Rust fungus is a pest that affects various crops. A mixed-farm fungus has become quite widespread, primarily settling on cereals - wild, cultivated. This fungus provokes the development of stem (linear) rust.
Where my food is, there I am
In recent years, the rust fungus has spread quite widely. This is due to changes in agriculture: more and more territories in different parts of the planet are planted with those cereals on which it can settle. Co-evolution closely links the rust fungus and cereals. As observations have shown, the greatest variety of pest forms is inherent in those areas where many plants grow on which the fungus can settle. Plants actively cultivated by man are gradually spreading all over the planet, along with them, the rust fungus is becoming more widespread.
Biology has long been studying this specific form of life. In particular, it was possible to reveal that the spore-bearing stage of development in rust fungi suggests the presence of five varieties of spores:basidio-, telito-uredo-, ecidiospores, spermogonia. The latter are formed as pycnidia. But telitospores exist consisting of only one cell or two, and can also include many cells. Such spores have a thicker shell than others.
Both here and there
The life cycle of rust fungi involves interaction with different plants, that is, the parasite changes hosts from time to time. The aetsial stage requires an intermediate, and the telio-, uredinio - the main one. In some cases, the spread of mushrooms is explained by the fact that their host, with the help of a person, captures new spaces - for example, fields are sown with a fundamentally new crop in a country where there was no such plant before. However, in rare cases, the opposite situation is observed: if the plant suffered from rust fungi and the cereal "moved" to another area in the form of clean, uninfected seeds, then the crop is freed from the parasite, which cannot be eliminated in the original place due to its high prevalence.
How is this happening?
The rust fungi shown in the photo (in this article you can see several varieties of parasites) are able to germinate inside the host. This is called a germ tube, penetrating the tissues of the host through the orifices. Mushroom mycelium eventually grows directly in the tissues of the plant, develops, filling living cells with haustoria, through which the parasite receives the necessary nutrients.
When penetrating the host plant, smut andrust fungi spread using hyphae. The parasitic, host cytoplasms contact the ends of the haustoria, where there is no sheath, but a membrane is present. This allows the parasite to siphon nutrient compounds from the plant.
I'll take the sweetest thing for myself
It is known that parasitic rust fungi can exist on certain plants, and each harmful plant has a rather narrow list of possible carriers - usually one or another cereal genus.
Special parasitic forms are usually divided into races. They differ from each other in that different rust fungi infect different plant varieties. For example, it is known that stem rust on wheat grown by man is more than three hundred physiological races of parasites. In different states, it is necessary to take into account how many and what kind of parasites are observed in cultivated plants at the present time. Based on the information received, it is possible to determine which diseases caused by rust fungi are easier to defeat, which are more difficult. You can also identify more resistant cereal varieties and those that are easier to "surrender" to parasites.
Rust cancer
A dangerous pest can also nest on trees. A rather characteristic form of rust affects fir, causing cancerous tumors. For a long time they have been popularly known as "witch's panicles". In some of its phases, the parasite lives on shoots, branches of trees, and also feeds from the trunk. Uredo-, telitostage occur on cloves. This cycle of development of rust fungi affects the chickweed, chickweed.
Basidiospore, progressing on the grass, gradually migrates to the tree. Young fir shoots and twigs are the first to suffer. You can notice the infection by thickening in the form of couplings. The next year after the initial attack, the shoots give rise to very peculiar branches covered with yellow needles: they are short, grow vertically upwards, have an unhe althy appearance. Already in the summer, aecidia appear on the branches, in the autumn the affected needles fly around. From year to year, aecidia will ripen in this place - short, in the form of a cylinder, reddish in color, rounded. Pads are usually observed on the needles from below. The spore-bearing stage of development in rust fungi is located along the midrib.
What's next?
