DISEASE: Brittle root
HOST: Horseradish
Dying, stunted, yellow to brown horseradish plants.

Brittle root | Horseradish
DISEASE: Brittle root
HOST: Horseradish (Armoracia rusticana)
PATHOGEN: Spiroplasma citri
SOURCE: C. Eastman, M. Davis
DISEASE: Brittle root
HOST: Horseradish
Close-up of stunted, yellow horseradish plants.

Brittle root | Horseradish
DISEASE: Brittle root
HOST: Horseradish (Armoracia rusticana)
PATHOGEN: Spiroplasma citri
SOURCE: D. Sherrod
DISEASE: Brittle root
HOST: Horseradish
Horseradish with discolored internal tissues. Healthy root segment (top right).

Brittle root | Horseradish
DISEASE: Brittle root
HOST: Horseradish (Armoracia rusticana)
PATHOGEN: Spiroplasma citri
SOURCE: J. Fletcher, M. Davis
DISEASE: Foamy canker
HOST: Koa
Foamy canker of koa is associated with bacteria and yeast. The causal agent has not been identified.

Foamy canker | Koa
DISEASE: Foamy canker
HOST: Koa (Acacia koa)
PATHOGEN: Causal agent unknown
SOURCE: H. Keyser
DISEASE: Foamy canker
HOST: Koa
Dieback of koa tree. The causal agent has not been identified.

Foamy canker | Koa
DISEASE: Foamy canker
HOST: Koa (Acacia koa)
PATHOGEN: Causal agent unknown
SOURCE: H. Keyser
DISEASE: Halo blight
HOST: Bean
'Baby Fordhook' with water-soaked leaf lesions without halos. This strain of the pathogen is not systemic on this cultivar.

Halo blight | Bean
DISEASE: Halo blight
HOST: Bean (Phaseolus lunatus 'Baby Fordhook')
PATHOGEN: Pseudomonas syringae pv. phaseolicola
PATHOGEN SYNONYM: Pseudomonas savastanoi pv. phaseolicola
SOURCE: M. Schroth