Fungus versus Worm
There is an invisible enemy hidden in the ground: Nematodes, also known as roundworms, infest the roots of important fruits and vegetables. According to Marc Rist, a researcher at Bayer, a nematode infestation alters the hormonal balance of plant roots, causing the cells in the roots to divide abnormally and triggering uneven plant and root growth. Once the nematode eggs have hatched, the nematode larvae cause further damage at the plant roots by boring and entering the roots. “The plants become weak and sick, and lumpy roots are not able to absorb sufficient water and nutrients. This also makes the plant more susceptible to other pests and diseases,” says Rist.
When a nematode attack occurs, the plants look ill, form small and yellowish leaves, and have stunted growth. Affected farmers run the risk of failed harvests. “For me, nematodes are a serious problem,” confirms Nihat Yildirim, a Turkish pepper grower. “They spread like lightning and can drastically reduce my harvest.” Huge economic losses can result. From tomatoes and potatoes to corn and grapes – experts estimate the losses caused by nematodes amount up to twenty percent across various crops worldwide, which equals USD 100 billion worth of damage. The problem is that the nematodes are so tiny that they are invisible to the naked eye, and infestations in plants are often difficult to detect. Only farmers with a trained eye know exactly what to look for in their plants’ roots and how to make an accurate diagnosis.
For me, nematodes are a serious problem. They spread like lightning and can drastically reduce my harvest.
Nematode infestations destroy twelve percent of the crops grown worldwide, which is equal to USD 100 billion worth
Source: Society of Nematologists
Getting to the Roots
There are more than 4,000 different types of plant parasitic nematodes. Further, nematodes are robust: Some species can survive for four to five years in the soil even without a host plant. “After four to five weeks, a female nematode may produce several hundred nematode eggs,” says Rist.
Rist and his fellow researchers at Bayer want to prevent nematode damage and are developing BioAct™, a biological crop protection product that contains active fungal spores – Purpureocillium lilacinum, strain 251. BioAct, which easily can be applied to the root system via drip irrigation, kills the eggs of a broad range of plant parasitic nematodes, thus protecting fruit and vegetable crops from the voracious creatures. The fungal spores attach to the eggs, break through the membrane and suck out the eggs’ contents. Bernhard Hitzberger, Global Product Manager of BioAct at Bayer, highlights another advantage of the product: “Farmers can treat their fields and plantations with BioAct several times and at different growth stages – even shortly before harvest.”
Nematodes Cause Harvest Losses Globally
Bayer is also developing an integrated approach to control nematodes, using BioAct in combination with other crop protection products like the new nematicide Velum™ Prime. Central American field trials evaluating this combination have shown good efficacy levels in perennial crops like bananas, which led to healthier banana plants and increased bunch weight. “Devastating nematodes are a real challenge to manage. Therefore, new advanced methods such as the integrated approach – Velum and BioAct within the same program – are needed and will become much more relevant in the future,” says Hitzberger.
BioAct is already available as wettable powder and water-dispersible granule formulations and provides effective and flexible nematode management. “Bayer is further improving BioAct by developing a liquid formulation with improved characteristics and more convenience.” says Rist. The Bayer biologist and his colleagues are continuing to research this truly urgent agricultural challenge.