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Unformatted text preview: pathogen spreads. Sporangiophores emerge on the new leaves and release their sporangia in the wind to spread. 8. (2 pts) What is damping off? List a pathogen (genus) that can cause damping off. Damping off is the rotting of a seed or young plant. Pythium is a common pathogen genus that causes this. 9. (5 pts) Describe the infection process of zoospores, including mobility, attraction, and site of infection for root rots caused by species of Phytophthora and Pythium The zoospores are released and swim through surrounding water before forming a cyst that starts an infection after germinated by a germ tube. Zoospores are attracted by chemical gradients in the soil to the roots of a host. In Phytophthora chlamydospores are also formed to ensure the survival of propagules. Bonus (1pt): Give the correct taxonomic sequence for family , class , phylum , genus , and order . Phylum Class Order Family Genus...
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- Spring '08
- Spore, Plant pathogens and diseases, downy mildew disease, zoospores, characteristic sexual spore, common pathogen genus