Spore Dispersal
Puccinia graminis produces all five of the spore types that are known for rust fungi.
Spores are typically deposited close to the source, but long-distance dispersal is also well documented. The following three categories of long-distance dispersal are known to occur:
- Extremely long-distance dispersal
This can occur unassisted (the robust nature of the spores allows them to be carried long distances in the air and then deposited by rain-scrubbing) or assisted (typically on human clothing or infected plant material that is transported between regions). This type of dispersal is rare and is very difficult to predict.
- Step-wise range expansion
This is probably the most common mode of long-distance dispersal and usually occurs within a country or region.
- Extinction and recolonisation
This occurs in areas that have unsuitable conditions for year-round survival of Puccinia graminis - typically temperate regions where hosts are absent during either the winter or summer. Spores overwinter or oversummer in another region and then recolonise when conditions are favorable.
Read more about this topic: Stem Rust