PCA - Plant Pathogens Exam Study Guide Latest 2026 Updated
Questions and Verified 100% Solutions (2026/2027) Grade:
A+|Status: Guaranteed Pass
Bacterial Plant Pathogen Characteristics - Answers -Prokaryotic, reproduce asexually, enter
through wounds or natural openings, ooze is a typical sign
How does bacteria enter plant tissue? - Answers -Enter through wounds or unhealthy tissue or
natural openings
How do bacteria reproduce? - Answers -binary fission, which is asexual
How are bacteria disseminated/spread? - Answers -Insect vectors, wind-blown water, birds,
people, tools
How do bacteria survive without a host? - Answers -Live intracellularly in phloem cells or survive
in dead matter for a period of time
Environmental conditions that are favorable for bacterial disease development - Answers -
Warm, moist temperatures; host to reproduce in; way to enter
Two kinds of prokaryotes that cause plant disease - Answers -Bacteria and mollicutes
1|Page
,Difference between bacteria and mollicutes - Answers -Mollicutes are much smaller and lack a
cell wall
Two major groups of mollicutes - Answers -Spiroplasma and phytoplasma
Pseudomonas sp. - Answers -Bacterial canker of stone fruits
Clavibacter sp. - Answers -Bacterial canker of tomato
Erwinia sp. - Answers -Fire blight/bacterial soft rot
Xanthomonas sp. - Answers -Black rot of crucifers
Agrobacterium sp. - Answers -Crown gall
fastidious vascular bacteria - Answers -rod-shaped, gram negative, has an undulating outer cell
membrane, and is highly sensitive to antibiotics
2|Page
,xylem-limited fastidious bacteria example - Answers -Xylella fastidiosa
phloem-limited fastidious bacteria example - Answers -Huanglongbing
Xylella fastidiosa host - Answers -Grapes and Almonds
Xylella fastidiosa - Answers -Pierce's Disease/Almond Leaf Scortch
Xylella fastidiosa vector - Answers -sharpshooters
Xylella fastidiosa disease reservoir - Answers -Bermudagrass, rye, fescue grass, watergrass,
blackberry, elderberry, cocklebur, and nettle
Phytoplasma - Answers -a plant-parasitic pleomorphic mollicute found in phloem tissue; cannot
yet be grown on artificial nutrient media
Corn stunt insect vector - Answers -Leafhoppers
3|Page
, Corn stunt disease reservoir - Answers -Infected corn
Cherry X-disease insect vector - Answers -Leafhoppers
Cherry X-disease disease reservoir - Answers -Clovers, sweet clovers, dandelion
Cherry X-disease alternate hosts - Answers -Boxwood, ceanothus, crabapple, hawthorn, lilac,
myrtle, privet, pyracantha, viburnum
Aster yellows insect vector - Answers -Leafhoppers
Aster yellows disease reservoirs - Answers -Weeds
viroid - Answers -A plant pathogen composed of molecules of naked, circular RNA several
hundred nucleotides long.
Virus - Answers -A tiny, nonliving particle that invades and then reproduces inside a living cell.
4|Page
Questions and Verified 100% Solutions (2026/2027) Grade:
A+|Status: Guaranteed Pass
Bacterial Plant Pathogen Characteristics - Answers -Prokaryotic, reproduce asexually, enter
through wounds or natural openings, ooze is a typical sign
How does bacteria enter plant tissue? - Answers -Enter through wounds or unhealthy tissue or
natural openings
How do bacteria reproduce? - Answers -binary fission, which is asexual
How are bacteria disseminated/spread? - Answers -Insect vectors, wind-blown water, birds,
people, tools
How do bacteria survive without a host? - Answers -Live intracellularly in phloem cells or survive
in dead matter for a period of time
Environmental conditions that are favorable for bacterial disease development - Answers -
Warm, moist temperatures; host to reproduce in; way to enter
Two kinds of prokaryotes that cause plant disease - Answers -Bacteria and mollicutes
1|Page
,Difference between bacteria and mollicutes - Answers -Mollicutes are much smaller and lack a
cell wall
Two major groups of mollicutes - Answers -Spiroplasma and phytoplasma
Pseudomonas sp. - Answers -Bacterial canker of stone fruits
Clavibacter sp. - Answers -Bacterial canker of tomato
Erwinia sp. - Answers -Fire blight/bacterial soft rot
Xanthomonas sp. - Answers -Black rot of crucifers
Agrobacterium sp. - Answers -Crown gall
fastidious vascular bacteria - Answers -rod-shaped, gram negative, has an undulating outer cell
membrane, and is highly sensitive to antibiotics
2|Page
,xylem-limited fastidious bacteria example - Answers -Xylella fastidiosa
phloem-limited fastidious bacteria example - Answers -Huanglongbing
Xylella fastidiosa host - Answers -Grapes and Almonds
Xylella fastidiosa - Answers -Pierce's Disease/Almond Leaf Scortch
Xylella fastidiosa vector - Answers -sharpshooters
Xylella fastidiosa disease reservoir - Answers -Bermudagrass, rye, fescue grass, watergrass,
blackberry, elderberry, cocklebur, and nettle
Phytoplasma - Answers -a plant-parasitic pleomorphic mollicute found in phloem tissue; cannot
yet be grown on artificial nutrient media
Corn stunt insect vector - Answers -Leafhoppers
3|Page
, Corn stunt disease reservoir - Answers -Infected corn
Cherry X-disease insect vector - Answers -Leafhoppers
Cherry X-disease disease reservoir - Answers -Clovers, sweet clovers, dandelion
Cherry X-disease alternate hosts - Answers -Boxwood, ceanothus, crabapple, hawthorn, lilac,
myrtle, privet, pyracantha, viburnum
Aster yellows insect vector - Answers -Leafhoppers
Aster yellows disease reservoirs - Answers -Weeds
viroid - Answers -A plant pathogen composed of molecules of naked, circular RNA several
hundred nucleotides long.
Virus - Answers -A tiny, nonliving particle that invades and then reproduces inside a living cell.
4|Page
