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Herbicides, their classification, methods and conditions for effective use. Herbicides: types, methods and terms of application Herbicides chemical composition

Ermakova V.I.

LECTURE #

TOPIC "HERBICIDES"

1.1. Classification of herbicides.

2.2. features of the effect of herbicides on the plant and the reasons for their selectivity.

3.3. Characterization of effective herbicides (new herbicides).

4.4. Terms and methods of application of herbicides.

Herbicides are chemicals used to kill weeds.

The name "herbicides" comes from the Latin words: "gerba" - grass, "cido" - I kill. In 1897, the French grower Bonnet noticed that copper sulphate caused the leaves of field mustard to die off and at the same time did not damage cereal plants. Currently, in the world practice of agriculture, more than 150 chemicals from various classes of organic and inorganic compounds are used to control weeds.

The most convenient and acceptable for practical use is the classification based on the following features:

1)1) chemical structure;

2)2) the degree of sensitivity of plants;

3)3) the nature of the effect on plants and the method of application;

4)4) the rate of toxic action.

1)1) According to the chemical structure, herbicides are divided into:

-- inorganic ( Cu, S);

-- organic (the rest).

According to the degree of sensitivity of plants into groups:

-- continuous action (general fighter, non-selective);

-- selective action (selective)

Continuous herbicides destroy both weeds and cultivated plants, making them unsuitable for chemical weeding of crops. They are intended for the destruction of weeds and unwanted vegetation on uncultivated lands, along railways and highways, in wastelands, along field roadsides, on slopes of irrigation canals, around current depots, power lines, firebreaks.

Depending on the duration of preservation of the toxicity of preparations in the soil, some of the herbicides of this group are successfully used for treating fallows, between rows in gardens, for preparing land for nurseries of forest and fruit crops, and in combating pockets of poisonous herbs in pastures.

2)2) Selective (selective) herbicides can destroy some plants and not damage others, which is explained by the anatomical, morphological and biological features of their structure and physiological activity.

Some chemicals have a wide selective effect and are able to destroy plants of one class and not damage representatives of another.

HC: preparations 2,4D and 2M-4x are toxic for dicots and are not active against monocots, which is the basis for their use in cereal crops.

The division into general destruction and selective is to a certain extent conditional. In many cases, they have a selective effect when used in small doses and a general destructive effect in large doses.

The selectivity of herbicides also depends on the type of cultivated and weed plants, the phase of their development, and many other factors.

3)3) According to the external nature of the effect on plants and the method of application, herbicides of continuous and selective action are divided into the following groups:

Contact;

Systemic.

Systemic Getting on the leaves or roots of plants, they have the ability to move along the vascular-conducting system of plants, reach vital organs and tissues and cause their death.

Herbicides that enter plants through the roots - soil preparations - are applied to the soil surface before sowing (pre-sowing treatment), at sowing or before germination (pre-emergence treatment). Herbicides that penetrate the plants through the leaves are applied on seedlings. Such drugs move through the plant and enter the roots. They can damage the roots of perennial weeds, which is very important in the fight against root shoots and other malicious weeds (2.4D, 2M-4x).

Contact herbicides damage the leaves of the stems of plants in places of direct contact. To increase the effectiveness of the use of these drugs, it is necessary that the spraying is uniform, and the wetting of the leaves of the plants is sufficiently plentiful. Contact herbicides almost do not move through plant tissues, they affect only their aerial part without damaging the root system. Therefore, perennial weeds often regrow shortly after treatment with these chemicals.

4)4) According to the rate of toxic effect on plants, herbicides are divided into:

-- drugs with acute toxicity;

-- drugs with chronic toxicity.

Acutely toxic drugs include contact herbicides. Acute toxicity is manifested in the intensive and rapid death of plants. Their penetration into plant tissues depends on temperature. At 13°C and above, many drugs penetrate in 30-60 minutes, at temperatures below 13°C - it takes several days.

Systemic herbicides are characterized by chronic toxicity (slow acting). The effect of their use may appear only a few weeks after spraying. Outwardly, their toxicity is expressed in yellowing of the leaves, acquiring signs of chlorosis, abnormal growth of organs and tissues.

Herbicides, penetrating into plants and being involved in metabolic processes, cause disruption of the vital processes of the organism. The plant, experiencing the toxic effect of substances alien to it, like any organism, counteracts, trying to neutralize them.

HC: 2.4D and 2M-4x, penetrating into plants sensitive to them, remain in a free state for a long time and sharply disrupt vital processes. In dicotyledonous plants, under the influence of these chemicals, photosynthesis is suppressed, the formation of organic substances is sharply reduced, carbohydrate and nitrogen metabolism is disturbed, and normal synthesis processes are suppressed.

External signs of the action of 2,4D on plants sensitive to them are manifested as follows: first, the leaf petioles begin to bend, the leaf blades are deformed, and the leaves curl. The tops of the stems form bends, their growth stops. In the lower part, the stem grows, forming ugly thickenings, which subsequently break.

Peculiar thickenings often appear on the roots, the tissues soften, in the future they grow and rot. Thus, herbicides 2,4D and 2M-4x, getting on the leaves of dicotyledonous plants, penetrating into them and moving through the vascular system, cause the death of not only the aerial part, but are also capable of partially damaging the roots of such root weeds as pink thistle, field bindweed ( 10 cm layer gd, in the garden they are used at the roots of trees). In cereal (monocot) plants, intensive detoxification of 2,4D molecules takes place. This is one of the reasons for the resistance of cereal plants to 2.4D.

Preservation of the activity of drugs 2,4D and 2M-4x in the soil depends on humidity and temperature, humus content, composition of microorganisms.

At high soil moisture and high temperatures, herbicides decompose faster. The average duration of decomposition of these preparations in the soil is 4-8 weeks. These chemicals do not significantly affect the soil microflora if the recommended doses are observed.

