2024 Author: Gavin MacAdam | [email protected]. Last modified: 2023-12-16 13:38
Cabbage downy mildew, known as downy mildew, is particularly harmful to young cabbage plants grown in greenhouse conditions. It affects vegetation quite strongly and closer to the end of the growing season. All types of cabbage suffer from this destructive scourge: kohlrabi and collard, as well as Savoy and white cabbage with Brussels sprouts. Downy mildew does not bypass the side and plants such as mustard, rutabaga. Periodically, it is found even on weeds
A few words about the disease
On young cabbage leaves covered with peronosporosis, you can see spots painted in yellowish tones. And from the lower sides of the leaves, a slight whitish bloom begins to appear. As for the older lower cabbage leaves, the spots on them acquire a reddish-yellowish color. Infected leaves gradually turn yellow and soon die off.
As a rule, cabbage plants attacked by downy mildew are noticeably stunted and appear weakened.
The causative agent of downy mildew in cabbage is Peronospora brassicae Guum - behind such a funny name is a harmful lower fungus that forms conidial sporulation released through the stomata.
The spread of a destructive disease is noted mainly through infected seeds through the spores of the pathogen fungus. Temperatures ranging from twenty to twenty-two degrees are largely conducive to the development of downy mildew on cabbage crops. And after the seedlings are planted in the ground, the development of the disease slows down somewhat, but the harmful fungus still remains in the plants. When wet weather is established, downy mildew may reappear.
The development of downy mildew is favored not only by conditions of high humidity, but also by excessive thickening of cabbage plantings. You can not overfeed the vegetation with nitrogen-containing fertilizers - it will become more susceptible to this scourge.
How to fight
When growing seedlings in film greenhouses, it is necessary to maintain the most favorable conditions. After harvesting, all crop residues must be immediately embedded in the soil.
Before you start sowing cabbage seeds, it is recommended to disinfect them. To do this, they are kept in hot water, the temperature of which reaches fifty degrees - such processing usually takes no more than twenty minutes. And after such disinfection, the seeds are placed in cold water for a couple of minutes to allow them to cool. You can process the seeds in any other known way. For example, they are often treated with Planriz or TMTD. And you should try to take seeds exclusively from healthy crops.
As soon as the first signs of downy mildew are found on cabbage plantings, seedlings are pollinated three times with ground sulfur. Such plants should be planted in permanent places as soon as possible, feeding the seedlings before planting with ammonium nitrate.
As for seed plants, when the first symptoms of a harmful disease appear on them, the cultures begin to be treated with copper-containing preparations.
It is extremely important to immediately eliminate all infected specimens from the beds in order not to allow the downy mildew to spread further. The seedlings, which are quite severely affected by the harmful ailment, are also discarded, preventing them from falling on the prepared beds.
It is possible to increase the resistance of cabbage plants to downy mildew, as well as to reduce its harmfulness, by applying potash and phosphorus fertilizers.
When signs of peronosporosis appear, cabbage beds can be sprayed with fungicides, among which a drug called "Ridomil Gold" has proven itself especially well. Such drugs as "Topaz", "Impact", "Skor" and "Vectra" also help in the fight against this ailment.
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