Controlling Wireworms: Seven Effective Strategies

Wireworms, the larvae of click beetles, pose a significant threat to the health and productivity of your plants. These slender, brown or yellowish pests have a voracious appetite for the roots, seeds, and tubers of various crops. However, once armed with the right knowledge and proactive measures, controlling wireworms is possible. In this article, we will explore a range of effective strategies to keep wireworms at bay.

Crop Rotation

Implementing a proper crop rotation plan is a key strategy in controlling wireworms. These pests have specific preferences for certain crops, and by rotating your plantings annually, you can disrupt their life cycle. Avoid planting susceptible crops in the same area for consecutive seasons, as this creates an ideal breeding ground for wireworms. Potatoes, radishes, and carrots are three of the most susceptible crops to wireworms. So follow these crops with a crop such as peas where wireworms will be far less of an issue.

Ploughing and Tilling

Wireworms tend to inhabit the top few centimeters of soil. By engaging in soil cultivation practices like ploughing and tilling, you can effectively expose them to predators and unfavorable conditions. Disrupting their habitat through cultivation helps break their life cycle and reduces their population. While farmers increasingly adopt no-till or min-till practices, wireworms could become a more challenging pest in the coming years.

Companion Crops / Trap Crops

Introducing trap crops can help divert wireworms away from your main crops. Plants like mustard, radish, and rye are known to attract wireworms. The idea is to sow these crops in designated areas within or around your main crop to lure wireworms away from your preferred plants. After a few weeks, remove and destroy the trap crops, effectively eliminating a significant portion of the wireworm population. Although the effectiveness of this method is a topic for debate among plant pathologists, it remains a viable option.

Traps

Monitoring wireworm populations is essential for early detection and control. Constructing traps using plastic drink bottles with holes drilled into the sides can help monitor wireworm activity. Fill the bottles with wheat, barley, or corn seeds, apply the lid, and plant them 10cm deep in the ground. The wireworms enter the bottle to feed and find it challenging to exit. By periodically counting the trapped wireworms, you can monitor their populations and assess the effectiveness of control measures. Weekly monitoring of the traps should be sufficient, considering wireworms spend several years in the ground before pupating into adults.

Biopesticides

Beneficial nematodes, specifically Steinernema spp. can be valuable allies in controlling wireworm populations. These microscopic worms parasitise wireworm larvae, leading to their demise. Purchase nematodes from a reputable supplier and apply them according to the instructions provided. Make sure the soil is adequately moist for the nematodes to move freely and seek out wireworms.

Biopesticides derived from naturally occurring soil bacteria, such as Bacillus thuringiensis (Bt), can provide effective control. Bt products specifically targeting wireworms are available in some countries, however, they are often only available to commercial growers. Follow the instructions carefully when applying biopesticides to ensure their optimal effectiveness.

Soil Sterilisation/Fumigation

Controlling wireworms with pesticides can be challenging for farmers and is simply not an option for gardeners. This is because no pesticides are authorised for use in gardens against wireworms. However, soil sterilisation offers an alternative approach. Solarisation involves applying a black plastic sheet to the infected area, trapping the sun’s heat and potentially raising the temperature beyond what wireworms can survive. Another method involves growing a mustard green manure and incorporating it into the soil. This method reduces wireworm populations due to the breakdown of chemicals within the mustard’s tissues.

Lime Sulphur application to heavily infested areas can also be an option, temporarily affecting soil biology but providing relief in severe cases. It is worth noting that Lime Sulphur is the only method of soil sterilisation that be done while the crop is growing without harming the plants.

Remain Vigilant

Early Detection is Key Regular monitoring is crucial for early detection and control of wireworms. Inspect the soil around the base of plants for signs of wireworm activity, such as chewed roots or wilted seedlings. By catching infestations early, you can take prompt action and prevent further damage.

Conclusion

While wireworms can be persistent nuisances in gardens, and a significant draw on profits for farmers. Employing the right strategies can effectively control their populations and safeguard your plants. Implement crop rotation, engage in ploughing and tilling, and consider introducing beneficial nematodes and trap crops. Embrace non-chemical control measures like handpicking and traps, and utilize biopesticides and soil sterilants if necessary. By remaining vigilant and taking proactive measures, you can minimize the impact of wireworms.