Ignoring yellow rust leads to loss of cereal crops and further spread of the infection. Infected seed material can manifest itself in a region free from the phytopathogen and infect clean fields. The fight against yellow, or striped (popular name), rust is carried out comprehensively, with special attention paid to preventive measures.
Description of the disease
A dangerous infectious disease of cereals, the causative agent of which is the basidiomycete Puccinia striiformis West, parasitizes only on living plants, since it requires water molecules for development.
This type of rust affects all cereals: rye, barley, wheat, oats. Sources of spread are weeds, which are also susceptible to the disease: wheatgrass, wheatgrass, hedgehog grass, bromegrass.
The pathogen Puccinia striiformis develops in two stages:
| Biological form | Spore | Structure | Color | Shape, size | Meaning |
|
Uredospores |
Unicellular |
Bright yellow |
spherical, 15-20 µ |
Summer spores: main distributor producing new spores | |
|
Teliospores |
Bicellular, short-legged |
Dark brown |
Elongated, club-shaped, 30*57*15-24 µ |
Winter disputes:
In this state, species tolerate adverse weather conditions |
The mycelium survives the winter on winter crops and wild cereal crops, forms active sporulation in the spring, and forms a reserve 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 air humidity is 95-100%. Pucinia feels especially at ease during the rainy, cold spring season and during prolonged rains during heading.
Geographical distribution
Yellow rust is widespread and damages 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 spread. In Russia, the disease was recorded in the Non-Black Earth zone, in the cool alpine and mountainous regions of the Caucasus and Transcaucasia. The regions of the Altai Territory and Central Asia suffer from it.
Symptoms of yellow rust on grain crops
Puccinia striiformis affects all vegetative organs of plants. The lower leaves are the first to suffer.Signs are the appearance of longitudinal, line-like uredopustules of lemon-yellow color. In some regions of Russia, the pathogen physiologically manifests itself in a brown-yellow color.
Note! It is the dotted pattern and elongation that distinguishes yellow rust from brown leaf rust, the spores of which are scattered and clustered.
In the grain, the fungus settles in the tissue of the fruit shell, around the embryo, slightly raising the epidermis. During the period of milky and waxy ripeness, even the awns and spikelet scales turn yellow. The affected field looks yellow, the lower leaves are shriveled and fall off. After some time, brown, almost black teletopustules appear under the epidermis.
Fighting methods
At the first signs of infection of cereals with rust, they are immediately treated with fungicides from the class of strobilurins, triazoles, and benzimidazoles. These drugs protect and treat the plant, eradicate the spores and mycelium of the fungus. During the season, 2 treatments will be needed, 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 of the soil.
Be sure to carry out stubble peeling in order to destroy weeds that are carriers of uredomycelia and uredospores.
Possible consequences
The danger of fungal disease lies in the disruption 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 becomes dehydrated;
- drought resistance decreases;
- frost resistance of cereal crops is weak;
- grain is not poured;
- vegetative organs become brittle and fall off.
Prevention
Preventive measures include:
- combating the sources of yellow rust: weeds, carrion;
- control of nitrogen content in crops (introducing large doses favors the development of phytopathogens);
- strengthening the cell membranes of cultivated plants, increasing immunity, and increasing protoplasm are achieved by the spring application of phosphorus-potassium components;
- cultivation of rust-resistant zoned varieties.
Yellow rust is a single representative of the species, which is transmitted through the seed stock; the risk of infection with the fungus is high. Treatment of seed material with fungicides in seed farms is a mandatory measure that neutralizes the risks of the spread of a dangerous disease of cereal crops.
