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: Fire blight
HOST: Apple
Severe infection of apple with dying twigs and branches.

Fire blight | Apple
DISEASE: Fire blight
HOST: Apple (Malus domestica)
PATHOGEN: Erwinia amylovora
SOURCE: S. Thomson
DISEASE: Fire blight
HOST: Apple
Diseased apple with copious ooze.

Fire blight | Apple
DISEASE: Fire blight
HOST: Apple (Malus domestica 'Jonathan')
PATHOGEN: Erwinia amylovora
SOURCE: S. Mohan
DISEASE: Fire blight
HOST: Apple
Canker on trunk oozing fire blight bacteria.

Fire blight | Apple
DISEASE: Fire blight
HOST: Apple (Malus domestica)
PATHOGEN: Erwinia amylovora
SOURCE: S. Thomson
DISEASE: Fire blight
HOST: Crabapple
Blighted shoot tip.

Fire blight | Crabapple
DISEASE: Fire blight
HOST: Crabapple (Malus sylvestris)
PATHOGEN: Erwinia amylovora
SOURCE: W. Sinclair
DISEASE: Fire blight
HOST: Hawthorn
Hawthorn with blossom blight.

Fire blight | Hawthorn
DISEASE: Fire blight
HOST: Hawthorn (Crataegus laevigata)
PATHOGEN: Erwinia amylovora
SOURCE: M. Shurtleff