Miscellanea

How to save the crop of potatoes and tomatoes from late blight

How to save the crop of potatoes and tomatoes from late blight


The Leningrad region is ranked among those zones of growing potatoes and tomatoes, where the harmful effects of a harmful disease on them late blight considered a frequent occurrence (every 2 years), especially if varieties are grown that are susceptible to this common pathogen, or if a warm and humid summer is established.

As a rule, on potatoes, the disease manifests itself first in the early varieties, then it moves on to later ones. Under conditions favorable for the development of this disease, a gardener in 1-2 weeks can lose not only recently normally vegetating tops, but also get a serious infection of the crop of tubers intended for long-term storage. In case of late blight disease, 3/4 of the leaf surface of potato tops completely stops increasing the yield, while its damage is 50-80%. Infection of tomato plants is usually observed 2-3 weeks after the appearance of late blight on the tops of potatoes. When infected during the filling period, tomato fruits do not ripen, turn brown and are not suitable for nutrition.

Fungal infection of late blight can persist in the soil in the form of conidia and mycelium for a short period, as well as on plant debris and tubers. At the beginning of the growing season, from diseased seed tubers, it gets to the shoots, from the tops - to the tubers of the new harvest. But more often the initial source of infection of the pathogen in the field is the infected and germinated tubers, carelessly thrown by the gardener near the potato plantings.

In warm rainy weather in our region, the defeat of the leaves and stems of potatoes by late blight due to the appearance of a new (more aggressive) race can be expected already in the phase of full germination (even before the beginning of budding). Symptoms of the disease are noted on the underside of mainly the lower tiers of leaves in the form of dark brown spots with a light bluish bloom (mycelium), which then quickly capture the entire leaf mass of the bush. The sporulation of late blight is especially noticeable - the bordering of the spot with a delicate bloom of white color - in the early morning after the dew falls. The mycelium is a characteristic feature of the disease.

The spread of the fungus infection occurs with spores, which are quickly spread from the affected potato tops by wind or spray of rain from plant to plant, from site to site throughout the district, falling on healthy plants of new plantings of this crop, as well as tomato. This phenomenon is facilitated by warm daytime weather, when spores are blown off diseased leaves by ascending air currents. Their active germination is facilitated by a temperature of 10 ... 20 ° C and high air humidity.

If such favorable conditions are repeated for 3-5 days in the morning hours, there is a widespread infection of potato and tomato plantings, especially unstable varieties. Flowing down together with drops of dew or rain on the soil surface, spores, possessing special flagella for movement, penetrate with water flows through the soil and infect tubers. Hard dark spots appear on the surface of diseased tubers; they spread into the tissues with brown uneven "tongues". The active spread of late blight on potato plantings will show the gardener how seriously he picked up varieties for cultivation - resistant or susceptible, since the use of immune varieties is considered the main measure of combating mycosis.

To slow down the process of infestation of potatoes with late blight and save it is possible only by spraying the plants with fungicides that are allowed for sale in the retail network. Solutions of drugs applied to the tops of potatoes prevent spore germination and protect the leaves from infection, but they are not able to kill the mycelium and do not cure the disease of potatoes. If we carry out preventive treatment of healthy tops before the onset of late blight, then significant crop losses can be prevented. The protective effect of the treatment lasts 12-14 days. The effectiveness of one-time treatments of potatoes in a plot with resistant varieties is somewhat reduced if they are surrounded by neighboring, uncultivated plantings of this crop, especially with susceptible varieties that serve as constant intensive sources of infection. It is useless to process already heavily infected plantings.

Late blight (brown rot) is called the most widespread and dangerous tomato disease (destroys up to 50-60% of the crop), affecting stems, leaves and fruits. Sometimes the last for 1-2 days completely turn black and become unsuitable for food. Late varieties or plants of late planting suffer greatly in tomato. The most favorable conditions for the development of this disease occur in the second half of summer and autumn, when the daytime temperature is quite high (20 ... 22 ° С), and the nighttime temperature is low (10 ... 12 ° С). With such a temperature difference, dew falls out, which contributes to the mass development of sporulation of the pathogen and the active re-infection of plants. Outbreaks of this disease are usually observed after prolonged rainy weather, especially with fog and dew.

