Yellow rust: description and symptoms of cereal disease, methods of control and prevention

Ignoring yellow rust leads to loss of cereal crops, further spread of infection. Infected seed material can manifest itself in a region safe for the phytopathogen, infect clean fields. The fight against yellow, or striped (popular name), rust is carried out comprehensively, special attention is paid to preventive measures.

Description of disease

A dangerous contagious disease of cereals, the causative agent of which is the basidiomycete Puccinia striiformis West, parasitizes only on living plants, since it needs water molecules for development.

This type of rust affects all cereals: rye, barley, wheat, oats. The sources of distribution are weeds, which are also susceptible to disease: wheatgrass, wheatgrass, cocksfoot, bonfire.

Puccinia striiformis pathogens develop in two stages:

Winter spores:

Biological form	Dispute	Build	Color	Shape, size	Meaning
	Uredospores	Single-celled	Bright yellow	Globular, 15-20 µ	Summer spores: main distributor producing new spores
	Teliospores	Bicellular, short stalk	Dark brown	Elongated, club-shaped, 305715-24 µ	In this state, species tolerate adverse weather conditions

Mycelium endures winter on winter crops, on wild cereal crops, forms active sporulation in spring, forms a stock of phytopathogen for the next year. Spores begin to germinate at +1, the optimal temperature "comfort" for the development of yellow rust is +11 … +13 ⁰C, relative humidity is 95-100%. Pucinia feels especially at ease in rainy, cold springtime and during prolonged rains during earing.

Geographic distribution

Yellow rust is ubiquitous, damaging crops in many countries. According to climatic indications, the weather conditions of Europe, North Africa, the American continents and Australia are 70% suitable for its distribution.In Russia, the disease was recorded in the Non-Chernozem zone, in the cool alpine and mountainous regions of the Caucasus, Transcaucasia. Regions of the Altai Territory and Central Asia are suffering from it.

Symptoms of yellow rust on crops

Puccinia striiformis affects all vegetative organs of plants. The lower leaves are affected first. Signs - the appearance of longitudinal, line-shaped uredopustules of lemon-yellow color. In some regions of Russia, the pathogen is physiologically manifested in a brown-yellow color.

Pay attention! It is the dottedness and elongation that distinguish yellow rust from brown leaf rust, the spores of which are scattered, heaped.

In the grain, the fungus settles in the tissue of the fruit shell, around the embryo, slightly raising the epidermis. In the period of milk and wax ripeness, even the awns and spikelet scales turn yellow. The affected field looks yellow, the lower leaves are shrunken, falling off. After some time, brown, almost black teliopustules appear under the epidermis.

Methods of struggle

At the first signs of infection with cereal rust, they are immediately treated with fungicides from the class of strobilurins, triazoles, benzimidazoles. These drugs protect, treat the plant, eradicate spores and mycelium of the fungus. 2 treatments will be needed per season, the effectiveness depends on the degree of damage, the concentration of the solution and how many crops are infected with the pathogen. Among the agrotechnical measures used:

• spring feeding of winter crops with phosphorus and potassium preparations;
• spring harrowing;
• crop rotation;
• deep plowing.

Be sure to carry out stubble plowing in order to destroy weeds - carriers of uredomycelium and uredospores.

Possible consequences

The danger of a fungal disease is in violation of the natural biological processes of crops:

• pustules take up space on vegetative organs, the area involved in photosynthesis decreases;
• metabolic processes decrease;
• evaporation of moisture from the leaf part increases, the plant is dehydrated;
• drought tolerance drops;
• frost resistance of cereal crops is weak;
• grain is not poured;
• vegetative organs become brittle, fall off.

Losses can range from 20 to 50%. After harvesting, the rust remains in the grain, the colonies of the pucinia fungus continue to accumulate spores on the living parts of the weeds.

Prevention

Preventive measures include:

• fight against sources of spread of yellow rust: weeds, carrion;
• control of nitrogen content in crops (introduction of large doses favors the development of phytopathogens);
• strengthening the cell membranes of cultivated plants, increasing immunity, increasing the protoplasm are achieved by the spring application of phosphorus-potassium components;
• cultivating rust-resistant released varieties.

Yellow rust is the only representative of the species that is transmitted through the seed fund, the risk of infection with the fungus is high. The treatment of seed material with fungicides in seed farms is a mandatory measure that eliminates the risks of the spread of a dangerous disease of cereal crops.

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