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By Alex Hubrig

ď‚ž Two

species of seed weevils are present on sunflowers in the northern Great Plains. There is red and gray sunflower seed weevil. It is important to be able to tell apart the two because different control strategies are needed for each.

Red sunflower weevil, 2.5 to 3 mm long

Gray sunflower weevil, 3 to 3.5 mm long

ď‚ž Red

sunflower seed weevil begins to emerge from the soil in early July and continues until about mid-August. Peak emergence occurs in late July to early August. Newly emerged adults feed on the bracts of sunflower buds.

ď‚ž The

gray sunflower seed weevil differs from red weevil. The gray sunflower seed weevil lays eggs on sunflower in early to mid bud stages. Which lays eggs on plants beginning at 40 percent pollen shed, the gray sunflower seed weevil does not lay as many eggs as the red.

ď‚ž Research

reveals that most seeds are only partially consumed or destroyed by the larvae and that the damaged seeds have lower oil content than the undamaged seeds.

ď‚ž Cultural

control: methods such as tillage and planting date have been effective against sunflower seed weevil. ď‚ž Trap crop: consists of a field margin planted to an early blooming sunflower that surrounds the remaining field area. The earlier planted sunflowers can then be treated to control weevils before they infest the rest of the field.


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