Enormous harvest losses all over the world are caused by tiny pests – nematodes that often go unnoticed as they drain crop roots of essential nutrients and open the doors to other pathogens that damage those roots. Bayer CropScience researchers are now taking a two-fold approach to control these global pests, combining a completely new chemical principle with a biological agent. This not only enables them to protect banana plantations in Costa Rica against these voracious nematodes, but also ensures successful harvests for vegetable crops, corn and soybeans on a global scale.
Nematodes threaten the harvests of a wide variety of crops around the world - and thus endanger farmers' livelihoods.
Fluopyram is an active substance discovered by Bayer researchers that can be employed in an integrated, environmentally friendly approach to effectively control nematodes.
An integrated solution to the nematode problem can even boost yields.
Costa Rica is a true Garden of Eden. This Latin American country situated between the Caribbean and the Pacific Ocean provides fertile ground for all kinds of important crops like sugar, cocoa, cotton and different fruits and vegetables. Costa Rican pineapples and coffee are exported all over the world. But the real bestseller is a small and curved yellow fruit, the jewel in Costa Rica’s crown – otherwise known as the banana. According to the UN Food and Agriculture Organization (FAO), the country exported more than two million metric tons of bananas in 2012, with the majority of them ending up in European and American supermarkets and fruit bowls. But the banana isn’t just a globetrotting fruit – it is also a healthy and extremely nutritious food, with a high potassium and magnesium content that strengthens nerves and muscles. Its combination of vitamins and easily digestible carbohydrates also provides a quick energy boost after a jog or as an office snack. “The banana has become a staple food that is helping to feed the global population. According to the FAO, its nutrients make it the fourth most important crop in developing countries after rice, wheat and corn,” says Dr. Heiko Rieck, a project manager at Bayer CropScience in Monheim.
But the banana is at risk, posing a major issue for both Costa Rica’s economy and the global food chain. The problem is that the plant is also very popular with nematodes (eelworms). These tiny pests that wriggle through the soil in search of food have a preference for the roots of banana plants. They use their sharp mouthparts to burrow deep into the finely branched structure of the roots and suck out everything that the plant needs for its survival – both nutrients and water. This method of attack causes serious damage to the roots, which then begin to decay, allowing fungi and bacteria to enter the plant and accelerate the decomposition process. Rieck’s team of researchers at Bayer CropScience knows all about the main culprit. Radopholus similis, also known as the “burrowing nematode,” is what is making life difficult for banana plants. “These eelworms are not even one millimeter long, but they are one of the ten most destructive nematodes for plants,” says Rieck.
Eelworms with a Fatal Impact
There are approximately 20,000 different species of nematode worldwide, most of which are parasitic on other living organisms such as banana trees, coffee shrubs or sugar cane plants. Experts estimate that nematodes make up about 81 percent of all animal organisms. These usually tiny, white to colorless creatures, also known as eelworms, generally prefer a humid environment.
Nematodes Damage Harvests in many Countries and Crops
Radopholus similis originally comes from the American continent. However, as a result of the globalization of agriculture and the vegetative propagation that occurs in the banana plant when shoots or roots are separated from the tree, the parasite has already spread to many countries in Europe, Africa and Asia, where it is causing huge harvest losses. The effects of other nematode species on other plants tell a similar story. In fact, almost every important crop is vulnerable to these subterranean root vampires. “Soybean cyst nematodes, root knot nematodes in vegetables, wheat cyst nematodes and both white and yellow potato cyst nematodes are decimating global harvests of the most important staple foodstuffs,” says Rieck.
of potato harvests worldwide would fall victim to pests or disease
Up to 20,000 nematodes or even more can live in 100 grams of banana roots. Once a banana plant has been severely affected, it is difficult to treat. And without the nutrients they need, banana trees grow slowly and are late producing fruit, which furthermore often ends up being smaller than usual.