The spread of late blight usually begins with the upper layer of leaves and goes to the lower ones. In diseased leaves, large brown spots are located mainly along the edges of the leaf blade: on the lower side, the fungus (at a relative humidity of 75%) forms a delicate white mycelium with spores; such leaves dry out quickly. With the emergence of a new aggressive race, causing the formation of long dark brown elongated spots on the petioles, as well as on the stems, leading to the appearance of constrictions on the latter and, as a result, to the death of the plant within several days, the control measures became somewhat more complicated.

If potato growers can still get away from a strong tuber disease with the help of high hilling of their bushes, then vegetable growers cannot mechanically protect the opened tomato fruits. Some of them, trying in vain to protect tomato plants from late blight, even stop growing it. On fruits, the disease that begins during the growing season manifests itself in the form of rot - brown rounded spots, and with early damage, the fruits can have an ugly appearance: the tissue from their surface and inside remains solid. If there are no symptoms of late blight on the fruits of an infected plant, the latter can quickly appear during transportation and ripening, since conditions favorable for the development of infection are created during these periods. Fruit re-infection usually does not occur during storage.

In general, it is not supposed to grow a tomato after a potato or next to it, but where can you go from that?

To prevent the disease, it is necessary to qualitatively destroy every autumn, it is better to burn all plant residues, dig up the plot well and observe crop rotation, returning the tomato to its old place only after 3-4 years. In our zone of strong spread of the disease, before the appearance of its signs, plants are fed with phosphorus and especially potassium fertilizers, which increases their immunity. At the beginning of flowering, foliar top dressing with a 0.5% superphosphate extract is useful (50 g is poured into 1 liter of hot water, infused for a day; the settled solution, without shaking, is drained and diluted tenfold with water). When spraying, 0.8-1 liters of this solution are consumed per 10 m². At the beginning of fruit formation, tomatoes are fed with potassium sulfate (10-15 g / m²).

Chemical protection of tomato is effective only if it is started before signs of late blight appear on it.

Preventive spraying with fungicides is carried out when the first symptoms are detected on potato bushes (1% Bordeaux liquid, copper oxychloride, cuproxate). 3-4 spraying is done per season (the interval between treatments is 10-14 days, in rainy weather - 7 days). The use of Bordeaux liquid is allowed no later than eight days before harvesting, copper oxychloride and cuproxate - for 20. Fruits from treated plants must be thoroughly washed with water. Some gardeners get a good effect when spraying plants during the period of fruit setting on the second bunch with infusion of garlic every 12-15 days (up to five times).

With the threat of a strong development of late blight, some gardeners practice early harvesting of fruits, and before ripening (to prevent disease) they immediately rinse with water and keep them (1.5-2 minutes) in hot (60 ° C) water. When laying tomatoes in a box with a lid for ripening, they additionally sprinkle the fruits with crushed garlic (10 g per 10 kg). In areas where late blight is especially harmful, it is preferable to cultivate early varieties.

A. Lazarev,
candidate of biological sciences,
All-Russian Research Institute of Plant Protection,
Pushkin


As you know, tomatoes are rather unpretentious plants and, it would seem, that can become a hindrance to obtaining large yields. This plant has an insidious enemy - late blight. Late blight, or "plant eater" in translation, can be called the most common and very harmful fungal disease that affects not only tomatoes, but almost all nightshades. When phytophthora attacks the plant, its leaves darken, and arbitrary brown spots appear on the stems and fruits, the fruits rot. What harvests are there! How to defeat phytophthora and save the tomato crop?

Of course, you can buy many different chemicals, which are plentiful in stores today. But, some of them do not give the good results that the manufacturer promises, while others are too aggressive, but we try to avoid, at least in our own private areas, the use of chemicals.

