TIPS ON HOW TO ELIMINATE THE MILDIU IN ONION

Hello friend of the farm today in this article we will talk about the mildew in the vegetables, in this opportunity of the mildew of the onion.

The onion is a plant of the family of the alliaceas, presents a stem from which the leaves and the bulb leave where nutrients and water accumulate. The onion has a typical smell and flavor with remarkable bactericidal power. It is a very simple crop whose sowing is done directly in the field or in seedbed for later transplanting.

Regarding their care, it is necessary to mention that it can be attacked by an illness caused by a fungus, called Peronospora destructor, this disease is called onion mildew and it appears in high humidity environmental conditions and in places of culture where drainage is insufficient and water is retained, so if you make onion crops in containers it is very important to ensure good drainage of the container in concrete and use a substrate that prevents water from accumulating.

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The mildew of the onion is manifested in the leaves and in the bulb, the leaves turn reddish brown and dry and the bulb rots. The final consequence of the disease is the total destruction of the onion plant.
Mildew is one of the fungal diseases caused by fungi, specifically the genus Phytopthora. And is that our fungus enemies act fast and goes unnoticed. For this reason, when we realize that something is happening, the plant beings are weakened. These microorganisms are favored by high relative humidity and mild temperatures between 10 and 30 degrees Celsius, which is why it is more frequent in spring and autumn than in the rest of the year.
Therefore, I will tell you what are the symptoms and treatment of mildew onion. In this way, you will know what to do if your crop is affected:

CAUSAL AGENT:
Peronospora destructor.

DISTRIBUTION:
Throughout the world, in temperate and cold growing regions

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SYMPTOM
In general, the first visible symptom is brown-purple-red sporulation of the pathogen on healthy green leaves.
As the disease progresses, the lesions, which are a little paler than the normal color of the leaf, grow and may surround the leaf. Irregular spots of oily appearance in the leaves that are quickly necrotic.
These lesions change from a yellow color to a brown necrosis and finally the tissue of the leaf collapses.
The stems of the infected seeds tend to remain a pale yellow color and, as in the foliage, they are often invaded by other fungi, usually of the Stemphylium or Alternaria species.

In the stems there are brown spots that are getting bigger and bigger. Often, infections in the field start as small patches and progress rapidly along it.
The bulbs can become infected and, whether they rot in the warehouse or even planted, they give rise to a pale green foliage. Around the affected area you will see a whitish fuzz.
Brown spots and irregular contours in immature fruits.

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CONDITIONS FOR THE DEVELOPMENT OF THE DISEASE
Fungi survive on wild onions, onion sets, crop remains or on the ground. The wind that spreads the spores of the fungus and the splashes of rain during the cool and humid climate are essential for the development of the disease. Rain, dew and high humidity are necessary for the germination of fungal spores and their infection. The fungus grows internally and continues to produce spores while the climate remains cool and humid.

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CONTROL
There is a control program with a standard spray fungicide based on climatic conditions can reduce crop loss.
Avoid planting onion sets that carry the fungus.
Remove crop residues and waste piles. Plant the rows in the predominant direction of the wind and use furrow irrigation instead of sprinkler irrigation.
A rotation of three to four years to a crop different from onion in soils where the disease is present can reduce losses.
To avoid the appearance of fungus Peronospora destructor, the disease-causing mildew onion should carry out preventive and shock treatments horsetail, an organic fungicide that strengthens the plant and makes it stronger at the onset of this fungus.
Another good preventive ecological fungicide that makes the plant stronger and thus prevents the fungus from developing in our onion crop is nettle slurry.
This type of ecological fungicide treatments are carried out on days when there is no wind and always at the first or last hour of the day. The treatment consists in wetting the aerial part of the plant with the help of a sprayer.
While onion is a vegetable crop, which is to be consumed by humans, the best and the most natural to remove mildew is treating the plants with fungicides containing copper carefully following the instructions shall be specified. In severe cases what needs to be done is to remove the affected plants and fruits.

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PREVENTION
To prevent onions from mildew, I advise doing / not doing the following:
Do not wet leaves or fruits (onions) when watering.
Plant them at a distance of about 20 centimeters between them.
Keep the growing area free of wild herbs.
Feed the onions with organic fertilizers once a month.
Disinfect the soil if there have already been cases of mildew in that area.

SOURCE:
https://www.jardineriaon.com/mildiu-en-cebolla.html
http://plantas.facilisimo.com/el-mildiu-de-la-cebolla-que-acabara-con-tu-cultivo-alerta_1869186.html
http://www.seminis.mx/recursos/guia-de-enfermedades/cebolla/chino-del-tomate/

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