Fungal diseases, such as rust, attack cereal crops and cause damage to plants, causing them to reduce yield. Let us consider the characteristics of leaf rust disease in wheat, the causes and symptoms of the disease. Types of the disease, how to fight rust using biological, agrotechnical, chemical methods, what to do to prevent the occurrence of the disease.
Features of the disease
Brown rust of wheat is a fungal disease of cereals, the causative agent of which is the pathogenic fungus Puccinia recondita. It affects wheat itself and related cereals. It is found everywhere in the crop growing area.
Brown rust is considered the most harmful of the rusts. As a result, crops are thinned out because plants infected in the fall die in the winter. The disease leads to a decrease in wheat yield. Rust causes great damage in the southern regions.
Causes and symptoms
The disease can be identified by the appearance of brown spots on the leaves of plants, which then turn black and become glossy. For the most part, spots appear on the upper surfaces of leaves, but also on the lower surfaces. Rust stains do not merge together and may be surrounded by chlorotic and necrotic stains. The leaves of diseased plants gradually begin to die, and the weight of the grains drops.
The causative agent is a fungus that belongs to obligate parasites and has 2 hundred physiological races that differ in virulence. There are two forms of this type of rust: European and Siberian. European rust uses yellow and small basilisk as an intermediate host, Siberian rust uses hazel. Spores can overwinter both on host plants and on the remains of winter wheat, rye, and barley. And also on carrion seedlings and cereal weeds.
Kinds
For stem rust, the intermediate host is barberry or mahonia. In spring and summer, spores from plants are spread by the wind and overwinter on plant debris. The disease mainly affects the stems and base of leaves, and less commonly leaf blades and ears.In such plants, evaporation from the surface increases, they develop faster than usual, but the quality and quantity of grains are significantly reduced. Signs of stem or line rust appear on wheat after flowering, less often in autumn; in spring the disease may appear again on seedlings.
If the damage is severe, the plants go down; if part of the stem under the ear is damaged, almost no grain is formed in it, which causes the yield to sharply decrease, sometimes by 60-70%. The quality of the finished grain decreases.
How to fight the disease
Several methods of protection and treatment are used to destroy leaf rust pathogens. The complex uses chemical and biological preparations and agrotechnical methods.
Biological
Wheat is sprayed with biological preparations to eliminate fungi when the disease develops poorly. The action of the products is based on the use of spore bacteria that inhibit brown rust fungi. Biological preparations have their own peculiarities: their effectiveness decreases during prolonged rains, which wash away the solution, due to solar radiation, which partially stops the activity of bacteria. Biological fungicides are safe, do not have an unpleasant odor, have no waiting period, and do not affect the quality of grain in any way. But they may be ineffective if the disease has passed the initial stage. Then you need to use more effective chemicals.
Agrotechnical
Wheat will be protected from rust by following the rules of agricultural cultivation techniques and the scheme for placing crops in crop rotation (you cannot sow wheat in an area where grain crops were previously located).Help to avoid disease is the accumulation and maintenance of moisture in the soil, harrowing, and fertilizing with fertilizers containing potassium and phosphorus.
Methods such as vernalization of seeds are also used to speed up their germination and reduce the time they spend in the soil to reduce the possibility of infection. Sowing time is also of great importance; it is necessary to sow the seeds in time so that they have time to quickly germinate and take root, which reduces the likelihood of infection if the seeds are left in the ground for a long time.
Other agricultural methods include weed control and peeling of crop residues in combination with deep autumn plowing. This allows you to remove residues on which pathogens remain deeper into the ground, and thus reduce the likelihood of them getting on germinating plants. It is also necessary to destroy the intermediate hosts of brown rust if they are located at a distance of half a kilometer from the field.
Chemical
Before sowing, wheat seeds are treated with fungicidal protectants, which include substances from the triazole group. The solution dries and covers the grains with a film that prevents the fungus from penetrating into the grain. Young shoots are also treated with preparations containing active substances from the classes of benzimidazoles, strobilurins and other agents with fungicidal activity.
Prevention
First of all, this is the use of resistant varieties, sowing after good predecessors and carrying out preventive spraying with fungicides even before signs of the disease appear.
In order for plants to have strong immunity, it is necessary to apply fertilizers with phosphorus and potassium to the site before sowing, to ensure a normal level of moisture during the growing season. In the fall, remove the straw and dig up the rest using deep plowing. For maximum effect, all methods of control should be used, if possible.
Brown rust of wheat is a dangerous disease that can affect crops in any growing region, but mainly in the southern regions, at high temperatures. If preventive treatments and treatment are not carried out in the early stages of the disease, then it will be difficult to fight rust. The result of the disease is always plant oppression and the inability to get a good harvest. Protection of grain crops from leaf rust involves treating the seeds, soil on the site, and treating young plants with fungicidal preparations.
