Pythium
Species of Pythium grow in water and soil as saprotrophs, but under suitable conditions, e.g. where seedlings are grown crowded together in poorly drained soil, they can become parasitic, causing diseases such as pre-emergence killing, damping off and foot rot. Damping off of cress (Lepidium sativum) can be demonstrated by sowing seeds densely on heavy […]
Conidium production in ascomycetes
There are several steps in the production and release of conidia, namely (1) conidiogenesis, i.e. conidial initiation; (2) maturation; (3) delimitation; (4) secession, i.e. separation from the conidiogenous cell; (5) proliferation of the conidiogenous cell or conidiophore to form further conidia. Conidiogenesis occurs in two ways which appear to be distinct at first glance: blastic […]
Phytophthora
The name Phytophthora (Gr.: ‘plant destroyer’) is apt, most species being highly destructive plant pathogens. The best known is P. infestans, cause of late blight of potatoes. This fungus is confined to solanaceous hosts (especially tomato and potato), but others have a much wider host range. For example, P. cactorum has been recorded from over […]
Oomycota
The phylum Oomycota, alternatively called Peronosporomycetes currently comprises some 800-1000 species. The vegetative hypha: Although some members of the Oomycota grow as sac-like or branched thalli, most of them produce hyphae forming a mycelium. The hyphae of Oomycota are coenocytic, i.e. they generally do not form cross-walls (septa) except in old compartments or at the base […]
Albugo
Classification: Division: EUMYCOTA Subdivision: MASTIGOMYCOTINA Class: OOMYCETES Order: PERONOSPORALES Family: ALBUGINACEAE Genus: ALBUGO OCCURRENCE: Albugo is an obligate parasite on a number of flowering plants. It is represented by 25 species. Albugo candida a common species responsible for the disease “white rust” on the members of family Crucieferae. PLANT BODY: The vegetative pant body is composed of […]