MANAGEMENT IMPLICATIONS DERIVED FROM BIRD DAMAGE ASSESSMENTS IN NORTH DAKOTA SUNFLOWER

The most recent estimate of blackbird damage to ripening sunflower (Helianthus annuus) in North Dakota in 1980 exceeded $6 million. Although less than 5% of the sunflower fields in the state received greater than 10% damage in each of four past survey years, as much as 50% of the total state-wide damage occurred in these fields. This loss can be combated with cost-effective control- Successful control requires timely action when blackbirds are in large concentrations. Frightening blackbirds from fields early in the damage season disperses damage and this can result in compensatory growth by sunflower, whereby yields at harvest are largely unaffected