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

Limitations of the Current Model for Predicting Yield Loss

At first the SBR pathogen forms lesions on soybean leaves and depending on the severity of the infection, complete defoliation of the canopy can occur within 20-30 days. The primary means by which SBR reduces soybean yield is not yet known, but it is possible that it could be due to its impact on defoliation. Hail damage defoliation studies conducted in the 1980s used percentage defoliation at various growth stages for determining impact on yield. The current preliminary model is based on data generated by researchers working on hail damage to leaf defoliation. There are several limitations of the current preliminary model. It is based on percentage defoliation, which can be highly subjective. It is unsure at this point whether the impact of SBR can be attributed to be solely to leaf defoliation (an assumption that will be tested during the progress of this project). Furthermore, the variability in yield predictions based on the hail damage data of percent defoliations has lead researchers to suggest that a mechanistic, physiology-based relationship between yield potential and defoliation must be developed. Here is a model based on the hail damage defoliation data.

This model is admittedly limited in its ability to predict yield loss, but is given purely as preview of functionality for the final calculator. Link to Preliminary Yield Loss Calculator (Based on Hail Damage Data).

The objective of the current project is to develop a more accurate model that is based on an improved relationship between leaf area and relative yield and would be more specific to the impact of Asian Soybean Rust. The new yield loss prediction model for SBR will be developed over the next three years, and tested and validated with independent data sets.