Clover Root Curculio in Alfalfa
Crop Injury: Clover root curculio (Sitona hispidulus) feeds on alfalfa and clover throughout North America. Young larvae impede nitrogen fixation by feeding inside root nodules. Older larvae prune lateral and taproots. Feeding injury increases yearly, causing severe root scarring and reducing nutrient and water flow. Feeding decreases alfalfa yield and nutritional value, reduces plant vigor, promotes winter kill, and can cause stand decline and loss. Root rot pathogens infect plants through larval feeding injury. Adult curculios feed on plant foliage.
Pest Description: Adult clover root curculios are small, brown, and covered with tiny bristles. They have wide, blunt snouts. Legless larvae are small grubs with white bodies and dark heads.
Life Cycle: Overwintering occurs most commonly as eggs laid near the plant base or on soil. Adults can also overwinter to lay eggs in the spring. Larvae hatch in the spring and begin feeding on roots. After pupation, emerging adults consume alfalfa tissue and then become inactive until fall egg laying. Clover root curculios have one generation per year.
Scouting: Check for root damage in spring. Scout for adults using a sweep net.
Management: Consider crop rotation away from alfalfa for two years in infested fields. Avoid planting new stands near infested fields. There are no registered insecticides for clover root curculio.
Prepared and reviewed by the Alfalfa Pest Management Working Group.
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