There are many environmentally friendly folk remedies to combat late blight. Most of them are used for prophylaxis, while others are used as a means of treating late blight on tomatoes.

1. Saline solution... If you find signs of late blight on your plants, do not hesitate, immediately tear off the damaged leaves and fruits, and then spray the bushes with saline. It can be prepared as follows: dissolve a glass of table salt in 10 liters of water. The saline solution, when dry, forms a film on the leaves and fruits, which will restrain the spread of the fungus.

2. Furacilin solution... Experienced gardeners advise sprinkling tomatoes with a solution of pharmaceutical furacilin. Grind 10 furacilin tablets and dissolve them in 10 liters of water and treat with this solution not only the affected plants, but also healthy ones, for the purpose of prevention: once - before flowering, after the appearance of the ovary - twice and with the onset of autumn - 3 times. And you will forget about late blight!

3. Ash and laundry soap solution... It is prepared as follows: 0.5 kg of ash must be stirred in 3 liters of water, put on fire and boiled for 30 minutes. Then it needs to be cooled, filtered and added 30g of grated laundry soap, stir to form a homogeneous liquid. Now you can spray.

4. Kefir solution... It is very simple to prepare it: 1 liter of fermented kefir (about 2 days) must be stirred in 10 liters of water. Tomatoes are sprayed with this solution every two weeks, after planting in open ground or in a greenhouse.

5 .Whey or non-fat milk... Instead of kefir, you can use milk or whey. The recipe is as follows: 2 liters of whey should be poured into 10 liters of water, you can also add a glass of sugar there. Mix everything well and spray the tomatoes.

6. Iodine milk solution... On the basis of milk, you can prepare another remedy to combat late blight and to accelerate the ripening of fruits: 1 liter of low-fat milk + 20 drops of iodine is poured into 10 liters of water. Treat the plants with this solution.

7. Mullein infusion... To spray tomatoes from late blight, prepare the following solution: dilute 1 liter of fresh mullein in 10 liters of water, and immediately process the tomatoes.

8. Mulberry mushroom... Some, to combat late blight, use a tinder fungus. How? The mushroom is dried, then chopped with a sharp knife, and poured with boiling water (1 liter of water is needed per 100g of mushroom). When the infusion has cooled, it is filtered. Plants are sprayed at the first signs of phytophthora, the treatment is repeated every two weeks. But it is better to prevent late blight than to cure it later.


Late blight of tomatoes

Late blight of tomatoes manifests itself in the form of gray-brown spots of various shapes with a light green border along the edge. If you look under the leaf, a snow-white bloom is clearly visible from below. These are very dangerous spores that travel long distances, infecting plants.

The development of the disease on a tomato leads to the death of inflorescences, peduncles and sepals. If the disease progresses, it will destroy the fruits, regardless of their degree of maturity. Dense brown spots of various shapes will appear on them. Tomato fruits affected by late blight quickly turn brown and rot.

The main measures for the prevention of late blight of tomatoes:

  • compliance with crop rotation,
  • sparse landings,
  • moderate watering,
  • introduction of phosphorus and potash fertilizers into the soil.

If the plant is already sick, remove the leaf blades affected by late blight, treat it with fungicides such as Oxyhom, Hom, Bordeaux liquid, Albit, Profit Gold, Skor, etc.


Late blight is a plant disease caused by mycelial organisms.

Most often late blight affects the nightshade family.

The most common disease in tomatoes is late blight. There are years when it almost completely destroys the crop.

I read a lot of literature on this issue. And, finally, one day I came across a recommendation from an agronomist to use a mixture against this insidious disease: Thanos, Quadris and Ridomil Gold. It was claimed that it suppresses late blight of potatoes and tomatoes by 92 - 93%, dry spotting of tomatoes by 96% and peronosporosis of cucumbers and onions by 90 - 91%. Since then, I have been using this mixture on my site. And she never let me down.


