Brown rust of wheat: causative agent and symptoms, how to eliminate

Fungal diseases such as rust infect cereal crops and harm plants, causing them to reduce yields. Consider the features of wheat disease with leaf rust, the causes and symptoms of the disease. Types of disease, how to deal with rust by biological, agrotechnical, chemical methods, what to do to prevent the onset of the disease.

Features of the disease

Brown rust of wheat is a fungal disease of cereals, the causative agent of which is a pathogenic fungus of the species Puccinia recondita. It affects wheat itself and related cereals. Found throughout the crop zone.

Brown rust is considered the most harmful of rusts. As a result, crops are thinned out, because plants infected since autumn die in winter. The disease leads to a decrease in wheat yield. Rust causes great damage in the southern regions.

Causes and symptoms

You can identify the disease by the appearance of brown spots on the leaves of plants, which then turn black and become glossy. For the most part, the spots appear on the upper surfaces of the leaves, but also on the lower ones. Rusty spots do not coalesce and may be surrounded by chlorotic and necrotic spots. The leaves of diseased plants gradually begin to die off, the weight of the grains drops.

Pathogen - the fungus belongs to obligate parasites and has 2 hundreds of 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 shoots of carrion, cereal weeds.

Infection occurs at a temperature of 2.5-31 ° C (the fastest at 15-25 ° C) and under the condition of drip or liquid moisture on plants. The infection persists and accumulates in humid cool weather, which is facilitated by warm winters, precipitation in the 1st half of the growing season and in the heading phase. The incubation period of an infectious disease lasts, depending on the temperature, 5-18 days.

Views

For stem rust, the intermediate host is barberry or mahonia. In spring and summer, spores from plants spread with the help of wind, hibernate on plant debris. The disease affects mainly the stems and the base of the leaves, less often the leaf blades and spike.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, the disease may reappear in spring.

When severely damaged, the plants lie down, when a part of the stem under the ear is damaged, grain is almost not formed in it, which sharply reduces the yield, sometimes up to 60-70%. Finished grain is declining in quality.

How to deal with illness

There are several methods of protection and treatment used to kill leaf rust pathogens. The complex uses chemical and biological preparations, agricultural methods.

Biological

Wheat is sprayed with biological preparations to eliminate fungi with a weak development of the disease. The action of the products is based on the use of spore bacteria that inhibit brown rust fungi. Biological preparations have some peculiarities: their effectiveness is reduced during prolonged rains, which wash away the solution, due to the radiation of the sun, 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 grain quality 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 observing the rules of agricultural cultivation, crop placement patterns in crop rotation (wheat cannot be sown in the area where grains were previously placed). The accumulation and maintenance of moisture in the soil, harrowing, fertilizing with the use of fertilizers containing potassium and phosphorus help to avoid the disease.

Practices such as vernalization of seeds are also used to speed up their germination and reduce the time they will be in the soil to reduce the possibility of infection. The timing of sowing is also of great importance, sowing the seeds in time to allow them to germinate and take root quickly, which reduces the chance of infection if the seeds are left in the ground for a long time.

Leaf rust can be controlled by planting disease-resistant crop varieties. Due to the resistance laid down by breeders, plants resist pathogens better, become less infected, and when fungicides are used, the risk of infection is minimal. Rotate crop varieties to reduce transmission.

Other agrotechnical practices are weed control and crop residue plowing combined with deep fall plowing. This makes it possible to remove residues on which pathogens have survived deeper into the ground, and thus reduce the likelihood of them getting on germinating plants.It is also obligatory to destroy the intermediate hosts of brown rust if they are located at a distance of half a kilometer from the field.

Chemical

Wheat seeds before sowing are treated with fungicidal protectants, which include substances from the group of triazoles. The solution dries and covers the grains with a film that prevents the penetration of the fungus into the grain. Young seedlings are also treated with preparations with 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 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 autumn, remove the straw, and dig the rest, using deep plowing. For maximum effect, all methods of struggle should be used, if possible.

Wheat brown rust is a dangerous disease that can affect crops in any growing region, but mainly in the southern regions, at high temperatures. If you do not carry out preventive treatments and treatment in the early stages of the disease, then it will be difficult to deal with rust. The result of the disease is always the oppression of plants and the inability to get a good harvest. Protection of grain crops from leaf rust involves the treatment of seeds, soil on the site, dressing young plants with fungicidal preparations.

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