US Soybean Rust Detection and Aerobiological Modeling

November 2004 presentation.

Authors

The Integrated Aerobiology Modeling System (IAMS) was used to simulate daily soybean rust spore movement (Isard et al., 2004)
Viable spore deposition (logarithmic) is modeled from September 15 to 19, 2004 in association with Hurricane Ivan
Uncertainty is associated with spore source strength and the absolute quantity of spores

Source area (17,000 sq Km) was from soybean production areas in northwestern South America
Spores were released near midday from August 30 to September 9, 2004
25% of the source area was infested with soybean rust
6 million spores were released per day per heavily infected soybean plant with a planting density of 500,000 plants/ha
33% of these spores were released near midday
15% of the released spores were able to escape from the canopy
Mortality due to UVB radiation exposure in the air was proportional to cloud-adjusted surface total incoming solar radiation
Wet deposition of viable spores was proportional to the observed surface precipitation total

Model domain was divided into 14 km2 grid cells
NWS reanalysis 2 dataset was used to calculate the most likely downwind direction for 6 pressure levels (altitudes) at 6 hr intervals
Spores were moved up or down among pressure levels in accordance to the vertical component of the wind
Mortality due to UV exposure and rainout of spores was calculated for each time step after downwind movement
Deposition of spores was accumulated for all days in the calculations and is given as the number of spores per hectare

Kudzu: Raw data Daryl Jewett (USDA-APHIS) unpublished data. Kudzu map Annalisa Ariatti and Scott Isard (PSU/UIUC).
Soybean Acreage: NASS, 2003; National Land Cover Data, 1992; Colunga, 2004
Spore Deposition: Isard, S., Main, C., Keever, T., Magarey, R., Redlin, S, and Russo, J. (2004) Weather-Based Assessment of Soybean Rust Threat to North America. Final Report to APHIS