Major genera of pathogenic oomycetes

AlbugoPlantsObligate pathogens of plants
AphanomycesAnimals and plantsMostly pathogens of aquatic animals, but includes pathogens of plants
BremiaPlantsObligate pathogens of plants
LagenidiumAnimalsPathogenic species in this genus infect aquatic animals
PeronosporaPlantsObligate pathogens of plants
PhytophthoraPlantsMost extensively studied genus, with more than 60 species that cause some of the most severe diseases of dicot plants
PlasmoparaPlantsObligate pathogens of plants
PythiumPlants, animals, and microbesMostly plant pathogens, but includes mycoparasites and at least one species that infects humans
SaprolegniaAnimalsPathogenic species in this genus infect aquatic animals, mainly fish