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

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

} 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.

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).

http://www.ars.usda.gov/Services/docs.htm?docid=11787

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

So, what do we need to do?

Simple weather data needed

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.

Output from STM2

Manipulated output

Unlikely base T and base ψ

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

Unlikely base T and base ψ

Better base T and base ψ

Perugia is one of many EWRS sites

EWRS soils were shaded in 2006

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

Rain in Perugia, Italy, 2006

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

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 www.ars.usda.gov/mwa/ncscrl Model is also being used as: Teaching aid Extension aid Research aid

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

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.