Emergence of Poplar Diseases or the “Arms Race” between Breeders and Diseases (Abstract)

Émergence de maladies sur peupliers ou la course aux armements entre l’améliorateur et les maladies (Résumé)

Pascal Frey , Katherine J. Hayden , Fabien Halkett

Poplar cultivation is an example of highly artificialized and intensive woody plant production (clonal and evenaged cultivation) that resembles crop production more than it does forest production. Since the 19th century, breeders have created poplar varieties, especially interspecific hybrids selected on the basis of agronomic criteria (speed of growth, wood volume, straightness of stem, quality of wood). Because of the compromise between growth and resistance classically described for plants, the poplar cultivars have become a target of choice for many diseases (bacterial canker, scab, leaf blight, rust, Dothichiza, viral disease, etc.) and pests (borer, Saperda, wooly aphid, hornet moth, weevil, etc.). European poplar cultivation experienced several health crises in the 20th century that led breeders to select new varieties on the criterion of resistance to the main diseases. As a result, there were periods of massive use of certain varieties endowed with satisfactory resistance to a disease that were subsequently gradually abandoned as it became apparent that they were too susceptible to another emerging or re-emerging disease. In the particular case of poplar rust caused by the fungus Melampsora larici-populina, we have documented the existence of cycles in the use of certain varieties resistant to rust. Because the fungus is able to circumvent qualitative poplar resistance, a number of wholly resistant varieties became susceptible after just a few years of cultivation. We have shown that the implementation on a regional scale of certain poplar varieties that carry qualitative resistances had structured the M. larici-populina populations on the scale of France. In this way, the varietal distribution of poplar trees has influenced pathogen distribution. These feedback loops between host populations (poplar stands) and pathogen populations are similar to models of host/pathogen co-evolution with an “arms race” between the poplar tree (via breeders and poplar tree farmers) and the pathogens.

Domaines: Sciences de l'environnement

Pascal Frey, Katherine J. Hayden, Fabien Halkett. Émergence de maladies sur peupliers ou la course aux armements entre l’améliorateur et les maladies (Résumé). Revue forestière française, 2018, 70 (6), pp.643-644. ⟨10.4267/2042/70315⟩. ⟨hal-03447441⟩