DISEASE: Bacterial blight
HOST: Grass
Timothy grass with light-colored lesions caused by unidentified Xanthomonas sp.

Bacterial blight | Grass
DISEASE: Bacterial blight
HOST: Grass (Phleum pratense)
PATHOGEN: Xanthomonas sp.
SOURCE: M. Shurtleff
DISEASE: Bacterial brown rot
HOST: Orchid
Phalaenopsis orchid with yellowish brown spot on leaf (left), an early stage of disease.

Bacterial brown rot | Orchid
DISEASE: Bacterial brown rot
HOST: Orchid (Phalaenopsis sp.)
PATHOGEN: Acidovorax cattleyae
PATHOGEN SYNONYM: Acidovorax avenae subsp. cattleyae
SOURCE: R. McMillan
DISEASE: Bacterial brown rot
HOST: Orchid
Leaves of Phalaenopsis orchid with advanced stage of decay.

Bacterial brown rot | Orchid
DISEASE: Bacterial brown rot
HOST: Orchid (Phalaenopsis sp.)
PATHOGEN: Acidovorax cattleyae
PATHOGEN SYNONYM: Acidovorax avenae subsp. cattleyae
SOURCE: R. McMillan
DISEASE: Bacterial bud and petal blight
HOST: Orchid
Miltonia orchid with brownish necrotic areas around edges of flower petals.

Bacterial bud and petal blight | Orchid
DISEASE: Bacterial bud and petal blight
HOST: Orchid (Miltonia sp.)
PATHOGEN: Acidovorax cattleyae
SOURCE: R. Raabe
DISEASE: Bacterial bud and petal blight
HOST: Orchid
Miltonia orchid with diseased water-soaked flower buds.

Bacterial bud and petal blight | Orchid
DISEASE: Bacterial bud and petal blight
HOST: Orchid (Miltonia sp.)
PATHOGEN: Acidovorax cattleyae
SOURCE: R. Raabe
DISEASE: Bacterial leaf spot (Blight)
HOST: Elderberry
Elderberry with dark brown to blackish angular leaf spots.

Bacterial leaf spot (Blight) | Elderberry
DISEASE: Bacterial leaf spot (Blight)
HOST: Elderberry (Sambucus racemosa)
PATHOGEN: Xanthomonas sp.
SOURCE: S. Mohan
DISEASE: Bacterial leaf spot
HOST: Orchid
Diseased leaf of Phalaenopsis orchid with large, dark necrotic area.

Bacterial leaf spot | Orchid
DISEASE: Bacterial leaf spot
HOST: Orchid (Phalaenopsis sp.)
PATHOGEN: Acidovorax cattleyae
PATHOGEN SYNONYM: Acidovorax avenae subsp. cattleyae
SOURCE: R. Raabe
DISEASE: Petal blight
HOST: Orchid
Flower petals of Vanda orchid with necrotic spots.

Petal blight | Orchid
DISEASE: Petal blight
HOST: Orchid (Vanda sp.)
PATHOGEN: Acidovorax cattleyae
SOURCE: A. Alvarez
DISEASE: Xanthomonas leaf blight
HOST: Onion
This was the first photo of onion leaf blight, which was considered a controversial finding for 10 years until an outbreak occurred in the West Indies.

Xanthomonas leaf blight | Onion
DISEASE: Xanthomonas leaf blight
HOST: Onion (Allium cepa)
PATHOGEN: Xanthomonas axonopodis pv. allii
PATHOGEN SYNONYM: Xanthomonas campestris pv. allii
SOURCE: A. Alvarez