Hard smut of wheat: 5 types and symptoms of appearance, methods of control

Smut diseases of cereals are ubiquitous. Consider the description of one of the types of the disease - durum smut of wheat, the causes of occurrence, the main symptoms, types of the disease. How to deal with the disease, what methods to use. Is smut-infected wheat grain allowed for use, what prevention methods should be used to prevent infection of crops.

Description of the disease

Bunt smut pathogens are several types of basidial fungi of the genus Tilletia, which differ in morphological features of teliospores. The signs of damage to cereals are the same.

The fungus Tilletia caries Tul has become widespread in central and western Russia. The species includes several forms and races that affect certain types of culture. Another species - Tilletia laevis Kuehn - is distributed in southeastern Europe, Western Siberia and Central Asia. The species Tilletia intermedia Gassner is found in the Caucasus and Moldova.

Bunt smut is considered a very harmful disease, it mainly affects soft varieties of crops. The causative agents of the disease develop in 2 stages. The basidial stage begins with the germination of spores in the soil and the formation of basidia, from which infectious hyphae are formed. Reaching the seedling, they spread throughout the plant, penetrate into the stems, leaves, and then into the ears. Favorable conditions for the development of spores are created at a moisture content of 40-60% and a soil temperature of 5-10 °C.

The next stage begins simultaneously with the formation of grains.Mycelium grows in them, and a spore mass is formed inside the outer shell. When harvesting and threshing, the affected grains are destroyed, the spores scatter and fall on he althy grains, especially a lot of them are found in the groove. When sowing infected grain, spores fall into the ground.

Causes of occurrence

New cereals are affected by spores if the predecessor was infected wheat. Emergence condition: no more than 2-3 weeks should elapse between plowing and sowing.

The source of infection for grain is agricultural implements, seeders, containers, if they got spores, and disinfection was not done. Severe smut damage is observed during early sowing of spring wheat and late winter wheat. At the same time, plants partially die at the germination stage, sowing density decreases.

Symptoms

Signs of smut in intense manifestation can be observed in the stage of milky ripeness, at its beginning.Infected spikelets have a slightly flattened appearance, their color is bright green with a bluish tint. The flower scales are splayed; when crushed, a grayish liquid with an unpleasant odor resembling herring, the source of which is the substance trimethylamine, is released from the ear. Upon reaching the stage of full ripeness, the difference in the color of the spikelets is almost imperceptible.

In place of grains there are dark rounded smut sacs. They break easily, while the spores spill out. Heads affected by smut can be identified by the fact that they do not bend down like he althy ones, because the spore sacs are light.

Views

The disease includes several types that differ in pathogens and symptoms.

Hard

Fungi infect cultivated cereals and perennial wild cereal grasses. Fungi are spread through seeds contaminated during harvesting and threshing.Plants are infected at the seedling stage. The development of the disease is promoted by soil temperature, which in the seed layer reaches 5-10 ° C and humidity of 40-60%, early or late sowing dates, especially in combination with cool weather, excessive seed deepening, thickening, growing wheat on poor or loamy heavy soils. .

Dusty

The fungus affects only spikelets. The causative agent is the fungus Ustilago tritici. A black dusty mass develops in the affected grains. Loose smut is found wherever wheat is grown; in regions with a warm climate, rye is also affected. The first signs of the disease become noticeable at the heading stage. Infected plants are eared earlier than he althy ones, but already at this time the ear is completely destroyed and looks like a burnt one.

Indian

Pathogen - mushroom Tilletia Indica.Wheat seeds are affected, the fungus destroys tissues in the part where the embryo is located and along the groove. At this point, a dark, dusty mass of spores appears. Due to partial damage, diseased grains do not swell, but Indian smut leads to a shortening of the ear, loss of up to a third of the volume of grain, deterioration in its quality and quality of flour.

Dwarf

Pathogen - mushroom Tilletia controversa J.G. Kuhn. By the nature of damage to plants, it resembles a hard smut, but affects not only the ear, but the entire plant. Infects wheat, rye, wild cereals, found in European countries and America.

Dwarf smut causes deformation of all parts of the plant, causes excessive tillering, more shoots are formed on plants than they should - from 4 to 54 pcs. Stems and spikelets are shortened and compacted. Ears have an almost normal appearance, harsh and fragile smut bags are formed in the grains.

Stem

The disease is caused by a fungus called Urocystis tritici Koern. It is manifested by the formation of slightly convex elongated stripes on the leaves, stems. At first, the stripes are light, then darken and become lead-gray. The peel dries up, the strips crack, dark spores appear under them. Sick wheat bushes poorly, lags behind in growth, the leaves curl, the internodes shorten, the ear droops. The grains remain underdeveloped or do not set at all. The yield of diseased crops can fall by 5 times. Head smut develops in regions with a warm climate on highly moist soils.

Disease control methods

To destroy the disease, the seeds are chemically treated with the preparations "Maxim Plus", "Attic", "Dino", "TMTD", "Comfort". In regions where common smut occurs, it is necessary to plant varieties of wheat resistant to it, sowing on time, not later and not too early.The site should be fertilized with organic or mineral fertilizers to provide the plants with nutrients for normal development and strengthening of immunity.

Can contaminated grain be used?

It is forbidden to use grain affected by smut to obtain flour for cooking from it for human nutrition and animal feed. It contains toxic substances that cause poisoning. In animals, the symptoms of poisoning are nervous disorders, problems with swallowing, unsteady gait, weakness, convulsions of the masticatory muscles, and decreased sensitivity. Gastrointestinal disorders, damage to the eyes and respiratory tract develop. In animals that died from poisoning, hyperemia of the kidneys, brain and lungs, and the mucous membrane of the digestive tract is noted. Smut toxins have a particularly strong toxic effect on pregnant animals.

When selecting seeds for sowing, the percentage of their infection is taken into account. If it exceeds 0.5%, the grain is not used as seed.

Prevention measures

Use wheat varieties resistant to smut to grow. Use of clean and pickled grain for sowing. Autumn and spring tillage: autumn plowing and stubble plowing. Adhere to the crop rotation scheme, not planting wheat after cereals, especially in areas where cases of disease have been observed. Compliance with the terms and methods of sowing, fertilization in the recommended norms.

Bunt smut is a dangerous fungal disease found everywhere. Cultivated plants attack wheat and rye. Infection occurs through infected and untreated seeds and agricultural implements.Violation of sowing time, favorable temperature and soil moisture for spore germination contribute to infection. Yield losses from the disease can be significant if preventive and curative measures are not taken.

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