How do we model aeciospore dispersal?

A Gaussian Plume Model (GPM) is used here to determine how far aeciospores would likely travel from a Berberis bush infected with stem rust. The model produces projection probabilities to show the density of aeciospores that would likely reach certain distances from an infected Berberis bush under current environmental conditions. This information can then be used to help guide monitoring of Berberis bushes and neighbouring cereal crops for stem rust infection.

What are the key factors in the GPM?

1. Source Strength. This is an estimation of the number of aeciospores that could be released from an infected Berberis bush. These have been approximated at different intensities of infection based on research at the John Innes Centre.
2. Shape of the Plume. This describes how the 'cloud of aeciospores' that are released from an infected Berberis bush may behave.

What affects the shape of the plume?

The plume shape is dependent on environmental conditions at the given location at the time of running the model. This includes:

Irradiance from the sun

Percentage of cloud cover

Wind speed

How do these factors affect the shape of the plume?

The plume can be:

1. Unstable. When wind speed is low and Irradiance is high (summer conditions).
2. Neutral. When it is cloudy and wind speed is high.
3. Stable. When the sky is clear and wind speed is low (at night - no solar radiation).