Repellents: How KWS attenuates the appetite of birds for organic maize with plant extracts

Crows, pheasants, doves, cranes: Many people may value them and preserve them as a part of unspoiled nature. But for organic farmers, the situation is very different during certain periods of the year. The birds’ love of nutritious maize seeds makes them invade the freshly sowed fields in masses in early May. Pheasants, for example, dig seeds of the earth. Crows pull the young seedlings out and then eat the grain (kernel). The damage can be as great as total loss.

The bitterer, the better

Because: Unlike conventional farming, organic seeds cannot contain any chemical and synthetic disinfectants that spoil the birds' appetite for the seeds. In accordance with the EU ecological regulation, only semi-natural and nature-identical substances can be used. Together with corporate partners and research institutions, KWS is therefore searching for a plant extract that would spoil the birds' appetite for grain (kernel) in a lasting way. Such substances are called repellents and can taste extremely bitter. In addition, they may not obstruct the germination of plants und should stick to the maize seeds for many weeks - also under moist conditions. It is not easy to ensure all these requirements.

We test the effect of organic disinfectants in a series of tests at KWS Organic farm "Wiebrechtshausen" near Einbeck as well as at certain other German organic farms. Bettina Jorek is the head of the respective KWS field tests - and following numerous previous feeding experiments in aviaries, she is cautiously optimistic. "I think that our current favourite of the extracts leads to the preservation of 65 to 70% of the seeds in the field. Our goal is of course 100%." With "our", she means herself and the KWS research team.

At first sight, the bird issue seems to be relatively small. After all, only around 20,000 hectares of organic maize are produced in Germany per year. But the potential of sustainable plant-based disinfectant is much greater: In Germany, conventional maize is sown on around 2.5 million hectares. Currently, there is an active substance Methiocarb (commercial name "Mesurol"), which protects against the frit fly in order to decrease the risk of infection with maize smut and also to prevent birds from eating the seeds. "But the trend is towards less chemicals on the field," says Jorek. "In addition, sustainability is one of the basic company goals of KWS." KWS offers farmers many different crop plants, among them also catch crops for an optimal and sustainable crop rotation. Other crops include many special species for organic farming. This makes the company in Einbeck different from many other breeders who concentrate only on a few types of crop plants.

Cooperation of many experts

Working with plant extracts, KWS also cooperates with certain vertebrate researchers at the Julius Kühn-Institut (JKI), experts of the FH Bielefeld and the company Phytoplan in Heidelberg, a specialist in natural active substances. Phytoplan produces and delivers extracts or individual fractions of extracts. The JKI is responsible for project coordination and feeding experiments in aviaries. The FH Bielefeld develops formulation possibilities for an increased durability and effectiveness of the disinfectant agent on the seeds. The project is funded by the Landwirtschaftliche Rentenbank.

The parties involved do not want to reveal how the extracts work and how well they work, so as not to endanger potential patents in this field. "We already have effective repellent extracts that have positive effects, even in the field, and do not harm the seedling. Now we have to make sure the substances adhere to the grain (kernel) in the best possible way and still have a concentrated effect in the bird's beak even after three weeks in the ground. Jorek and her team always sow the maize treated with the promising plant extracts around the 1st of May and then observe the experimental areas and the birds in detail.

No fear of scarecrows

As in the previous years, they are also closely observed by hundreds of bird eyes. Especially the intelligent crows have learned how to deal with humans. They seem to know that they are not allowed to be hunted. The large scarecrow kites some 30 meters in the air do not scare them either, Jorek says. The crows also ignore round scarecrows in the field, that move in the wind (brand: “Böser Blick“). On top of that: "It seems as if the crows have "messengers" in their ranks, that recognise when the farmer is working on the field. They then inform their own kind", Jorek has observed again and again. But the research team keeps a close eye on the situation: After each test the researchers know a little bit more about the tastes birds do not like.