The potato late-blight disease is caused by the pseudofungus Phytophthora infestans (Oomycetes). This pathogen was of historical importance as it caused the Irish Potato Famine. There is currently a worldwide resurgence of the disease. Following worldwide migrations as well as being able to discriminate P. infestans from related species are key issues. We present sequence variation of five inte...

In Poland, about 20% of forest nurseries use irrigation water coming from natural superficial reservoirs, presumed to be the first source of infection caused by harmful pathogens belonging to the Oomycota class, especially Phytophthora genus and Pythium genus. The forest nursery is the only place where forest managers can react before pathogens leave it with asymptomatic plants or soil attached...

Plant disease epidemics resulting from introductions of exotic fungal plant pathogens are a well known phenomenon. An associated risk-that accelerated pathogen evolution may be occurring as a consequence of genetic exchange between introduced, or introduced and resident, fungal pathogens-is largely unrecognized. This is, in part, because examples of natural, interspecific hybridization in fungi...

Paradox (Juglans hindsii × J. regia), the dominant rootstock used in California, USA walnut production, has many desirable horticultural characteristics, but is highly susceptible to crown gall. Crown gall, caused by the bacterium Agrobacterium tumefaciens, is not consistently controlled with soil fumigation. This observation, in conjunction with observations of galls occurring in above ground ...

Agathosma species, which are indigenous to South Africa, are also cultivated for commercial use. Recently growers experienced severe plant loss, and symptoms shown by affected plants suggested that a soilborne disease could be the cause of death. A number of Phytophthora taxa were isolated from diseased plants, and this paper reports their identity, mating type, and pathogenicity to young Agath...

Phylogenetic analyses of extant species of Juglans (Juglandaceae) with the New and Old World distributions were performed using five cpDNA intergenic spacer (IGS) sequences (trnT-trnF, psbA-trnH, atpB-rbcL, trnV-16S rRNA, and trnS-trnfM) to elucidate the origin, diversification, historical biogeography, and evolutionary relationships within the genus. Overall, 3848 characters were sampled, yiel...