When looking for cutworm feeding in emerging sunflower early damage is usually found on south facing slopes or areas where the soil tends to warm up quickly. The difficulty with this insect is scouting due to night-time feeding. Thus, entomologists recommend an evening insecticide application. The NDSU recommended threshold level is 1 larva per square foot. For more detail see the April 2010 story on Cutworm Vigilance in The Sunflower magazine.
There are many different species of cutworm. The various sunflower production guidebooks mention these species as damaging to sunflower:
Each species has special identifiable features. See the pictures or go to the Guidebooks listed below for more information. Damage has been significant in some years and replanting has been required. Reduced tillage appears to result in greater numbers.
- Army Cutworm (Euxoa auxiliaris) Manitoba
- Redbacked Cutworm (Euxoa ochrogaster) Manitoba and North Dakota
- Darksided Cutworm (Euxoa messoria) North Dakota and High Plains
- Dingy Cutworm (Feltia jaculifera) North Dakota and High Plains
- Pale Western (Agrotis orthogonia) High Plains
- Sandhill (Euxoa detersa) High Plains