1. Weeds & Weather: Local to Regional Daily Simulations
7 October 2009
Midwest Weather Network

2. Aurora, South Dakota (S. Clay, SDSU)
4 wks
Common Ragweed
Sunflower emerges before ragweed.
Emergence was earlier in 2007.
At 50% emergence, gap between years was substantial.
Why the difference?
What are causes for patterns?
Can patterns be predicted?
2 wks
Common Sunflower

3. } Soil Microclimate Temperature Water O2, CO2, etc. Seed density
Seedling emergence
potential 70 60 50 40 30 20 10 80
Soil Microclimate
Many variables change substantially with each cm of depth in the soil profile.
Several of these variables affect weed seeds.
Thus, understanding their dynamics with soil depth is critical.

4. New Tools SeedChaser SolarCalc SolarCalQ Global TempSim STM2
Kurt Spokas
Curt Bredeson
SeedChaser
SolarCalc
SolarCalQ
Global TempSim
STM2
WeatherEze
Greta Gramig
Jim Eklund
Dean Peterson
All lead to a new and more universal WeedCast-type software that we tentatively are calling PhenPac (phenology package).

6. Insect development
Pesticide fate
Nematode activity
Fertilizer fate
Plant uptake
Cyst survival

7. So, what do we need to do?

9. Simple weather data needed

10. In STM2 specify soil type and organic matter, and attach simple weather data file.
Organic matter scale
Also needed or optional:
More sophisticated soil traits can be entered for site specificity.
Percent shade and water runoff choices are optional.
Geographic location & elevation.

12. Output from STM2

13. Manipulated output

14. Unlikely base T and base ψ

15. Better base T and base ψ
Fit a Weibull or other type of function to data, and that’s the HTT model.

16. Unlikely base T and base ψ

17. Better base T and base ψ

18. Perugia is one of many EWRS sites

19. EWRS soils were shaded in 2006

20. Simulated average daily soil temperatures
Perugia, Italy
(Shaded soil option in STM2)

21. Rain in Perugia, Italy, 2006

23. Weed Seed Movement Largest factor is farming operations
- soil tillage: mostly vertical redistribution
- combine harvesting: mostly horizontal movement
Excellent data already collected in Europe on this topic

24. SeedChaser Colored Beads buried at known depths Transition matrices
Implement Pass
Beads excavated. Depth, color, and horizontal displacement of each bead is recorded
Transition matrices
SeedChaser
Literature data
Availability? Web download
Model is also being used as:
Teaching aid
Extension aid
Research aid

25. Lambsquarters in Perugia, Italy (Depth distribution of seeds known)

26. Summary Predictions are not yet perfect, but they are getting better.
Ability to simulate soil microclimate easily, at several depths, & worldwide, has been a critical achievement for us.
Resulting models (& software) have universal application for helping fine-tune weed management decisions.
The next step is daily automated downloading of data from region-wide weather stations. We do this already with WeatherEze & METAR sites.