In this article, we present the significant added value provided by the formulation of certain plant protection products (Buvicid K, Vegesol R and Vegesol eReS) that are widely used in Hungary, particularly in horticultural crop protection. We also describe the key elements of the underlying patent, supported by experimental results.

In crop protection, it is increasingly important that the substances used achieve the desired effect while placing the lowest possible burden on the environment. It is therefore essential to facilitate the absorption of applied active ingredients and preserve their efficacy for a sufficient period. Following application, environmental factors often render plant protection products ineffective prematurely. Among these factors, particular attention must be paid to rain-induced wash-off, hydrolytic processes and exposure to light, all of which can significantly reduce the intended result. Consequently, in addition to the inherent properties of an active ingredient, the role of formulations developed through colloidal, physical and chemical innovations has become increasingly important.

Our objective was to develop a plant protection product that, when applied to leaves or other plant surfaces, irreversibly forms a protective film, thereby improving the utilisation of the active ingredient and, consequently, the biological efficacy of the product. One of the most important properties of our family of plant protection products containing the film-forming carrier—and of the coating formed after application—is its ability to extend the duration of action of contact active ingredients. At the same time, the resulting film facilitates the penetration of systemic active ingredients by regulating their release without inhibiting the plant’s metabolic processes, such as water and electrolyte uptake and release or respiration.

We achieve this objective by using a carrier containing drying vegetable oils. In a natural oxidative environment—that is, in the open air—the plant protection product polymerises within a few hours to form a solid yet flexible film with a cross-linked structure, resulting in enhanced crop protection efficacy. Various mineral oil derivatives, such as paraffin and petroleum jelly oils, have long been used as adhesion enhancers; however, they are becoming increasingly unacceptable from an environmental perspective. Moreover, they can re-emulsify to a considerable extent and be washed off during rainfall, and may also cause phytotoxic scorching under certain environmental conditions.

Substances widely used in chemical crop protection to enhance efficacy or improve the reliability of treatment are intended to perform several functions when added to plant protection products. An important property of adjuvants is their wetting function: they reduce the surface tension of the water-based (polar) spray solution, enabling droplets to spread more effectively across waxy (non-polar) leaf surfaces covered with glandular hairs. In addition to improving wettability, enhancing adhesion and reducing evaporation of the active ingredient are equally important properties.

Although currently available adjuvants perform these functions effectively during application, they also have a disadvantage. Once sprayed and dried, if the leaf surface becomes wet again due to condensation or rainfall, the adjuvants remaining on the leaf bind water and return to solution, just as they did during spraying. In heavier rainfall, they are washed off the leaf, taking with them contact active ingredients or active ingredients that have not yet been absorbed. Thus, upon rewetting, the beneficial effect observed during spraying is reversed and becomes a disadvantage.

Thanks to their polymerising additive, our plant protection products containing drying oils provide several advantages through enhanced adhesion. By slowing the wash-off of the active ingredient, they make it possible to achieve the same biological effect with less active ingredient than competing products. This also means a lower environmental burden.

Furthermore, our film-forming technology provides improved protection for active ingredients sensitive to atmospheric oxygen, both through the barrier effect of the film layer, which slows oxygen uptake, and through the natural antioxidant effect of vegetable oils.

The field phase of the first active ingredient wash-off trial was conducted in Pomáz in 2020. The application of various formulations of copper-containing fungicides commonly used in Hungary, as well as leaf sampling, was carried out at a GEP-certified trial site. The amount of active ingredient residue was measured by the pesticide analytical laboratory of Szent István University.

The maize plants were at the 5–7-leaf stage at the time of treatment. During the two weeks following spraying, a total of 25 mm of rain fell, and the crop received one application of 14 mm sprinkler irrigation. Sampling and measurements were carried out on several occasions, but here we present only the reduction in active ingredient between the first and final sampling dates (Figure 1).

Following treatment with Vegesol R, a film formed on the plant surface, protecting the active ingredient crystals from being washed off. Nearly 40 mm of precipitation and other environmental effects over a two-week period significantly reduced the amount of metallic copper on the plant surface in every treatment, but the greatest amount of metallic copper clearly remained on plants treated with Vegesol R! Vegesol R delivered outstanding adhesion enhancement compared with the competing products. The plant species is not relevant to the trial, as the drying oil in Vegesol R polymerises in the same way on all plant surfaces.

The second active ingredient wash-off trial was conducted in 2021 on oilseed rape plants with waxy leaves at the rosette stage. The field phase was again carried out at a GEP-accredited trial site, while active ingredient residues were measured by an accredited laboratory. The doses of the products applied once to the plants were adjusted to provide an equal amount of metallic copper (585 g/ha) from Vegesol R and from a competing WG-formulated product containing copper hydroxide as its active ingredient. The active ingredient was measured after the spray deposit had dried and then 5 and 11 days after treatment (Figure 2).

The patented method not only reduces the loss of active ingredient, as demonstrated in the first trial, but the oil-based formulation also substantially improves adhesion from the moment of spraying. In other words, the purchased active ingredient reaches its intended target instead of readily dripping onto the soil. Once the film layer has dried, it also protects against subsequent wash-off.

Thanks to their formulation, Vegesol R and BVN Növényvédő Kft.’s other oil-based products offer outstanding performance among plant protection products. In this way, we provide growers with modern, effective and environmentally responsible solutions.

patentscope.wipo.int

Patent title: Carriers for pesticides and process for forming adherent pesticide film.