Crabgrass/Annual Bluegrass Preemergence Timer (GDD 32)
through Sun, Dec. 14. 2025
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Please Note
The GDD models have only been “ground-truthed” in the Great Lakes region. Use of models outside of this region, including the North East, Great Plains and Transition Zones, should be used with caution. We do not recommend the GDD models we use for the mid/southern transition zone and southern states.
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Latest Updates
February 15th, 2025Welcome to the 2025 GDD Tracking Season
Although winter seems very much entrenched in the Great Lakes region with snow and frigid temperatures in the forecast, GDDTracker starts counting on February 15. Spring is when GDDTracker receives the most attention for alerting turfgrass managers of optimal application timing windows for suppressing annual bluegrass seedheads and crabgrass preemergence applications. Beyond the spring models, there are several models that may be helpful throughout the season including the early season dollar spot DMI timer and the Smith-Kerns dollar spot prediction model. To learn about all the available models, click on the "About" tab at the top of the screen. Thanks for your continued support and use of GDDTracker and best wishes for a successful 2025!March 18th, 2024Timing crabgrass preemergence applications in spring
Don't miss this update from from Kevin Frank regarding timing of crabgrass preemergence herbicides.