Fungal diseases of potatoes and measures to combat them

We have already met the main ones, the next step is the disease.

I thought to fit into one article, but there were so many potato diseases that they were even enough for three articles. I never thought that our beloved potatoes have so many difficulties in the growing season.

There are many obstacles on the way to the table for our "second bread".

All living things are susceptible to diseases, plants, of course, are no exception. Potato has a lot of problems with its plant health: there are frequent potato diseases, there are also little-known ones.

The plant breeder, cherishing his wards, tries to protect plants from diseases. Sick - treats in accessible ways.

It is firmly registered in the menu, without it we can no longer imagine the diet.

Therefore, efforts to protect against potato ailments are always being made.

Types of potato diseases

In order to defeat the enemy, one must “know him by sight”.

Many potato diseases are manifested by rot, they are similar.

You can get confused and not take timely measures or, acting at random, not help the plant.

And diseases affect potatoes:

Fungal - provoked by fungal microflora;
Bacterial - caused by pathogenic bacteria;
Viral.

There are also physiological, non-infectious diseases of potatoes.

fungal diseases

Numerous group of fungal infections. Most harmful in wet years or over watering.

The fungus loves coolness, humidity, thickened crops, shading.

late blight

Potatoes are susceptible to phytophthora, as are a number of its relatives - nightshade (tomatoes, for example).

Susceptibility to widespread potato disease depends on varietal resistance, season weather, growing conditions.

Late blight begins to manifest itself outwardly on leaves located near the ground.

If it warms during the day, the weather is humid, and at night there is a temperature difference (cold), it is necessary to carefully observe the lower leaves.

Weather conditions are conducive to an outbreak of late blight.

If dark spots have formed on the leaves, late blight is most likely to begin.

Wet cool weather is typical for the summer in the northwestern part of the country. Phytophthora has been prescribed here thoroughly, preventive measures are important: you don’t even need to expect signs.

The disease progresses rapidly, rapidly spreading up - along the leaves and down - to the tubers.

The translation of the word phytophthora is noteworthy. Literally: destroying plants. And she destroys. Leaves die, tubers rot.

Sporogens can be anywhere.

Comfortable for them:

The soil;
Tops (vegetating or abandoned after harvesting on the site);
Tubers remaining in the ground after digging;
Container after infected potatoes;
Walls and storage shelving (other parts of them too).

Spores of a dangerous potato disease spread by wind, moreover, they are amazingly hardy, they can “doze” in the soil for years until a suitable food source appears - something from nightshade.

Spores become active, germinate, attack plants.

Fight against late blight and other fungi

It has a preventive (precautionary) character:

Compliance with crop rotation. Whether there was phytophthora on the site in the previous season or not, it is not necessary to plant potatoes there again. Do not plan for predecessors and all nightshades, they can leave an infection of a malignant disease in the soil.
Weeds, especially nightshade, must be destroyed in a timely manner by burning the remains. Nightshade is poisonous, but the plant is medicinal. Therefore, not everyone completely removes it from the site. The peculiarity of the nightshade is to be a carrier. The plant looks healthy, but phytophthora winters well on its remains, berries, then shoots. And it is transmitted simultaneously with nightshade to ascending potatoes. Sometimes from such a neighbor, potato shoots are already affected, covered with spots. Potato disease transmitted by such a neighbor develops rapidly.
Checking seed potatoes (visual) is carried out immediately, during harvesting. It is supposed to dry the tubers in a place remote from cultivation.
Dried potatoes are sorted out, carefully examining the tubers. With visible damage, signs of disease, they are rejected. Only healthy material is stored.
The storage is prepared in advance, disinfected. It is advisable to treat it with a fungicide. Brick walls are whitened. Concrete ones too. During the summer, the storage (basement, cellar) should be dried.
In the spring, before planting, the tubers are prepared. Sort, pickle with polycarbacin, nitrafen. Sprouting helps well: it both enhances growth and reveals infected tubers before planting.
At least twice, and with lingering humidity - three times a month, potato plantings need to be processed. Before the appearance of a fungal disease of potatoes, prophylactically. Traditionally Bordeaux liquid is used for this, any modern fungicides can be used.
If potato phytophthora has already appeared, it is sprayed with azocene four times during the growing season. Three weeks before harvesting, it is necessary to withstand planting without chemical treatment. To ensure that no chemicals are left in the product.
The fungus does not like copper: therefore preparations with copper destroy it. Copper oxychloride, medex can be used against late blight.
But he loves the fungus - liming. Lime acidic soils - in moderation, do not create a phytophthora resort.
Landings cannot be thickened. The yield will not increase from a huge number of tubers in a small area. And shading and humidity - here they are - will increase. Which will please the fungus. Rarely planted plants are better illuminated and ventilated. And they have better food.
Properly fertilized, plants increase immunity. You can not be zealous with nitrogen: its excess is at the hand of the disease.
Hilling protects potatoes from early damage by phytophthora fungus. If the area of \u200b\u200bthe potato is small, and yellowing of the leaves near the soil is noticed on it, it is better to cut them off. After - carry out hilling.
A good preventive measure is pre-harvest (for half a month) mowing the tops and burning it. Reception is good protection against other potato diseases.
When digging - a careful selection of tubers, even incised and very small. Any remaining is a potential apartment for wintering pathogenic microflora.

