Entomopathogenic Fungi: “Perfect” Phyla

Abstract

The 500 species of the group Oomycota that are now considered to be protoctists were historically thought to be aquatic fungi (see Chapter 8). Oomycetes are heterotrophic and contain a variety of free-living and pathogenic members. Several groups such as the rusts, root rot, and downy mildews are plant pathogens, whereas others such as the Saprolegnia species are parasites of fish and various invertebrates. The causal agent of late blight in potatoes is the oomycete Phytophora infestons, In 1846 this plant disease infected the potato crop in Ireland, causing the great famine which resulted in one million human deaths and stimulated the massive emigration of the Irish people. A second plant disease, the downy mildew of grapes, threatened the European wine industry in the 1800’s and led to the development of the first chemical fungicide, the Bordeaux mixture.