Where the Peppers Grow

To earn a living for himself and his family, pepper farmer Nihat Yildirim keeps around 7,500 plants in his greenhouse.


Pepper growers in Turkey are battling a particularly obstinate pest: nematodes. The minuscule roundworms are responsible for severe crop losses. To help the pepper farmers, Bayer is currently testing a new substance in the fight against these tiny but dangerous creatures.

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Turkey grows around 1.8 million tons of peppers annually, making it the world’s third largest capsicum producer.

Nihat Yildirim is a careful person. And he has a keen eye. Every morning, as he does the rounds of his greenhouse, he examines his capsicum plants meticulously: Are the leaves green enough? Do the stems look healthy? Are they the right height? He crouches among the plants, focused, intent on discovering even the slightest abnormality. “If the leaves look a little yellow or the plant itself is a touch too small, it could mean that parasites are at work – and if that’s the case, I have to act immediately.”

Every year, around 7,500 pepper plants – also known as paprika or by the genus name capsicum – flourish in Nihat Yildirim’s greenhouse. Yildirim grows either the green or red form of the vegetable, depending on how long he lets them ripen. The 28-year-old farmer sells his harvest to a regional wholesaler, who in turn supplies market vendors and supermarkets in the tourist center of Antalya and along the country’s Mediterranean coast.

The peppers trade in Turkey is a thriving business: There, as in the entire Mediterranean region, the vegetable is on the menu of the local people practically every day. In countries like Spain, Greece and Turkey, peppers are served in every conceivable variation: Stuffed with minced meat, pickled in oil, fried, grilled, or raw in salads. As a foodstuff, it plays an important role in ensuring a diet with sufficient vitamins and nutrients: The vegetable is one of the chief sources of vitamin C and is also rich in potassium, magnesium, zinc and calcium.

One of the favored pepper type is the long, green one.


Capsicum is part of the nightshade family, and both the plants and fruit are known by a variety of names depending on place and type, size, color and how hot they are. In general, a distinction is made between bell peppers (as they are known in the United States) and the spicy chili peppers, which are normally smaller and longer.

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The spicy variations include peperoncinos and cascabel chilies, but there are many kinds. With their high capsaicin content, these types of capsicum are relatively spicy, because the capsaicin triggers a heat or pain reaction in the body. The so-called Scoville scale measures the capsaicin content of the various kinds of capsicum. On this scale, a regular bell pepper would be considered mild, while cascabel chilies and peperoncinos are piquant, jalapeños are medium-hot, and cayenne peppers count as hot.

Because of their capsaicin content, hot peppers are also a component of a number of medicinal products. Heat plasters, for example, use the heat effect of cayenne pepper to ease rheumatic pain, and capsaicin-containing products are also used to treat lumbago and migraine. The consumption of capsicum is supposed to be beneficial to human health, because the vegetable is exceptionally rich in vitamin C. Capsicums also contain flavonoids, which have an antioxidant effect, while the carotene they contain helps to protect cells.

For the Yildirim family, too, hardly an evening meal passes that does not include peppers. “For us, it’s just part of what we eat,” the farmer explains. “Even when I was a child, I loved to eat them, even as a snack – especially the red ones.” His family has been growing peppers for thirty years. Their ambition is to supply top quality produce, and Nihat Yildirim knows exactly how to recognize a good capsicum: “The perfect capsicum has an intense flavor and a glowing color, and is large and plump, but not watery.”

Nihat Yildirim explains how roundworms damage his plants.

30 %

of the farmland used for growing capsicum in Antalya is infested with nematodes.

The capsicum farmer studied agricultural science in Istanbul and, after graduation, returned to his home town of Antalya to run his parents’ farm. Since then, his worst enemies have been the tiny parasites, less than a millimeter long, in his greenhouse: nematodes. These pests, also known as roundworms, are particularly obstinate. They attack the roots of the plants and extract nutrients and water. The plants then have problems getting enough for themselves, and – if the nematode count is high enough – can die.

Nematodes Cause Harvests Losses Globally

On his daily greenhouse inspections, Nihat Yildirim can immediately see if nematodes are damaging the roots of his capsicum plants. The plants become sickly, their leaves are small and yellow, and they barely grow. “For me, nematodes are a serious problem,” he says. “They spread like lightning and can drastically reduce my harvest.” For small farmers like him, especially, a nematode infestation can therefore rapidly threaten one’s economic existence.

When he discovers a sick plant, Nihat Yildirim has to fight the infestation immediately with large quantities of conventional nematicide – i.e. a plant protection product that targets nematodes. The nematicide has to be spread in the soil three to four times a year. Even so, the little parasites are difficult to control, and quick to return.

Nematodes are not bigger than on millimeter.

The parasite

Nematodes are mostly colorless roundworms that require a sufficiently moist environment to survive. Globally, there are more than 25,000 different types, of which some 4,000 are harmful to plants.

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All over the world, the parasites attack a large number of different plant types, causing considerable damage to basic food crops. They are responsible, for example, for massive crop losses in banana, coffee and sugar cane plantations, and also damage soybean and potato farms. The widespread root knot and root cyst nematodes are particularly devastating.

Nematodes cause not only severe damage to vegetable and grain crops and fruit plantations, they also attack oilseeds, flowers, ornamental plants and lawns. Around the world, nematodes are responsible for damage exceeding a billion euros every year.

You will have healthy roots, even months after treatment

Now, however, this never-ending struggle could become easier thanks to a new Bayer product called Velum™. Its active substance, fluopyram, is already successful in combatting fungal diseases. Researchers have discovered that fluopyram’s operating mechanism can also be employed against nematodes in the soil. The substance has already received regulatory approval in a number of countries.

Fluopyram’s mode of operation is efficient: “We kill off the nematodes by cutting off their energy supply,” explains Marc Rist, a researcher in Bayer CropScience’s Research Pest Control department. To find the roots and to attack them, the tiny worms need energy. To get this, cells in their bodies produce molecules of adenosine triphosphate – or ATP for short. “Fluopyram interferes with the nematodes’ metabolism by blocking the production of ATP,” says Rist. The result is that the nematodes remain motionless in the soil and die off.

How nematodes damage plants

The Bayer researchers emphasize integrated solutions, alternately applying fluopyram and a naturally occurring microorganisms, like Bacillus firmus an active component in the biological product Flocter™ or the Purpureocillium lilacinum fungus, strain 251, an active component in the biological product BioAct™. These products have already been approved in a number of countries, but researchers continue to work on product improvements.

The fungal strain in BioAct™ feeds on eggs of nematodes that are harmful to plants, thus preventing the larva from hatching. If the soil has already been cleared of the larval infestation by fluopyram, the fungus prevents new larva from hatching. “Like this, you are able not only to control the nematode infestation in the short term, but also to find healthy, active roots even months after treatment,” explains Helmut Fürsch from the Global Agronomic Development department at Bayer CropScience.

Nihat Yildirim tried the new product, Velum™, this year for the first time, and the capsicum farmer is thrilled at the results. “It’s unbelievable,” he says. “The plants I’ve treated are much bigger and healthier – and the peppers look fantastic.” This August, his harvest will once again be undamaged, for the first time in years. “For me, this is an enormous relief. With the low yields I was getting, I was already having doubts about the future,” he says. “Now it looks as if I’ll be able to keep running my parents’ farm long-term – and that has always been my big dream.