From improvised means will come in handy:

Harmless "chemistry" - spraying with a solution of potassium permanganate. The color of the solution is pink.
Garlic is useful not only for human health, it will also help the plant. Good infusions from any parts of a burning vegetable. Phytoncides - burning substances, disinfect the leaf, kill the pathogen. Only one hundred grams of a leaf of garlic, arrows or its cloves is enough. After grinding the therapeutic mass, pour 300 g of ordinary raw water into it, and stand for a day. Strain the infusion directly into a ten-liter bucket filled with water. This is the working solution. Mix and get started. Spray twice a month. You can add a little soap - for sticking. After rains, this treatment procedure is prophylactically repeated.
Ash-soap solution is a station wagon familiar to many gardeners. He is both nourishment and protection. Pests can not stand it, diseases too. You can just sprinkle with ashes, but it does not last long.
Iodine with milk. It is not costly as it may seem. They take only a liter of milk, iodine - up to 15 drops. The mixture is diluted with a bucket of water - the cure for fungal diseases of potatoes is ready. The frequency of treatments is 2 weeks.
You can treat potatoes and Trichopolum. Ten tablets, a bucket of water. Dissolve, insist day and spray.

Alternariosis

This disease affects the whole plant - all its parts. Visually detected first on the leaves, before flowering.

The leaf is covered with large brown spots. The spots dry, have a characteristic pattern along the perimeter - a series of circles of diameter tapering towards the center.

Stalks and tubers are covered with spots. Sick leaves die off, turning yellow.

On the tubers, the spots are depressed, with circular wrinkles. Inside the tuber is affected by dry dark rot.

Alternariosis spreads like phytophthora - the biology of fungi is similar.

The difference is that this potato disease begins to develop earlier. Plus two - and Alternariosis gives a start. 25° is just as comfortable for him as 2.

The range of acceptable temperatures allows Alternaria to cause significant damage to potatoes. A third of the crop is lost.

Sprinkling, dew, rain are the conditions for germination of spores. They manage to grab moisture and “wake up” in a couple of hours.

Struggling with alternariosis in the same way as with late blight.

You can add biological products: integral, planriz - for preplant antifungal treatment of tubers.

Fusarium dry rot

Another fungus is a contender for a fifth of the potato crop. The losses are considerable.

Fungal diseases of potatoes have adapted to nest wherever food is provided to them. It affects the entire plant.

Even healthy tubers in infected land cannot protect themselves from Fusarium.

The spores are so small that they will find a crack to get into the tuber.

Mushrooms develop rapidly (remember the expression "grow like mushrooms"), capturing all parts of the potato bush.

The time is coming to bloom, and the bush withers. This is Fusarium wilt, there is such a term for the disease.

It is not difficult to diagnose an ailment by the whitish tips of the leaves. They turn white before they wither, it is important to observe how the potato plant feels.

If this sign appears, consider the stem. A pinkish coating is another sign of potato fusarium.

The fungus is so harmful that even a healthy tuber can penetrate during transportation and storage. Or infect tubers in the field, but not be visible at first.

And in the storage, where we left the potatoes to winter and are infrequent, the potatoes become spotty. Later, they simply dry out, while rotting into dust.

Fusarium cannot be cured, so the emphasis is on prevention.

All preventive measures are similar to the prevention of phytophthora: fungi are different, but their development conditions are the same.

