Plant-parasitic nematodes are some of the most destructive pests in agriculture. These microscopic, worm-like organisms feed on plant roots, disrupting water and nutrient uptake, stunting growth, and reducing yields. With over 4,000 species of plant-parasitic nematodes worldwide, identifying and managing the right ones in your fields is crucial. In this post, we’ll explore five of the most common and damaging plant-parasitic nematodes—where they’re found, the crops they affect, how they attack, and what symptoms to look for. We’ll also discuss how TELONE™ soil fumigant offers effective, proven control against these persistent pests.
1. Root-Knot Nematodes (Meloidogyne spp.)
Root-knot nematodes are among the most notorious plant-parasitic nematodes, capable of causing severe damage to a wide variety of crops. They are found worldwide, with species such as Meloidogyne incognita and Meloidogyne javanica being especially destructive.
Crops Affected:
Root-knot nematodes attack over 2,000 plant species, including vegetables (tomatoes, peppers, carrots), fruits (melons, citrus), and field crops (soybeans, cotton). These nematodes are versatile and can wreak havoc in both greenhouse and open-field conditions. In the United States, Meloidogyne incognita is especially destructive to sweetpotato crops in the Southeast and Mid-Atlantic. In the Pacific Northwest, Columbia Root-knot nematodes are problematic for potatoes.
How They Attack:
These nematodes penetrate plant roots, where they establish feeding sites known as “giant cells.” As they feed, they cause the formation of galls or “knots” on the roots, which interfere with the plant’s ability to absorb water and nutrients, ultimately reducing both quality and yields.
Symptoms:
- Swollen, knotty roots
- Stunted growth and yellowing leaves
- Wilting, even when water is sufficient
Size and Appearance:
Root-knot nematodes are microscopic, typically measuring 0.3 to 0.8 mm long. The galls they cause on roots are often the first visual indication of their presence.
2. Lesion Nematodes (Pratylenchus spp.)
Lesion nematodes are another destructive group of nematodes found worldwide, especially in temperate climates. They are migratory endoparasites, meaning they move freely within plant roots, causing extensive damage.
Crops Affected:
Lesion nematodes are particularly harmful to potatoes, cereals, corn, strawberries, and tree crops like apples and peaches.
How They Attack:
Lesion nematodes enter roots and move through the root tissue, feeding and leaving behind necrotic lesions. These wounds make the plant more susceptible to secondary infections from fungi and bacteria.
Symptoms:
- Necrotic (dead) root tissue
- Poor root development
- Wilting and yellowing of the foliage
- Reduced crop yield and quality
Size and Appearance:
Lesion nematodes are small, typically around 0.4 to 0.8 mm long. They can be challenging to detect without a microscope, but their distinctive lesions on roots are tell-tale signs of their presence.
3. Cyst Nematodes (Heterodera and Globodera spp.)
Cyst nematodes, including soybean cyst (Heterodera glycines) and potato cyst nematode (Globodera rostochiensis), are highly specialized pests that target specific crops. They are widespread and can persist in soils for years, even without host plants.
Crops Affected:
Soybeans, potatoes, and sugar beets are particularly vulnerable to cyst nematodes. These nematodes can severely reduce yields if not managed properly.
How They Attack:
Cyst nematodes infect plant roots and create specialized feeding sites called syncytia. They cause extensive root damage and form protective cysts that contain hundreds of eggs, allowing them to persist in soil long after the crop is harvested.
Symptoms:
- Stunted plants
- Yellowing, particularly in patches across the field
- Poor root development and nodulation
- Reduced yields
Size and Appearance:
Cyst nematodes are tiny, approximately 0.4 mm long. However, the cysts they leave behind are visible as small, lemon-shaped structures on the roots, turning brown as they mature.
4. Stubby-Root Nematodes (Trichodorus and Paratrichodorus spp.)
Stubby-root nematodes are common in sandy soils and are known for their distinctive effect on plant roots. These nematodes are found in many parts of the world and are especially problematic in the Southeastern United States.
Crops Affected:
Stubby-root nematodes attack a wide variety of crops, including corn, small grains, turfgrass, potatoes, and tobacco.
How They Attack:
These nematodes feed on the tips of plant roots, causing them to stop growing and become stubby. They are also vectors for tobacco rattle virus, which can cause corky ringspot disease in potatoes.
Symptoms:
- Short, stubby roots
- Wilting and nutrient deficiencies
- Patchy stunted growth in the field
Size and Appearance:
Stubby-root nematodes are slightly larger than other nematodes, typically around 1 mm in length. The stunted root system they cause is a key diagnostic feature.
5. Reniform Nematodes (Rotylenchulus reniformis)
Reniform nematodes are common in warm, tropical, and subtropical regions. They are particularly prevalent in the Southeastern United States and parts of Asia and Africa.
Crops Affected:
Reniform nematodes cause significant damage to cotton, soybeans, pineapples, and sweet potatoes.
How They Attack:
These nematodes infect the roots of plants and form a “reniform” or kidney-shaped body. They stunt plant growth by feeding on the root system, reducing the plant’s ability to take up water and nutrients.
Symptoms:
- Stunted growth
- Yellowing leaves
- Reduced yield
Size and Appearance:
Reniform nematodes are around 0.3 to 0.5 mm long, and their unique kidney-shaped bodies distinguish them from other nematode species.
TELONE™: The Best Defense Against Nematode Damage
Nematodes can be difficult to control once they’ve established in your fields, making prevention key to managing these persistent pests. TELONE™ soil fumigant is one of the most effective defenses against all five of these nematode types. Whether you’re dealing with root-knot, lesion, cyst, stubby-root, or reniform nematodes, TELONE™ treatment fumigates the soil profile, targeting nematodes before they have a chance to damage your crops.
TELONE™’s ability to be applied using various methods—broadcast, in-row, and more—means it can be customized to suit your specific farming needs. By reducing nematode populations before planting, TELONE™ helps ensure that your crops can establish healthy root systems, leading to higher yields and better-quality crops.
With TELONE™, you can confidently protect your fields from nematode damage and ensure a productive growing season. Remember, there’s no coming back from a poor start!
Interested in learning more about nematodes? Check out our blog post “What Are Nematodes” for an overview of nematodes—what they are, which crops they affect, and how to prevent them.
Disclaimer:
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.
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