When the spore-bearing stage of development of rust fungi matures, the mature spores fall off, thereby re-infecting grass - stellate and other suitable carriers. A mycelium is formed in the leaves, which provides nutrients for the two stages of the parasite. Over time, mature fruits protrude on the leaf through tears. In the spring, another infection of the tree occurs and mushroom threads sprout in the fir. Mushroom mycelium usually nests in the cambium, the wood of young shoots.
Branches are only the first stage of tree infection. Further, the mycelium penetrates deeper into the trunk of the tree, the cambium dies off, the trunk in this place becomes thicker, and the bark is covered with cracks from the bottom up. Over time, it cracks and falls off, and the wound opens up to the environment. Such outgrowths cover the entire tree trunk, slowly increasing in size. Average per yearthe circumference increases by 6mm and the height by 7-13mm.
Dangerous and massive
The witch's panicle has been known to exist for up to two decades. A tree infected with cancer can look he althy for decades. In many ways, the state of the plant depends on which element was affected by the parasite. If the fungus grows in the crown, the top or part of it dies out. The most dangerous are the lesions of the under-crown sections of the trunk. The tree dies when the fungus takes over half the circumference of the trunk.
The thickenings that cover the infected trunk are covered with cracks. Through them, fungi provoking putrefactive processes enter the tree. Often, such a tree falls during a windbreak. The appearance of new wounds, the progress of putrefactive processes are not only dangerous for the life of a tree, but also reduce its value for the national economy, as the percentage of useful wood extracted from the plant decreases.
Who is the scariest?
As shown by statistical studies, white, Siberian, Caucasian varieties of fir are more susceptible to the disease. Rust fungi, somewhat different from each other in the way of feeding, appear in a variety of forest plantations, both old and young. The risk of infection of a tree growing in a humid area is increased. In addition, the likelihood of rust is greater when the grass cover consists of an impressive percentage of intermediate hosts, that is, cloves. The incidence rate is quite high in pure fir forests.
BAt present, it is the rust fungus that is one of the main causes of large areas of dead wood in the forests of our country. It is because of him that the quality of plantings is greatly reduced. In the areas of fir, rust fungus is very widespread. Periodically, measures are taken to prevent infection, but so far their results are unsatisfactory.
Mycology: Uredinales
Mushrooms of this category cause significant damage to agriculture and forestry from year to year. Fungi are widespread throughout the planet, but different countries use different measures to combat them in terms of effectiveness. The pleomorphism of such fungi is quite characteristic, and yet the number of stages varies greatly between species. Based on this feature, it is customary to distinguish several groups.
Modern science knows single-host and multi-host parasites with incomplete and full cycle of development. The first all the time live on the same plant. Quite often, these affect flax, sunflower. But the second group is the parasite that settles on mountain ash and juniper. There is a fungus that grows alternately on wheat and barberry or on buckthorn, cane. If a particular plant normally goes through all possible stages during its existence, it is called a full-cycle fungus. Another option is also possible - when there are only a few of all possible stages of development. These are most widely distributed in temperate latitudes, where the duration of the growing season is severely limited by weather factors.
Pucciniaceae
Puccinia is the most typical example of a fungus that changes hosts over several periods of existence. This fungus provokes rust on cereal crops. In addition to cereals, the parasite also lives on barberry bushes. This is a heterothallic fungus that has several stages, classically numbered from zero to four. In spring, heterosexual basidiospores fall on the leaves of the plant, release hyphae and penetrate into the tissues of the plant, then move through the intercellular spaces with the spread of haustoria through the cells.
During this period, you can notice that reddish small dots appear on the leaves on the barberry - spermogony. An alternative name for this stage is pycnia. They are also heterogeneous. If the leaf is cut across and examined under magnification, jar-shaped bodies immersed in the parenchyma can be seen. The parasite consists of mycelium formed by red oil-filled cells. Spermogonium is the source of pycnospores moving to the surface of the leaf affected by the disease. Male reproductive cells do not spread infection, do not produce mycelium.