1. Plant untreated seeds and use soil from the garden.

If you grow seedlings from purchased material, then, as a rule, it is not required to disinfect it. Seeds collected with their own hands must be pickled before soaking, otherwise fungal diseases will destroy the plants. At the same time, it is advisable to use a special soil, but if the soil in the garden is nutritious enough, then you can take it too, but be sure to heat it in the oven or warm it up in a water bath.

2. Long time to soak the planting material.

You can keep tomato seeds in water for only a few hours, but not a day or several days. If you leave them in water for a long time, then, having hatched, they will simply suffocate. As a result, you will have to acquire others, since the suffocated ones will not rise.

3. It is too early to plant seeds for seedlings.

In early spring, tomatoes usually do not have enough light for normal development, so it is better to do this in mid-spring. In addition, overgrown seedlings are less adaptable. Otherwise, you will have to illuminate with lamps, transplant into a large container, since it will be cramped in small pots.

4. Excessively moisturize young seedlings.

Fragile plants need a lot of moisture, but waterlogging is destructive for them. Watering tomato seedlings should be done when the topsoil dries up. You can check this by dipping your finger into the soil. If the surface has become crumbly, dry to the touch, then it's time to water the plants.

5. Remove foliage from mature bushes.

Many gardeners cut off almost all the foliage, leaving only fruits so that the greens do not turn black, being amazed by late blight, and the fruits ripen faster.Plants are stressed, the process of photosynthesis practically stops, vegetables begin to crack, since excess moisture cannot evaporate from the surface of the leaf plates. If you really want to speed up the ripening, then you can just pick the green tomatoes, put them to ripen in a dark cool place.

6. Neglect preventive treatments for late blight.

If the disease affects the bushes, then saving the harvest will be problematic. Even prematurely harvested green fruits can turn black if the disease begins to develop. Treatment of late blight drugs once every 2 weeks will help prevent the problem.

Tomatoes will grow juicy and tasty, you just need to adhere to the rules during cultivation, and avoid mistakes.


Prevention of disease and drugs for late blight

Prevention of late blight. Spraying potatoes with Bordeaux mixture. Photo: Good-Tips.PRO

For the prevention of late blight, I recommend the following measures:

  1. Isolate tomato crops as much as possible from potato crops
  2. Carry out a crop rotation and return all nightshade crops (tomatoes, potatoes, peppers, eggplant) to their original place no earlier than after
  3. Remove and burn all plant residues, and dig up the soil
  4. Treat seeds of your own harvest and purchased before sowing with a 1% solution of potassium permanganate for 20 minutes, and then thoroughly rinse and dry
  5. Regularly feed tomato seedlings with phosphorus-potassium fertilizers.

During the growing season, plants should be treated with drugs for late blight, such as:

  • 1% Bordeaux liquid
  • 0.4% suspension of chloroxydehyde (40 grams per 10 liters of water)
  • 0.2% copper-soap emulsion (20 grams of copper sulfate and 200 grams of soap per 10 liters of water)
  • 2% ditan (200 grams per 10 liters of water)
  • 2-5% Cuproxat grams per 10 liters of water).

The seedlings are sprayed with solutions of drugs before planting in the ground, then 2 weeks after planting the seedlings. Spray again in the phase of the beginning of fruit formation.

In wet years, in addition to preventive treatments, therapeutic treatments are carried out when the first signs of the disease appear. Frequency of processing - every Consumption of working fluid - 1 liter per 10 m 2. The last spraying with Bordeaux mixture is carried out days before harvest. Other drugs in the days before the start of the harvest.

Potatoes are infected with late blight Potato late blight is treated by treating the leaves with Bordeaux liquid. Photo: Good-Tips.PRO

Spraying tablets for 10 liters of water with Oxyhom is also effective). Plants are prophylactically treated with this drug in the budding phase, then - when the first signs of the disease appear, later - every

It is necessary to spray the leaves from the bottom side and with a very thin spray so that the solution does not drip from them.


Watch the video: Early blight of potato by Anamika Singhvi