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: Aster yellows
HOST: Wheat
Healthy head (left) and diseased head (right). Diseased seedlings may die within 2 to 3 weeks. Infected heads of surviving plants are small and sterile, with distorted awns.

Aster yellows | Wheat
DISEASE: Aster yellows
HOST: Wheat (Triticum aestivum)
PATHOGEN: 'Candidatus Phytoplasma asteris'
PATHOGEN SYNONYM: Phytoplasma Aster yellows group
SOURCE: L. N. Chiykowski
DISEASE: Aster yellows
HOST: Zinnia
Yellowing and shoot proliferation of foliage.

Aster yellows | Zinnia
DISEASE: Aster yellows
HOST: Zinnia (Zinnia violacea)
PATHOGEN: 'Candidatus Phytoplasma asteris'
PATHOGEN SYNONYM: Phytoplasma Aster yellows group
SOURCE: J. Forsberg, M. Shurtleff
DISEASE: Bacterial leaf spot (Blight)
HOST: Beet
Seedling blight stage of the disease.

Bacterial leaf spot (Blight) | Beet
DISEASE: Bacterial leaf spot (Blight)
HOST: Beet (Beta vulgaris)
PATHOGEN: Pseudomonas syringae pv. aptata
PATHOGEN SYNONYM: Pseudomonas aptata
SOURCE: C. Schneider
DISEASE: Bacterial leaf spot (Blight)
HOST: Beet
Leaves with dark brown necrotic regions and streaks; two petioles also are infected.

Bacterial leaf spot (Blight) | Beet
DISEASE: Bacterial leaf spot (Blight)
HOST: Beet (Beta vulgaris)
PATHOGEN: Pseudomonas syringae pv. syringae
SOURCE: C. Schneider
DISEASE: Bacterial leaf spot (Blight)
HOST: Begonia
Initial symptoms appear as small, blisterlike lesions. As lesions age, they enlarge, producing broad patches of necrotic leaf tissue.

Bacterial leaf spot (Blight) | Begonia
DISEASE: Bacterial leaf spot (Blight)
HOST: Begonia (Begonia sp.)
PATHOGEN: Xanthomonas axonopodis pv. begoniae
PATHOGEN SYNONYM: Xanthomonas campestris pv. begoniae
SOURCE: APS
DISEASE: Bacterial leaf spot (Blight)
HOST: Begonia
Advanced stage of disease with dark, large necrotic areas on leaves and interveinal chlorosis.

Bacterial leaf spot (Blight) | Begonia
DISEASE: Bacterial leaf spot (Blight)
HOST: Begonia (Begonia sp.)
PATHOGEN: Xanthomonas axonopodis pv. begoniae
PATHOGEN SYNONYM: Xanthomonas campestris pv. begoniae
SOURCE: APS
DISEASE: Bacterial leaf spot (Blight)
HOST: Coriander
Coriander with spots and yellowing of blighted leaves.

Bacterial leaf spot (Blight) | Coriander
DISEASE: Bacterial leaf spot (Blight)
HOST: Coriander (Coriandrum sativum)
PATHOGEN: Pseudomonas syringae pv. coriandricola
SOURCE: L. Fucikovsky