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How to deal with late blight potato


Late blight occurs on the green parts of plants: stems, leaves, peduncles, and also affects the tubers. The disease affects the potatoes more intensively with high humidity and moderately warm weather. Of course, growers want to get rid of the disease in a short time and protect planting in the future.

How to fight

You can fight the disease in various ways: this and chemical means of protecting potatoes and folk. Consider what are the main methods of control and prevention of the appearance of phytophthora.

The manifestation of blight on potatoes

Preparations and processing time before planting

In the ground there may be vegetation infected with spores of the fungus. In order not to spread the infection, in the spring, before planting, the soil is watered with Bordeaux mixture or copper sulphate solution (1-3%), then the earth is dug up.

To combat late blight on potatoes, tubers are sprayed before planting with Prestige; for this, 60 ml of the drug is dissolved in 0.6 l of water. This composition is enough to handle 60 kg of tubers.

The composition is prepared on the day of landing, and before spraying it is mixed. Place the solution in a sprayer and spray the sprouted potatoes, wait 1-2 hours, then plant the tubers. It is advised to deliver tubers to the landing site in closed packages.

You can instead process drug Maxim.

What to process - seeds or tubers

Usually, when planting, it is the tubers (and not the seed for planting) that are sprayed with late blight medication.

How to ensure the protection of potatoes against late blight after planting

To protect the culture from the disease, apply compounds with copper, for example, Bordeaux mixture 1% (it is prepared by pouring 100 g of copper sulphate, 100 g of lime into a ten-liter bucket of water).

The intervals between spraying 7-10 days. Last sprayed 21 days before harvest.

Simultaneously with spraying Bordeaux mixture can not use other fungicides.

Bordeaux mixture

Means of preventing potatoes from phytophthora

Varieties of potato that are resistant to late blight: Arina, Spring, Blue, Mavka, Nevsky, Spark, September.


  • Isolate healthy bushes from sick people, including garbage collection, weeding, this will delay the appearance of the disease on the stems and leaves until the time of budding.
  • For planting pick only healthy potatoes.
  • Treat fungi seed crops.
  • Keep crop rotation: they plant potatoes a year, after 2 years lupins, beans, beans, and then potatoes again.
  • If you pile up the bushes high, it will partially protect them from secondary infection.
  • Sanitary measures - do not allow stagnation of moisture; you should not water the potatoes by sprinkling in the evening, as otherwise dew will appear in the morning; timely weed out the weeds.
  • Avoid excess nitrogen.
  • Mow the tops one week before harvest.if you plan to use potatoes, and for 10 days, if you plan to plant the tubers in the future.
  • Harvest when there is no rain, after drying the potatoes for 5 hours. Dig the aisles 5 days before harvest. This makes picking potatoes easier and removes weeds.

Fungicides for potatoes

Contact fungicides

Must remain on the plants, when the pathogen comes into contact with them, he will die.

Table 1. Contact fungicides for late blight and application rate

FungicideNorm kg / ha
Cupric, copper oxychloride2.4-3.2
Bordeaux mixture3.0
abiga peak2.9-3.8


Distributed only in places of irrigation, penetrating into the leaf tissue. This is an acrobat, kurzat.


The principle of operation of systemic fungicides: they pass inside the stems and leaves, spread, inhibit the development of a pathogenic microorganism, as they act directly on it or as a result of metabolism. So the drug helps from phytophthora.

After 2-6 hours from the time of treatment, the rains will not reduce the effect of their action. And they clean out of the pathogen for 2-3 weeks. But pathogens produce resistance to them.

Therefore advise apply them 2 times per season. And if you still need spraying, you can use contact drugs or systemic fungicide with a completely different composition.

System contact

table 2. Systemic contact fungicides and the rate of their dilution

Thanos0.6 l / ha
Acrobat Mc50g 10 liters of water
Tattu100ml 10 liters of water
Ridomil GoldNot more than 2.5 kg / ha

50g 10 liters of water

Folk remedies


Buy medicine at a pharmacy, dissolve 1 tablet in 1 liter of water. Spray the bushes every 2 weeks.

Wood ash

When potatoes rise, sprinkle ashes between the rows. When the potatoes bloom, then repeat.

Milk with iodine

1 liter of skim milk pour in a ten-liter bucket of water, drip 15 drops of iodine. Solution spray the bushes every 14 days.

Means to fight own cooking

Garlic infusion with manganese

The recipe for garlic infusion from late blight: 100 g of garlic (take the heads of garlic, arrows and leaves) finely chop. In a glass of water, place the garlic and leave for a day. After strain and pour into a ten-liter bucket with water, add 1 g of potassium permanganate to the same place.

Spray the solution bushes every 2 weeks. Pour half a liter on the bush.

Milk serum

In the serum from yogurt, add the same amount of water and spray the bushes every 2--3 days.

Three-time processing scheme landings

It means that landing process 3 times:

  1. From the emergence of shoots to closing the foliage in a row use - Shirlan, Tattu.
  2. From closing the tops to blooming buds used - Ridomil Gold, Infinito.
  3. From the appearance of flowers to the topping of the tops - Acrobat Mc.

Phytophlorosis disease

What is phytophthora potato

Phytophthalosis of potatoes is a dangerous disease that arises from the spread of fungus, it develops very quickly, and as a result, yields are greatly reduced.

Signs of late blight

The most obvious sign of late blight: brownish-brown specks are visible on the leaves and stems of the culture, after some time a fluffy gray-whitish bloom appears on the spots. With further spread the plant may die.

When precipitation spores from the leaves fall to the ground, then to the tubers, secondary lesion occurs.

Late blight on potato leaves

Phytophthora on tuber crops, primary lesion: small gray specks are visible, they grow and merge into darkish areas of flesh, the rind becomes reddish-brown.

Secondary lesion of tuber crops: they rot, decompose, have an unpleasant smell, then become soft. The disease can affect the very center of the tubers and in the winter, when the fungus begins to multiply, it becomes visible.

What is the causative agent of late blight?

Causative agent - pathogen oometsit Phytophthora infestans. Suggest that he originally from Mexico.

There are 2 strains of the disease: A1, it does not form a spore that can overwinter; A2 has spores that are resistant to frost. When oomecytes are crossed, new strains appear that are resistant to frost and fungicides.

Late blight and late blight - is there any difference

From the phytophthora fungi, the disease itself appears - late blight. She may be tomatoes, pepper, potatoes, eggplants, buckwheat, strawberries.

Why fight with blight

Late blight spoils every year 10-15% of harvested tubers, during the epitaphs - up to 70%.

If you do not fight blight, for 2 weeks without the use of chemicals 2-3 plants can infect the land of 1.5 hectares. Landing will die.

The smallest temperature at which the disease is observed - 1.3 ° C, the largest - + 30 ° C. The incubation period lasts depending on the air temperature 3-16 days.

Spores of the fungus multiply more intensively at a temperature of + 10 ° C and ambient humidity 75%. Spores of the fungus are transferred by wind and rain from one plant to another. The wind carries spores 2-3 km from the originally affected plant, it is proven.

And remember that it is better to carry out preventive measures so that the plants do not get sick with late blight than to eliminate the disease and eliminate the consequences!