Phytophthora on potatoes: description, control measures
Among the fungal infections that affect vegetable plants, the most insidious is considered phytophthora of potatoes, tomatoes and other plants. Now we will talk about root crops. The experience of many years of growing on nutrient sludge allows us to cope with this trouble. Although it is impossible to completely eradicate the pathogen, prevention helps to keep the disease “in EEC”. Under undesirable conditions, the crop can be saved if treatment is started in time.
Description of late bugs
Phytophthora is a faunal disease caused by mycelial microorganisms called phytophthora. The fungi can infect many crops. They penetrate the soil and persist there for many years. They wait for favorable conditions to develop.
What phytophthora infestations look like:
- Dark watery spots appear on the leaves, they spread and turn brown. On the bottom of the leaves appear whitish sign – these are sacs. In which spores develop. The fungus rises from all the tissues of the bush. The tips may darken completely and wither at the root.
- On the tubers appear gray-brown spots, the potatoes are uneven with indentations. With scab, the spots enlarge, become dark brown, soft. Fausta pulp on the cut is clearly visible and recognizable by an unpleasant odor. Over time, it turns into mucus.
If the fungus is not dealt with, the entire crop dies in the cellar and basement until the first signs of infection appear in the spring. With a mass lesion, fungicides help to at least save something, which is what I will talk about next.
Causes, symptoms of potato late blight disease
First, a few words about the ways in which the spores spread. In addition to wind, they are carried by:
- People from clothes, shoes;
- Insects, the same Colorado potato beetle, butterflies.
The infection can be carried into the ground:
- Insidious late blight on tubers does not appear immediately when infected tubers are planted.
- With untreated tools, containers;
- When making compost from decomposted haulm;
- With manure;
- When watering with infected water from open reservoirs, barrels; When favorable conditions come: temperature drops, rains begin.
Mycelium begins to develop under increased humidity, contrast of night and day temperatures. Near the plants burst and sink. Even individually point – dangerous rot. If tomatoes are affected in the greenhouse or it occurs on apple and berry trees, it is necessary to urgently check potato plantings, spray them to prevent the appearance of late stolbur.
By the way, if we are talking about individual bushes, it is better to dig out the affected potatoes ahead of schedule. Harvest from infected plants and store separately from the rest of the potatoes. It is not used at all.
The infection spreads through the plant from bottom to top, first the leaf plates near the floor, then the trunk, the top. Cells dry out, dehydrate, leaves, shoots become brittle.
What is phytophthora dangerous for potatoes and people?
I was not surprised when I read that up to 25% of the crop is lost each year due to late blight. Gardeners lose much more in rainy, cool years. Under favorable conditions, late blight spreads very quickly, spreads to other plants, and goes into the ground and water. Spores remain viable in soil, compost for at least 4 years.
Other diseases develop in the background of Fäunceactive lesions, the spots are a target for other infections. Chemicals used by some farmers disinfect the harvested root vegetables in the pulp. It is not safe to eat such potatoes.
Treating Potatoes with Phytophate
I know from personal experience that the best control measures are prevention. The main measures that reduce the risk of late stolbur infection:
- In late fall, I necessarily treat all buckets, rakes, shovels, and other equipment with a concentrated solution of furatilin or humus potassium.
- In the spring, the seed is sure to crack and soak in the sun for several days. Solonin, which is formed under the rind, is poisonous, such tubers rarely get sick. When planting, neighbors throw a mixture of wood ash and phytosporin in handfuls of 4: 1 into the holes. Agronomists recommend fungicidal treatment: fill the tubers prepared for planting with the preparations.
- If the fungus appeared in the neighbors or in the greenhouse stokers, they urgently need to treat potato plantings, then it will be too late.
- In the place where I annually plant tubers, every autumn I sow rye. In the spring I put the sprouts of the siderat in the ground during the trench. It’s an effective way to improve the soil, plus fertilize it. I have noticed that as soon as you do not sow rye, potatoes sprout worse. Every now and then a tuber with rot.
I’ve noticed that the seed material is less diseased. Scientists have really learned how to select varieties for late feeding.
Safe fungicides are safe for insects and animals
If potatoes are still diseased, I use herbal shots, minerals and folk remedies with small lesions. If the lesion is severe, you can’t do without chemicals. At the first signs of late lesions I conduct spraying. Frequency of treatments depends on weather conditions and the effectiveness of the composition.
Mineral compositions on copper, the most popular – Burgundy liquid. I dilute 100 g of copper sulfate in hot water, bring the volume of liquid to 10 liters and add half a cup of chalk.
Copper chloride is part of the preparations:
- Abiga-Pic, which is a medium toxic compound;
- Oxyhom, this is a chloride from copper and oxadixyl, quite toxic;
- Hom is pure butane chloride.