When spraying crops of cereal crops against dicotyledonous (broad-leaved) weeds with contact preparations, the external structure of plants is of great importance. In monocotyledonous cereal plants, the leaves are covered with a thicker wax coating than in broad-leaved dicotyledons. A protective wax coating prevents the penetration of the herbicide into the cultivated plant. In addition, the leaves of cereals are usually narrow and almost vertical, so herbicide droplets roll off easily when sprayed. In dicotyledonous plants, for example, in wild radish, field mustard. The leaf surface is larger, the leaves are almost horizontal, and the droplets of the chemical solution adhere well to them. The position of the growth point is also of great importance. In cereals, it is hidden in the leaf sheath, and when sprayed, the drug does not directly fall on it.

In broad-leaved dicotyledonous plants, the growing point is located at the top of the stem or in the axils of the leaves, it is open, not protected. When spraying, drops of herbicide easily fall on it. As a result, the plant suspends or stops growth and development.

At present, herbicides synthesized on the basis of organic compounds are used in agriculture to control weeds, which have high efficiency and selectivity compared to inorganic preparations.

For example, Avadex affects a very limited number of weed species - one (wild oats). It acts on it for a very limited time (only in the phase of 1-2 leaves).

Herbicides of selective action enter plants in various ways: some through the leaves (they move through the vessels of the phloem), others through the roots from the soil solution, and therefore the methods of their application are different. The former are used for spraying the ground organs of plants, the latter are applied to the soil.

Timing and methods of applying herbicides

The timing and methods of applying herbicides depend on their properties, formulations, routes of entry into plants, the selectivity of cultivated plants and the spectrum of action, that is, the set of affected weeds.

The use of herbicides in autumn in combination with autumn tillage is promising for the destruction of perennial root shoots and rhizomatous weeds. During this period, many herbicides can be used both by spraying vegetative weeds with systemic and contact preparations, and by applying them to the soil at a high rate of their consumption, since they are completely inactivated during the autumn-winter period and will not harm spring sowing crops.

1)1) in the fields littered with thistle, field ostoma, field bindweed, in the fall after harvesting, amine salt 2.4 D is used at a consumption rate of 40% of the drug 5-7 kg / ha.

2)2) to suppress creeping couch grass in the fields allocated for flax, potato, cabbage, sugar and fodder beet, carrot and cucumber, autumn spraying of TCA (sodium trichloroacetate) is recommended when N 90% of the preparation 23-50 kg/ha can be used in autumn and many other preparations and their mixtures.

Before planting and sowing cultivated plants, herbicides can be applied to the soil in a mixture with mineral fertilizers, as well as by spraying the field, followed by cultivation or harrowing. Herbicides suppress germinating weeds and their seedlings.

Herbicides contribute in the form of granules in rows or in the form of solutions, suspensions, emulsions - in row spacing. This method is effective, as drugs are economically consumed. Before their introduction, the soil is well leveled, herbicides quickly close up especially volatile ones (treflan, triallat, tillam, eptam).

For pre-emergence application(after sowing before wheat shoots) herbicides are applied by spraying with emulsion, suspension, solutions. Both vegetative and germinating weeds are affected. The time for pre-emergence application (sowing - shoots) is limited to a few days, and herbicides cannot be incorporated into the soil by processing, so less volatile preparations are used and applied so that the solutions get into the moist soil layer.

Pre-sowing and pre-emergence application of herbicides is very effective, as they suppress weeds in the earliest phases of development of cultivated plants, when they are most susceptible to infestation.

Post-emergence treatments carried out by spraying. Granular herbicides are also used (10% granular butyl ether 2.4 D) is recommended for spring processing of winter crops simultaneously with top dressing with ammonium nitrate (sprouts of many weeds are suppressed).

When post-emergence application of herbicides, it is important to establish the timing of application and application rates of the herbicide in order not to damage the cultivated plants and to destroy the weeds at an early age, when they are more susceptible.

In row crops, post-emergence directional spraying is practiced, in which herbicides are applied in rows or only between rows.

Granular herbicides are applied to the desired depth, as well as in rows or aisles, or scattered over the surface of the field. In the form of granules, they act in the soil for a longer time, are more slowly destroyed by microorganisms and under the influence of physicochemical processes and a.i. gradually released into the soil solution. In areas prone to wind erosion, herbicides are used on fallows to reduce the number of treatments, and therefore less spraying of the topsoil. In RIAH, when using herbicides in pairs, mechanical treatments are reduced by 50%. After two spring tillages with flat-cutters, as root shoot weeds grow (mid-June), the field is sprayed with 2.4 D salt N 1.6 kg AI / ha.

The second chemical weeding of the fallow is carried out 30 days after the first (at the end of August), the field is practically cleared of weeds, the soil is not sprayed, has an optimal density, erosion processes do not develop.

Herbicide application rate

The correct calculation of the application rate of herbicides is important. For all herbicides, the optimal consumption rates for different crops have been experimentally established, the timing and methods of their application have also been determined.

N should be set in each specific case, depending on the species composition of weeds, the degree of weediness, the mechanical composition of the soil, the content of organic matter in it, take into account the weather conditions during the application of herbicides and their possible residual effect on subsequent crops in the crop rotation.

The maximum dose of herbicide 2.4 D in the form of 40% amine salt should be used in cereal crops in the presence of many. root shoot weeds, the minimum - if the crops are dominated by weeds more sensitive to this herbicide, for example, hazeweed.

It is more convenient to use N consumption of herbicides, expressed in a.i.

D - consumption rate of the drug, kg / ha

d- rate of consumption of a.i., kg/ha

Calculated d- herbicide consumption rate in a.i. per 1 ha. It's on cereals.

When cultivating tilled crops, herbicides are applied using a belt method, only rows are sprayed, and the aisles are treated with cultivators. N p is less.

D l - N with band application, kg/ha

D s - N with continuous application, kg/ha

S - spraying belt width, cm

M - row spacing, cm

Liquid consumption rate

N depends on the nature of the action of the herbicide and on the machines and equipment used. High N for contact herbicides and soil acting herbicides. When using tractor-mounted and trailed sprayers, N is higher than with aerial spraying.

N for ground tractor sprayers (l/ha):

-- contact herbicides 300-600

-- systemic herbicides 150-300

-- herbicides of soil action 300-400

For air

1.1. On grain crops - 25 l / ha - here, with a decrease in the relative humidity of the air to 50%, the rate is increased to 50 l / ha.

