Fungicides

The mechanism of action of fungicides is divided into contact and systemic. Contact preparations form a protective barrier on the plant surface, destroying pathogen spores upon direct contact, but they do not penetrate the tissues. Systemic fungicides are capable of penetrating the plant's vascular system, spreading throughout the organism, which ensures protection not only for existing organs but also for newly formed shoots.

Biochemically, fungicides affect the vital functions of pathogens: they inhibit respiration processes in fungal mitochondria, disrupt the biosynthesis of ergosterol in cell membranes, or block cell division. Many modern preparations possess translaminar activity, allowing the active ingredient to move from one side of the leaf to the other.

The effectiveness of using these substances largely depends on the preparation's ability to maintain stability in field conditions under the influence of ultraviolet light and precipitation. To prevent the formation of resistance in disease pathogens, agronomists recommend alternating fungicides from different chemical classes, which is critical in intensive protection schemes.

In addition to directly destroying fungal spores, some systemic fungicides have an additional curative effect, stopping mycelium development in the early stages of symptom manifestation. This allows for the salvation of crops even in the event of an epiphytotic outbreak, provided that the disease diagnosis is conducted in a timely manner.

This group of preparations is used to combat a wide spectrum of pathogens that cause such dangerous diseases as powdery mildew, cereal rust, late blight of nightshades, gray mold, and various types of leaf spots. Fungicides are effective against ascomycetes, basidiomycetes, and oomycetes that affect field, horticultural, and vegetable crops.

Fungicide application rates are calculated based on the degree of crop infestation, the biological characteristics of the crop, and its growth stage. Minimum dosages are used for preventive treatments, while for curative measures, the dose of the preparation is increased to achieve the necessary concentration of the active ingredient in plant tissues.

The application of fungicides requires strict adherence to safety measures and pre-harvest intervals (PHI). It is necessary to account for the timing of the last application before harvest to ensure the absence of pesticide residues in market produce. Handling chemicals must be performed using personal protective equipment to exclude toxic effects on personnel.