From the word “Phytophthora” gardeners and gardeners shudder — not again.! And-running to your plants: check, look around, evaluate and take action. And so-every year, especially in regions where summer is short, with August rains.
Why still no means of destroying this pernicious disease of tomatoes and potatoes to leave her forever? It seems to me that late blight is similar to a spy and saboteur at the same time: it can sneak up on you and hit powerfully, she has a good ability to Dodge and hide.
A little about the causative agent
Late blight — fungal disease that causes it, Phytophthora infestans. Phytopathologists, studying the pathogen, find an extraordinary ability to survive. For example, he lives in plants and on plants, not 2003 in water.
The causative agent of Phytophthora lives in plants and on plants, does not perish in water
It has a mycelium, like any fungus, it spreads (grows) in the cells and intercellular fluid of the plant. Mushroom have extraordinary on — zoosporangia, it formed zoospores is a stage in the life cycle. Of zoospores, which begin to divide, growing new mycelium is the asexual reproduction. However, Phytophthora there is a possibility of sexual reproduction. In this case, there are zoospores, they are at rest, unlike zoospores, which are also called vagrants. Zoospores infect plants and cause disease. Zoospores also lead to disease if sprout.
As late blight can infect plants
The main place of wintering-tubers, which are affected by the pathogen. He was peacefully “asleep” until the tubers are stored. Should put them on the germination, as the mycelium grow into new potato plants. And there really is transmitted from one plant to another by developed over Millennium scheme. This happens infection of potato plants, and only two weeks after disease of potatoes, the disease affects tomatoes.
I believe that in the soil, infection can be stored, if left diseased plants or part of the crop, if preserved zoospores. Then you will be amazed and tomato, and potato plants at the same time.
However, it happens that tomatoes begin to hurt earlier. This can happen if the infected soil (with plant residues) from the greenhouses gets into the open ground with seedlings.
What makes the pathogen in the plant
To live, every living organism must feed. The pathogen Phytophthora is no exception. Him plants need for this important goal. The consequence of this feeding is a change in breathing, a change in mineral nutrition, water absorption, that is, the plant is weakened and aging begins. Earlier aging, not by age aging. Still not aging, if the chlorophyll in the leaves becomes smaller, if photosynthesis is diminished if the nutrients are not accumulated.
The disease attacks
Because it seems to be saved plants can not give a full crop. Seeds from such plants cannot be taken, they can be infected. Tubers potatoes borrow on seeds, too, cannot be.
It is usually said that there are weather factors that help the disease to progress. This dew and fog, when the leaves of plants settle the smallest droplets of water, and humidity is high. More from + 15 °C… + 22 ° C heat. The most unfavorable weather conditions for plants, but the most favorable for Phytophthora.
It would seem that feeding should help plants resist the onslaught of the aggressor. However, fertilizer containing nitrogen, on the contrary, worsens their condition. Plants are severely affected and may die.
Races of Phytophthora
The Phytophthora has races. They differ aggressiveness relative to plants and go to war with each other. We consider the specialization exists: tomatoes, tomato parasitic race (two of them) and the potato race.
In gardens potato and tomato beds are always located nearby because sites small, and there is no opportunity to distinguish territorially fields of potatoes from fields of tomatoes as it becomes in large farms. That is, there is no spatial isolation of plantings of different cultures. If the summer resident also will divide as-that the beds, there is no guarantee that the neighbor under a barrel won’t attach the plants. No truckers have available 500 metres away.
The first specks
It is a kind of compote of races during rain and high humidity. Then the epidemic begins, which has its own name for plant — epidemics. It’s a massive progression of the disease for a certain territory. Different race can be dominant or main, sometimes one race supersedes another.
It is important that it is difficult for plants to survive in the fight against different aggressors. There are varieties of tomatoes are more resistant to Phytophthora, there are less resistant. During the mass incidence of damaged plants can even very resistant varieties. First, more susceptible are affected, and then the pathogens can move to more stable.
Part of the fruit has matured to the invasion of Phytophthora
If you grow only stable varieties, the aggressiveness of the pathogen will decrease. Race does not always appear: in the time that can be called a crisis for Phytophthora, there are only one tomato and some potato race. The hope is that breeders will bring varieties that late blight will not be a problem, because the work on selection for resistance against races. But it is a matter of near future.
Fast-growing varieties of tomatoes
They give the harvest before the time of the attack of the Phytophthora. There are varieties with some resistance-they may not suffer from Phytophthora in quiet years, but during epiphytotics and they become infected.
How to adjust to the habits of Phytophthora
Country land is small, almost meaningless rotation. Last year here on the garden tomatoes, and this year, neighboring her — the same that grow in the same place.
Phytophthora destroyed the fruits collected for dosing
The weather here is unpredictable, we cannot understand. We cannot predict what will fly from the sky in our particular place and how long it will fly. Therefore, the main strategy is prevention. If the weather is such that you can anticipate the attack of Phytophthora, processing plants need to spend ahead of time without waiting for the first spots on the leaves. It is necessary to start with systemic-contact drugs, in this case, fungicides will be good. Fungicide of contact action will be ineffective, because washed away by rain.
In the struggle for harvest gardeners trying different drugs, including medical. It is unlikely that agronomists will advise them, but after all summer residents and gardeners are allowed everything on the site that is not forbidden by the law. Therefore we try as prevention any acceptable means: serum, bacterial preparations…
The list of effective means can be borrowed in the comments, based on their experience in the fight against Phytophthora.