2.2. When using air desiccants 100-200l/ha

Working solution concentration

K. varies depending on the rate of fluid consumption, which is associated with the use of ground or aircraft equipment and is calculated

K - concentration, %

D - N consumption of herbicide by preparation

Q - liquid consumption rate, l/ha.

Integrated protection system - the basis for preventing the negative impact of pesticides on the environment

Integrated - complex systems, the basis of which is the possible full use of environmental factors that cause the death of harmful organisms or limit their vital activity at a safe level (up to the level of the economic threshold of harmfulness).

M-dy: agrotechnical, biological, chemical, mechanical cars. When organizing chemical pest control measures, it is necessary to be guided by the economic thresholds for damage, the drugs used and the timing of the chemical treatment.

E.p.vr. - the density of a harmful object, at which 3-5% of the crop is carried away, and up to this level, the use of chemical measures is inexpedient and unprofitable.

SZS - 20 goose per 100 ears (10 wet) in the phases of milk and number of dreams.

Psh.thrips - 40-50 copies. per ear in the phase of grain filling and milky ripeness

(drought - 30 larvae).

Hv. piavitsa - 10-15 beetles / m 2 in the phases of tillering and exit into the tube

Grass aphids - 10 aphids per flowering stalk, 20-30 aphids per ear in phase

grain ripening.

There are environmental thresholds for diseases and weeds. Find and write.

Avadex BV (K.E.)

A pre-emergence soil herbicide is the most common wild oat control worldwide.

Avadex (3-4 l/ha) is applied before sowing cereals with a shallow incorporation into the soil. Destroys r-I wild oats during their germination and retains herbicidal action for 6-8 weeks.

When embedded to a depth of 3-4 cm, Avadex forms a protective screen on the path of wild oat seedlings. Cereal seeds, which must be sown at great depths, germinate through this layer of soil without any damage.

Wild oats are destroyed with avadex in rape, flax and sugar beet crops (these crops are resistant to herbicides, so the depth of planting and sowing does not matter). Its toxicity is low, it has been used for more than 30 years around the world and during this time has earned an excellent reputation in terms of its environmental friendliness.

Avadex does not kill wild oats after germination, they must be destroyed by cultivation.

It has low toxicity and a slight irritant effect on the skin and eyes. Incorporate Avadex bv into the soil immediately or no later than 3 hours after the sprayer to prevent evaporation of the herbicide (not for disc cultivators). Avadex destroys 85-95% of wild oats.

Influence of wild oats on yield reduction

Wild oats, pcs/m 2	Yield loss in %

Roundup (glyphosate) - general purpose systemic herbicide. Sufficient soil moisture content is essential for good results.

The popularity of Roundup is explained by factors:

-- destroys weeds both on the surface and in the soil, including the root system pl. weeds;

-- devoid of soil activity. Any culture can be sown directly after the application of the drug;

-- one of the safest herbicides, not dangerous to the environment and humans.

Apply roundup:

-- Couch grass control: spraying crop residues after harvest or 10-14 days before harvest.

-- In vineyards and gardens, perennial and annual weeds (humai, couch grass, field bindweed, sow thistle, etc.) are destroyed.

-- Control of hydrotrophic weeds: destruction of aquatic weeds such as cattail, reed, etc. in canals, fish ponds.

-- Silviculture - destruction of weeds of all kinds in nurseries before planting in young coniferous stands.

Roundup is applied at a dose of 3-4 l/ha N slave. solution 100-200 l/ha. After 7-14 days, the foliage and rhizomes of weeds die.

Roundup is applied at any time after harvesting until the first frost. During pre-harvest processing, grain without residues goes to bread and brewing.

Fundamentals of Pesticide Application

Sanitary and hygienic classification gives a description of various pesticides, to determine which pathological effect is the most dangerous.

Depending on the toxicity and degree of danger, pesticides are divided into a number of groups according to the main criteria.

1.1. According to toxicity when injected into the stomach - oral.

-- Strong poisons SD 50 to 50 mg/kg.

-- Highly toxic SD 50 50-200

-- Medium toxic SD 50 200-1000

-- Low toxicity SD 50> 1000 mg/kg.

2.2. According to toxicity when entering through the skin (skin-resorptive toxicity).

-- pronounced SD 50< 300 мг/кг.

-- pronounced SD 50 300-1000

-- mild DM 50 > 1000 mg/kg.

1)3) According to the degree of volatility

-- very dangerous substance (saturated concentration > or = toxic)

-- hazardous substance (saturating concentration > threshold)

-- low-hazard substance (saturating concentration does not have a threshold effect).

Highly volatile drugs penetrate through the respiratory organs and are characterized by inhalation action. Fumigants and mercury-containing preparations are very dangerous (gas masks are needed).

2)4) By cumulation

-- substances with supercumulation;

-- pronounced cumulation;

Moderate.

Cumulation- accumulation of poison in the body as a result of incomplete detoxification and removal from the body.

Cumulation material - accumulation of poison in the body as a result of repeated contacts (CHOS and mercury preparations).

Cumulation functional - this is not the accumulation of poison, but the summation of the effect of the action (FOSS (metaphos, karbofos).

3)5) By durability (in soil)

-- very persistent substances (decomposition time into non-toxic parts > 2 years))

Persistent - (0.5-2 g) decomposition time (DNOC, simazil)

-- moderately resistant (1-6 months) - chlorophos, cynat 2.4 D, karbofos)

-- low-resistant (≈ 1 month) - fumigates.

Above, we have listed the main criteria (toxicity, volatility, persistence, cumulation) - this allowed us to give a hygienic assessment of pesticides.

In addition to them, other pathological effects of pesticides are also being studied:

-- blastomogenicity - the ability of the pesticide to cause the formation of tumors;

-- carcinogens - if the tumor is malignant;

-- mutagenicity - the appearance of mutations in plants, animals;

-- embryonicity - pesticides disrupt the normal development of the embryo;

-- allergenicity - the property of the pesticide to cause a change in the body's reactivity to repeated treatments (edema, rash, itching, etc.).

