Wireworms: A major threat to potato production

Wireworms (Agriotes spp.), the larvae of click beetles from the Elateridae family, pose a significant risk to potato cultivation.

These slender, cylindrical larvae feed on underground plant parts, including potato tubers, creating tunnels and lesions that compromise quality and marketability.

Infestations can lead to reduced yields, increased susceptibility to other pests and diseases, and severe economic losses for farmers.

Recognising wireworm infestations

Several key indicators signal wireworm activity in potato fields.

Damaged tubers often exhibit irregular or shallow holes, along with tunnels and feeding marks.

In the early growth stages, wilting or stunted plant development may indicate root damage.

Monitoring adult click beetles, which lay eggs in the soil, helps predict infestations and provides insights into the species present and their life cycle.

Digging soil samples to check for wireworm larvae – slender, cylindrical, and typically yellow to brown – is the primary method for confirming an infestation.

Effective control with beneficial nematodes

Entomopathogenic nematodes, commonly known as beneficial nematodes, are microscopic roundworms that naturally parasitise insect pests, playing a crucial role in biological control.

Research has demonstrated that Koppert’s Casea (Steinernema carpocapsae) form an effective biocontrol strategy against wireworms in irrigated potato fields.

When applied to the soil, these nematodes actively seek out wireworm larvae, infecting them with symbiotic bacteria that cause death within days.

Trials have shown that integrating beneficial nematodes into pest management programs can reduce tuber damage by up to 30%, leading to higher yields and increased revenue.

Highly adaptable, these nematodes tolerate both hot and cold conditions and are available in large, agriculture-ready formats with a soluble biodegradable formulation – offering a sustainable and practical solution for wireworm control.

Application techniques and timing

For maximum efficacy, nematodes are applied to irrigated potato fields through soil drenching or standard agricultural irrigation and spraying systems, ensuring thorough coverage of the root zone where wireworm larvae are most active.

Timing is critical – nematodes are most effective against young larvae, making early spring or late summer applications ideal, as these periods coincide with peak wireworm activity.

A split-dose strategy can be used to provide continuous protection throughout the risk period.

Beneficial nematodes offer a superior alternative to traditional pesticides for both organic and conventional growers.

They integrate seamlessly into Integrated Pest Management (IPM) programs, are compatible with most pesticides, and pose no risk to humans, animals, or plants.

Koppert’s biological solutions allow growers to effectively control wireworms while maintaining sustainable and environmentally friendly farming practices.

Field trials and collaboration

To validate the effectiveness of nematodes in real-world conditions, Koppert and Dr Richard Binks – Koppert’s market development and technical consultant – have collaborated with agronomy experts and grower groups, including James Klug of Deben Agronomy, an independent potato specialist overseeing crops across East Anglia.

Approximately 95% of the potato fields James advises are located in East Suffolk, designated for the pre-pack market, where tolerance for wireworm damage is extremely low.

Since the withdrawal of Mocap, wireworms have become his number one concern.

With conventional nematicides proving ineffective, James and his colleagues explored alternative solutions and identified Koppert’s nematodes through the Vegetable Consultants Association (VCA).

In 2024, fully replicated trials were conducted on a Suffolk sandy loam site, where wireworm populations had been confirmed through bait trapping.

This approach aimed to maximise impact, as wireworms at different life stages remain active throughout the season.

Applying nematodes in higher water volumes and ensuring soil moisture were also critical factors, with applications timed just before rainfall or irrigation.

Promising results and future considerations

Although wireworm pressure was slightly lower than expected based on trapping data, untreated plots still showed 5% tuber damage – a level high enough to cause economic losses in a commercial crop.

“We found that three treatments of Casea at 2Bn/ha reduced that 5% to 0%, and this was a statistically significant result, representing a considerable return on investment if it were in a commercial situation,” James notes.

While he acknowledges this is just one year’s experience, he is already considering nematode
use on a commercial scale due to the lack of alternative options.

“The results exceeded my expectations and are very promising.

“We now have data to support this approach, and although further research is needed, I would consider using nematodes in fields with high wireworm pressure,” he adds.

Visit Koppert’s website for more information.

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