I. Features
    Many plant pathogens, also human pathogens, others saprophytic. Consist of a mass of coenocytic non-septate hyphae.

II. Examples.

A. Saprolegnia - fly fungus
   Saprophytic; - often attack injured tissue of living organisms
1. Asexual Reproduction
   Ends of hyphae cut off by cross-wall - include many nuclei. Cytoplasmic division occurs till there are many uninucleate biflagellate zoospores - primary zoospores. These swim around then form cell wall & enter resting stage, then form new flagella - Secondary. zoospores, & seek suitable substrate to infect.
2. Sexual Reproduction
   If food reserves diminish, sexual reproduction. may be initiated. Oogonia form at tips of short hyphae - 1-20 eggs/oogonium. Antheridia formed near tips of branches - several nonmotile gametes. Meiosis occurs at gamete formation. Antheridium contacts oogonium, special hypha - germination tube grows from antheridum to oogonium. male nuclei fuse with female, form zygospore. months later - germinate - small hypha, forms zoospores.
B. Pathogenic Oomycetes
   Include very serious plant pests.
1. Phytophthora infestans - late blight of potato
2. Plasmopara viticola - downy mildew of grapes
3. Albugo spp. - white rusts
   Reproduction. involved conidiophores, conidiosporangia & conidia (spores) Sexual reproduction. - similar to Saprolegnia. Bordeaux mixture - lime & copper sulfate.

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