II. Regulations for the use of pesticides

The toxicity of pesticides for humans, their ability to persist in the external environment, accumulate in the resulting products require the development of strict scientifically based recommendations, standards, restrictions (regulations) for each drug, ensuring their effective and safe use.

-- Regulations are developed by the Ministry of Agriculture together with the Ministry of Health.

-- The "List of chemical and biological pest, disease and weed control agents approved for use in agriculture" is approved annually, which gives the name of the drugs that can be used in the current year, N consumption, restrictions on the use of individual crops in the use of the treated area and the products obtained on it. The list annually includes new, industrially tested, effective and usually less toxic drugs.

-- You can not focus on the old lists - this is a (gross) violation of the restrictions on the use of pesticides.

1. Strictly observe the recommended consumption rates of preparations (so as not to accumulate pesticides in the environment and in products).
2. MPC (maximum permissible concentrations). Established hygienic standards for MPC in the air of the working area, in H 2 O, soil, in the presence of persistent substances in the arable layer (sevin, polychlorcamphene) in quantities greater than the MPC, it is allowed to grow cereals.
3. For sanitary control of pesticide residues in food products, MRLs (maximum allowable levels) are approved, expressed in mg/kg of the product. An MRL is set for each pesticide.
4. Based on the MRL for residues, set the waiting period or last treatment time (time between last treatment and harvest). This is the period during which the pesticide is destroyed and does not exceed the MRL.
5. In order to prevent poisoning of people when working on fields treated with pesticides, the terms for plant care are regulated (this is 6 days and with soil loosening - 14 days - 2 weeks).
6. Strict observance of safety regulations, instructions. Strict implementation of the accepted norms and rules governing the use of pesticides will ensure reliable prevention of poisoning and environmental protection.

Some herbicides are marked by narrow selectivity. For example, targa, fusilade, Poast, furor super destroy weeds of the thin-legged family in crops of dicotyledonous crops, and the drug puma super is able to destroy wild oats and common bent grass in winter wheat crops, although they belong to the same family.

The selectivity of herbicides is often due to differences in the anatomical and morphological structure of plants. Such selectivity is called topographic. Thus, plants with a dense cuticle and wax coating, as well as with dense pubescence, are more resistant to herbicides, since these anatomical features prevent the drug from entering the plant. In plants with narrow vertical leaves (onions, garlic, etc.), the working fluid drains from the surface of the leaf blade, while the herbicide almost does not penetrate into the tissues.

Plants with a deep root system show resistance to preparations that are contained in the upper soil layer and do not reach the zone of activity of the roots. Such plants include the listed field sow thistle, creeping mustard, field horsetail, field birch and other perennial weeds.

Herbicide-resistant crop plants exhibit biochemical selectivity due to the rapid degradation of the herbicide molecule to inactive components. In some cases, plants are able to quickly release herbicides through the root system in an unchanged state without harming them. The resistance of cereal plants to the action of 2,4-D is explained by the detoxification of the herbicide by binding it with protein complexes of cellular structures, cytoplasmic membrane proteins, and also by the formation of complexes with compounds of non-protein origin. The sensitivity of weeds to the action of herbicides is explained by significant irreversible disturbances in metabolic processes, which leads to the death of these plants. The selectivity of derivatives of symmetrical triazine is explained by the peculiarities of the movement of herbicides and the accumulation of their toxic effects. It was found that in resistant plants (corn) the herbicide accumulates in the roots, while in sensitive species it quickly accumulates in the leaf apparatus, in places of photosynthetic activity, which is why it exhibits its toxic effect. In addition, due to the destruction of the herbicide by redox enzymes in the corn plant, symtriazines, the herbicide is degraded to non-toxic compounds.

With the development of achievements in biotechnology and genetic engineering, opportunities are opening up for managing plant resistance to the action of herbicides. Determination of the genetic code of plant resistance to herbicides makes it possible to transfer resistance genes in a crop and solve the problem of controlling the weediness level of sugar beet, corn, soybean, rapeseed and other crops with the help of herbicides of continuous action, to which there was no resistance in the culture (glyphosate, ammonium glufosinate and etc.).

Depending on the characteristics of the effect on plants:

contact;
systemic.

Contact herbicides are preparations capable of infecting plants in places where they are wetted with the working mixture. Contact herbicides are practically unable to move along the leading system of plants, so they do not penetrate the root system of perennial weeds that are able to grow back.

Systemic herbicides are able to move in the vascular-conducting system, affecting the entire plant and causing the death of both its aboveground and underground organs. When moving through the vessels of plants, herbicides interact with the cellular content, which leads to their partial inactivation through absorption by cells, destruction by enzymes, and the formation of complex compounds. Herbicides move into the root system, in the generative organs, accumulate in the zones of active growth, causing deep disturbances in physiological processes, which leads to the death of sensitive plants. With the soil solution, herbicides are absorbed by the root hairs, transferred to the xylem vessels, and move along the transpiration flow to the aboveground plant organs. It is advisable to use systemic preparations in the fight against perennial weeds, the root system of which penetrates deep into the soil.

Absorption and movement through the plant of systemic herbicides occurs in a passive way using thermal diffusion energy or transpiration energy. Active absorption and transport of herbicides occurs due to the use of energy from adenosine triphosphate (ATP).

According to the method of penetration into the plant:

soil;
ground.

Soil herbicides penetrate through the above-ground organs (leaves, stems, petioles) and are applied after the emergence of crops and weeds (Betanal, Roundup, Poast, Grodil, etc.). Soil herbicides penetrate into plants through the root system and have an effect on seed sprouts, they are also called root action herbicides (dual, Zenkor, prometrin, etc.).

In Russia, a "List of pesticides and agrochemicals permitted for use" is periodically published, agreed with the Main State Sanitary and Epidemiological Directorate of the Ministry of Health of Russia. It lists all chemical pest control agents approved for use, incl. and herbicides, and regulations for their use, compliance with which is the main component of safety in relation to the environment, animals and people.

Timing of herbicide application

The timing of the application of herbicides depends on:

properties of a drug;
biological characteristics of crops and weeds;
selectivity;
action spectrum, etc.

