Photo: Nicolas Feau

Rust is a disease that infects the leaves of poplar trees. While not a serious problem in natural forests, poplar rust can cause extensive damage in tree nurseries.

Researchers with the Canadian Forest Service and the ministère des Ressources naturelles et de la Faune du Québec conducted a study on two poplar leaf rust species in plantations and nurseries throughout Quebec: an indigenous species (Melampsora medusae f. sp. deltoidae) and a species native to Europe (Melampsora larici-populina) which was recently discovered in Quebec.

In this study, poplar leaves were collected from a natural poplar stand and in 10 plantations and nurseries. The goal was to determine the geographic distribution of the two types of rust. The European rust, found in Quebec for the first time in 2002, appears to have spread rapidly in nurseries and plantations in most regions of Quebec, except the Abitibi-Témiscamingue region.

Some families derived from poplar clones are resistant to the indigenous rust, but they may show a greater susceptibility to the European variety. Because this exotic rust is able to complete its life cycle, it can persist and spread year after year. What effect this will have on the growth and survival of susceptible poplars remains to be seen.