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: Viola (Horned violet)
The disease causes distortion and overgrowth of axillary buds.

Bacterial fasciation (Leafy gall) | Viola (Horned violet)
DISEASE: Bacterial fasciation (Leafy gall)
HOST: Viola (Horned violet) (Viola cornuta)
PATHOGEN: Rhodococcus fascians
SOURCE: M. Putnam
DISEASE: Bacterial leaf spot
HOST: Hydrangea (Oak-leaf)
Leaf with individual brown necrotic lesions and coalesced lesions that formed large necrotic areas. The disease is caused by an unclassified xanthomonad.

Bacterial leaf spot | Hydrangea (Oak-leaf)
DISEASE: Bacterial leaf spot
HOST: Hydrangea (Oak-leaf) (Hydrangea quercifolia)
PATHOGEN: Xanthomonas campestris
SOURCE: W. Uddin, W. Sinclair