Activator adjuvants

Activator adjuvants optimize the bioavailability and efficacy of crop protection products. They play a crucial role in enhancing the performance of the tank mix by improving absorption, penetration, and effectiveness.

Ways in which tank mix adjuvants improve the spray application:

Wetting/Spreading

As soon as a spray droplet makes contact with a leaf, it should adhere to the surface and spread rapidly to achieve optimal coverage the active ingredient. Measuring the surface tension of a liquid is a common method to determine the ability of the droplet to spread onto the leaf´s surface. For pure water, the surface tension is about 72 mN/m, which can be reduced to 20 mN/m with a potent wetting agent. Another crucial factor is the timescale in which of the process takes place. The time a droplet covers the distance from the spray nozzle onto the leaf is typically around 20 milliseconds. Therefore, an effective wetting adjuvant not only decreases the surface tension and contact angle on a leaf but also acts quickly enough to ensure that this process occurs while the droplet is still on the leaf.

Humectant

To facilitate the penetration of the crop protection product into the leaf tissue, it is crucial to keep it in a mobile form. Once the spray coverage dries on the leaf, the crop protection product becomes immobile due to agglomeration or precipitation as crystals. Therefore, delaying the drying-up of the spray coverage is essential. Adjuvants that maintain a liquid spray coverage are called humectants. They can be hygroscopic salts, polymers, polyols, etc.

Penetration enhancer

The penetration of crop protection products through the outer layers of the target plant is another crucial and the rate-limiting step in the application of plant protection agents. Even if all other physicochemical factors are optimized, crop protection products that are absorbed too slowly lead to ineffective disease control. Furthermore, an insufficient uptake of plant protection agents increases the risk of building up resistances or contaminating the environment. Penetration enhancers enable or support the crop protection products in passing through the leaf's outer boundary layer into the plant.