Autumn (early) application of herbicides is carried out in the system of the main (autumn) tillage in order to destroy perennial rhizomatous and root weed species using, for example, roundup or Basta against creeping couch grass, sow thistle species, rose mustard, etc. Herbicide treatment is carried out after the growth of rosettes or shoots of weeds due to post-harvest stubble stubble of grain crops. The next (after spraying) tillage should be carried out not earlier than systemic herbicides penetrate into deep-lying rhizomes, i.e. not earlier than in 10-15 days. The destruction of perennials becomes more difficult in years with a dry summer-autumn period, when weeds do not grow without watering. Pre-sowing application of soil herbicides (Treflan, dual, Zencor, prometrin, etc.) is carried out during pre-sowing cultivation with a disc or tooth harrow in a moist soil layer. At the same time, a gap in time between spraying and wrapping is not allowed. This is due to the use of volatile herbicides (Treflan, Eptam, Eradikan, etc.). Violations in the technology leads to unproductive losses of drugs, a decrease in their effectiveness, environmental pollution, and financial costs. The use of herbicides for sowing or planting seedlings allows you to successfully destroy annual weeds in the seedling phase.

Pre-sowing application of herbicides occurs simultaneously with sowing by introducing granular preparations using special applicators or by applying working mixtures in a band and into the protective zone of wide-row sowing of row crops.

Tape application of herbicides is one of the areas of environmentally safe and rational use of pesticides.

Pre-emergence application of herbicides is carried out after sowing or on the ladder of weeds, but before the emergence of seedlings of cultivated plants. It is more expedient to carry out this event on the third or fourth day after sowing, when the appearance of weed seedlings coincides in time (they are in the “white thread” phase) and pre-emergence harrowing. In the pre-emergence period, soil preparations are successfully used: harnes, dual gold, super trophy, Frontiera, etc. However, it must be remembered that the time for applying pre-emergence herbicides is quite limited - from sowing to the appearance of crop seedlings, which can be damaged by pre-emergence harrowing. The disadvantages of pre-emergence application of herbicides can be the drying of the topsoil and, as a result, the lack of effectiveness of herbicides, as well as the situation when heavy rains occur during the period of herbicide application and the optimal processing time is lost. In addition, the application time is further reduced when the air and soil temperatures are above 20-24°C.

Best practice in crop protection against weeds convinces that in the zone of sufficient moisture, the pre-emergence application of herbicides is not inferior (in some cases even exceeds) the effectiveness of their pre-sowing application. In the zone of unstable moisture and risky farming, it is more expedient to apply herbicides for pre-sowing cultivation with their wrapping in the moist soil layer. Post-emergence application has an advantage over others due to the fact that during this growing season it is possible to determine the number of weeds and the feasibility of using herbicides, knowing the species composition of weeds, you can purposefully select drugs and use them with the greatest efficiency. In addition, weed control measures can be combined with protection against pests and diseases, with the use of growth regulators (retardants), foliar top dressing with microelements and macroelements.

When spraying with post-emergence herbicides, it is especially important to take into account the phases of crop resistance, the growth phases of weeds and their sensitivity to treatment with one or another preparation, carefully observe the norms for the consumption of preparations and liquid, and take into account weather conditions. Post-emergence herbicides can be applied in a continuous and belt way, processing the protective zone of the rows of row crops (corn, sunflower, sugar beet, soybeans, cotton, vineyards, fruit plantations, vegetable crops, etc.). Post-emergence application is used in fallow fields to kill weeds to reduce tillage costs and limit wind and water erosion.

Granular forms of herbicides are used before sowing with or without wrapping in the ground, before germination or after germination of crops and weeds in a continuous or belt way. Granular preparations act on weeds much longer, are slowly destroyed under the influence of meteorological factors and microbiological processes, do not evaporate, they can be applied simultaneously with the dispersion of mineral fertilizers.

Herbigation

On irrigated lands, crops of rice, sugar beet, sunflower, corn can be treated with herbicides simultaneously with furrow irrigation or in sprinkler units. This method of applying herbicides is called herbigation. With a sufficiently large dilution (1:50000-100000), even such volatile preparations as eptam, radikan, Tilly, yalan, Ronit, etc. do not go to evaporation. This achieves a uniform distribution of the herbicide over the area and a high death of weeds.

New ways of using herbicides (subsoil, nesting, recirculating, contact, etc.) are being developed and are gradually being introduced, which reduce the unproductive costs of drugs that reduce the negative impact on environmental objects, are much more economical, etc.

Repeated and systematic treatment of weeds with herbicides can give lasting results for the whole season. They are chemicals that adversely affect the development and growth of plants. Herbicides are used only against weeds.

In order to know which drug is better to treat weeds, you need to know the specifics of its action. The main distinguishing feature of such funds is their spectrum of action. All herbicides are divided into two groups: continuous action and selective.

Continuous action drugs

Those substances that are part of continuous herbicides are capable of destroying all vegetation that was at the time of spraying. Such radical drugs are used in areas where vegetation is contraindicated.

The action of herbicides of this type is divided into subgroups, namely:

. contact preparations,
. systemic,
. soil.

Contact herbicides begin to act on the plant only when the drug has got on the leaves or stems. The leaves begin to turn yellow, wither and dry. All this leads to the complete destruction of the weed.

The use of soil herbicides is appropriate in cases where the weed has had time to pour its seeds into the ground. Such preparations are applied directly to the ground. They have a detrimental effect on weed seeds, thus preventing them from germinating.

Systemic herbicides are considered one of the most popular, as they quickly and effectively affect the development of the weed. When such a herbicide hits a weed, it not only attacks the outer sheaths, but is absorbed into the plant itself. It spreads throughout the weed, which means that its action is also aimed at destroying the root system.

Of course, systemic preparations are incomparable with soil herbicides. Systemic herbicides can have a complex effect on the plant, while soil herbicides can only affect the seeds.

Selective drugs

The second large group of herbicides is headed by drugs of selective action. These substances can destroy only certain types of weeds. When choosing such drugs, you must carefully read the instructions for use of herbicides. Often, it contains a complete list of weeds that can be adversely affected by the selected drug.

