Identification, Pathogenicity and Comparative Virulence of Fusarium spp. Associated with Diseased Euphorbia spp. in Europe

Fusarium spp. isolated from diseased Euphorbia spp. in Europe were assessed for pathogenicity to North American accessions of leafy spurge ( Euphorbia esula/virgata ). Of the nine strains of Fusarium spp. isolated from diseased E. stepposa or E. virgata in the Caucasus region of Russia and E. esula/virgata in southern France, all were pathogenic to leafy spurge. There were significant differences in virulence among strains. Four strains, including the two that were most virulent, were identified as F. oxysporum . Four of the five other strains were identified as F. solani and one was identified as F. proliferatum . Three of the four most virulent strains to leafy spurge were isolated from E. stepposa . The most virulent strain was associated with root damage caused by insect biological control agents, as found earlier with domestic strains of Fusarium spp. pathogenic to leafy spurge. Two strains identified as F. solani were vegetatively compatible. It was concluded that further screening of a larger set of strains of foreign Fusarium spp. under quarantine conditions in the US or in limited overseas facilities would be justified, and could yield promising biological control agents for leafy spurge.     

Distinguishing rice (Oryza sativa Poaceae) from wild Oryza species through Phytolith analysis: Results of preliminary research

Asian rice is an important grain, not only in its homeland but in many areas of the world. Identifying rice in the archaeological record is a challenge, especially in the moist tropics, where organic materials preserve only when charred. Phytolith analysis, the identification of opaline silica bodies, provides an alternative method for identifying this important crop. Results of our research suggest thatOryza contributes phytoliths that are genus-specific, that bulliform characteristics alone do not permit separation of wild and domesticatedOryza in regions where species overlap, and that a number of phytolith types, especially silicified glumes, show promise for separating wild from domesticated forms. With further research it should be possible to identify rice through its phytolith assemblage in archaeological soils in the heartland of its domestication and use.