But back to Costa Rica. “Nematodes are one of the most significant threats in banana cultivation,” says Boris Coto Calvo, Head of Development for Central America and the Caribbean at Bayer CropScience in Costa Rica. “Up to 20,000 nematodes or even more can live in 100 grams of banana roots. Once a banana plant has been severely affected, it is difficult to treat. And without the nutrients they need, banana trees grow slowly and are late producing fruit, which furthermore often ends up being smaller than usual,” says Coto Calvo. In the worst cases, the plants can fall over and die completely. “Plants are particularly at risk when they are in fruit,” adds Dr. Helmut Fürsch from Global Agronomic Development at Bayer CropScience. Strong winds frequently sweep across the coastal plains of Costa Rica, and a fully laden banana plant that is no longer able to keep a stable grip on the ground through its roots will simply be knocked down and die. “Up to 18 percent of all banana plants in Central and South America that are affected by nematodes are ripped out of the ground this way,” estimates Coto Calvo.
Crop Protection Secures Food Supplies
The agriculture sector is facing major challenges worldwide – rising populations, higher demands for food and changing eating habits. More than seven billion people around the globe now need feeding every day, and each year the figure increases by another 82 million. Some 8.8 million people die as a result of famine and its consequences annually – more than the total for HIV/Aids, malaria and tuberculosis put together. Every three seconds, someone somewhere in the world dies of hunger, which is equivalent to the entire population of Berlin disappearing in just 140 days. Without modern crop protection methods, securing global food supplies is virtually impossible. Wheat yields for example have been increased by 50 percent since the 1960s. However, even using pesticides cannot provide absolute crop protection. Currently, only around 60 percent of worldwide harvests can be secured.
Harvest Losses Threaten the Existence of Both Big Farms and Small-holdings Worldwide
This is a serious loss for farmers, as each banana trunk comes into fruit only once per lifetime. This means that a whole year’s work is wasted, which can be disastrous for big farms, but even more so for small-scale farmers. Besides, banana plants can live up to 40 years. Once a plant is infected, each new shoot is at risk, so the farmer’s yield is threatened year after year. “The damage caused by nematodes is responsible for global harvest losses worth several hundred million euros,” says Fürsch. This total figure relates to many different countries and farmers of course, but in a developing country, even losing just a few hundred euros can mean the loss of a small-holder’s entire livelihood. For this reason, Bayer CropScience researchers have already spent many years looking for an effective nematicide that will also be safe for both plants and humans. Now the scientists have found an approach that at first glance seems rather unusual. The substance that the crop protection specialists are using to control the greedy eelworms is in fact one that has been used by fruit and vegetable farmers as a fungicide against harmful fungal diseases since 2012 – fluopyram.
Breathing, eating, digesting, moving - every living creature needs energy to perform these important bodily functions. This energy is produced by each individual cell from adenosine triphosphate, or ATP for short. If the cell lacks ATP, it will die, and if this happens in a lot of cells the entire organism will die as well.
15 - 50 percent
of all food is lost after harvesting.
Discovery of the Century: Fluopyram is Effective against Fungal Diseases and Nematodes
Rieck and his team received the crucial tip from colleagues in Costa Rica involved in fungicide research. Initially, the product had been sprayed as a foliar treatment in banana plants to treat their leaves against Black Sigatoka. But after their colleagues’ tip the researchers tried out the product in the soil to see if they could find an additional application method for the fungicide. This demonstrated for the first time that the substance also benefits the roots and reduces nematode counts. And although only a relatively low dosage was applied, it had a long-term effect. “Our researcher Rodolfo Ceciliano and technical manager Omar Arias, who first observed the nematicidal effect of fluopyram in bananas, were immensely impressed by the effects observed in the field trials,” says Dr. Robert Brinkmann from the Global Field Trials Operations team at Bayer CropScience. He was there in person for the first tests in Costa Rica in 2009. “I had never seen anything like it in my twenty years of work – the roots looked truly healthy,” says Brinkmann, who is still enthusiastic about it even now. A closer examination under the microscope quickly brought the team its confirmation – fungicidal treatment using fluopyram also provides protection against nematodes. “Our objective was to investigate and look for other substances until we found a new solution that would be both effective and safe for farmers and consumers,” says Fürsch. Fluopyram met those criteria perfectly. Soon after the first tests, Bayer scientists set about studying the effects of fluopyram even further in fields in Costa Rica, the United States, Italy and South Africa, and in laboratories and greenhouses in Germany.
