The ancient Romans dedicated April 25 to a festival called the Robigalia. It was celebrated with chariot races and a dog sacrifice. The dog had to be rust colored, as it was an offering to the gods to protect the cereal crops from rust, a group of plant diseases.
There are thousands of different species of rust which cause disease to a wide range of host plants. Rusts have some of the most complicated life cycles of any fungal pathogen, with some species requiring two host plants and producing up to 5 different spore types.
One of the most important hosts is wheat, which can be a host to several different rust diseases. The Latin word "robigo" refers to rust on both metal (as oxidation) and on plants (as disease). Over time, sacrifices were made to the minor god Robigus (or possibly the minor goddess Robigo) who could protect the all-important cereal crops from disease, including the dreaded rust.
|Wheat leaf rust on an individual plant; note the raised, rust-colored pustules on the surface of the leaf|
|Wheat leaf rust in a severely infected field|
Today the cities of Urbana and Champaign are hosting, not chariot races, but the Illinois Marathon. Most of the major roads in town have been shut down to form the route. Hopefully the gods will be content with the sacrifice of sweat and inconvenient traffic, and will overlook the fact that it's a day late and we're missing the dog.
Happy Robigalia, and may our plants be free from disease in 2014!