Cow milk

Cow milk acts as a biological contact fungicide in agricultural plant protection. Its effectiveness is attributed to the presence of specific proteins, such as lactoglobulin, which undergo chemical reactions triggered by sunlight, thereby inhibiting the development of fungal pathogens.

When applied to the leaf surface, the milk solution forms a thin protein and lipid film. This film creates a physical barrier that prevents fungal spores from germinating and blocks them from attaching to or penetrating the plant tissue.

Beyond its direct fungicidal effect, milk provides easily assimilable micronutrients and amino acids. Regular applications stimulate metabolic processes in leaves, which encourages the development of the plant's natural immunity against unfavorable environmental conditions.

Milk components also alter the pH level on the leaf surface, creating an environment unfavorable for the colonization of pathogenic microorganisms. This makes the process of secondary infection significantly more difficult for fungal spores.

A major advantage of using milk solutions is their environmental safety. Unlike synthetic fungicides, milk leaves no toxic residues in the soil or produce, allowing for applications even during the fruiting period without the need for pre-harvest intervals.

The primary use of milk in agriculture is the prevention and control of powdery mildew (Erysiphales). This method is highly effective on vegetable, berry, and ornamental crops, particularly in greenhouse conditions and home gardens.

In addition to powdery mildew, milk treatments help reduce the intensity of early-stage late blight (Phytophthora) development. Due to its antiseptic properties, regular spraying slows down the spread of the infection, preserving the leaf biomass.

Milk can also be used as a prophylactic measure against various leaf spots affecting roses and other ornamental shrubs. It protects young shoots from pathogen penetration during periods of high humidity.

To increase effectiveness against pests, milk is sometimes used in tank mixtures with soap solutions to combat aphids. The sticky base of the mixture makes it difficult for insects to breathe and move freely across the plant surface.

This treatment is particularly effective on cucurbits, such as cucumbers and zucchinis, which are highly susceptible to fungal diseases in enclosed spaces.

For preparing the working solution, it is recommended to use low-fat milk to avoid the formation of an overly thick film, which could impede the plant's gas exchange. The optimal ratio is between 1:5 and 1:10, depending on the severity of the disease.

Treatments should be carried out in dry weather during the early morning or evening to avoid the risk of leaf scorching. It is crucial to ensure even wetting of the entire leaf surface, including the undersides where fungal spores frequently cluster.

The frequency of application is once every 7–10 days for prophylaxis. If the first symptoms appear, the frequency can be increased to once every 5 days until the spread of the pathogen is fully suppressed.

To improve adhesion, small amounts of horticultural or mild soap can be added to the solution. This increases the mixture's resistance to rain and extends the duration of its protective action.

Only fresh solutions should be used. Storing diluted milk for extended periods leads to souring, which alters the chemical properties of the mixture and can lead to the growth of unwanted microorganisms.

The main limitation of milk-based treatments is their poor resistance to rainfall. After rain or heavy watering, the protective film is washed away, necessitating repeat applications since the substance has no systemic action and does not penetrate the plant tissues.

Excessive fat concentration in the solution can block plant stomata. This slows down photosynthesis and transpiration, which can lead to stunted growth in plants during hot weather instead of the expected protection.

Milk is not a reliable fungicide under conditions of severe epiphytotics. In cases of advanced disease, biological agents are unable to halt pathogen spread, and professional synthetic fungicides should be utilized instead.

Care should be taken to avoid large quantities of undiluted milk reaching the soil, as this can temporarily alter the microbial balance of the rhizosphere and attract soil pests or ants.

When working in greenhouses, air humidity must be monitored after application. Excess moisture combined with organic milk residues can potentially trigger the growth of secondary mold on the soil surface or the greenhouse frame.