When buying selective herbicides, you need to know:

. drug expiration date,
. herbicide application rates
. ways of application.

Can a herbicide harm a person? The instructions for herbicides always indicate the level of danger and toxicity to humans. All substances that are part of the selected drug have different degrees of toxicity.

The price of herbicides varies depending on the system of action. The average price of one liter of herbicide can be 200-5000 rubles per 1 liter.

Popular drugs

What herbicides are considered the most popular in the market of chemicals? The action of herbicides is directed against weeds that could have been permanent "residents" of any territory or plot for years. Therefore, the fight against them is considered one of the most difficult.

After reading dozens of reviews about herbicides, we can conclude about the most popular drugs that can really help radically:

Herbicide Roundup is considered a non-selective systemic drug. It has a wide range of effects, especially on perennial weeds. It is considered one of the most radical drugs in the world. The final destruction of the weed falls on 14-15 days after treatment.

Herbicide Tornado is aimed at systemic effects. It is used as a universal remedy for weeds. It contains an increased concentration of the main active substance.

Herbicide Prima is considered a powerful drug that has two active ingredients. Often it is used to control weeds that grow in areas with cereals and corn.

Herbicide Gold is applied against cereal monocotyledonous and dicotyledonous weeds. It is used in fields with corn, rapeseed, sunflower, soybeans, etc.

Herbicide Hurricane is a systemic preparation that can be used both in fields and on private land plots. It shows itself perfectly among vineyards, forest plantations, orchards and fields. It has a wide field of action, therefore it is considered a universal remedy.

Herbicide Stomp is used to control weeds in vegetable beds. It is considered a dual-action herbicide, as it can act systemically on the weed and destroy seeds through the soil.

Herbicide Titus is a post-emergence preparation that is used to control weeds in areas where tomatoes, potatoes and corn will be planted. It is considered a systemic drug. It is popular for its low application rate, high selectivity and long-term efficiency.

Herbicide Zenkor is designed for systemic exposure to the weed. The drug has a wide spectrum of action. Differs in the long period of protection. Controls annual dicotyledonous weeds.

Herbicide Eurolighting - post-emergence preparation. It is aimed at the destruction of cereals and dicotyledonous weeds. It acts both through the vascular system of the plant and through the soil. One treatment will be enough to keep the soil clean throughout the growing season.

Herbicide Granstar is used for weed control for barley, wheat, sorghum, soybeans, rapeseed. Has a wide range of effects. It perfectly destroys dicotyledonous weeds, as it affects systemically.

The herbicide Gezagard is distinguished by a rather long period of exposure - 10-12 days. It is used for potatoes, vegetable crops, corn, coriander, sunflower, grain crops. Not phytotoxic.

The development of large farms has determined the need to find an easier solution for getting rid of weeds. Chemists, studying the properties of various substances, came across the ability of copper sulfate (when studying the properties of Bordeaux mixture) to inhibit dicotyledonous weeds. Later, the same property was discovered in the action of ferrous sulfate, copper nitrate, sodium chloride, sodium arsenite, sulfuric acid and other compounds.

The successful development of a new direction in chemical production began - the production of substances capable of destroying green plants. They were called herbicides (1944), from herb - plants, cide - to destroy. Herbicides have been separated into a separate group of chemicals.

Types of herbicides

The development of the herbicide industry was initially limited to a continuous action on green plants. Later, by changing the concentration, the selective effect of the herbicide on uncultivated plants was made possible. Their scanty doses at high dilution contributed to the acceleration of plant growth, that is, they no longer oppressed the plants, but acted as a stimulant. Having identified a number of necessary properties, for the selective destruction of weeds, herbicides were divided into 2 groups:

full action,
selective (selective) action.

Today, the first group of herbicides is used in the construction of roads, stadiums, airfields, high-voltage lines, etc. Selective herbicides have found their niche in the cultivation of crops.

Methods of herbicide action on weeds

Herbicides of continuous action destroy all vegetation, even cultivated plants. They are practically not used today in agriculture.

Selective herbicides are divided according to the spectrum of action into:

widely selective. Destroy mono- and dicotyledonous weeds;
narrowly selective. They affect a certain class of weeds, up to individual species. Can be used in crops of cultivated plants.

According to the method of influencing weeds, herbicides are also divided into:

contact,
systemic.

The group of contact herbicides needs contact with the plant. When spraying, the area of contact of the pesticide with the surface of the weed is significant, which has a depressing effect on the entire plant.

Systemic herbicides, when in contact with a plant, penetrate inside and spread with a fluid flow to all its organs. This property is especially important for the destruction of perennial weeds with a strong root system.

In agricultural production, widely selective systemic herbicides are most often used, especially for multi-species contamination.

Herbicides are available as:

emulsion concentrates,
wettable powders in various colours,
suspensions.

How to use herbicides

To choose the right herbicide, you need to carry out some preparatory work before buying it:

approximately estimate the degree of contamination of the field;
determine the species composition of weeds.

Accounting for weediness of the field is a very important indicator. If the dose of herbicide is insufficient (desire not to poison the soil too much), not all weeds will disappear. Some will survive under these conditions, and it will be necessary to apply the pesticide again. If too high a dose is applied, cultivated plants will suffer.

In special reference books, norms and combinations of herbicides are given according to: the species diversity of weeds, the degree of contamination of plantings, the type of soil and its properties.

Methods and terms of introduction

The timing and methods of processing by pesticides depend on the type of herbicides. If a continuous non-selective herbicide is used, then it is necessary to protect the cultivated plants before applying it. When using a targeted herbicide, the age of the weeds must be taken into account. Some weeds increase the degree of herbicide resistance with age, intensively clog the crop, which reduces its yield (sometimes up to 30-40%).

According to the terms of application, they are divided into pre-emergence and post-emergence.

Pre-emergence application is carried out before sowing seeds, during sowing and for some time after sowing.

Post-emergence preparations are applied from the phase of weed germination, tillering and reaching a height of 5-10 cm. Most of the weeds die when introduced into the germination phase, with age their resistance to the herbicide increases.

