SDSU Extension publishes the South Dakota Pest & Crop Newsletter to provide growers, producers, crop consultants, and others involved in crop production with timely news pertinent to management of pests, diseases, and weeds in South Dakota.
The sunflower moth and its subsequent caterpillar are sunflower pests that need to be scouted for after the inflorescences begin to open through head maturity. Sunflower heads are most-susceptible to caterpillar damage from the onset of anthesis to when the petals begin drying.
While insecticides are often necessary to reduce pest populations and prevent yield loss in sunflower, it is important to consider the impact they may have on beneficial insects, like bees and other native pollinators.
Grasshoppers continue to be an issue in some areas of South Dakota. The hotspots seem to be along the Missouri River, but it is a reminder that everyone should be monitoring their crops for grasshopper feeding.
Every year, there is a risk that sunflower in South Dakota will be infested by Dectes stem borer larvae. At this point in the season, adults are active, and females have likely been laying eggs in sunflower plants.
Sclerotinia diseases are a concern in sunflowers, because the fungus can infect the plant through the root, mid-stalk or the head. Wet weather and cool temperatures two-to-three weeks prior to and during flowering favor disease development.
In South Dakota, sunflower flowering is getting underway. That means it is time to start scouting fields for red sunflower seed weevils.
When scouting sunflower, the most observed weevil is the red sunflower seed weevil. However, there are two species of seed weevils that can be present on sunflower heads in South Dakota.
Banded sunflower moths are active in South Dakota, which means it is time to start scouting sunflowers for their eggs. Banded sunflower moth caterpillars can reduce yields and oil content by feeding on the developing florets and tunneling into developing seeds.
Last week we received reports of snail populations causing issues in South Dakota sunflower fields. Snails are normally not an issue in South Dakota crops but like their slug relatives, they can pose a threat to crops when field conditions are just right.