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 blight
HOST: Photinia
Symptoms of photinia bud blight shown here are similar to those of blast of pear and apple, caused by Pseudomonas syringae pv. syringae.

Bacterial blight | Photinia
DISEASE: Bacterial blight
HOST: Photinia (Photinia glabra)
PATHOGEN: Pseudomonas syringae pv. photiniae
SOURCE: M. Goto
DISEASE: Black chaff (Bacterial leaf streak)
HOST: Wheatgrass
Lesions on leaves first appear as water-soaked, translucent, long, narrow streaks. They later turn brown and necrotic and often coalesce into blighted areas.

Black chaff (Bacterial leaf streak) | Wheatgrass
DISEASE: Black chaff (Bacterial leaf streak)
HOST: Wheatgrass (Elytrigia intermedia)
PATHOGEN: Xanthomonas translucens pv. cerealis
SOURCE: S. Mohan
DISEASE: Black chaff (Bacterial leaf streak)
HOST: Wheatgrass
Close-up of leaf with brown necrotic streaks.

Black chaff (Bacterial leaf streak) | Wheatgrass
DISEASE: Black chaff (Bacterial leaf streak)
HOST: Wheatgrass (Elytrigia intermedia)
PATHOGEN: Xanthomonas translucens pv. cerealis
SOURCE: S. Mohan
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