Pesticide registration and the procedure for their approval for use

The requirements for pesticides during their registration vary in each country, although the objectives of registration are practically identical: pesticides authorized for use must be safe for the manufacturer, the consumer of the product, the crop itself, and the environment. Furthermore, a fungicide must be applied only in accordance with the manufacturer's accompanying recommendations; otherwise, its biological effect will be lost.

In the UK, registration is voluntary and is a two-stage process, which is accepted by all major organizations involved in the production and application of fungicides:

• At the first stage, the safety of the pesticide is determined. Data on its toxicity to warm-blooded animals, persistence, and environmental impact must meet the requirements of the Regulations on safety measures for handling pesticides. Initially, the use of the pesticide is permitted on an experimental, usually small, area. When treating a food crop, all produce is often destroyed at the end of the experiment or evaluation.
• The second stage is the authorization for commercial (limited or full-scale) use, when a large area or the entire crop is treated with the preparation, and the resulting produce is sold.

Authorization must be obtained for both new and old preparations if new methods of application have been developed for them, in particular, on different crops using different treatment methods or in mixtures with other pesticides. Thus, a large amount of biological information is accumulated regarding the development of the treated crop and its quality, and the results of the experiments serve as proof of the compound's effectiveness in controlling a specific disease.

If the objectives set by the manufacturer are achieved, as indicated by the obtained information, the fungicide is considered approved and authorized for use in accordance with the Regulations on the Authorization of Agricultural Pesticides. Labels for such preparations are marked with the letter "A", and their list is published annually by the Ministry of Agriculture, Fisheries and Food.

Authorization for use is highly specific, i.e., a preparation approved as a means of controlling a given disease on a particular crop will be authorized for use against the same pathogen on a different crop only after new, relevant information has been collected.

Spraying. Fungicide spraying is the most common method of treatment and, as a rule, the most effective and cost-efficient in terms of labor input. Preparations for spraying are usually produced by the industry in the form of wettable powders, which form suspensions when mixed with water, where the surfactant of the preparation ensures more complete wetting of all fine particles of the active ingredient.

If the active ingredient is not water-soluble and is produced in a liquid form, for example, based on oils that are immiscible with water, the formulation is called an emulsifiable concentrate. When added to water, this preparation spontaneously disperses, forming tiny droplets suspended in water — an emulsion. To accelerate this process, a surfactant is also added.

As a rule, fungicides are applied with water; the volume of the spray solution per unit of treated area largely determines the effectiveness of the treatment and the time required to complete the operation. The consumption of the spray solution in high-volume (standard) spraying can reach up to 9000 l/ha, averaging 2000 l/ha. Treatments are carried out using motorized sprayers equipped with tanks.

There are various modifications of sprayers that allow for a significant reduction in the consumption of the spray solution. In low-volume spraying, 225—552 to 56—214 l/ha is applied, while in ultra-low-volume spraying, the consumption of the spray solution is less than 56 l/ha. Such treatments require special equipment and, often, special fungicide formulations.

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a — "Cheshunt" high-volume sprayer; b — mechanized method of performing high-volume spraying; the sprayer boom (or hose) is attached to a support beam; c — device for adjusting the concentration of the applied fungicide; -2 — "Turb-air" apparatus for applying small quantities of fungicide.

Low-volume spraying formulations are often produced as mineral oil emulsions and used without prior dilution with water. Reducing the volume of the working solution significantly cuts down on the time required for treatment. For instance, with low-volume spraying, 0.4 ha of land can be treated in two hours, while ultra-low-volume spraying takes even less time. In low-volume spraying, droplet size sometimes decreases so significantly that a larger portion of the fungicide dose settles on the plant surfaces. Some sprayers are equipped with powerful fans, and blowing air through the plant foliage ensures more complete coverage of both sides of the leaf blades with the fungicide. Electrostatic charging of the working solution droplets as they exit the sprayer nozzle may potentially improve coverage of the undersides of leaves; however, the development of such "electrostatic" sprayers is still in its early stages.

For a fungicide to be effective, the product must be distributed quickly and evenly over the plant surface. This is particularly critical for crops with a dense waxy coating on their leaves. To address this, wetting agents (soaps or surfactants) and components designed to improve particle adhesion to the leaf are added to the formulations.

Technologies for applying fine-dispersed fungicides

Dispersing tiny fungicide particles into the air with subsequent settling onto plants is an economical protection method. It requires minimal labor, but is only suitable when the product needs to work on the external surface of leaves. Special forms are used for such treatments: mists, dusts, smokes, and vapors.

Thermal foggers are used to create mists. In practice, jet machines, in which heat is generated by fuel combustion in a nozzle, have proven to be the most effective. During treatment, the operator directs the aerosol stream over the plants while moving along a designated technological path.

• Treatment strip from one side of the path — 10–15 m
• Distance between vaporizers — about 9 m
• Operation time of vaporizers per night — about 6 hours

Other fine-dispersed forms also require adherence to application rules. The choice of method depends on the available equipment and the type of soil being protected. The specifics of working with them have the following nuances:

• Dusts. Contain less active ingredient compared to wettable powders. They are applied using manual or tractor-mounted dusters, directing the stream upwards over the crop for uniform settling.
• Smokes. Generated by chemical generators that release heat. The warm air lifts the fungicide, after which it settles on the crops. The application rate is calculated strictly by the volume of the greenhouse in cubic meters, following the label instructions.
• Vapors. Released when a fungicide is heated by an electric heater, next to which a container with the product is placed. This method has been used for many years in greenhouses to protect roses with sulfur vapors.