Plant Pathogenic Rust Fungi
Methods of Dispersal:
Spores are passively distributed by scattering. This means that they are
untargeted and only a very small proportion reach their target (i.e. a host
plant). As a result of this inefficiency large numbers of spores need to be
produced to maintain effective rates of migration. A good analogy would be
sending out millions of sales letters as part of a marketing campaign. Very
few will reach people who are actually interested in the letter, but the large
volume compensates for this to ensure at least a few sales. Spores can travel
incredibly long distances on wind currents, particularly during outbreaks
of the disease. For Example, in 1966, an outbreak of coffee leaf rust caused
by Hemelia vastatrix produced spores which travelled from Angola to Brazil
on wind currents: a distance of around 4000 miles. (Nagarajan and Singh) (A)
There is a greater body of scientific knowledge about Urediospores, as they
are the most frequently studied.