European Journal of Forest Pathology (1999) 29, 411-423

S. Miot, P. Frey and J. Pinon (1999)
Varietal mixture of poplar clones: Effects on infection by Melampsora larici-populina and on plant growth
European Journal of Forest Pathology 29 (6), 411-423
Abstract: The effects of poplar varietal mixture on infection levels caused by Melampsora larici-populina and on plant growth were studied during two consecutive growing seasons. The varietal mixture consisted of an intimate mixture of three poplar clones, Populus x interamericana 'Boelare', 'Rap' and Populus candicans 'NNT', expressing different race-specific resistances. Infection levels of M. larici-populina were assessed in monoclonal and polyclonal plots. Plant heights were determined at the end of each growing season. Infection levels in the growing season of the first year were not significantly different between monoclonal and polyclonal plots at the end of the epidemic. During the second growing season, a naturally occurring complex pathotype, able to infect clones 'Boelare' and 'Rap', invaded some plots prematurely and changed the composition of pathogen population. During this season, four infection assessments were conducted. Infection reduction in polyclonal plots compared with monoclonal plots was observed on 'Boelare' and P. candicans plants. Nevertheless, no significant difference was observed for growth between monoclonal and polyclonal plots. Biological factors which may be involved in the reduction of infection levels in polyclonal plots are dilution of susceptible individuals, physical barriers caused by resistant plants and cross-protection. A high auto-infection ratio may have partly hidden the positive effects of the clonal mixture.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Pascal Frey

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host
environment - cropping system/rotation

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Melampsora larici-populina	Poplar/aspen (Populus)	France