Outlook •  9/30/2022

Most Nematodes are Threats to Farming and Need Proper Control Strategies

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Many nematodes are threats to farming and need proper control strategies

In a thriving field of soybeans or wheat, the part of the crop above ground garners most of the attention. But the soil itself deserves attention too. The soil is teeming with life—in fact, every farm hosts millions of unseen creatures. Some of them are tiny, nonsegmented worms known as nematodes. While a few species of nematodes help farmers by eradicating other pests, the vast majority are a threat to farmers, impacting nearly every crop grown around the world. In fact, nematodes alone cause between $80 billion and $118 billion worth of damage each year on a global scale. These ubiquitous pests are usually practically invisible and are highly adapted to attack specific crops. Their damage can be particularly devastating to subsistence farmers who lack up-to-date tools and information. Fortunately, new research, management practices, and technologies are coming together to provide more-effective tools to combat nematodes.
 

A high-impact pest

In Bonn, Germany, Professor Richard Sikora has devoted his career to the study of these pests. He uses an example from sub-Saharan Africa to illustrate just how detrimental nematodes can be to human beings. In that region, he says, 80 million or more subsistence farmers “are already susceptible to climate change, drought, disease, and war, and their population is going to double in the next 30 years.” Adding crop decimation from nematodes, Sikora says, is “a disaster in the making.”

Green soybean field
Green soybean field

In a thriving field of soybeans or wheat, the part of the crop above ground garners most of the attention. But the soil itself deserves attention too. The soil is teeming with life—in fact, every farm hosts millions of unseen creatures. Some of them are tiny, nonsegmented worms known as nematodes. While a few species of nematodes help farmers by eradicating other pests, the vast majority are a threat to farmers, impacting nearly every crop grown around the world. In fact, nematodes alone cause between $80 billion and $118 billion worth of damage each year on a global scale. These ubiquitous pests are usually practically invisible and are highly adapted to attack specific crops. Their damage can be particularly devastating to subsistence farmers who lack up-to-date tools and information. Fortunately, new research, management practices, and technologies are coming together to provide more-effective tools to combat nematodes.
 

A high-impact pest

In Bonn, Germany, Professor Richard Sikora has devoted his career to the study of these pests. He uses an example from sub-Saharan Africa to illustrate just how detrimental nematodes can be to human beings. In that region, he says, 80 million or more subsistence farmers “are already susceptible to climate change, drought, disease, and war, and their population is going to double in the next 30 years.” Adding crop decimation from nematodes, Sikora says, is “a disaster in the making.”

Of course, nematodes aren’t confined to one crop or one continent. They are present in nearly every cultivated plant to one degree or another.
 

Multiple combat strategies

What can farmers do to combat these rampant pests? The answer is complex. Even identifying an infestation can be challenging, since it requires soil analysis and close observation, which can be costly, time consuming, and sometimes nearly impossible for farmers cultivating thousands of acres. And farmers are understandably reluctant to purchase inputs if they are unsure the inputs will be needed.

When a pest is this prevalent, destructive, and easily overlooked, a nimble approach with a broad scope is required. Sikora and others in the field recommend IPM—integrated pest management (or when tailored to nematodes, INM)—as a commonsense solution to nematode control that has the additional benefit of improving soil health and sustainability. INM uses multiple methodologies working in concert. According to Sikora, “the pillars of INM are rotation, cultivar choice, soil management, targeted control, and monitoring and evaluation.” While completely eradicating nematodes may never be possible, the goal, he says, is “to keep the population below a certain threshold that causes severe damage.” If the various strategies involved in applying INM are daunting to farmers, apps like IPM Pro can help manage their timing and application.

Root Lesion Nematodes
Root Lesion Nematodes

Of course, nematodes aren’t confined to one crop or one continent. They are present in nearly every cultivated plant to one degree or another.
 

Multiple combat strategies

What can farmers do to combat these rampant pests? The answer is complex. Even identifying an infestation can be challenging, since it requires soil analysis and close observation, which can be costly, time consuming, and sometimes nearly impossible for farmers cultivating thousands of acres. And farmers are understandably reluctant to purchase inputs if they are unsure the inputs will be needed.

When a pest is this prevalent, destructive, and easily overlooked, a nimble approach with a broad scope is required. Sikora and others in the field recommend IPM—integrated pest management (or when tailored to nematodes, INM)—as a commonsense solution to nematode control that has the additional benefit of improving soil health and sustainability. INM uses multiple methodologies working in concert. According to Sikora, “the pillars of INM are rotation, cultivar choice, soil management, targeted control, and monitoring and evaluation.” While completely eradicating nematodes may never be possible, the goal, he says, is “to keep the population below a certain threshold that causes severe damage.” If the various strategies involved in applying INM are daunting to farmers, apps like IPM Pro can help manage their timing and application.