To work with mineral compositions it is desirable to use a respirator, which is accompanied by gloves. Repeated treatment is carried out at intervals of 5-7 days when for the first time it is not possible to defeat late Blight.
Biological preparations affect plants superficially and consist of microorganisms that develop on spores with pathogenic fungi. They are quite a lot, I will list those that I used in greenhouses to treat tomatoes and eggplants, spraying potato plantings: gliokladin, phytosporin or phytosporin-m, Gamair, alirin-b. Universal means against all types of fungi Trip Hodermin, Planris, Rizoplan.
Apply the remedies in the evening, if there is no precipitation. I use dry powder in the morning and spray it on wet leaves until the dew dries out.
Treatment with biological preparations can be done every three days.
Folk remedies are necessary to prevent late rot, increase the immunity of plants and create unfavorable conditions for the development of fungal diseases. Treating damaged bushes with it makes no sense.
- Ash is good for drying the floor and leaves. The best is from birch firewood. I do not particularly sift it when I scatter it under the bushes with a shovel. It is more practical to use a dust sieve.
- Dairy and fermented milk products are effective for individual beds, so large plantations should not be treated. Stale kefir, whey or sour milk is diluted 1:10 with water.
- Trutovik – a mushroom that grows on the trunks of deciduous trees, dried, crushed. A liter of boiling water need 100 grams of mushrooms. Allow the mixture to infuse for 3 hours, strain, pour into a bottle with a sprayer.
- Garlic infusion is prepared as follows: Pour 100 g of the pulp 10 liters of water, insist a day, then add 50 ml of liquid soap. The smell from this treatment holds up to two days.
Chemical preparations should be diluted according to the instructions. The last treatment of the tops is carried out at least 3 weeks before harvesting. There are many resources, all of which are very helpful. They are
- Epin or Epin Plus;
This is not a complete list of chemicals. But it is better not to bring the planting to a serious lesion.
Phytophthora-resistant potato varieties
On garden plots, it is recommended to grow varieties that have good resistance to grass rot.
Early-ripening varieties that are harvested in August before the fall rains:
- Spring white – tubers with light skin, 80-140 grams in size;
- Spring pink – oval, with red eyes, the average size of potatoes is 135 g;
- Gimpel – with tubers up to 90 g, resistant to ripening, suitable for long-term storage;
- Demand – with pink skin, yellowish flesh;
- Lotus Polish – oval-round light tubers measuring 90-135 g, cream flesh.
- Snow White – resistant to many diseases, well cooked,
- Fairy tale – bright with pink spots on the eyes, appreciated for its taste, tubers of medium size;
- Magician Ai – distinguished by the yield, tubers of medium size;
- Rainbow – with oval tubers up to 150 g, appreciated for taste, quality retention;
- Sante – rounded with a light skin, the flesh is yellowish.
- Tempe – oval large tubers with a light rind;
- Blueberries – rounded with flaked skin, flesh white;
- Asterix – with purple skin, light flesh;
- Meuve – pink, oval tubers, light yellow flesh.
I have noticed that the early-ripening varieties are much less diseased, because before favorable conditions, they fall ill for phytophthora. However, long-term storage is not possible, but the tubers quickly shed in the spring. As a bookmarking for long-term storage, we lay late varieties Asterix and Blueberry. We collect them in separate bags.
Spine rot of potatoes
Every vegetable grower faces diseases and pests, the increase in the number of which leads to crop losses. One such disease is potato stub rot, which can destroy up to 50% of the tubers. In this case the tops and the underground part are affected within a few days.
Potatoes are susceptible to the grass rot pathogen (pictured) on the tops and tubers
External signs of infection
The causative agent of this disease, Phytophthora Infestan, a phytogenic microorganism (Oomycete) formerly classified as a fungus, was introduced to Europe from the American continent and came to our places with the supporting fruits: tomatoes, potatoes, eggplants.
Externally, the dangerous disease can be identified by characteristic signs such as the appearance of dark brown spots on the underside of leaves, the development of the lord fungus as a light blue, fluffy badge.
The spots increase rapidly and take over all the leaves. The above-ground part of the plant becomes sluggish and wilted. Pathogen spores mix with dew or rain droplets and penetrate into the soil, infecting the tubers. Dark, irregularly shaped foci form on the potato.
After cutting the tuber, rusty-brown “tongues” can be seen, which differ from the external lesion by the lesion in the middle of the pulp.
The earlier the problem is detected, the more chances to take measures to save the crop.
Factors provoking the appearance of late blight spores
Late Blight spores are active at cool temperatures (10. 15 ℃). Their spreading is facilitated by high humidity, abundance of existing mealybugs, and precipitation. If the weather is favorable for conidia (spores) for 3 to 5 days, you can prepare for mass infestation of potatoes on a plot.
