From active substance to formulation

With the current decline in crop protection applications and agents, the industry is looking for new and replacement varieties. But, how is such a new active ingredient developed and manufactured?

At the fourth meeting of the Agricultural Sprayer Academy (SO), organized at Syngenta in Enkhuizen, a broad spectrum of topics was covered. Partly a repetition, but often in-depth information about the origin of plant protection products, the effect of herbicides, various additives, new mechanisms of action and integrated crop protection.

How herbicides work
For example, weeds are controlled to limit competition with crop cultivation and to suppress host plants of, for example, nematodes, viruses and insects. The mechanisms of action of herbicides vary from the growth agents to the chlorophyll inhibitors and from the amino acid inhibitors to the photosynthesis inhibitors. The effect of the active substance, the application stage and the damage pattern of the main groups were discussed.

When asked why so many products with similar active substances are being marketed, it is explained that in order to find new active substances, manufacturers must publish by means of a patent question. This allows other manufacturers to find out which (new) active substance has been used. If they are able to make a modification on a molecular scale (which is not covered by the patent), they can market a similar product. Sometimes confusing, but it is still important to have a wide range with comparable effects. This is to limit resistances through combinations and alternation of agents.

New mode of action
A new technique that was introduced is RNA-based biocontrols (RNAi). The 'i' stands for interference with an insect's active DNA. Until now, the agent has been effective when insects eat the leaf containing the agent. The action is described as an RNA trigger, which ensures that the crucial messenger RNA of an insect is switched off, so that control takes place.

The important criteria of the effect are the dose, the time at which an insect is combated and the spectrum. The spectrum is related to the advantage of this technique; it is very selective. Within a certain family, this technique can only control a specific species that is harmful to the crop. This keeps non-harmful insects alive. In short: it has no effect on the non-target organism (NTO).

Keeping these NTOs alive is one of the first questions a greenhouse grower would ask when introducing a new product. Since this sector often works with natural enemies, it is desirable that chemical control is only used to combat a natural pest. In this way the participants got an idea of ​​the techniques and applications of crop protection in another sector.

Excipients
The last presentation discussed how a crude active substance is transformed into a formulation. The aim is to allow dissolution in water and to obtain a homogeneous mix. In addition to the active substance, a formulation includes other components; so is the adjuvant, or excipient. The use of this is geared to 3 important aspects: retention, spreading and leaf uptake.

Retention includes the sticking of a drop to a leaf surface. This is particularly desirable at a stage of crop with little leaf area. A low surface tension of a drop is desirable to cause good retention.

At the end of the presentation, the participants' situations were discussed. Since the products themselves already contain excipients, the use of products with additional excipients is only necessary in various deviating circumstances.

In short: the presentations gave the participants of the ASA additional insights into the creation, formulation and application of the resources. At the end of the meeting, a tour was given through the seed factory and new research department of Syngenta.

Continuation
The next meeting is about weather conditions and their influence on crop protection. This meeting will take place at Weerplaza in Houten.

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