out some type of tillage on the land, since in this way we encourage it to warm up sooner and for mildew to spread more easily on the vine.

What parts of the vine does it affect and how can we detect it?

It mainly affects the leaves of the shoots and the bunches, causing in most cases their disappearance because they dry out and fall off. The main warning that the vine gives us are small spots on the leaves, called “oil spots.” If we look at these spots on the underside of the leaf, we can check if there is a lot of moisture, which forms like a kind of white fluff.

It is very important that if we are not sure, we contact a knowledgeable person, such as our field technician, to tell us if it is mildew or not, since there are other types of diseases that closely resemble mildew, producing similar spots on the skin. leaves.

How can we control mildew?

My advice is prevention. It is very important to carry out a preventive treatment when the shoots of the vine are around 10-15 cm high, in this way the product reaches both the leaves and the clusters, and then continue treating depending on the weather conditions.

If we decide to wait to see signs of the disease, we must act very urgently and if the weather is not on our side, we may lose a large amount of harvest, therefore, it is very important to carry out preventive treatments so that we can cure the outbreaks from a young age. .

What products can we use?

The substance that has been used for many years to combat mildew has been Copper Oxychloride, but this substance alone acts only in the part where it is deposited and is very sensitive to washing, which is why it is currently mixed with other systemic/penetrating substances that penetrate into the leaf, even reaching the sap, such as: folpet, metalaxyl or cymoxanil.

We have three types of fungicides to choose from:

Contact: They only act on the area on which they are applied, their action lasts around 7 days and they are very sensitive to washing. They are generally those that are formed only by Copper Oxychloride.
Penetrating: These penetrate into the area where they are applied but without reaching the sap, so their action lasts around 10 days and they are very resistant to washing if the product has been applied for more than an hour. They are made up of Copper Oxychloride and other systemic/penetrating substances.
Systemic: These penetrate the area where they are applied and circulate through the vine sap. Their action lasts around 12 days and, like penetrants, they are very resistant to washing if the product has been applied for more than an hour. . They are made up of Copper Oxychloride and other systemic/penetrating substances.

I advise you to use at least a penetrating fungicide, although if it is systemic, the better, so that the vine is more protected, although this will depend a lot on the weather conditions and it is always highly recommended to ask your trusted technician for advice.

I hope the information has helped you understand a little bit about what mildew is and how to control it. At Bodegas La Aurora we carry out very exhaustive control of the quality of the grapes with which our wines are made, in order to offer you the best. If you found it interesting and if you liked this article, you can subscribe to our blog for free to receive our next articles comfortably in your email. All the best!