Crop rotation is first on Sikora’s list since nematodes have adapted to very specific diets. Without a soybean crop, for example, the soybean cyst nematode (SCN) will simply starve. However, according to Dr. Greg Tylka, a researcher at Iowa State University, to completely eradicate the pests, farmers would need to take 10–15 years off from growing soybeans—an impossible undertaking. Typically, Midwest farmers will rotate corn and soy annually, which does slightly reduce the nematode population. However, since some cover crops can also host nematode species, farmers must be judicious in their choices.
 

Nematode resistance is key

Coupled with crop rotation, the use of nematode-resistant seed is key. Tylka notes that “in the 1990s, Iowa farmers had 20-something SCN-resistant seed varieties to choose from. In the fall of 2021, there were 872 resistant varieties.”

Fields of multi-colors
Fields of multi-colors

Crop rotation is first on Sikora’s list since nematodes have adapted to very specific diets. Without a soybean crop, for example, the soybean cyst nematode (SCN) will simply starve. However, according to Dr. Greg Tylka, a researcher at Iowa State University, to completely eradicate the pests, farmers would need to take 10–15 years off from growing soybeans—an impossible undertaking. Typically, Midwest farmers will rotate corn and soy annually, which does slightly reduce the nematode population. However, since some cover crops can also host nematode species, farmers must be judicious in their choices.
 

Nematode resistance is key

Coupled with crop rotation, the use of nematode-resistant seed is key. Tylka notes that “in the 1990s, Iowa farmers had 20-something SCN-resistant seed varieties to choose from. In the fall of 2021, there were 872 resistant varieties.”

This massive increase is a boon to agriculture, but Tylka is quick to note that the resistance level is waning. “There are different exotic soybean lines that have resistance genes,” he says, “But for yield reasons, 836 of the 872 varieties available use the same source of resistance.” Tylka is encouraged, though, that plant breeders are beginning to note this downward trend in efficacy and hopeful that they will shift their practices accordingly.
 

A vision for the future

Whether they are protecting soybean crops in North America or sugar beets in Germany, farmers around the world will need to continue to adopt new strategies to combat nematodes. How will these strategies evolve in years to come? Agronomists and farmers shared their findings on this in an open-access ebook edited by Professor Sikora, Integrated Nematode Management: State-of-the-Art and Visions for the Future. It collects the findings of 82 authors from five continents, writing about sugar beets, African groundnuts, rice, carrots, and other crops that are central to our diets and our economies.
 

Sikora refers to the volume as “a handbook for the future” and emphasizes the importance of sharing information, particularly for rural farmers who are often disconnected from global dialogues. This emphasis on communication also extends to farmers and scientists, who will need to keep information flowing freely. As Sikora writes, “[Nematode] control requires persistence, motivation, and solid collaboration between actors in the food production chain and also between fundamental and applied research.” Whatever the future holds, the question isn’t whether farmers will contend with nematodes, but how.
 

For more on controlling nematodes, please visit our Reklemel™ site.

Male farmer pouring soybean seeds in machine
Male farmer pouring soybean seeds in machine

This massive increase is a boon to agriculture, but Tylka is quick to note that the resistance level is waning. “There are different exotic soybean lines that have resistance genes,” he says, “But for yield reasons, 836 of the 872 varieties available use the same source of resistance.” Tylka is encouraged, though, that plant breeders are beginning to note this downward trend in efficacy and hopeful that they will shift their practices accordingly.
 

A vision for the future

Whether they are protecting soybean crops in North America or sugar beets in Germany, farmers around the world will need to continue to adopt new strategies to combat nematodes. How will these strategies evolve in years to come? Agronomists and farmers shared their findings on this in an open-access ebook edited by Professor Sikora, Integrated Nematode Management: State-of-the-Art and Visions for the Future. It collects the findings of 82 authors from five continents, writing about sugar beets, African groundnuts, rice, carrots, and other crops that are central to our diets and our economies.
 

Sikora refers to the volume as “a handbook for the future” and emphasizes the importance of sharing information, particularly for rural farmers who are often disconnected from global dialogues. This emphasis on communication also extends to farmers and scientists, who will need to keep information flowing freely. As Sikora writes, “[Nematode] control requires persistence, motivation, and solid collaboration between actors in the food production chain and also between fundamental and applied research.” Whatever the future holds, the question isn’t whether farmers will contend with nematodes, but how.
 

For more on controlling nematodes, please visit our Reklemel™ site.


Sources

Integrated Nematode Management: State-of-the-Art and Visions for the Future, Edited by Richard SikoraInterview with Dr. Greg Tylka, Director of the Iowa Soybean Research Center
US Department of Agriculture Web Site, Agricultural Research Service
Interview with Professor Richard Sikora, Professor and Head of Soil Ecosystem Phytopathology & Nematology, Institut für Pflanzenkrankheiten, Bonn, Germany
University of Minnesota Extension Web Site