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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 cultivated plants, but also the time of awakening of the destructive late blight. This insidious disease, which mainly affects nightshade crops, can mow down, 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, eggplants and potatoes and harvest before the late blight season begins. Other gardeners are actively and, most importantly, effectively fighting this scourge. Below, we will talk about ways to combat late blight in potato beds.
What is late blight
Late blight, late blight or brown rot is an extremely common disease of the nightshade crop. 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 19th century. And in our country, about 4 million tons of potatoes are disposed of annually due to late blight.
Late blight is translated from Latin as destroying a plant. This disease received 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 process of its life.This fungus is spread by zoospores, which may be contained in contaminated soil or potato tubers. Phytophthora zoospores may also be present in potato storage facilities 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 their spread occurs.
The first signs of the disease will be noticeable on the lower leaves of potato bushes, but then the rest of the tops, along with underground tubers, are affected. On potato leaves, late blight appears in the form of brown spots with an inconspicuous fluffy white coating, which is formed by fungal spores. On the stems potato tops Instead of spots, stripes of dark brown color are formed. At the same time, in humid weather, the spots and stripes become wet and rot, which makes it easier for new spores to spread. In dry weather, the spots and stripes dry out. Potato tubers affected by late blight also have dark spots, which subsequently 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 during the autumn harvesting period.
Preventive measures
Before we tell you how to treat potatoes before planting against late blight, we will tell you about measures to prevent this disease. The set of agrotechnical measures proposed below will significantly reduce the likelihood of potato infection with late blight:
- Tilling the soil in a potato bed against late blight and its subsequent mulching.
- Select tubers from only those potato varieties that are highly resistant to late blight as planting material. Among all potato varieties resistant to this illnesses, Vesna, Nevsky, Red Scarlett and Udacha 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, you need to carefully inspect 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.
- Maintaining crop rotation in the beds.
- Separate planting of nightshade crops in beds. This measure is necessary to protect different crops from late blight if one of them is infected.
- Maintaining the recommended distance between neighboring potato bushes. Heavily dense potato plantings are poorly ventilated, resulting in ideal conditions for the spread of late blight.
- Hilling potatoes. Moreover, the thicker the layer of soil near the stem of a potato bush, the less likely it is for late blight to develop.
- Timely removal of all diseased potato bushes and their subsequent burning.
Treatment of potatoes against late blight
Coupled with preventive measures, pre-sowing treatment of potatoes is almost a 100% guarantee of success in the fight against late blight.Treatment of potato tubers before planting can be carried out using folk remedies or chemicals.
Folk remedies
Folk remedies will perfectly help in the prevention of late blight, as well as in its initial stages. But in the event of a large-scale infection, folk remedies will be powerless.
The following recipes are most often used in the fight against late blight:
- Garlic infusion. To prepare it, you need to finely chop 100 grams of garlic and add 10 liters of water to it. This solution should infuse for 24 hours. Only after this should the finished infusion be filtered and sprayed onto the potatoes. The treatment must be repeated every week for 30 days. In this case, each time to process potatoes, you need to prepare a new solution.
- Infusion of sour kefir. Using fresh kefir in the fight against late blight will not give the desired results, so it is important to use sour kefir. It should be mixed in a volume of 1 liter with 10 liters of water and mixed 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. To prepare it, you need to dissolve a teaspoon of each component in 1 liter of boiling water. After they have cooled, the resulting 3 liters must be mixed with another 7 liters and the potatoes must be processed. Treatment with this solution is carried out twice per season: in July and August with an interval of several weeks.
Chemicals
Chemicals 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 drugs should be carried out only when other means are powerless and only in the dosages specified by the manufacturer.
For potatoes, there is one effective scheme for using 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 treated against late blight. In this case, its height should be at least 25 - 30 cm. For treatment, you can use any drug with a fungicidal effect, for example, Bordeaux mixture, copper sulfate or copper sulfate.
- The third treatment of potatoes against late blight should be carried out before flowering. If weather conditions contribute to the spread of late blight, then Exiol, Epin or Oxyhumate should be used for treatment. If the weather is warm and dry, then you can limit yourself to drugs such as Krezacin or Silcom.
- After one to two weeks from the third treatment against late blight, the potatoes should be treated with fungicidal preparations with contact action. Such drugs include Ditan M-45 and Efal. If the infection becomes widespread, then these drugs must be replaced with stronger ones, such as Oxychom and Ridomil. In this case, repeated treatment should be carried out 2 weeks after the first.
- After flowering, potato bushes can be treated against late blight with Bravo.
- At the stage of formation and ripening of tubers, it is recommended to treat potatoes with Alufit.
Conclusion
Treatment of potatoes against late blight produced until the crop is harvested. In most cases, if the fight against potato late blight is started in a timely manner, it will not be difficult to defeat it. But it is much better to prevent the development of this disease by pre-sowing soil cultivation and careful selection of potato tubers for planting.
We recommend watching the video, which will tell you what to do with potatoes if they are infected with late blight:
