Yield Loss Prediction Tool for Field-Specific Risk Management of Asian Soybean Rust

Project Updates - LSU September 2008

USA, Louisiana - March 23rd, 2009 (Joe Omielan) - Project Update

Summary of summer 2008.

The design of the experiment has been modified to better “simulate” the effects of SBR and to measure the impact on Radiation Use Efficiency (RUE).  This year only DP4331RR (Group IV) was planted in 38 inch rows.  The plots were defoliated over the course of the season to reduce their Effective Leaf Area Index (ELAI) as a percentage of the control plots.  These reductions over time “matched” what was found in our 2007 Brazil trial when SBR started at R1 and at R5 (see the graph below).  The yield reductions in this experiment were compared to the Brazil trial.

chart showing reductions in ELAI as percent of control when SBR started at first flower (R1)versus at beginning of seed fill (R5)

Reductions in % of Control ELAI in plots when SBR started at R1 or R5.  Data from 2006/2007 trial at Londrina, Brazil.

photo of soybean test plot where 100% defolliation has been reached

The photo above shows an example of one of the plots after 100% defoliation was reached.

plot showing showing linear relationship to leaf area duration reduction from SBR infestation (simulated as defoliation)and yield loss

Relationship between effective leaf area duration (ELAD) as % of control and % control yield for trials with SBR (Londrina, Brazil 2007) and simulating SBR damage (Baton Rouge, LA 2008).  The linear regression for Brazil 2007 is plotted.  The LSU yield reductions were similar to those from Brazil.

Stay Tuned for future updates!


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