Photo found on SDSU igrow, taken by J. Gavloski, MAFRI
Now the seed is planted, fields have been fertilized, a pre-emergent is applied and the perfect amount of rain has fallen to activate it. All that means you can finally go fishing now!? Wrong.
Sunflowers can have irreversible damage in the seedling stage by cutworms if you are not monitoring your field until they reach 4 to 6 leaf. They cause damage by cutting off the seedling, sometimes below the cotyledon or before they even emerge out of the ground. Damage can first be noticed by bare patches in a field or walking in a field and you may notice a bunch of missing plants.
For scouting check south facing slopes first (the soil warms up faster) and fields that border a lot of grass or had weed problems in the fall. They feed at night so checking fields closer to dusk is often more productive. If you can’t make it out to the field at 9 pm, no worries, try looking underneath the soil surface near the plants or underneath stubble. I find bringing along a little garden shovel can help. Economic threshold is when you have 25-30% stand reduction or when there is 1 small larvae per square foot (1 inch or smaller). Several insecticides work well (see table), spraying towards nightfall is best.