Cranberry Degree-Day Map and Update: as of June 8, 2016
The maps below show degree-day accumulations for cranberry plants and Sparganothis fruitworm across Wisconsin up through June 8, 2016. Temperature thresholds used for these calculations are 41 ºF and 85 ºF for the plant, and 50 ºF and 86 ºF for Sparganothis.
Throughout WI, plant degree-days ranged from a low accumulation of 426 DD to a high of 1293, while Sparganothis degree-days ranged from a low of 177 DD to a high of 716 DD.
The image at right details life history benchmarks of interest for Sparganothis fruitworm and associated degree-day estimates. With flight initiation around 595 DD, Sparganothis flight is predicted to have started in parts of WI. Indeed, we did see the first Sparganothis moths in some parts of central WI in the past week. Reminder that insecticide applications aimed at Sparganothis adults will have the greatest effect on population reduction if timed for peak flight (approximately 885 DD).
The table below allows for comparison of degree-days over the past three years. Observations from the past couple of years suggest that, in central WI, most beds may be beginning to enter bloom. In northern WI, plants are more likely in roughneck and hook.