Marc Rist, a Monheim researcher who works in the Research Pest Control department at Bayer CropScience, explains how the substance works. “We ‘switch off’ the nematodes by interrupting their power supply.” This works because eelworms, like any other living organism, need energy so that they can get into the banana roots. This is why their cells produce adenosine triphosphate molecules – ATP for short. It is thanks to this cellular energy source that living organisms can respire, digest food, move and reproduce. “Fluopyram interferes with these processes by preventing the formation of ATP,” says Rist. The result is that the nematodes become paralyzed – they remain immobile and stretched out like needles in the soil until they finally die. “The substance also affects the early stage of nematode development,” says Fürsch. “The eggs hatch later and the growth of the next generation of nematodes is interrupted.”
Interview: Miguel Quesada Badilla
research talked to Miguel Quesada Badilla, former head nematologist at fruit and vegetable producer Del Monte, about the global nematode problem.
How dangerous are nematodes to crops?
Root-knot and cyst nematodes are the two most widespread and economically important plant-parasitic nematodes. They cause serious losses to all crops, including fruit trees, vegetables, cereals, oil seeds, flowers, ornamental plants, turf grasses, etc.
Are nematodes a problem outside Costa Rica as well?
The problem has global dimensions. Nematodes are found in almost all habitats. Plant-parasitic nematodes have been described as the “hidden enemy” due to their microscopic nature and the fact that they live in the soil. National and international quarantine measures are crucial to avoid infestation with this pest.
Can nematodes threaten the global food supply?
It is expected that over the next decades farmers will face deadly crop pests that have never been seen before. Nematode management will then become a huge issue for our food supply. We need new strategies – especially in developing countries.
But fluopyram, marketed under the brand names Velum™ and Verango™, is only one part of the Bayer team’s successful battle against the nematode problem. The researchers are using this chemical crop protection product in combination with a natural organism – the soil fungus Purpureocillium lilacinum strain 251, a so-called biologic, marketed as BioAct™. This product colonizes nematode eggs so that hatching of larvae is inhibited.
Interview: Prof. Dr. Harald von Witzke
Experts say that yields would plummet worldwide without crop protection. research talked to Professor Harald von Witzke, an agricultural researcher at Humboldt-Universität in Berlin.
What role does crop protection play in helping to safeguard harvests?
We did a study to compare what happens when we use crop protection products with the outcome when we don’t use them. We found that the added value generated by using crop protection is of the order of EUR 4 billion annually in Germany alone. This means that crop protection in Germany is safeguarding the food supply for up to 200 million people.
Can you be more specific?
Wheat is a good example. On average, farmers in Germany who use modern methods have yields that are over 120 percent higher than those obtained on comparable organic farms. Our study showed that the difference is less marked with canola, but here too, conventional farmers produce yields that are about 50 percent higher.
Why are there such enormous differences?
Because 40 percent of the world’s potential agricultural production is still being lost to crop diseases and pests. We could reduce this by half if farmers all over the world had adequate access to crop protection.
How reliable are these figures?
We only use validated, publicly accessible data. For example, we use the results generated by farms in the test farm network organized by the Federal Ministry for Agriculture. Every year this resource documents the differences in yields between conventional and organically operating farms. Never before have such comprehensive sets of data on yield differences in agriculture been analyzed.
What do these figures from Germany mean for the global food supply?
The global demand for food products will more than double in the first half of the 21st century. The only way for us to meet this rapidly growing demand is to increase the area under crops or to improve productivity. The options for increasing the area under crops are very limited since the amount of land available worldwide for growing food is finite. Our main approach must therefore be to boost productivity on the land that is already being used for agriculture. And this is where crop protection plays a major role.
