Potatoes cannot be completely protected from this dangerous disease, but the risk of its development can be reduced to an acceptable minimum.
To do this, follow the 14 simple rules for preventing infection of potato with late blight:
- The use of phyto-resistant varieties. Highly resistant varieties of potatoes include Lugovskoy, Batya, Bryansk novelty, Luck, Agria, Sante, Snow White, Fascinator, Bullfinch, Russian souvenir, Romano, Herta, medium-tolerant varieties are Nadezhda, Prior, Bronitsky, Nida, Detskyselsky, Doris, Nela, Estima Prigoy 2, Andretta.
- Use of quality seed material. Tubers intended for planting need to be sorted out and immediately discarded deformed, diseased, and small.
- Pre planting germination. For this, the tubers are kept in the light for 2-3 weeks at a temperature of +12 … 18 degrees. During this time, it is useful to spray the tubers once a week with a solution of copper sulfate (2 grams / 10 liters), or boric acid (50 milligrams / 10 liters), or potassium permanganate (10 milligrams / 10 liters), or immunocytophyte (3 grams / 1 liter). In the end, sort through the planting material again and delete the specimens with signs of late blight.
- Timely landing. Tubers are placed in the soil when it warms up to +8 … 10 degrees at a depth of 8-10 centimeters. In Central Russia, this usually happens in the last decade of April or early May. If you cut tubers before planting, then do not forget to disinfect the knife each time in a one percent solution of copper sulfate. And do not plant potatoes too closely – leave between the rows a distance of 60-70 centimeters for high-quality ventilation of the plantings.
- Competent crop rotation. It is advisable to place the potato field every year in a new place, away from the beds with tomatoes ( late blight also does not spare this crop). Recommended precursors for potatoes are beans, peas, celery, garlic, onions, radishes, and unsuccessful ones – tomato, pumpkin, sunflower, eggplant, pepper, cucumbers.
- Joint landing. To protect potatoes from late blight, plant the second bread with horseradish or plant a potato field next to bird cherry and red rowan.
- Soil fertilizer since autumn. Organic materials at a rate of 40-60 kilograms per 100 sq.m. it is better to bring in the autumn digging so that by the spring they have time to decompose. When deoxidizing the soil, do not exceed the rate of lime application, an excessive amount of which also provokes the development of late blight.
- Foliar top dressing with macro and micronutrient fertilizers. When the height of the plants is 20-30 centimeters, they are sprayed with the following mixture: 0.02-0.1% solution of copper sulfate + 0.5-1% solution of ammonium nitrate + 4-5% aqueous extract of superphosphate and 1% potassium salt solution. On 100 sq.m. potato plantings you need 4-5 liters of such a mixture. At the same time, it is useful to spray potato bushes with a decoction of horsetail or nettle infusion. This will strengthen the immunity of plants and make them less susceptible to fungus.
- Moderation in nitrogen top dressing. In nitrogen-saturated soil, potatoes intensely chase the tops, which are the main target of late blight.
- The regular breakthrough of weeds and hilling. These simple tricks allow you to accumulate a decent harvest before the mass defeat of the tops of the fungus phytophthora. In addition, hilling will prevent the infection from reaching the tubers. During the summer season, it is carried out at least three times. The last time the earth is raked to the bushes before closing the tops as high as possible.
- Mulching. A ten-centimeter layer of mulch will reliably protect potato plantings from late blight. You can cover the beds with straw, nettle, dried grass, and hay.
- Spraying with one percent Bordeaux liquid before flowering. Preventive treatment is carried out when the first flowers appear on potato plants. Bordeaux liquid is prepared as follows: on the day of work, 120 grams of quicklime is dissolved in a three-liter jar, and 60 grams of copper sulfate is dissolved in another of the same volume, but with hot water. Before spraying, the solutions are combined and poured into a garden sprayer. Working solution consumption per 100 sq.m. makes 5-7 liters.
- Pre-harvest mowing tops. 7-10 days before digging potatoes, the tops are cut out and harvested from the plantation. This contributes to the coarsening of the skin of tubers and increases resistance to late blight. After harvesting, it is necessary to remove all the tops and weeds from the field, since next year they will become a hotbed of infection.
- Drying the crop. When harvesting in dry weather, the tubers are left on the field for 3-4 hours to dry. With a severe defeat of the tops of the fungus or in rainy weather, the potatoes are dried under a canopy for 2-3 weeks, then they are carefully sorted and sent for storage.