Let's go, let's go, don't linger
Over time, the spermatozoa are close to the hyphae of the opposite sex, which provokes the onset of the sexual process with the production of mycelium that penetrates the leaf tissue. Visually, this can be seen if you look at the greenery of the affected shrub from below - red aetsia appear here. There is a division of the mycelium, a rupture of the peridium. At the same time, spores can spread further - they are carried away by the breeze. Barberry they are no longerthey will infect, because the parasite needs those nutrients that the leaf of this plant cannot give it. Therefore, the mycelium travels in search of cereals. Once on a suitable surface, it gives gifs.
How to fight?
In general, you can cope with rust if you destroy all infected plants. Of course, such tactics are not suitable for a large forest area, but for a small garden plot it is quite applicable. In this case, it is necessary to get rid of, among other things, those plants that are intermediate hosts. In order for plantings on the site to resist infection with parasites with a greater degree of success, it is necessary to regularly fertilize the soil with potassium, phosphorus and various micronutrients, but reduce the amount of nitrogen fertilizers to a minimum.
It will not be superfluous to regularly use those preparations that are designed specifically for the preventive treatment of garden plots from rust. Please note: some funds that were in use several decades ago are prohibited today, as their danger to humans has been identified. It is strongly not recommended to use such poisons, even if there are supplies left at home.
How to warn?
The best way to deal with a problem is always to prevent it from occurring. Every effort must be made not to bring the infection to your site. In particular, when purchasing seedlings, cuttings, it is necessary to use the services of only trusted suppliers, whose bushes are guaranteed to be he althy. Alsothe land should be constantly fed with phosphorus, potassium, and foliar top dressing should be carried out regularly with the use of useful microelements.
All plant residues must either be completely destroyed, or taken to a disposal site, or buried deep into the ground. By leaving them to rot on or near the surface, the farmer increases the likelihood of a wide variety of parasites and diseases. Rust is no exception. In the spring, when the snow has just melted, and the buds are still sleeping, it is necessary to carry out timely high-quality treatment of plantings with fungicides.
Saving roses
Among other plants cultivated by man, rust can even infect rose bushes. At the same time, wild rose, a rose, is a plant that is the main host for the parasite. Usually infection occurs with a variety of Phragmidium, which grows only on them, does not need intermediate owners.
You can suspect infection already in the spring, when on the buds, stems, neck at the root of a young rose you can see peculiar growths of a bright orange color. Over time, petioles, leaves are covered with yellow, orange spots protruding above a flat surface. Closer to August, the affected areas become black, the leaves crumble, the shoots dry. A diseased plant is hard to tolerate winter. The parasite feels good at high humidity, especially in spring coolness. Its development is facilitated by irregular, insufficiently plentiful watering, as well as a lack of potassium in the soil. If hot, dry weather sets in, the disease becomes noticeably weaker.
How to save?
To protect roses from this scourge, it is necessary to carefully inspect all plantings in the spring and cut out at the soil level those places where lesions were found. These plant elements are immediately destroyed, otherwise the infection will spread further. At the headquarters, the formed sores are cleaned, wiped with blue vitriol and treated with var. In the spring, while the kidneys are still sleeping, it is necessary to spray times with vitriol (copper, iron). When the buds begin to bloom, they are treated with Bordeaux liquid. The second stage of the same treatment is immediately before flowering. The liquid can be replaced with special agricultural preparations "Topaz", "AbigaPik".
Saving the plum
Drain rust can occur if the area is infested with Tranzschelia prunispinosae. In addition to plums, this parasite can settle on other stone fruits. Some stages of the fungus reside in the body of the anemone. Trees usually become infected in early summer. You can notice this by the leaves - chlorotic spots appear, which by the end of the season cover the leaves from below completely. Spores form brown pads that change color to brown. Leaves shed prematurely, and the parasite hibernates in fallen leaves and infects anemones in spring. Such an infection greatly weakens the tree.
To protect the plum, it is necessary to isolate the host plant and cut out diseased individuals. All other trees should be regularly sprayed with Bordeaux liquid - at least once every two weeks, but more often.