One Single Treatment per Year in Combination with a Biologic is Sufficient
Consequently, if the fluopyram treatment has already been applied to remove adult nematodes from the soil, using the biologic prevents a new generation from growing and damaging the plant at a later stage. “This combination of the complementary technologies of biological agents and fluopyram provides the best of both worlds,” says Rieck. “The chemical product efficiently kills off the living nematodes, and the biological substance impairs their reproduction.” The tests so far have shown that this integrated crop protection strategy is the way forward. Using fluopyram on its own was already a breakthrough in these tests. However, in combination with the biologic it is unique because the Bayer substance isn’t just extremely effective – it also offers farmers some very practical advantages. Just one single application of fluopyram per year along with a biological control agent or a chemical nematicide that the grower might choose is enough to protect plantations from nematodes. By contrast, nematicides used in the past brought a number of disadvantages: “In the 1970s, there were certainly some very effective nematicides on the market,” says Rieck. “But most of them had highly toxic properties. Fluopyram as a substance is much less toxic than the previous products.” For each hectare, farmers had to treat their plants three to four times each year with several kilograms of the nematicides, as they were only effective in high doses. But thanks to the innovation of the Bayer researchers, that is now history. “Even a dose of 500 grams of fluopyram per hectare is enough not just to counter a nematode infestation in the short term, but also to guarantee healthy roots months after treating the crops,” says Fürsch. An increase in yield is not the only advantage. Since the banana plants are systematically strengthened by the fluopyram treatment, farmers who use the Bayer product also have a reduced need for substances that protect the plants from other diseases. Given the current trend for increasing health awareness, this is a significant point. “The rise in consumer expectations regarding quality affects our partners throughout the entire food chain, including wholesalers such as Chiquita, Del Monte, Dole and Univeg,” says Heiko Rieck. For many years now, these companies have been pressing for a sustainable way to keep supermarket shelves sufficiently stocked with bananas.
of plants grown worldwide are lost to weeds, insects and disease
Yet fluopyram is securing more than just the world’s supply of bananas – this integrated strategy works on nearly all species of nematode, offering improvements for both corn cultivation and soybean crops. The product is especially effective on root-knot nematodes such as Meloidogyne incognita, which affect many vegetable varieties and cause considerable quality and yield losses. Carrots , for example, become deformed and develop characteristic swellings at the roots that are known as galls. “Carrots with these substantial quality deficits are unfortunately unmarketable,” says Rist. Affected vegetables can no longer be sold, with serious consequences for farmers. “For many crops, this leads to massive yield losses,” estimates Rist, who is currently further investigating the compound and its effect on tomatoes and cucumbers.
In many developing countries, people are not even aware that nematodes can cause crop failure. Many simply don’t understand why their harvests are so poor.
Well Received by Farmers and Wholesalers in Costa Rica
All of this explains why fluopyram has caused such a sensation among banana farmers in Costa Rica and other countries in Central America. “Its popularity with farmers and wholesalers has been immense,” says Coto Calvo. They praise the product’s ease of use, the reduced chemical exposure and the health and abundance of roots. The effectiveness of the nematicide is regularly checked on test fields by researchers such as Fürsch, Brinkmann and Coto Calvo, who examine the roots after treatment. Their tests show that the banana plant roots are healthy. However, the research does not end here. How much fluopyram is taken up by the root systems of each type of plant? What is the influence of the soil condition? And how long does fluopyram protect a plant from infestations by nematodes? These are some of the questions that researchers at Bayer are looking into in the field, greenhouse and laboratory. But there is an even more fundamental one: how can we make sure that farmers all over the world know about these pests and the damage they can cause? “In many developing countries, people are not even aware that nematodes can cause crop failure. Many simply don’t understand why their harvests are so poor,” Rist explains. “If we manage to raise awareness of the risk that nematodes pose, we will be contributing to increasing yields – and we will help farmers protect their crops and secure our global food supply.”