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Integrated Nematode Management 101 for Potato Growers

May 3, 2022

By The Certis Team

We’re no strangers to sneaky nematodes lurking in the soil, waiting to ruin our roots.

The truth is, most growers already have plant parasitic nematodes somewhere beneath the ground, but there’s no telling where or when they could cause damage before it’s too late to protect potato yield.

Nematode Problems for Potato Growers

Since plant parasitic nematodes live in soil and plant tissues while feeding on plant roots, potato crops can be a gold mine for them.

Their symptoms and risk to potato crops is wide ranging and depends on environmental factors, but when nematodes establish feeding sites invade roots and eventually tubers, their feeding reduces plant vigor and causes blemishes on tubers, resulting in a lower quality crop, both below and above the surface.

  • Varying types of nematodes can cause root damage so that potatoes are unmarketable due to lesions, increased susceptibility to Verticillium wilt, stubby roots, swellings, corky ringspot, or other diseases and issues due to root damage and reduced crop health.
  • Aboveground symptoms (which could also result from other causes) can include stunted, yellowing, brown-spotted, chlorotic, or dying plants, which are likely to wilt under temperature or moisture stress; however, some nematodes cause deep root damage but no initial aboveground damage.

For edible potato crop producers, nematodes cause unsightly damage to crops so that they cannot be sold to fresh markets or for potatoes that go into production due to visible damage that would hinder foods like fries, chips, or other items. Since potatoes have a low profit margin, growers cannot afford to lose any yield due to nematode damage.

3 Steps to Implement an IPM for Nematodes

Although you may be aware of general guidelines to combat nematodes, integrated pest management is a sustainable practice that is helpful for potato growers in all regions. Here’s a crash course in how it can benefit crops and how to implement best practices.

1. Test Soil Regularly

To effectively manage nematodes, you need to know what types are present in the soil and their population estimates. That’s where regular soil and root testing is advantageous for potato growers.

If your previous season’s crop had problems caused by nematodes, it means you should implement a management program for your future plantings as they will most likely still be present in the soil and cause damage, so you should test soil samples to identify types and numbers. You can do this via a diagnostic laboratory or participate in a nematode testing program.

  • You should sample the soil from the root zone of the previous crop after harvest if possible, and then again (most importantly) just before the new harvest.
  • Divide the field into sampling blocks of about 5 acres and take subsamples to mix and form a composite sample of 1 quart for each block.
  • Be sure to keep samples cool without freezing them.

The main nematode types that concern growers currently are the Southern root knot, Northern root knot, and Columbia root knot nematodes. Columbia root knots are growing worse because they have multiple hosts and can spread rapidly. If you are not sure if you have nematodes or damage is not visible upon harvest, damage could appear after potatoes are put into storage. Pale cyst nematodes are also becoming a growing threat mainly in Idaho because they are seriously invasive to potato crops in the area and there may be a potential quarantine for this crop due to the potential PCN damage.

Regular soil testing will enable you to plan ahead, protect crop yield, and effectively manage the health of your soil and potatoes.

You may be eligible for free soil testing. For more information, visit the Soil Testing Program page.

2. Follow Integrated Pest Management Best Practices

If you’re already familiar with integrated pest management (IPM) programs, you know that some of the benefits are more sustainable practices, increased resistance management, reduced residue, and more.

In potatoes, nematode IPM management can be simple as long as you are consistent in your prevention methods before it’s too late to control them.

Follow these best practices:
  • Start prevention of nematodes by testing and treating at planting
  • If you’re not doing a fumigation program, you should apply a nematicide at planting and typically follow up every 4-6 weeks (follow label instructions)
  • Be sure your seed is clean so you’re not introducing nematodes to your field upon planting
  • Be sure your equipment is clean and has not been in a contaminated area

It’s helpful to understand the lifecycle of a nematode to understand how they feed, grow, and multiply in order to effectively fight them from damaging your crops.

3. Choose Sustainable Crop Solutions

As our industry moves towards implementing softer and more sustainable growing practices to protect our resources, bionematicides can be a highly effective method to introduce into your nematode management practices.

Going the sustainable route doesn’t mean you have to sacrifice performance.

Bionematicides contain active ingredients derived from natural sources or microorganisms, which can be alive or inactivated based on biochemicals produce by such organisms. One product based on active fungal spores that are natural predators to nematodes, promotes healthier rootsand leads to increased yield for organic or conventional growers in IPM programs is MeloCon LC.

MeloCon® LC is a convenient and flexible liquid formulation biological nematicide that fights nematodes at every stage of growth. It contains Purpureocillium lilacinum (synonym Paecilomyces lilacinus) strain 251with 20% active ingredient that is not harmful to non-target or beneficial species, soil, or environment, and is ideal for powerful performance against even the most damaging nematode pests

Recent field trial in Washington state (CER-2021-7135) proved that a single application of MeloCon LC significantly reduced nematode damage to tubers and it also had increased yields over the UTC and Vydate, an effective chemical used frequently to protect potato crops against nematodes.

Learn more about MeloCon LC and view field trials data here

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