What are nematodes?

What Are Nematodes?

You know that TELONE™ soil fumigant targets plant parasitic nematodes—but what are nematodes? And why are they so damaging to your crops?

Nematodes are incredibly diverse, thread-like roundworms that live in a wide range of environments, including soil. Mostly microscopic in size, nematodes have varied methods of survival. A majority of nematodes are microbial feeders found in the soil. They can feed on diverse food sources, including bacteria, fungi, and even other nematodes!

You may be surprised to learn that nematodes play an important role in nutrient cycling, and as a result have a tremendous impact on soil health. While not all nematodes are harmful, we specifically want to focus on plant parasitic nematodes. These are the nematodes that feed on plant parts and can negatively impact the development and yield quality of a crop.

Why are nematodes important?

Not all nematodes cause harm, but not all nematodes in your soil are beneficial either. A subset of nematodes, called plant parasitic nematodes, live in the soil and can wreak havoc on growing plants. Scientists have identified more than 4100 types of plant parasitic nematodes, causing an estimated $125 billion of economic losses each year! Left uncontrolled, these soil-dwelling parasitic nematodes can have a severe negative impact on agriculture crop production. Growers understand that these microscopic pests can cause huge amounts of damage, so it’s important to understand which nematodes are in your soil and how to properly manage these populations.

Are nematodes good?

While nematodes in soil can’t harm humans, growers know that left unchecked, plant parasitic nematodes can devastate crops by devouring root systems and negatively impacting a plant’s ability to grow and uptake nutrients properly.

Juvenile and adult nematodes attack the root cortex by passing through the root epidermis. Some species fully pass into the root while others remain largely outside and feed on cells within the root cortex region. Once the root begins to decay, the nematodes leave and attack other healthy roots. Adult female nematodes will lay eggs in roots and the surrounding soil, creating a never-ending cycle of plant feeding and damage. Specific nematode damage includes:

  • Physical/mechanical injury to cells and tissues
  • Reduced or modified root mass
  • Decreased water and nutrient uptake
  • Total root destruction—root cells are killed or modified to serve as a food source to nematodes

That’s right. Not only will nematodes physically damage the roots of the plant, but they can also restrict the plant’s nutrition to serve their own purposes!

What crops do nematodes affect?

Virtually all crops can be impacted by plant parasitic nematodes, including vegetable crops, field crops, fruit and nut crops, and nursery crops. It is also important to remember that tree roots can live and host nematodes for several years after removing a mature tree. Therefore, root removal to the maximal possible depth will help reduce nematode populations before planting a new orchard.
Depending on which crop you are growing, the symptoms of nematode damage might be attributed to other factors. .For instance, symptoms may appear spotty throughout a field, and early visual clues may be blamed on limited fertility and/or water. Nematodes may not kill a plant outright, but the ensuing damage left in their wake will cause the plant’s health to decline, often to the point of death.

Here are a few examples of nematode damage in different crop fields:

Nematode damage in potato field
Patchy nematode damage in field

Root damage from parasitic nematodes can result in galled roots, stunted roots, root lesions, and an increase in lateral roots. Nematode feeding can provide entry points for secondary pathogens such as bacteria and fungi. The root structure can be distorted, and the root mass can be reduced to the point where the plant’s ability to absorb water and nutrients is compromised.

It is important to state that once nematodes have compromised a plant’s roots, the damage is done and cannot be fixed. This is why it is vital for growers to manage nematodes before they plant, so they give young seedlings the best chance at growing into strong, healthy plants in an environment free of nematode pressure.

Here are a few examples of nematodes in plant roots:

Nematodes on celery roots
Columbia root-knot nematodes on potatoes
Guava root-knot on sweet potatoes
Meloidogyne nematode damage on strawberry roots
Galling on cotton roots

What are the most common types of plant parasitic nematodes?

While there are thousands of known species of plant parasitic nematodes, the four most prevalent nematodes across all crop types are:

The Root-Knot Nematode

The Root-Knot Nematode

The root-knot nematode is a sedentary endoparasitic, meaning it doesn’t move much and keeps a portion of its body inside the root to feed. Basically, this is a root-feeder that remains connected to the plant. The root-knot nematode causes cells in the root to swell, which forms galls. Eggs are laid in a gelatinous mass on or below the surface of the root.

The Cyst Nematode

Cyst nematodes on potato roots.

The cyst nematode is a sedentary semi-endoparasitic, meaning it doesn’t move much either, but it places a portion of its body inside the root to feed. So, the majority of its body is on the outside, forming a cyst-like appearance. It can hold 300–400 eggs within the cyst.

