European Corn Borer: Unilvoltine (single generation) Strain
In addition to the "traditional" bivoltine (two-generation/yr) strain of ECB, the univoltine strain has become more common in southern Minn., as well as continuing as the dominant strain in northwest MN and in ND. In southern MN, this strain is typically most active from late June to late July. Of interest, the unilvoltine strain has maintained a presence in southern MN for at least the past 20 years, albeit at low numbers (as estimated by annual black-light trap moth data). Beginning with the 2018 growing season, we are providing Degree-day (DD) model updates, and 7-day forecasts for univoltine moth flight timing, to assist growers, processors and agronomists in scheduling scouting plans and IPM decision-making. The modified DD model is based on a lower (50F) and upper threshold (86F), and January 1st as the start date; this is similar to the original model developed by Hoard & Weiss (1995) at NDSU, and reviewed by Phil Glogoza via the NDSU Extension publication. Degree-days were calculated from current and 7-day forecast daily temperature data provided by the& U.S.A. National Phenology Network. Note: DD model projections can also be compared to the weekly ECB moth flight data on VegEdge.