For pre-emergence application, soil herbicides are usually used. They are usually applied to moist soil, which makes it easier for the drug to spread in the applied layer. Special root herbicides are applied in the form of granules and embedded in the calculated soil layer. Leaf herbicides are applied to green plants by spraying vegetative organs (leaves, stems).

Duration of action of the herbicide and its harmfulness

To increase the effectiveness of the herbicide, it is necessary to create certain conditions in the environment. So, soil and root herbicides are applied to moist soil. In the dry, they are inactive and only accumulate, and then, when watered or rainfall, their increased amounts destroy all types of vegetation (weeds and cultivated species).

After herbicide treatment of the aerial parts of weeds, dry sunny weather is necessary for 2-4-6 hours. Washing off the drug from plants requires re-treatment. Once in the soil, the drug has no effect on weeds, but accumulates in the soil.

Undecomposed herbicides with large amounts of water are washed out of the soil and enter various water bodies (ponds, lakes, rivers, seas), where they enter plants, organisms of river and marine animals and, as a result, into the human body.

Of course, timing plays a role. Some herbicides are destroyed over time under the influence of biological degradation, physico-chemical absorption, enzymatic destruction. But all of them, incl. and part of the herbicides decomposed into chemical components, have a negative impact on the soil biota involved in the formation of humus. As a result, humus formation decreases, and hence soil fertility. Some of the systemic toxins end up in the crop and on the dinner table. In general, the effect of the drug and its toxins lasts a very long time.

The duration of herbicide action is clearly demonstrated by Agent Orange, which was used by the United States in Vietnam. The drug, a mixture of defoliants and herbicides, was intended to destroy forest vegetation, but at the same time it was dangerous for people. Upon returning home, American soldiers were ill for a long time and died from oncological diseases of the gastrointestinal tract, respiration, and damage to the nervous system. After the war and up to the present, children are born in Vietnam with various disabilities. Therefore, even if your home area is heavily infested with weeds, think before using pesticides.

The use of herbicides in summer cottages

If it is impossible to do without the use of pesticides, check out the catalog of drugs approved for use in agriculture. Choose herbicides that have a short decomposition time and do not accumulate in the soil.

Today, in small packaging, Lintur, Hurricane, Tornado, Agrokiller, Fizilad are offered for processing plants and soil. The most effective technique is to prepare the solution according to the accompanying recommendation and spray the green weeds. The exposure period is from 8 to 12 days. Within a month, the above preparations decompose and do not accumulate in the soil. The effect and duration of preservation of the components of the decomposed preparation are in the special literature.

Health protection during herbicide treatment

Herbicides are poisons with a high degree of harm to health. Therefore, when using herbicides in the work, it is necessary to take measures of personal protection.

Work only in calm weather.
Work in clothing that completely covers open areas of the body (headgear covering the neck, glasses, respirator, long-sleeved gown, gloves, trousers, boots).
after work, completely change clothes, take a shower, drink milk.

Drinking alcohol can be fatal.

Worldwide production and use of herbicides is estimated at 4.5 million tons of drugs annually.
Natural living herbicide. In the Amazon, ants (n / s formycins) live in symbiosis with trees of the genus Duroya. By injecting formic acid into any kind of undergrowth, except for Duroya, they clear the forest of weeds and other trees.
According to No-Till technology, weed control without herbicides is possible if, without allowing flowering, weeds are destroyed, leaving their remains between plants. Leave all crop residues on the field. Due to the layer of mulch, weeds cannot sprout and germinate freely. A few years later, the field is cleared.
The use of siderates. Green manure crops sown before leaving for the winter, releasing allopathic substances, act as herbicides.
In large fields, the soil is kept in the form of green fallow. Under green fallow, dense sowing of perennial fodder crops is used. For two years under green fallow, the number of weeds is reduced by 3 times.

In the fight against weeds, the use of more than 120 types of chemical preparations is currently allowed in agriculture. The range of available herbicides is constantly improving and increasing due to the creation of highly selective in relation to weeds and at the same time does not affect the growth and development of cultivated plants, does not accumulate in agricultural products and does not pollute the environment. For the systematization and effective use of herbicides belonging to different classes of chemical compounds, they are classified according to various characteristics and properties.

According to the nature of plant damage, herbicides are conditionally divided into herbicides of continuous action (general extermination) and herbicides of selective (selective) action.

Herbicides of continuous action destroy all plants - both cultivated and weeds. In this regard, they are used on uncultivated heavily weeded lands - roadsides and fields, in open-air storage areas for agricultural machinery, etc., and on cultivated fields free from cultivated crops: in the post-harvest period, on fallows. In some cases, general-purpose herbicides are used in gardens, forest plantations, in row crops with wide row spacing, and in vineyards. Herbicides of continuous action also include herbicides of selective action, which destroy in high doses those plants that they do not affect at recommended doses.

Herbicides of selective action make up the largest group of those used in the practice of agriculture. They do not damage cultivated crops, but destroy or suppress the development of certain types of weeds.

The division of herbicides into general exterminating and selective ones is also conditional because general exterminating herbicides, more often used in the form of additives in small doses to other compounds, are used as selective preparations. Conversely, selective herbicides used in high doses can cause the complete death of all vegetation.

The phytotoxicity of individual herbicides of selective action for different plant species is not the same. Therefore, herbicides with a wide and narrow spectrum of action on plants are distinguished. Broad-spectrum herbicides are capable of destroying many plant species, even those that are far from each other in their systematic position. Narrow-spectrum herbicides are used to control individual species or groups of weeds.

Depending on the nature of the action on plants, herbicides are divided into contact and systemic. Herbicides of contact action damage only those organs or tissues of plants on which they fall and with which they come into contact. However, their influence on weeds is limited, since in perennial weeds, when the aerial parts of plants, leaves and stems die off, the root system retains its viability and can give new shoots. Systemic, or moving, herbicides easily penetrate into plant tissues through aboveground or underground organs and, moving along the phloem or xylem, enter into various chemical reactions that occur in plants. This disrupts the normal metabolic process in plants, causes a violation of their physiological and biochemical reactions, which leads to various pathological phenomena. Representatives of this group of herbicides are especially effective in the fight against perennial weeds that develop powerful vegetative reproductive organs.