The Lesion Nematode

Lesion Nematode
Lesion nematode

The lesion nematode is a migratory endoparasitic, meaning it is mobile throughout its lifespan and will burrow its body into a root to feed. This nematode can feed inside and outside of the root—in fact, it goes back and forth as it moves to feed, causing large lesions across the plant. This is a very mobile and aggressive nematode. Lesion nematodes can also lay their eggs inside AND outside the plant root.

The Ring Nematode

Ring nematode

The ring nematode is a migratory ectoparasitic. It is mobile throughout its lifespan but remains outside the root to feed. This nematode just migrates and feeds on the outside of a plant, causing damage by stunting its roots.
In addition to these four, here are a few more common nematodes that vary by region, crop, and soil type:

  • Dagger
  • Lance
  • Pin
  • Needle
  • Reniform
  • Spiral
  • Sting
  • Stubby root

Want to know which nematodes may pose the biggest threat to a crop you manage? Click here to download our handy at-a-glance Threat by Crop chart. [insert file]

How do I manage nematodes?

Left uncontrolled, nematodes can quickly damage an agricultural crop. There’s no way to reverse this damage. Once the plants have been injured, the economic damage has been done.

The best way to defend plants against nematode damage is by preparing the soil before anything is ever planted. Enter TELONE™ II, an innovative solution in the fight against nematodes. Distributed exclusively by Teleos Ag Solutions, TELONE™ II is the leader in controlling nematodes in the United States and around the world, successfully changing how farmers manage nematodes.

TELONE™ II: the best defense against nematodes!

By using TELONE™ II to treat the soil before planting, you are effectively scrubbing the zone of soil, leaving no residual behind. TELONE™ II gets to work with a single priority in mind: Protect the root zone. After all, nematodes want to feast on the roots and allow harmful soil-borne diseases to enter the root system. If left unprotected, the roots are vulnerable to attack and overall plant health and crop yields are compromised.

When fumigation occurs, TELONE™ II establishes a treated zone in which roots can develop stronger and faster. The advantages of fumigation don’t stop there. In recent research, soil fumigation applications averaged 98% efficacy across all nematodes studied, which included root lesion and stubby root nematodes.

By treating the area that will eventually surround delicate roots, you keep the soil free of parasitic nematodes, giving your crops the best chance at success and leading to healthy soil, heartier plants, quality production, improved yields, and higher profits for the farmer. As a pre-plant soil fumigant, TELONE™ II delivers powerful results in the fight against nematodes. It’s quick, effective, and efficient.

Here are several examples showing treated vs. untreated crops side-by-side. Notice how the crops treated with TELONE™ are healthier with improved quality, compared to the untreated controls.

Untreated vs. treated w/TELONE™ II in almond orchard
Treated w/ TELONE™ and chloropicrin vs. untreated in apple orchard
Treated w/ TELONE™ and chloropicrin vs. untreated in potatoes

The science leads to TELONE™

Furthermore, fumigation with TELONE™ was found to not greatly alter the soil microbial community. Research conducted by Colorado State University and Oregon State University observed only minor effects on both bacterial and fungal communities after fumigation, suggesting other agricultural practices—including tillage, cover crops, and irrigation—may have a greater impact on soil.
Studies also show that fumigation with TELONE™ shifts populations of beneficial soil organisms, which rebound quickly post-fumigation. It does not decimate organism populations, as previously thought.

The active ingredient of TELONE™ II is 1,3-dichloropropene (or 1,3-D). This liquid formulation allows for highly targeted injection at depths other crop protection products cannot achieve. This means TELONE™ II is capable of finding nematodes deep within the soil profile, resulting in greater control.

Controlling nematode populations is essential to greater crop outcomes. Contact your TELONE™ specialist to learn how TELONE™ can target nematodes ahead of planting to set you up for a successful growing season. Remember, there is no coming back from a poor start!

Prior to any application of TELONE™, make sure to see the supplemental labels for further information. TELONE™ Trademark of the Dow Chemical Company (“Dow”) or an affiliated company of Dow. TELONE™ is a federally Restricted Use Pesticide. Always read and follow label directions.

The resources and information provided are meant purely for educational discussion, contains only general information about legal matters, and is not to be construed as advice. Please note that any information or resources provided are not legal or regulatory advice, and should not be treated as such. You must not rely on the information provided as an alternative to legal advice from your attorney or other professional services. Teleos Ag encourages readers to consult with counsel, and their local, county, and state regulators. We make no representations or warranties, express or implied, in relation to the information provided through our resources and blog posts. It is the readers responsibility to know the laws related to 1,3- D, appropriate PPE, Licensing, etc., in his or her City, County, State, and Country.

Randy Huckaba