Fungal pathogens on Scotch broom (Cytisus scoparius) and French broom (Genista monspessulana) from Chile

Abstract

Scotch broom (Cytisus scoparius) and French broom (Genista monspessulana) are two woody legumes native to Europe and North Africa that have become invasive in different countries around the world. In Chile, they are among the most serious invasive plants of the central southern regions, where they cause severe negative impacts to natural environments, and have become a serious problem in plantation forestry. Numerous studies have sought biological control agents for both species, however, this approach has not been explored in Chile. The aim of this study was to prospect for pathogens and diseases occurring in these weeds in invaded areas of Chile and explore these as potential biocontrol agents. Surveys were conducted in 13 invaded areas between the Biobio and Araucanía regions, and diseased plants of both species were collected for isolation. The putative pathogens isolated from each broom species were inoculated into healthy plants, and isolates producing symptoms identified by DNA sequencing. These isolates were used in pathogenicity tests on both weed species and on Pinus radiata and Eucalyptus globulus plants. The most aggressive pathogens were Fusarium sambucinum, F. solani and Phytophthora multivora on C. scoparius; Neofusicoccum parvum and Chondrostereum purpureum on both weeds, and F. tricinctum s.l. on G. monspessulana. Except for F. trincinctum s.l., all isolates caused lesions on both weeds, and except for P. multivora, all isolates caused lesions on E. globulus and/or P. radiata. Most pathogens on C. scoparius had been reported previously on this host elsewhere, while most pathogens on G. monspessulana represent novel associations.