DISEASE: Aster yellows
HOST: Watercress
Diseased watercress (left) and healthy plant (right).

Aster yellows | Watercress
DISEASE: Aster yellows
HOST: Watercress (Nasturtium officinale)
PATHOGEN: 'Candidatus Phytoplasma asteris'
PATHOGEN SYNONYM: Phytoplasma Aster yellows group
SOURCE: W. Borth
DISEASE: Bacterial fasciation (Leafy gall)
HOST: Petunia
Note hyperplasia and leafy galls.

Bacterial fasciation (Leafy gall) | Petunia
DISEASE: Bacterial fasciation (Leafy gall)
HOST: Petunia (Petunia sp.)
PATHOGEN: Rhodococcus fascians
SOURCE: M. Shurtleff
DISEASE: Fire blight
HOST: Photinia
Fire blight cankers on photinia.

Fire blight | Photinia
DISEASE: Fire blight
HOST: Photinia (Photinia fraseri)
PATHOGEN: Erwinia amylovora
SOURCE: M. Schroth