Relationship of Sunflower Planting Dates to Damage by Smicronyx fulvus (Coleoptera: Curculionidae) in North Dakota

A 4-year (1981–84) planting date study with cultivated sunflower, Helianthus annuus L., showed that damage caused by red sunflower seed weevil, Smicronyx fulvus LeConte, was lowest (6.59%) in 1981 on early planted sunflowers and highest (84.9%) on late planted sunflowers in 1982. Achene weight varied between years and location. Percent oil content of achenes was lowest for late planted sunflowers in 1981 (24.9%) and 1983 (35.7%) and lowest for early planted sunflowers in 1982 (28.8%) and 1983 (31.9%). Planting sunflowers early would reduce achene damage caused by S. fulvus and would not appreciably reduce oil content and achene weight.