Most 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.”

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.”