The downy mildew in onions is a type of fungus that usually occurs in places where temperatures are more relaxed. Usually attacks onions are planted in mountainous areas.
If you want to prevent or eliminate this problem, read on.
How to identify Mildew Onion?
The first thing we must be clear is that the mildew does not usually kill the onion, but if it is true that affects the development of the bulb. It causes the tissues in this area to become spongy, even losing their storage qualities.
It is considered one of the most destructive diseases in onion, affecting mainly the production of seeds.
The key symptom of downy mildew in onions will find it in their leaves and flower heads infected. These areas are yellow-green or brown.
Symptoms begin to be visible in the older leaves, usually when the weather is wetter and when lower temperatures. Infected leaves will soon be covered with masses of spores in color from gray and violet. The leaves begin to twist on themselves. They will fall and die.
In this dead tissue appear purple spots, although a darker shade.
How does the disease onion?
During the growing season of onion, a mushroom can produce spores that are carried by the wind, to infect new plants. These spores are produced at nights when the relative humidity is high, plus moderate temperatures (from 4 to 25). It is estimated that the optimum temperature for this is about 13ºC. To germinate spores have to have water and heat between 7-16ºC.
At the time when the fungus has already been established, this will complete its life cycle in 11-15 days. The new spores than can infect fresh leaves and plants and the cycle will repeat.
A whole sheet can be attacked and eventually die under certain conditions.
If the environmental conditions are dry, the spores will disappear, and the possibility that the problem will spread will be less. However, if circumstances change, the environment relative humidity rises, and the temperature drops, the situation could arise.
How to prevent and combat mildew in onions?
- Cultivation: It is not recommended to plant onions in the same area where there are remains of old onions, as these conditions may be favorable for the fungus to get to generate.
- Irrigation: Do not use overhead irrigation; If there is no choice, this type of flooding will take place during the day, so that the crop reaches dry.
- Quality: Always use certified seed free of diseases. This we can buy guaranteed establishments.
- Stubble Treatment: Once we have finished harvesting the crop will get rid of all traces that have been left. Make compost piles and cover everything with a layer of soil.
- Pesticides: If symptoms are detected Mildew in onions, it’s time to use specific pesticides. Use only those that are legal in the country you reside, as well as ensure that you can treat the plant without effect in any way. It is recommended to apply for seven days when conditions are cold and wet and up to 10 days when the weather is dry.
With these considerations will be easier to treat the mildew in onions.