Cutworm Scouting – Alison Pokrzywinski | Nuseed Technical Agronomist
When everything looks great from a distance, don’t forget to get out of the pickup and check your sunflower fields for cutworms this time of year. Sunflowers can have irreversible damage in the seedling stage from several species of cutworms. Damage is caused by cutting off the seedling, sometimes below the cotyledon or before they even emerge out of the ground. As the plant matures, damage moves to the leaves and the plant is typically able to recover (V4-V6 stage).
Damage can first be noticed by bare patches in a field or several missing plants in a row. Generally, cutworms can be first be found on south facing slopes (warmer), areas that border grass/pasture or a spot in the field that had weed issues the year before. Scouting towards evening can be helpful, otherwise look underneath the soil surface or stubble during the day. If there is a row of plants missing start by looking for the larvae near the next undamaged plant.
Economic threshold is when you have a 25-30% stand reduction or when there is 1 small larvae per sq ft (1 inch or smaller). Several insecticides work well and spraying towards nightfall is best.
Wireworm Wary – Dr. Janet Knodel | NDSU Entomologist
There are more than 9,000 wireworm species in the world, with 885 of those in North America. Around 20 wireworm species are considered pests in field crops and often more than one species is present in a field.
These insects have a long life cycle, from three to five years, making them pests in the same field year after year. When wireworms are in the larval stage, they cause the most damage to sunflower plants by feeding on the roots and stems. They also tunnel up the stems and feed on secondary roots, and the holes they create allow diseases to enter the plants. Wireworm feeding damage causes poor plant stands and stand loss due to blank spots in fields or skips in rows.