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The second half of summer is not only a wonderful time when it is already possible to collect the first fruits from grown plants, but also the time for the awakening of the destructive phytophthora. This insidious disease, which mainly affects nightshade crops, can mow, if not the entire crop, then most of it. Some gardeners do not try to fight it, but simply choose early varieties of tomatoes, peppers, eggplant and potatoes and harvest before the start of the phytophthora season. Other gardeners are actively, and, most importantly, effectively fighting this scourge. Below, we will talk about ways to combat late blight on potato beds.
What is Phytophthora
Phytophthora, late blight or brown rot is an extremely common disease of nightshade culture. To a lesser extent, it can affect strawberries, castor beans and buckwheat. It was this disease that caused the great famine in Ireland in the 4th century. And in our country, about XNUMX million tons of potatoes are annually disposed of from late blight.
Late blight is translated from Latin as destroying the plant. This disease got its name due to its causative agent – the simplest fungus Phytophtora infestans. It reproduces incredibly quickly, devouring up to 70% of the crop in the course of its life. This fungus is spread by zoospores that can be found in contaminated soil or potato tubers. Phytophthora zoospores may also be present in potato stores if affected tubers have ever been stored there. Zoospores of the fungus that causes late blight spread along with moisture from diseased potato tops to healthy ones. Moreover, the more moisture and the warmer the weather, the faster they spread.
The first signs of the disease will be noticeable on the lower leaves of potato bushes, but then the rest of the tops are also affected, along with underground tubers. On potato leaves, late blight appears as brown spots with an inconspicuous fluffy white coating, which is formed by spores of the fungus. Instead of spots, dark brown stripes form on the stems of potato tops. At the same time, in wet weather, spots and stripes get wet and rot, which facilitates the spread of new spores. In dry weather, spots and stripes dry up. Potato tubers affected by late blight also have dark spots, which later begin to grow in depth and width and rot.
At this time, the signs of late blight on potato tubers are not yet as pronounced as in the autumn harvesting period.
preventive measures
Before telling how to treat potatoes before planting from phytophthora, we will talk about measures to prevent this disease. The set of agrotechnical measures proposed below will significantly reduce the likelihood of potato infection with late blight:
- Soil cultivation on a potato bed from phytophthora and its subsequent mulching.
- The choice of tubers as planting material only of those varieties of potatoes that are highly resistant to phytophthora. Among all varieties of potatoes resistant to this disease, Spring, Nevsky, Red Scarlett and Luck are popular. If potato varieties susceptible to late blight are used as planting material, then before sowing it is necessary to determine whether they are carriers of spores or not. To do this, potato tubers must be placed for several weeks in a room with a temperature of +15 to +18 degrees. All this time, it is necessary to carefully examine the potato tubers for the presence of darkening, and if they are found, throw away the affected tuber. In order to prevent further spread, the remaining tubers must be treated with Fitosporin-M or Agat-25K.
- Compliance with crop rotation in the beds.
- Separate planting of nightshade crops in the beds. This measure is necessary to protect different crops from late blight, if one of them is infected.
- Compliance with the recommended distance between adjacent potato bushes. Heavily thickened plantings of potatoes are poorly ventilated, resulting in ideal conditions for the spread of phytophthora.
- Hilling potatoes. At the same time, the thicker the layer of earth is at the stem of the potato bush, the less likely it is to develop phytophthora.
- Timely removal of all diseased potato bushes with their subsequent burning.
Processing potatoes from phytophthora
Together with preventive measures, pre-sowing processing of potatoes is almost 100% the key to success in the fight against late blight. Processing of potato tubers before planting can be carried out using folk remedies or using chemicals.
Folk remedies
Folk remedies will perfectly help in the prevention of phytophthora, as well as in its initial stages. But in the event of a large-scale infection, folk remedies will be powerless.
Most often, the following recipes are used in the fight against phytophthora:
- Infusion of garlic. To prepare it, you need to finely chop 100 grams of garlic and add 10 liters of water to it. This solution should be infused during the day. Only after that, the already prepared infusion should be filtered and sprayed onto potatoes. Repeat the treatment every week for 30 days. At the same time, each time a new solution must be prepared for processing potatoes.
- Infusion of sour kefir. The use of fresh kefir in the fight against late blight will not give the desired results, so it is important to take sour kefir. Mix it in a volume of 1 liter with 10 liters of water and mix well. After infusion for 2 – 3 hours, the solution will be ready. Potato bushes should be treated with this infusion every week until harvest.
- A very effective method of combating late blight is the use of a solution of copper sulfate, potassium permanganate and boric acid.. For its preparation, it is necessary to dissolve a teaspoon of each component in 1 liter of boiling water. After they cool down, the resulting 3 liters must be mixed with another 7 liters and processed potatoes. Treatment with this solution is carried out twice per season: in July and August with an interval of several weeks.
Chemicals
Chemical preparations are the most effective means in the fight against late blight. But they have one drawback: they can accumulate in tubers and soil. Therefore, the treatment of potatoes with these preparations should be carried out only when other means are powerless and only in the dosages indicated by the manufacturer.
For potatoes, there is one effective scheme for the use of chemicals against late blight. It includes the following steps:
- Before planting, it is recommended to treat the tubers with Fitosporin-M.
- At this stage, only potato tops are processed from phytophthora. At the same time, its height should be at least 25 – 30 cm. For processing, you can use any drug with a fungicidal effect, for example, Bordeaux liquid, copper sulphate or copper sulfate.
- The third processing of potatoes from phytophthora should be carried out before flowering. If weather conditions contribute to the spread of phytophthora, then Exciol, Epin or Oxygumat should be used for processing. If the weather is warm and dry, then you can limit yourself to drugs such as Krezatsin or Silk.
- After one to two weeks from the third treatment from phytophthora, potatoes must be treated with fungicidal preparations with contact action. These drugs include Ditan M-45 and Efal. If the infection becomes widespread, then these drugs should be replaced with stronger ones, such as Oksihom and Ridomil. In this case, re-treatment should be carried out after 2 weeks from the first.
- After flowering, potato bushes can be treated for phytophthora with Bravo.
- At the stage of formation and maturation of tubers, it is recommended to treat potatoes with Alufit.
Conclusion
Processing of potatoes from phytophthora is carried out until the crop is harvested. In most cases, with the timely start of the fight against late blight of potatoes, it will not be difficult to defeat it. But it is much better to prevent the development of this disease by pre-sowing tillage and careful selection of potato tubers for planting.
We recommend that you familiarize yourself with the video, which will tell you how to deal with potatoes in case of infection with late blight:
