Content
Potatoes are grown in every homestead and summer cottage. It's hard to imagine that there are no potatoes on the table. This vegetable contains a lot of vitamins and microelements that a person needs every day. And how many delicious dishes can be prepared from it! Moreover, tubers are used to treat diseases and to prepare cosmetic preparations.
Growing potatoes is not particularly difficult. Any beginner can cultivate a garden. But illness and pests they can deprive the harvest overnight. Among the common diseases, potato Alternaria blight should be noted. To get rid of the problem, you need to know about the characteristics of this disease of nightshade crops. We will present you with a photo, description, and tell you about methods of treatment and prevention of Alternaria disease.
General information
Humanity has been growing potatoes for a long time. Russians owe the appearance of tasty tubers to Peter I. If you follow agrotechnical rules, you can get good harvests. But this plant has its own diseases.
Alternaria potato disease is often found in Russian gardens. The culprits of the problem are imperfect fungi - Alternaria alternata Keissler and Alternaria solani. Alternaria and late blight – potato diseases and its relatives - peppers and tomatoes. It is also called brown spot. Because of this disease, which affects nightshade crops, more than 5% of the harvest may be missing. In recent years, Alternaria blight on potatoes has spread widely in the Baikal region and the Far Eastern region. Here, due to Alternaria disease, agricultural producers lose almost half of their harvest.
Growing young shoots are first affected by Alternaria potato disease. If emergency control measures are not taken, spores can germinate on root crops.
Most often, early-ripening potato varieties suffer from Alternaria blight, but vegetables with a medium and late ripening cycle suffer much less.
Why and how does Alternaria disease occur? The thing is that in recent years mineral fertilizers have been used less and less. There is a clear lack of calcium, nitrogen and excess phosphorus in the soil; plants are not able to resist the disease due to decreased immunity. Where nitrogen-containing and potassium mineral fertilizers are used, damage to bushes by Alternaria is minimal.
Description
The time of occurrence of the potato disease Alternaria is the second half of June, when the first flowers appear on the plant. If the process is not stopped in time, by the end of summer it will infect the entire potato plantation and can easily move on to other nightshade crops.
The onset of the Alternaria disease cannot always be seen immediately, since at first the focus of the disease is on young green shoots with succulent leaves. Small brown spots can be found on them in a chaotic manner closer to the center.Their diameter is from 10 to 3.5 ml. With Alternaria blight, oval-angular spots form on potato leaves; concentric rings are visible in the pattern, as in the photo below.
Gradually these spots increase in size. Alternaria disease spreads to other leaves, shoots, and can affect tubers. The tissue in the affected area gradually dies, a depression forms in it, which over time turns into a hole.
Alternaria potato spores formed in the first outbreak of the disease become the cause of further development of the disease. Dried leaves with curled edges stop participating in photosynthesis. They are brittle and lifeless. As a result, potatoes slow down, which causes low yields. In addition, weakened plants may be attacked by other pests.
At temperatures from +25 to +27 degrees and low humidity, spores begin to multiply intensively.
How does Alternaria migrate?
Now let's figure out how the disease ends up in our gardens. Having appeared in one place, potato Alternaria can quickly turn from a focal disease into a widespread one. The reason for the spread is simple. Spores are easily carried by wind, raindrops, and insects.
The Alternaria fungus multiplies several times during the summer season, so stopping the disease is not so easy. In addition, mycelia and conidia overwinter well and tolerate low temperatures. Any plant remains are used for wintering.In addition, the potato disease Alternaria affects not only the leaves and stems of plants, but also penetrates the tubers and quietly waits there for spring.
Signs of tuber disease
The potato tuber (photo below) has clear signs of Alternaria blight.
Pressed spots are visible on the surface of the potato. They have an irregular shape and differ in color from the tuber. Large spots have wrinkles arranged in a circle. If you cut a potato, tissue necrosis is visible to the naked eye. It looks more like dry rot. The spot is dense, hard and dry, dark brown in color. Hence the name - brown spot.
If potato Alternaria blight affects tubers in the soil, then signs of the disease can be noticed immediately. But healthy potatoes affected by the fungus will be no different during harvesting or contact with the ground. The spots will appear in 2-3 weeks.
Treatment of potato diseases
Plants infected with Alternaria need to be treated at the first signs of the disease. Potatoes can be processed:
- One percent Bordeaux mixture. Spraying is carried out 4 times a day for a week.
Prepare Bordeaux mixture:
Copper oxychloride. Twice a day for a week. - Chemicals. Today there are a number of fungicides that can cope with Alternaria.
The drugs that are recommended for treating potato Alternaria blight are partially presented in the table.
| A drug | Mode of application |
|---|---|
| Alirin B | Before planting tubers. For three times spraying from the moment of germination. Repeat after 10 days. |
| Baktofit | Spray twice. |
| Acrobat MC | Spraying up to three times during the growing season. |
| Albite | Spray when the bushes close. Twice a season. |
| Gamair | Treatment of tubers before planting and spraying twice. |
| Vitaplan | Before planting, treat tubers and growth period. |
| Bravo | Spray three times every 7-10 days. |
| Integral, Ridomil Gold, Skor | Pre-sowing treatment of tubers. |
The list of fungicidal drugs for treating potatoes against Alternaria blight goes on. In specialized stores, sellers will tell you what other means can be used to defeat the fungal pest, and, most importantly, what is available. The dosage and frequency of treatments is indicated in the instructions. Work is carried out in protective clothing in calm, windless weather.
Precautionary measures
- Do not drink, eat or smoke while spraying.
- At the end of work, you need to change clothes and wash with soap.
- The solution is diluted strictly according to the instructions.
- To treat plants, use a sprayer with a long nozzle.
- The sprayer must be washed with any detergent so that no fungicide residue remains in it. They can harm the plants if you apply foliar feeding later.
The best way to fight disease is prevention
We have presented you with a photo description and treatment of potato Alternaria blight.But experienced gardeners know very well that it is easier to prevent any plant disease than to fight it. If potatoes are infected, you will have to spend money not only financially. Imagine how much time and effort it will take to spray a potato field. It’s good if several buckets of potatoes are planted. What if several bags are planted on the plantation?
Over the years of growing potatoes, gardeners have developed preventive measures against potato Alternaria blight. They are based on knowledge of agricultural technology. Let's take a look at the recommendations:
- Only healthy tubers are prepared for planting. If you purchased potatoes from another farm, check each tuber. The slightest suspicion of Alternaria disease, the planting material is discarded. Sprouting tubers and warming them up reveals signs of disease.
- If possible, treat the seed with fungicides. There are potato varieties that are resistant to Alternaria blight. These are Alena, Snow White, Lasunok, Resource, Temp and some others. Although no one gives a 100% guarantee that these varieties will not get sick.
- The use of crop rotation is an important point in preventing any diseases. The place for planting potatoes needs to be changed after 2-3 years.
- It is not recommended to leave it on the field weeds, tops and tubers. They must be destroyed. After all, it is in organic residues that a fungal disease can easily overwinter.
- Before digging potatoes, many gardeners mow down the tops. Thus, they prevent the penetration of Alternaria spores into the tubers. Moreover, the skins on the potatoes harden better.
Conclusion
Fortunately, the disease is not common in all regions of Russia and the former USSR republics.Most often, outbreaks of potato Alternaria blight, which reduce yields, are observed in Belarus, northern Ukraine, European regions of Russia, the Baikal region and the Far East.
Agricultural producers need to be careful when planting potatoes to prevent the spread of Alternaria disease. And the best thing is to carry out prevention.
