Technical
“And, in the same way as pharmaceuticals, there is a very strict registration process, with a significant quantity of data being necessary to scientifically prove that a product is not only completely new and different, but that it is fit for its intended purpose and meets the wealth of environmental and safety criteria. This entails a great deal of experience and patience over a significant period of time. Refining and re-testing is conducted with meticulous attention to detail, which takes place at the laboratory and right through to field scale conditions.”
Formulation technology
The efficacy of a treatment relies heavily on the correct formulation technology. An effective product will be optimally developed for the target plant (the grass sward, in the case of turf), and will focus specifically on the growing conditions and the mode of action, which is how the treatment acts (such as by contact or translocated activity). There are, however, many other variables to consider, for example, whether the plant has hairy leaf surfaces, waxy cuticles or whether its typical environment and intended use is within a temperate or more humid climate. An example of finely developed formulation technology can be found in the way certain formulated products evenly distribute active ingredients over the area of each leaf in order to control damaging fungal diseases. In order for a fungicide to deliver the active ingredient to where it is required, each droplet needs to be transported via hydrophobic wax crystals that cover the leaf ’s surface. This ensures the liquid makes contact, where droplets would otherwise simply bounce off. To ensure that the product stays on the leaf is then a further challenge. Scientists add other substances to cushion the impact or reduce the surface tension. This ensures that the spray mist of droplets adheres firmly to the leaves and that, by creating large wet areas, the active substance can penetrate quickly. “Without the right formulation, even the best active ingredient is useless,” notes Dorin.
More than just an active
A formulated active ingredient alone won’t give the optimal biological performance. During the development of a formulation, several other factors have to be considered too. Testing under different climatic conditions needs to be carried out to ensure the product
remains stable, even if stored for several years. Further testing needs to be undertaken to guarantee that the spray liquid can be prepared easily and that, even in mixtures, this spray solution remains stable for long periods of time. Obviously, the blocking of filters in the spray equipment has to be prevented with the highest priority, so the solution needs to be formulated to ensure a smooth delivery through the nozzles. With this in mind, Bayer scientists have evaluated a large number of adjuvants which affect droplet size and are vital in ensuring the pesticide effectively covers each leaf. There are many substances that are available to put into formulations, and many more being discovered. It is, therefore, a highly skilled job to select the right mixture, at the right concentration, and in changing combinations from the thousands of potential substances. Special additives may also enhance leaf penetration by softening the cuticle or, where required, by ensuring that the active substance forms insoluble crystals. “This all goes a long way to delivering the quality branded products associated with our company, and shows the number of variables involved in this complex process, where a reliable level of consistency is necessary to ensure every product delivers in exactly the way it should.” Within the company’s team of formulation experts, there are about ten scientists who are dedicated to testing how stable the spray solution is. “All of our products undergo this practical testing, so we know that, when a product goes to market, it will spray well,” says Dorin.
He adds that once a formulation is
registered, it cannot be changed. “For this reason, we ensure the formulation is perfect from an early stage, and that is a standard for all of our products. This is something that most generic companies can’t offer.”
It is not uncommon for formulation companies to include the same active ingredient in different formulations. The presence alone of an active ingredient does not ensure the efficacy of the pesticide for any one situation. An agricultural pesticide designed for wheat will not bring success when applied to turf. Specificity is key when it comes to formulation technology. For example, a pesticide formulated to adhere easily to hairy tomato leaves, or even smooth apple leaves, will simply be repelled by
“A pesticide formulated to adhere easily to hairy tomato leaves, or even smooth apple leaves, will simply be repelled by turf
because of the large number of small wax crystals on the leaf”
DECEMBER/JANUARY 2013 PC 103
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