DISEASE: Aster yellows
HOST: Potato
Chlorotic and stunted foliage with necrotic leaf margins. Other symptoms may be phyllody, virescence, purple or yellow pigmentation, and rolling of leaflets.

Aster yellows | Potato
DISEASE: Aster yellows
HOST: Potato (Solanum tuberosum)
PATHOGEN: 'Candidatus Phytoplasma asteris'
PATHOGEN SYNONYM: Phytoplasma Aster yellows group
SOURCE: S. Thomson
DISEASE: Aster yellows
HOST: Potato
Stunted, chlorotic plants (left) with stiff, rolled leaves.

Aster yellows | Potato
DISEASE: Aster yellows
HOST: Potato (Solanum tuberosum)
PATHOGEN: 'Candidatus Phytoplasma asteris'
PATHOGEN SYNONYM: Phytoplasma Aster yellows group
SOURCE: S. Thomson
DISEASE: Aster yellows
HOST: Potato
Diseased plant with malformed tubers.

Aster yellows | Potato
DISEASE: Aster yellows
HOST: Potato (Solanum tuberosum)
PATHOGEN: 'Candidatus Phytoplasma asteris'
PATHOGEN SYNONYM: Phytoplasma Aster yellows group
SOURCE: S. Thomson
DISEASE: Aster yellows
HOST: Squash
Diagnostic characteristics for the disease are yellowing of young leaves, proliferation of secondary shoots, and rigid erect habit. Leaves are misshapen and smaller than normal and have stiff, thick laminae.

Aster yellows | Squash
DISEASE: Aster yellows
HOST: Squash (Cucurbita sp.)
PATHOGEN: 'Candidatus Phytoplasma asteris'
PATHOGEN SYNONYM: Phytoplasma Aster yellows group
SOURCE: S. Miller
DISEASE: Bacterial leaf spot and blight
HOST: Fern
Leaf with small lesions that coalesced into large, reddish brown necrotic area.

Bacterial leaf spot and blight | Fern
DISEASE: Bacterial leaf spot and blight
HOST: Fern (Asplenium nidus)
PATHOGEN: Burkholderia gladioli pv. gladioli
PATHOGEN SYNONYM: Pseudomonas gladioli pv. gladioli
SOURCE: APS
DISEASE: Bacterial leaf spot
HOST: Fern
Leaf with large, dark, longitudinal necrotic areas that differ from symptoms normally described for this disease.

Bacterial leaf spot | Fern
DISEASE: Bacterial leaf spot
HOST: Fern (Asplenium nidus)
PATHOGEN: Pseudomonas asplenii
SOURCE: R. Raabe
DISEASE: Bacterial ring rot
HOST: Potato
Stunted plant with withered leaves (right).

Bacterial ring rot | Potato
DISEASE: Bacterial ring rot
HOST: Potato (Solanum tuberosum)
PATHOGEN: Clavibacter michiganensis subsp. sepedonicus
SOURCE: M. Schroth
DISEASE: Bacterial ring rot
HOST: Potato
Infected leaf with advanced stage of interveinal necrosis.

Bacterial ring rot | Potato
DISEASE: Bacterial ring rot
HOST: Potato (Solanum tuberosum)
PATHOGEN: Clavibacter michiganensis subsp. sepedonicus
SOURCE: S. Thomson