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Red Sunflower Seed Weevil Increasing (08/02/18)

The USDA NASS reports that 54% of the sunflowers were blooming in North Dakota as of July 30th compared to only 31% last year (USDA NASS News Release).

Red Sunflower Seed Weevil Increasing

The USDA NASS reports that 54% of the sunflowers were blooming in North Dakota as of July 30th compared to only 31% last year (USDA NASS News Release).

Economic threshold levels of red sunflower seed weevils (RSSW) were present in blooming oilseed sunflowers in southeast ND (Cass County), and southwest ND near Dickinson (Stark County). Please send me your field reports including locality and numbers.

Scouting should continue until the economic threshold is reached or most plants have reached 70% pollen shed. At 70% pollen shed, plants are no longer susceptible for egg laying or significant damage. On older flowering plants (after R5.7), larvae of RSSW (and banded sunflower moth larvae) will be feeding inside the seeds and protected from the insecticide. By then, much of the feeding damage has already occurred and no foliar insecticide is recommended then.

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Janet J. Knodel

Extension Entomologist

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