Rhizoctonia (black scab)

Before cleaning, the housewives usually wash the tubers. Sometimes it is not possible to wash - the tubers are covered with hard black spots.

For jacket potatoes, these tubers are unsuitable; stains can be removed, but only with a peel.

This is a black scab - a fungal infection of the tuber. The view is unsightly, but the tubers are edible - the black scab of potatoes (rhizoctoniosis) struck them partially, it will be removed during cleaning.

The peels cannot be composted, the tubers are unsuitable for planting.

Otherwise, a very unpleasant fungus, rhizoctoniosis, will settle on the site. It can overwinter both on tubers and in the soil.

Rhizoctonia causes harm at all stages of the life of potatoes.

If the mushroom only hibernates in the storage, it wakes up on the site. Having waited for the planted tuber (or having got into the soil together with the already infected one), the scab begins to “work”.

Spores germinate, the fungus infects the entire growing potato plant. The root system, stolons extending from the stem, young tubers - everything is affected by mycelium.

The temperature difference from warm to cold gives a rapid start to rhizoctoniosis.

Potato sprouts have already begun to grow, the root system is being formed. And suddenly it got cold.

Five degrees in the soil is not dangerous, but uncomfortable for potatoes, it slows down growth.

And the black scab tolerates this cold snap easily and actively feeds on the entire underground part of the potato.

If the bush has already risen, the scab will continue its dirty work in all its above-ground parts.

Check the leaf axils. If strange formations appeared there - nodules - the plant is affected by rhizoctoniosis.

The whole complex of symptoms:

Rotting of tubers and stolons;
Ulceration of the neck of the plant;
The formation of air nodules is typical for rhizoctoniosis, in the aerial part (leaf axils);
Thickening of the stem below;
Folding of the upper leaves, changing their color;
Growth retardation.

This disease has another characteristic feature: "white leg". This is the base of the stem covered with a spore-bearing white shell.

It forms in wet weather. The white leg is a diagnostic sign of rhizoctoniosis.

Prevention - as with late blight. Difference: black scab does not like to settle on manured lands.

Specific precautions:

Application of nitrogen or manure;
The tubers will be protected by the introduction of ash;
Shallow landing;
Landing on light soils is important;
It is not too early to plant - for warmth;
Do not be late with cleaning, you need to be in time for wet weather.

common scab

The very word "scab" - whether it is ordinary or not - a priori does not evoke pleasant associations.

Lousy, in a word, disease, and tubers look - respectively. Common potato scab prefers its underground part.

Any kind of potato scab is also insidious and illegible "on the menu".

The harvest is reduced, it may be lost altogether. Scab affects the eyes, they do not germinate. If the defeat is insignificant, the crop shortage will still be considerable.

Potatoes lose their taste, are poorly stored. It is impossible to plant an infected one, the soil becomes infected.

If the harvested potato is covered with a whitish coating, it is an ordinary scab. Later it will manifest itself as an ulceration of the skin.

For some reason, the scab loves the red skin of the potato more. Plaque on freshly dug tubers may have a different color. Greenish, grayish - any.

Radiant mushrooms affect potatoes, there are many varieties, the result is the same: scab.

A feature important in diagnosis: plaque quickly disappears when in contact with air. The fungus hides, the tuber looks healthy.

The common scab is actually unusual. Potato disease is fungal, and progresses - in the heat, drought.

Scab types are therefore important to distinguish.

The insidiousness of this fungus is in the same relation to soil acidity - with cultivated plants.

Common scab thrives in alkaline soils and near neutrality. She does not like acidification, like most cultivated crops. Scab with potatoes live in conditions of the same acidity.

For the fight, they follow the general agrotechnical rules and techniques.

In a hot summer, after precipitation, plants are examined - an ordinary scab may appear.

Moderate acidification of the soil (fertilization - sulfates) is acceptable with common scab.

If the acidity is slightly higher than comfortable for potatoes (this can be seen from the weeds - wood lice, plantain), do not liming before planting.

Potatoes will tolerate mild soil acidification more easily than scab damage.

macrosporiosis

Dry spotting (macrosporiosis) first appears on a potato leaf.

But the mycelium grows throughout the body of the plant, even if it can not be distinguished immediately. Dark brown, sometimes gray, round spots with concentric stripes are visible on the leaves.

They are dry, may crumble, forming perforation of the sheet.

During the formation of spotting, a gray coating of mycelium is visible from the bottom of the leaf.

