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Bacteria
- Small number cause plant disease
- rod-shaped
- volume is 1000 times smaller than plant cell
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Agrobacterium
- Rod-shaped, motile, gram-negative
- smooth and white
- associated with plant roots & soil
- tumor like growth
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Clavibacter
- irrgualarly rod-shaped, club end
- most non-motile
- gram-positive
- white then become orange/yellow
- develop slowly
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Erwinia
- rod-shaped, motile, gram negative
- mostly paracitic
- cream colored some yellow
- facilitative anerobes- can live w/ or w/o O2
- Some divided into brenneria, Pantoea, Pectobecterium
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Pseudomonas
- rod-shaped, motile, gram negative
- white, pigments fluoresces under UV light
- broken into- Acidovaorax, burkholderia, ralstonia
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Xanthomonas
- rod-shaped, motile, gram negative
- yellow
- only plant pathogens not saprophytes
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Streptomyces
- filamentous bacteria
- produce aerial conidia chains
- gram positive
- dry granular/powdery
- most soil inhabiting and few cause scab disease
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Gram Reaction
- Staining: + stay blue, - decolorise red
- KOH
- - premeable = stringy, viscous b/c cell wall break
- + not premeable = not viscus
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Soft rot bacteria on potatoes
- Cuts heal faster b/c suburbanization
- if covered with water the O2 is depeated & can't heal
- if it is below 20 C it can't heal
- 95-90% humidity and cool
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Soft Rot of Veg caused by Erwinia carotovora
- very wide spread
- starts as water soaked, then collapes, discolored, cracks and oozing
- Likes wet and cool
- maggots spread the bacteria
- Management: crop rotation, remove infected produce, clean, seed treatment, keep in dry cool place
- can make the plant a host to salmonella
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Fire Blight of apple, pear, cause by erwinia amylovora
- Symptoms: flowers discolor and drop, hooked twigs, wilting leaves
- Signs: milky bacterial ooze under humid conditions
- Likes: humid and wet
- Management: resistant trees, control incest to spread, remove infected
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Crown gall caused by agrobacterium tumefaciens
- Symptoms: Overgrowth, galls, near soil line, stunted plants
- Signs: none
- Likes: wooden plants
- Management: resistance, reduce root chewing insects, crop rotation, don't plant there
- Mess with the T1 plasmid
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