The source of the pathogen is the remains of diseased plants not destroyed in time, tuber flooding, and compost topped with spores.
Infected plants should not be put into compost pits (piles) when removed from the vegetable garden, all suspicious tops should be removed and burned.
Phytoplankton remains viable until infested organic matter has completely decomposed.
Measures to combat late potato diseases include compulsory prevention, the basis of which is the observance of agronomic rules:
- It is recommended to return the culture to its previous planting place after 3-4 years, and it should not have shallow predecessors.
- In addition to predecessors, it is necessary to intelligently select companion plants. For example, potatoes get along well with garlic, which prevents the development of fungal diseases.
- The risk of apex lesions is reduced by using mineral fertilizers (phosphoralis “Nitrogen” at a ratio of 1: 1.3: 1.3) and trace elements (copper, magnesium).
- Plants are desirable to purchase early and relatively resistant to late varieties (Rosara, Bellarosa, Bryanskaya early, Spreng, Zorachka, Korpysh, etc.). It should be taken into account that susceptibility to the disease increases from year to year with the spread of “their” tubers.
- Do not overgrow, each plant must actively carry out the process of photosynthesis.
- Infested shrubs on the building site should be completely eliminated as soon as possible.
When planting, each plant should be given ample space so that the tops do not receive sunlight and moisture does not stagnate at the roots.
In addition to the above measures, timely disinfection of memory and bacteria is important.
Bushes on which signs corresponding to the description of the disease are found, can not be saved. It is necessary to get rid of them immediately. In order to protect healthy plants from infection, chemical treatments and folk remedies are used, which reduce the activity of spreading the phytopathogen.
Fungicides that help in the fight against late blight are divided into different ways:
|Type||Effect||Preparation||Functions of application|
|Contact||Cannot cure the disease, but protects plantings from infection||“Anthracol.”||The treatment is carried out 2-3 times with 1 week intervals. 40 days before spraying, stop harvesting. Suitable for the treatment of Alternaria|
|Systemic||Allow to stop the disease in the initial phase.||“Fundazyme.”||Used for pre-sowing treatment (20 g per 40 kg of tubers)|
|“Quadris.”||Bushes are sprayed twice with a solution (6 ml per 5 liters of water). It is used not only for late wilting, but also for other similar diseases.|
|systemic contact||Have both preventive and curative effects||“Ridomil Gold.”||The first treatment is carried out before closing the caps. During the season it should be sprayed two more times. To prepare a solution, 25 g of the drug is diluted in 10 liters of water.|
|“Metaxil”.||The drug with low phytotoxicity, effective for 14 days after treatment|
|Translaminar||Penetrates into plant tissues, but, unlike systemic fungicides, does not spread through them||Thanos||Forms an indelible film on the surface of leaves and stems. For prevention, carry out four sprays (consumption of 40 ml per 1 m 2)|
|“Acrobat.||It is enough to use 2 times during the vegetation period|
When choosing a chemical, be sure to read the instructions before using it.
Known to most farmers, copper sulfate is also one of the effective preparations in the fight against late blotchiness. It is used to prepare a solution (100 g of powder per 10 liters of water), in which the tubers are dipped before planting.
To protect potato beds, some gardeners suggest using the following options:
- wood ash. It is poured between the rows when the seedlings appear. At the beginning of flowering, the process is repeated.
- Trichopol. A solution is prepared from the drug (1 tablet per 1 liter of water), with which the bushes are sprayed. The treatment is repeated every 14 days.
- milk serum. The drug is diluted with water in a ratio of 1:1 and used to spray the plants every 3 days.
- Iodine and milk. Add 15 drops of iodine and 1 liter of milk to 10 liters of water. The bushes are treated every 2 weeks.
- Garlic infusion with potassium permanganate. Prepare 100 g of crushed garlic, pour 200 ml of water and leave for 2 days. Then filtered infusion diluted in 10 liters of water and add 1 g of potassium permanganate.
It is worth remembering that folk remedies are effective only as a preventive measure or in the earliest stages of the disease.
Late blotch is difficult to treat and under favorable weather conditions can quickly affect the entire area. Therefore, the fight against the pathogen is worth starting with preventive measures already when selecting planting material. Compliance with agronomic rules and comprehensive treatment will help to save the harvest.
Experts and experienced vegetable growers share best practices for combating late blight of potatoes in the following videos:
Gardening is her biggest hobby. She loves to stock up for the winter and spoil her friends with it. She is an experimental gardener, constantly adding new types and varieties of plants to her plot. Likes to share her experience with inexperienced gardeners.
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