The defeat coincides with budding, its early phase, the potato does not bloom yet.

Early varieties suffer more, the lower leaves turn yellow. Later the stems become stained. Dry spots are characteristic (hence - dry spotting). There is no decay, a dark coating is present.

Wind, rain, dew are assistants to the spread of the disease.

The mycelium overwinters in the soil, settling on the remains of tops and weeds. Moreover, it can take years to wait for nutrition (a suitable nightshade plant).

Tubers are also an acceptable substrate for wintering. A bush affected by macrosporiosis cannot have full growth.

It will not be possible to grow a high yield either - up to a third of the possible is lost.

Control measures:

Compliance with agricultural technology (the whole complex, as with late blight);
Deep digging / plowing of the site in autumn - the pathogen hibernates shallowly and may partially freeze;
Optimal nutrition. The balance of the main elements (N, P, K - nitrogen, phosphorus, potassium) strengthens the plants, helps them resist the fungus;
If necessary, treatment with antifungal drugs, as with late blight.

Early varieties are affected more and more often - the fungus withstands cold and develops at any temperature above zero, even if +1 ° is not yet.

potato cancer

Very harmful fungal disease. An alien from Germany since the war, but even in the USSR they almost did not know about such a potato disease.

Quarantine inspections worked to prevent the spread of the pathogen. Now potato cancer is common.

Cancer is called this fungal infection due to the formation of tissues unusual for healthy potatoes, growths.

Only the roots are not covered with growths, the remaining parts visually betray the disease.

It starts with the eyes of tubers. Growths near the eyes look like warts. There are many of them, they increase, sometimes they become larger than a tuber.

The stolons are also infected. The aerial part changes: you can see growths on the leaves, in their axils. The flowers are connected in a growth, the inflorescence is not formed.

When digging, it is found: the tubers are rotten, there are few whole ones. The survivors rot in storage. This is really cancer, it destroys the plant.

In the country, there is no potato cancer where there is intense heat or freezing of the soil. This fungus is a sissy: it cannot withstand such extreme conditions for it.

The rest of the regions are less lucky - fungal spore stores, special formations - cysts - remain viable for three decades.

Cancer spreads in many ways:

Through gardening tools;
Planted infected tubers;
On the grower's shoes;
It is carried by melt waters;
Even earthworms carry it.

Control measures are common for fungal. Agricultural technology, search for resistant varieties.

Specific measures:

Sick potatoes are forbidden to be given to animals and used as a food product. The plant - all parts - are burned.
Cancer does not like manure - you need to make it in areas where there was a painful mycelium.
Sowing legumes or corn after diseased potatoes. The spores of the fungus are “deceived”, they open and germinate from the presence of these cultures, but without the necessary nutrition (potatoes) they die. The same effect - from sowing rye.

rubber rot

A disease with an interesting name, but with deplorable consequences, spread in the country not so long ago, at the end of the 80s - the same age as perestroika.

England got acquainted with rubber rot - the first, back in the post-war years.

The fungus infects either sprouts or tubers. If the sprouts, then they quickly rot, without even having time to sprout.

Tubers become stained when infected. The spots are brown, with a dark border. Beneath the spots is a tuber tissue that feels like rubber to the touch. This gave the name to potato rot.

The tubers are unsuitable for food. If the infection has not entered a noticeable phase, and the tubers go to seeds, the soil also becomes infected.

Of the solanaceous, pepper and tomato are susceptible; these crops should not be planted nearby.

Healthy potatoes are easily re-infected in storage if an affected one is added to it.

There are no varieties resistant to harmful rubber rot.

Control measures are agrotechnical, as with all fungi.

Specific:

Do not overfeed the earth with nitrogen;
Germinate tubers and discard the affected ones by sprouts;
Cultivate soils: on heavy rubber rot progresses more strongly.

Potatoes are not our only food. But it firmly takes the place of the leading products on the menu.

Especially in winter, so they store it for a long time. In order for the tubers to be safely preserved, they need health.

Fungal diseases like to attack our main food. Therefore, the gardener has to be careful.

Look closely at the plants - from the seed tuber to the harvest, throughout the growing season. And don't forget about it in the vault too. Then the losses will not be large even in meteorologically difficult years.

We got acquainted with fungal diseases. Now fully armed, but there is still a whole host of diseases. But about them in the next article.

See you soon, dear readers!