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Potatoes are a staple crop around the world; they also grow in home gardens. Unfortunately they can be susceptible to a number of pests, and the wireworm is among them. Early detection and cultural controls are necessary for ridding your potatoes of wireworms. With diligence and care you'll be able to mange this pest in your garden.
Description and Life Cycle
Wireworms are the larval stage of the click beetle. They live underground and are found throughout the world. There is some variation in appearance across the species but in general they are thin and wormlike with hard, shiny bodies about 3/4 inch to 1 inch in length. Wireworm larvae can live in the soil for anywhere between two and five years as they grow, mature and eventually become adults. In early spring the cream to white larvae become darker before pupating. Females prefer to lay eggs in grassy or weedy fields.
Wireworms are omnivores and will feed with equal voracity on underground insects or plant roots. Occasionally they will feed on seed potatoes, resulting in weak plants. More often, however, they feed on the developing tuber, leaving tunnels in the flesh of the potato. Tunnels provide openings for pathogens, which can lead to tuber rot.
Because there are no effective chemical controls for the home grower, according to Rutgers, early detection of wireworms is crucial to a successful harvest. To check for wireworms before you plant you can place bait for them. Place germinating peas, beans, corn, cull potatoes or stiff dough in the ground at 3- to 10-foot intervals, 2 to 4 inches deep, and cover them with boards or tiles. You can use carrots as bait; plant them every 3 feet. After about three to five days, dig up the bait to see if you have wireworms. Baits can continue to be used as a control method if you do find wireworms.
Avoidance is often the best control for difficult pests like wireworms. Avoid planting potatoes in areas you know have wireworms. Avoid planting them in areas that were once sod or were just weeds. Wireworms proliferate in these areas and will readily feed on potatoes planted in these areas. Wireworms are less likely to survive in well-drained soils, you may need to add soil amendments to improve drainage. Ornamental plants like phlox, aster, gladioli and dahlias attract wireworms so avoid planting them next to your potatoes. Wireworms are closest to the surface of the soil when temperatures are around 21.1 degrees C. Tilling the soil at this temperature in either spring or fall may bring them to the surface and attract predators.
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