Plant diseases are one of the main causes of crop loss in both quantitative and qualitative terms. Damage is caused by a number of phytopathogenic microorganisms, fungi, viruses, bacteria.
To combat plant diseases in agriculture, it is advisable to use fungicidal preparations. These are chemicals, a special type of pesticide that can fight pathogens of various cultures.
Why fungicides are needed?
Fungicidal preparations for plants are used to:
- the fight against the disease during the formation and development of culture;
- increase crop productivity and market attractiveness of fruits;
- increase the shelf life of harvested fruits, vegetables, tubers and seeds;
- eliminating the risk of diseases and poisoning in people and animals eating damaged plants.
The role of fungicides in disease management
In a number of agricultural activities aimed at increasing the yield and quality of harvested fruits, fungicidal agents play an important role. In practice, they are able to adequately control the occurrence and development of plant diseases. At the same time, they slightly increase the cost of crops.
For the most effective result, fungicidal preparations are used before the onset of the disease or at the first appearance of symptoms. This is primarily due to the fact that damage from plant diseases is not compensated. Chemicals can protect only new uninfected areas.
Manufacturers use protective drugs at the minimum threshold level. As a rule, they are used for prevention, taking into account the forecasts of agronomists. This is done to reduce the cost of the final product, and therefore increase the profitability of the enterprise, as well as to protect the environment from chemicals.
Usage Methods
Fungicidal preparations are available in the form of powder, granules, gas or in liquid form. They apply in such cases:
1. Processing of seeds, bulbs, seedlings. Procedures can be done both in the seed company and immediately before planting. Traditionally use:
- The drug "Fundazole". Available in powder form, has a wide spectrum of action, the solution is prepared in the proportion: 1 g of the drug per 1 liter of water.
- Means "Fitosporin-M". It is used to prevent fungal and bacterial diseases. It is valuable in that it has low toxicity and is not dangerous for bees.
- The drug "Maxim-KS." Effectively used to pickle potato tubers before planting, as well as seedling rhizomes. Not toxic to plants, birds and insects, low toxicity to humans. Since it is dangerous for fish, the drug must not be allowed to enter water bodies.
2. Presowing tillage in furrows or in holes, depending on planting methods. As a rule, liquid fungicidal preparations are used for impregnation by the drip irrigation method or in the form of directional spraying around the base of the plant.
3. Processing foliage and other aerial parts of plants with a spray. Both small, hand-held devices and huge containers transported by tractors or air can be used.
For processing use such fungicidal agents:
- Toxic chemical "Topaz". Used for prophylactic purposes and as a treating drug. It has a wide range of effects. It is toxic to insects, therefore the treatment of plants with this drug during flowering is prohibited. Hazard class - 3.
- Means of "Vectra". The drug also prevents and simultaneously treats plants for many fungal diseases. Available in the form of a solution in ampoules of 2 or 5 ml. Non-toxic to plants, low toxic to humans and animals, but highly toxic to bees. Therefore, during the flowering of plants, the drug is not used.
- The drug "HOM" (or "OxyHom"). A broad-spectrum fungicide, highly effective and low toxicity. Allowed to use 3 weeks before harvest.
- Sulfur colloidal. Available in powder form. Effectively combats powdery mildew and scab. It is non-toxic, therefore its use is allowed a few days before the harvest.
4. Injection of trees through vaccinations.
5. Processing plants indoors. A chemical in gas form is released into the air in greenhouses. Such remedies are called "fumigants." This method is very effective for combating pathogens, since the resulting smoke or fog completely envelops the plant and provide simultaneous processing of all its parts.
For indoor indoor use HCN, chloropicrin, dichloropropene, carbon disulfide, dibromoethane-1.
With any type of treatment, it is rational to reuse fungicides no later than 5 days after the first pickling. This is due to the chemical effect on the preparation of light, temperature, as well as the erosive influence of such natural factors as rain, wind.
Types of fungicides and definitions
Fungicides are classified in several ways based on various characteristics:
1. Mobility in the plant. The most optimal combination of efficiency and safety are bi-directional chemicals that do not remain on the surface, but, being absorbed by the roots, move up the stem to the leaves and also move mobile from leaves to roots.
2. Role in defense: preventive or curative.
3. Perimeter of action: on one site or on several.
4. Pharmacological effects. Fungicidal drugs can kill fungi by damaging their cell membranes, inactivate vital enzymes or proteins, interfering with key processes such as energy production or respiration. Some recently developed products are unique in that they do not directly affect the pathogen itself. These remedies produce the so-called "acquired resistance system" (SPU) in the host plant. These SPUs induce chemical signals that activate specific defense mechanisms such as thickening of cell walls and the production of antifungal proteins. That is, the plant, as it were, receives immunity from pathogenic organisms.
5. Type of chemical composition: inorganic or organic. Many of the first fungicides had inorganic compounds based on sulfur ions or metals, such as copper, tin, cadmium and mercury, which are toxic not only to fungi, but also to the plants themselves. Copper and sulfur are still widely used.
Organic are those that contain carbon atoms in the structure of molecules of chemical compounds. Today, these fungicidal preparations are mainly used. These products are nontoxic not only for flora, but also for insects, animals and people. They have a hazard class 4. They disastrously affect pathogens, while maintaining the health of agroecosystems.