Before digging up the crop, potato tops turn yellow, and dries out slightly. This is considered the norm, but if the tops of the potatoes dry out and turn black while the tubers are not yet ripe, in this case one can judge that a disease has arisen. Moreover, such changes occur unexpectedly and quite quickly.
Let's look at the main reasons for blackening of potato tops and what to do to avoid or eliminate the problem.
Causes
Everyone who grows potatoes has the main goal of obtaining a healthy harvest of tubers.And everyone tries to properly care for them, hill them in a timely manner, and remove weeds. How nice it is to admire your work when potatoes are blooming white or purple flowers.
But it happens that, despite efforts, black spots appear on the plant on the 2nd–3rd day. The tops turn black and yellow and gradually dry out. Less than half a week has passed, and instead of lush potato bushes, bare, dry stalks stick out.
Why do potato leaves turn black? This mainly happens if the plant has become infected with a fungal disease called late blight.
Those plants that are planted too close are especially quickly affected by this disease. Once spores land on one plant, wind, dew and rain transport them to other leaves and stems. This is how a large area of potatoes is gradually affected by the disease.
Therefore, you need to know what control measures should be taken against late blight in order to protect your crop.
Most often, plants are exposed to this disease when the period of budding and flowering begins. Therefore, it is necessary to consider the condition of potato leaves. Darkening of the lower ones is the beginning of late blight.
From the history of late blight
This disease began to appear 200 years ago. It is fungal in nature, so it is difficult to combat. Late blight gradually affects the entire plant: first it is found on the leaves, spreads to the stem, flowers, and then interferes with the development of the root crop. Initially, it is noticed in the lower part in the form of a white coating, then the tops turn black and they dry out.
The cause of blackening of potato tops is most often cold, wet weather with prolonged rains. Once the top of the plant has dried out, the tubers stop growing.
Other diseases
In addition to late blight, there are also diseases that lead to blackening of the tops and stems. Almost all of them are fungal in nature and develop very quickly thanks to bacteria.
Potato tops turned black if they were exposed to:
- Alternaria;
- fusarium;
- rhizoctonia;
- black leg.
In some cases, improper care leads to blackening of potato tops - the soil is in the form of clay, which retains moisture, as a result, the root part begins to rot. The reason is frequent heavy rains.
Control measures and prevention
The danger of the disease is that it spreads very quickly, covering large areas in just a few days, the leaves on the potatoes darken, wither and dry out very quickly. It is almost impossible to get rid of the disease and stop its spread.
What to do to prevent late blight?
Prevention must be observed potato diseases, namely:
- As soon as the buds begin to appear, it is necessary to treat the tops by spraying the plants with a spray bottle. After 2 weeks, it is advisable to carry out the treatment again. If the weather is rainy and humid, the plants need to be treated a third time.
- Unfortunately, this fungal disease affects not only the above-ground part, but also potato tubers. Due to rain washouts, fungal spores fall on the tubers. When harvesting diseased plants, they must be completely removed from the field, otherwise the fungal spores will persist the following year and infect the next crop.
The best prevention is to change the location of planting potatoes every year.
- Before harvesting, it is recommended to mow the affected stems with a sickle, dry them a little and burn them. They should not be placed in compost barrels.First, it is advisable to treat the tubers with the drug “Prestige”, which is an excellent prevention of fungal diseases.
- It is recommended to germinate tubers. It is better to do this in the light, as you can see potatoes affected by late blight and remove diseased tubers. Black spots appear on diseased potatoes. Planting sprouted potatoes provides more guarantees of obtaining a healthy harvest, since it will have time to ripen much faster before autumn fogs and cold rains appear.
- In order for the soil to warm up faster in the spring, it is better to cover the area under potatoes with agrospan: that is, black mulching material.
- You can’t plant tomatoes next to potatoes, because they belong to the nightshade family. Among their diseases is stem blight. The tomatoes become diseased, and then the potato stems and potato tops become infected as well.
- When harvesting, it is necessary to carefully sort out the tubers, because among them there are potatoes affected by the fungus. Potatoes need to be dried in the sun, but not stored in the cellar for at least 2-3 weeks. Then go through all the plants again.
Features of choosing a potato variety
If late blight is very common, it is recommended to find potato varieties that are least susceptible to this disease. But after a few years, it is recommended to update the acquired variety, because after some time its protective qualities are lost.
It is imperative to look for varieties with a record that they are least susceptible to late blight. But when purchasing seeds, it is necessary to take into account that this variety is suitable for the given area and soil composition.
The following varieties are considered resistant to fungal diseases:
- Fairy tale.
- Sudarushka.
- Luck.
- Sorcerer.
- Laura.
- Blue.
When choosing a variety, you must always remember about this insidious potato disease and buy seeds taking into account disease resistance.
How and with what to spray potatoes?
It is better to choose a dry sunny day for spraying. Morning or evening hours are suitable for this. It is advisable to check the weather forecast for that day. Precipitation is undesirable for at least 5–6 hours after treatment. After all, if you wash off the chemicals, their protective properties weaken.
When processing, it is necessary to observe safety measures: dress properly so that there is no contact of the chemical with human skin.
Chemicals
Of course, you want to choose the most effective and less toxic chemicals. For these purposes, Bordeaux mixture is most often used. It contains copper sulfate and lime.
They are diluted in water at the rate of half a glass of copper sulfate and the same amount of lime. They are added to a bucket of water and mixed thoroughly. With this liquid spray potato tops.
The most commonly used means of prevention are chemicals:
- Agate.
- Home.
- Maksim.
- Oksikhom.
- Fitosporin.
- Trichocin.
- Gamair.
But very often the period of action of fungicides is shortened by rain, so plants have to be treated more often. But everyone who carries out the prevention of late blight should know that 15–20 days before harvesting, plant processing stops.
Traditional methods for processing
Garlic tincture is considered an excellent remedy for blackened leaves on potatoes. You can do it like this: take about 100 g of garlic cloves, grate them and add them to a bucket of water. Leave for about 24 hours.In order for a film to form, pureed laundry soap is added to the tincture. Wait until the soap dissolves, then filter the infusion and use it to spray potato tops.
It is advisable to carry out this treatment every 2 weeks.
Effective folk remedies include whey, which is obtained after preparing cottage cheese. If late blight on potato leaves is difficult to treat, then prevention is necessary to protect your crop. And most importantly, it is recommended to carry out processing in a timely and systematic manner, only then can healthy potatoes be grown.
