Red Sunflower Seed Weevils   

    Late-planted sunflowers (with about 3 out 10 plants blooming) can still be scouted for seed weevils.  Information on economic thresholds and insecticides can be obtained by clicking the picture above. I did include a very easy method of calculating economic thresholds, using current market value of oilseed sunflowers, the cost of controlling the weevils using an insecticide, and the plant population.

    We were near Lucas last Friday (8-6-99) and scouted some fields for seed weevils. Most of the fields were already in full-bloom and had low numbers of seed weevils. After looking at about 200 flowers, we calculated the average number to be 4 seed weevils per flower.

    At $9.25 per hundred pounds market value, $8.00 insecticide plus application cost, and 22,000 plants per acre, the economic threshold is 6 seed weevils per flower. These information were suggested by Gary Erickson when we figured out a threshold for growers in Brown County.

    At $7.00 per hundred pounds, $10.00 insecticide plus application cost, and 20,000 plant population, the economic threshold is 11 seed weevils per flower.

   Variegated Cutworms Strike Again     

    Seedling alfalfa planted in early-spring or summer must be scouted for variegated cutworms. Gary Erickson informed me yesterday (8-11-99) of about 60 acres of alfalfa (planted last month) being infested by variegated cutworms. In fact there have been several outbreaks of these insects from Mitchell, Jerauld County, Parkston, and now Brown County.

    Unlike other cutworms, variegated cutworms have at least 2 broods in our state. Therefore, we must always be on the lookout for signs of feeding on the regrowth after a cutting, or on alfalfa seedlings of recently-planted alfalfa. Damage can be very heavy with the field taking the appearance of that being sprayed with a herbicide. For more first hand information, contact Ray Gosmire, Marcia Deneke, or Gary Erickson. They have had experience with this insect this season.

    Economic threshold is about 2-4 cutworms per square foot. Baythroid 2, Lorsban 4E, Pounce 3.2E, and Warrior T are labeled for use on alfalfa.

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