Efficiency and Criteria for Choosing Herbicides

Protection of crop plants from pests and weeds — a key factor directly affecting yield. A properly selected herbicide will improve productivity, save material and labor resources. Using this protective agent allows destruction of harmful plants in crops, creating favorable conditions for growth, increasing yield. It is crucial to choose the optimal type of preparation, observe proportions and application rules.

Types and Mechanism of Action of Herbicides

Weed infestation directly affects the productivity of crop plants. Since weeds deprive them of light, water, and nutrients. They also increase costs for soil cultivation, seed cleaning, reduce livestock product quality, and create a breeding ground for pests and disease-causing organisms. Compared to other agronomic practices, herbicide application shows very high efficiency and, when applied according to technology, causes minimal or zero harm to soil.

The first selective chemical substance against pests (the term 'herbicide' comes from Latin 'herba' — grass, 'caedo' — kill) is copper sulfate. Initial attempts to improve yields using chemical substances were made as early as the 4th century BCE. However, scientific research progressed very slowly until the end of the 19th century. The true revolution in agricultural protection methods was achieved after Liebig's theory of nutrition was developed. Substances of this class act by suppressing photosynthesis, toxic effects, altering nucleic acid synthesis, disrupting metabolic processes in unwanted plants, without affecting crop plants. The herbicide 'Dissulfam' (analog of 'Prima') shows excellent effectiveness in eliminating annual and perennial dicotyledonous weeds. Spraying crops is recommended during the stage from initial emergence to the formation of the second internode.

There is no universal classification yet, but they are grouped by various criteria:

• chemical composition (derivatives of amines, carbamic acid, simple ethers, etc.);
• mode of action (non-selective, selective, contact, systemic);
• application timing (pre-sowing, pre-emergence, post-emergence);
• toxicity level (characterized by LD50 — lethal dose of the preparation for test subjects; five hazard classes have been developed);
• duration of toxic effect (very persistent, persistent, moderately persistent, short-lived, non-persistent).

Before using any herbicide, it is important to study contraindications. For example, they cannot be applied when plants are covered with dew, if precipitation is expected within 3-4 hours after treatment, etc.

How to Choose an Effective Herbicide

Modern chemical formulations for protecting crop plants have well-designed formulas and application techniques that minimize harm and toxic effects on crops. Many act on a broad spectrum of weeds, have a wide technological window for application, and convenient practical dosage rates. Products from many manufacturers with different characteristics are available on the market. When selecting, it is important to consider the following factors:

• type, age, growth stage of the crop plant;
• degree of weed infestation, weed species composition;
• subsequent crop in the crop rotation;
• availability of the product, price.

It is also necessary to consider the likelihood of damage to subsequent crops due to residual herbicide amounts in the soil and choose safe concentrations.