With the loss of essential chemistries from the market, growers are looking for new management tools for their toolbox when controlling soil-dwelling insects.

North Carolina leads the United States in sweetpotato production, followed by California and Mississippi (USDA-NASS,2023)¹. With acres up for sweetpotato production, the industry still faces many challenges, above and below ground ². Growers face many pest pressures from nematodes, weeds, and root-feeding insects that cause significant yield losses annually. In the top sweetpotato production areas throughout North Carolina, growers are battling with a nearly invisible pest, wireworms.

A close up shot of a Tobacco Wireworm feeding on Sweetpotato captured in the field by a BASF agronomist.

📸: BASF employee, Dr. Reeves/Featuring Tobacco Wireworm feeding on Sweetpotato.

Wireworms are the larval stage of adult click beetles, which come in many shapes, sizes, and species. The larvae feed on the roots of corn, tobacco, and many other economically important crops like sweetpotatoes, turf grass, sugarcane, and sorghum. Adult click beetles move from host-to-host laying eggs under the soil surface. Once larvae hatch, they seek food and are attracted to roots and tubers under the ground. Wireworm larvae burrow holes into crop roots and tubers, killing young plants and causing unmarketable fruit in sweetpotatoes. Approximately eight different species of wireworms can be found in a single sweetpotato production field. Still, in North Carolina, the corn wireworm (Melanotus communis Gyllenhal) and tobacco wireworm (Conoderus vespertinus Fabricius) are the most common species³.

A close up shot of Sweetpotatoes damaged by wireworms captured in the field by a BASF agronomist.

📸: BASF employee, Dr. Talton/Featuring Sweetpotatoes damaged by wireworms.

Life Cycle

Adult click beetles are known to be nocturnal, with most of their mating and egg-laying activity occurring overnight. Adult and larvae populations tend to rise, with emergence occurring mid-spring to late summer in North Carolina. The female's eggs can hatch in approximately three weeks, and larvae go through many larval instar life stages before forming into a pupa and an adult. Wireworms can remain in the larval stage for up to four years. Thus, you can find multiple generations throughout the year over time in the soil. With so many species, a long lifecycle, and an extensive host range, management of this pest can be very challenging for sweetpotato growers, as the damage is directly correlated with unmarketability⁴.

Management Options for Wireworms

Infestations of wireworms can be managed with a combination of cultural and chemical solutions. Once the monitoring tool is perfected, growers will soon be able to time adult flights and manage populations. For lead recommendations for management on your farm, contact your county extension agent or local BASF representative.

Cultural management for Wireworms

Despite the challenges of corn wireworm species, there are management options growers can turn to. Cultural management, such as crop rotation of nonhost species, remains the most effective strategy for managing wireworm populations. Baiting traps are being developed to monitor populations and make timely insecticide applications for adults. Rotating to a nonhost crop like soybean can decrease the chances of the wireworm larvae from completing their full life cycle.

Chemical Management

Nurizma^® Insecticide

Nurizma^® Insecticide provides a new mode of action that protects crops from soil-inhabiting insects like wireworms and white grubs. Nurizma^®Insecticide has a low use rate, which means less packaging, waste, and easy handling in the field. Nurizma^® Insecticide has shown to be a helpful chemical management tool compared to not treating a field for wireworms. To learn more about how to purchase and apply Nurizma^® Insecticide, speak with your local BASF representative.

Always read and follow label directions. Grow Smart and Nurizma are registered trademarks of BASF. Copyright 2024 BASF Corporation. All rights reserved.

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Endnotes

United States Department of Agriculture – National Agricultural Statistics Service (USDA-NASS 2023). Quick stats. USDA National Agricultural Statistics Service. https://quickstats.nass.usda.gov/
North Carolina Organic Commodities Production Guide, Chapter 8: Crop Production Management – Sweetpotatoes Publication date: June 24, 2019 AG-660 https://content.ces.ncsu.edu/north-carolina-organic-commodities-production-guide/chapter-8-crop-production-management-sweetpotatoes
North Carolina SweetPotato Commission. (2022). North Carolina sweetpotatoes industry. Industry - North Carolina Sweetpotatoes (ncsweetpotatoes.com)
“Wireworms in Turf” NC State Extension, 2023. https://content.ces.ncsu.edu/wireworms-in-turf