8 min.
1419 pplIt is impossible to get a good harvest from any agricultural crop without detail care. Today, many agents are responsible for optimal growth and active development of plants, the effectiveness of which has been tested over decades of economic activity and treatments. They protect against many negative factors — microorganisms, weeds, pests and diseases, which can lead to loss of acreage and significantly reduce all the efforts of farmers to obtain high yields. In this article, we deal with plant protection agents that are most actively used and the reasons for that.
Table of Contents
General classification of PPA
All plant protection agents are divided into several categories, taking into account various characteristics:
- Chemical composition.
The chemical component in PPA can be represented by an organic and inorganic compound. The group also includes biological methods, which today have become the basis for the bioecological control of unwanted organisms in crops and contribute to the greening of agriculture.
Each class includes its own drugs, which have different toxic and pesticide properties, differ in purpose and strength of influence. But for all their differences, they demonstrate similar characteristics and mechanisms of action.
- Nature of action on the source of infection.
Thus, digestive agents work through the digestive system of the pest; they are added to feed. Contact agents penetrate through the integumentary cells of tissues and thus poison harmful organisms. Systemic drugs, also known as intraplant drugs, make plant sap poisonous because they easily penetrate the cell through the root, seeds and vegetative tissues. Fumigants are presented in the form of gas or vapor, which enters the respiratory system of the body and inhibits its vital functions.
- Hygienic class.
It can be determined by such characteristics of PPA as volatility, stability, teratogenicity, cumulativeness, allergenicity, and embryotoxicity. Assignment to a class occurs when all properties are assessed taking into account the impact on human health:
- І — extremely hazardous. As a rule, such drugs are practically not used in the agricultural sector.
- II — hazardous. Such drugs are used in agriculture when there is a high need and only under the supervision of a plant protection specialist in compliance with strict regulations.
- III — moderately hazardous. Such drugs are most widely used due to their effectiveness and greater safety. Agents are used in accordance with sanitary standards.
- IV — low-hazard. Such agents are also actively used by farmers in accordance with the instructions for breeding and spraying, and the manufacturer’s recommendations.
- Release form.
Most PPAs are available in the form of solutions, granules, powder and concentrates. Modern agents can also take the form of a flowable suspension and microgranules, which instantly dissolve in water and form a stable working liquid. Wettable pastes and powders have become very popular; when water is added, they turn into an emulsion. The choice of a certain product depends on the required effectiveness and application methods.
Biological methods of protection
The expansion of cultivated areas and the increase in the diversity of food crops contributed to the development of biological laboratories. Their tasks today include the development of new methods for protecting crops while simultaneously increasing yields. And although after the advent of chemicals, yields tripled, today the biological protective method is becoming increasingly widespread as a safer and more natural method for the environment and humans.
This method of controlling pests and viruses is based on the use of living organisms and products with a bacterial component. There are 4 main directions:
- Enrichment of the soil with beneficial microorganisms that work as attendants and fight harmful infections. Examples include phytosporin, trichoflor and many others.
- Spraying during the growing season. For this purpose, biological products such as trichodermin or biolarvicide are used.
- Attracting insects such as ground beetles, ladybirds, lacewings, amblyseius, encarsia, and birds to farmland.
- Mechanical processing. This means manual collection of larvae, temperature treatment of seed material before planting, and installation of traps.
PPAs containing fungal and viral microorganisms are widely used. In the natural environment, they are the worst enemies of ticks and many insects, since they lead to diseases of bacterial origin, paralysis and death of the individual.
In addition to creating a barrier to viruses and insects, biological protection involves dealing with rodents. To do this, pathogenic microorganisms are used, for example, preparations based on salmonella or rat typhus. Many are produced in granular form; consumption leads to the death of the rodent on the 3rd–5th day.
Despite the fact that biological protective methods have proven themselves well and are the safest, they depend on many abiotic factors that humans cannot influence. And if they do not bring the desired result, chemical PPAs come to the rescue.
Chemical protective methods
Such plant protection involves the use of pesticides that disrupt the development of harmful organisms. The group includes many PPAs, each intended for a specific object that needs to be dealt with.
Herbicides
They help destroy weeds in agricultural crops. They are available in the form of powder, emulsion, solution. In addition to the active ingredient, the composition usually contains various additives.
Herbicides can be selective or nonselective. The latter negatively affect both the weeds and the crop itself. Therefore, they are used in very overgrown fields where there are no cultivated crops. If the area is cultivated, then a nonselective herbicide is used after harvesting, before sowing, or in naked fallow. Selective, or insurance post-emergent PPAs suppress weeds, but the plants themselves continue to develop under the influence of such pesticides.
However, the division is conditional. Depending on the rate of application and concentration, the agents can work either completely or selectively.
Insecticides
These pesticides are effective against insects, their eggs and larvae, including mites and nematodes. The release form directly affects the final result. It can be dust, powder, emulsion, aerosol spray. The composition also contains surfactants, solvents and other additives.
The agents are constantly being improved, as many organisms have acquired resistance to the most well-known active substances. In addition, manufacturers are striving to improve their safety.
Desiccants
Plants are dried 10 days before harvest to speed up ripening. This makes it easier to harvest flax, sunflower, wheat, soybeans, rice, potatoes, sugar beets, clover and alfalfa in high humidity conditions, especially if the crop area is heavily weeded. In addition, desiccation allows reducing the cost of subsequent drying and, in general, overall losses during the harvesting campaign.
These PPAs are based on diquat, glyphosate or ammonium glufosinate. They do not damage the grain or tubers, but create optimal conditions for the combine harvester to operate. In addition, perennial weeds are partially destroyed.
Growth regulators
This category includes synthetic or natural low-molecular substances that change the life processes of the plant. They contain a balanced complex of phytoregulators, microelements and biologically active substances. They help increase the crop's resistance to damage by pests, diseases, temperature fluctuations, toxic effects of pesticides, and moisture deficiency. The use of growth regulators increases plant productivity and improves crop quality.
Protectants
These PPAs are classified as fungicides and are intended for disinfection of planting and seed material. Due to this, plants receive protection at the initial stage of development.
Protectants can be single-purpose, which fight, for example, only against diseases, or combined, consisting of several substances and protecting seeds, seedlings from insects and soil microflora.
Fungicides
They ensure plant protection from diseases by suppressing pathogens. They can be inorganic, such as copper, mercury, sulfur, and organic, which are derivatives of acids. They can work as preventative and protective when the growth of the pathogen stops even before it spreads. Eradication and medicinal fungicides affect the mycelium, overwintering stages and reproductive system of the pathogen.
Treatment is carried out based on the phytosanitary condition of crops and their resistance to a specific disease. When used in a timely manner, crops retain their productivity.
Adjuvants
These agents do not have pesticide properties. They are added to the working solution to increase its effectiveness by changing physical and chemical characteristics. The group includes various activators, emulsifiers, antifoaming agents and sterilizers.
The use of adjuvants allows minimizing or eliminating completely instability and incompatibility of drugs, foam, surface tension, and evaporation. Their functions include wetting, adhesion, emulsification and reduction of water hardness.
Regardless of the selected PPAs, it is important to understand that the product can demonstrate high efficiency if it is properly selected in accordance with the existing problem, optimal processing time, compliance with technology and application rates. The correct preparation of the solution and the condition of the sprayers, the use of suitable sprayers and taking into account natural factors such as heat, wind, thunderstorms are of great importance. By strictly following the instructions and recommendations of the manufacturers, crops receive reliable protection from the most of negative factors.
