JUNE 2018 SEEDWORLD.COM / 37 to Wanner. In fruit crops, wire- worms will eat into fruit that touches the ground. They also damage other row crops and vegetable crops. “These wily worms feed on the seeds before or just after germination,” Wanner says. “Once you have wireworms in your field, they will feed on whatever crop you plant. That is why crop rotation offers little protection.” Scouting Practices You can scout to determine if wireworms are present: • Before crop emergence to determine economic thresh- olds. You can scout before planting, but your findings may be more variable because of the cold soil. • After crop emergence to inform management for the next year. • Use baits such as corn or wheat seed to attract wire- worms. Soak seed overnight in water so it will germinate quickly. An ordinary sock makes an effective trap. Put the soaked seed bait in the sock and bury it 6 inches deep. Come back in 7 to 14 days — the seed will have germinated and it will attract wireworms. • If you find wireworms, save some in alcohol to send to an entomologist to deter- mine the species. Cultural practices are generally not very effective. “Wireworms are a very difficult pest to manage,” Wanner says. “Continuously cropped irri- gated wheat fields are at high- est risk. Once a field is infested with high wireworm popula- tions, most crops except alfalfa will be damaged.” Management Tips A 5 – 7 year rotation with alfalfa will reduce wireworm population but will probably not eliminate the populations because the larvae feed on such a wide variety of material. Plant spring crops later in the spring so the seeds will not be in the ground any longer than necessary for germination. Smaller seed- lings are more susceptible to damage. Make sure fall crops are well established so they will grow quickly in the spring and have a better chance of outgrowing wireworm damage. Regular irrigation keeps the surface soil moist and this allows wireworms to stay at the surface throughout the summer. All About Control Insecticide seed treatments to protect stand development and crop yield is the most effective control method. If more wireworms are found in the soil, Wanner recommends using a higher rate of seed treatment. If springtime scout- ing finds at least one wire- worm in each trap, applying a seed treatment is recom- mended. If more than four wireworms are found, apply seed treatment at the high- est labeled rate, and increase seeding rate to compensate for wireworm damage. “There is no post-emergent insecticide option for wire- worm control,” says Mitch Stamm, BASF biology project leader for seed solutions. “In terms of economic cost-ben- efit, wireworms are very hard to predict. When advisors give a recommendation for pest control methods, they like to have a reasonable degree of confidence of what the out- come will be. With wireworms, this is very difficult.” Both BASF and Syngenta continue to research wire- worms, and both have products in early stages of development. Wireworms in 2018 Wireworm populations appear to be becoming more abun- dant and thus more of a problem, heading northward; they are also moving west- ward from Indiana and across the Midwest into the Great Plains. This increase in wire- worm populations results from several factors. “One reason for the increasing wireworm popu- lation is the elimination of lindane as a control method,” says David Belles, techni- cal asset lead, Seedcare, Syngenta Crop Protection. “Although lindane provided effective wireworm control, its Kevin Wanner is a Montana State University assistant professor of Entomology and Extension specialist for Cropland Entomology.