According to the nature of penetration into plants, herbicides are divided into:

1) penetrating through leaves and other aboveground organs, foliar herbicides that are used to control vegetative weeds;

2) penetrating through roots or seedlings, herbicides of root or soil action, which are applied to the soil before emergence of weeds;

3) herbicides of combined action penetrating into plants both through above-ground organs and through the root system.

In relation to the botanical class of plants, their systematic position, herbicides of systemic action are divided into two groups: anti-dicotyledonous and anti-monocotyledon (anti-cereal). Antidicotyledonous herbicides damage only those plants that belong to the dicotyledonous class and have no effect on monocotyledons. This is mainly due to the anatomical and morphological features of the structure of plants. Herbicides 2,4-D, 2M-4X and others are used for the destruction of broad-leaved dicotyledonous weeds in crops of monocotyledonous crops (cereals).

With the introduction of optimal norms of anti-monocotyledonous, anticereal herbicides, monocotyledonous plants are destroyed and dicotyledonous plants are not damaged. Herbicides sodium trichloroacetate, dichloralurea, dalapon and others are used for the destruction of cereal weeds in crops of broad-leaved dicotyledonous crops - sugar beet, sunflower, cotton, etc.

According to the method of application and treatment of plants and soil, herbicides are also divided into two groups. Herbicides, which are used only by spraying vegetative weeds to suppress and destroy them, and soil herbicides, which are applied to the soil in a dry form or by spraying the soil surface. These herbicides are applied to the soil either without subsequent incorporation or with incorporation into the soil by harrows or cultivators. Some herbicides that evaporate quickly or decompose in the light require immediate incorporation into the soil.

According to the duration of the residual action, herbicides are divided into the following.

1. Herbicides with a long residual effect. The residual effect of these herbicides, even at the recommended application rates, remains in the soil for more than one year, especially on low-humus soils and in years with insufficient moisture. The aftereffect for a long time on uncultivated lands, in gardens, tree plantations has a positive value in the fight against weeds. At the same time, in field, fodder and vegetable crop rotations, where these herbicides are most often used, such an aftereffect is undesirable, since crops that are sown or planted the next year after the application of herbicides are often damaged.

2. Herbicides with a short residual effect. After applying these herbicides at the recommended doses for weed control, crops can be grown in the next year without much risk according to their rotation in the crop rotation. When using herbicides 2,4-D derivatives in crops, for example, cereals, and 2M-4X in flax crops, other crops can be sown in two months.

Composition and forms of technical preparations of herbicides, terms and methods of their application Herbicides used in agriculture are technical preparations containing from 10 to 90% of the active substance (a.i.) of the chemical compound of the herbicide itself. Various compounds are used as inert fillers, ingredients, which give the technical preparation good flowability, non-caking during storage and prevent the decomposition of herbicides. To improve the physicochemical properties of herbicide solutions prepared for application to the soil, surfactants are introduced into the composition of their technical preparations. Thanks to them, the surface tension of the solution decreases, the surface of the plant or soil is better wetted by the herbicide solution. To increase the phytotoxicity of a herbicide against resistant weeds, it is often mixed with some inorganic substances, most often with mineral fertilizers, immediately before use.

Currently produced technical preparations of herbicides have different physical and chemical properties.

According to the physical state of the technical preparation, herbicides are produced in the following forms.

Wettable powders which form an aqueous suspension with water.

Soluble powders that form true solutions with water.

Mineral-oil suspensions that form water-oil suspensions with water.

Aqueous solutions and water-soluble concentrates. Both forms of drugs dissolve well in water in any ratio, but they easily freeze at low temperatures and lose their phytotoxic properties.

Emulsion concentrates that form non-separable emulsions of various concentrations with water.

Granular preparations (granule size of the order of 0.1-0.2 mm). They can be soluble or insoluble in water.

Some herbicides can be prepared in various forms.

The timing of herbicide application depends on the biological characteristics of cultivated and weed plants, the properties of technical preparations. In pre-sowing application, herbicides are applied to the soil before sowing or planting cultivated crops and, as a rule, with their subsequent incorporation into the surface soil layer by harrows or cultivators. Typically, soil herbicides are used in these cases. When sowing, the application of herbicides is carried out simultaneously with sowing or planting crops. Post-sowing - immediately after sowing or planting crops. With pre-emergence application of herbicides, the soil is treated two to four days before the emergence of seedlings of potatoes, corn, carrots and other crops, but when there are already mass shoots of weeds. In this case, both foliar and root herbicides are used. At the beginning of the growing season of cultivated plants and during the period of mass emergence of weeds, as well as on clean fallows and on uncultivated plots of land against especially malicious weeds, post-emergence application of leaf herbicides is carried out. The effectiveness of post-emergence application of herbicides largely depends on the phase of development of both cultivated plants and weeds, the amount of herbicide used, and weather conditions during the period of herbicide application. For the destruction of malicious weeds in the post-harvest period, both leaf and root herbicides are used, which should be completely inactivated by the time of sowing or planting subsequent crops.

The introduction of herbicides into the soil and the treatment of weeds with them can be carried out in various ways. With the wrong method, the entire surface of the field is treated with the preparation. Row application of herbicides is used in tilled crops. In this case, the treatment of weeds with herbicides is carried out only in the rows of cultivated plants, and weed control in the aisles is carried out mechanically with tillage implements. Tape introduction of herbicides allows to destroy weeds in a strip of rows of tape crops (carrots, millet, etc.). With a directed method of applying herbicides, they are sprayed with the lower tier of cultivated plants (with their height of at least 30-40 cm) and the soil. At the same time, low-growing weeds and the soil surface are well wetted with the working solution of the herbicide, and dense integumentary tissues and old leaves of cultivated plants well protect their lower parts from the penetration of the herbicide into them. For the destruction of malicious and quarantine weeds, a focal method of processing curtains and individual plots of uncultivated land is used.

Tape, row and directional application of herbicides in crops is more economical than continuous treatment of crops, as this reduces the consumption of herbicide preparations per unit area without reducing the efficiency of weed control and, in addition, is of ecological importance, since the soil is less polluted .