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 canker (Leaf and fruit spot)
HOST: Kiwi
Diseased blossoms, a stage of bacterial canker.

Bacterial canker (Leaf and fruit spot) | Kiwi
DISEASE: Bacterial canker (Leaf and fruit spot)
HOST: Kiwi (Actinidia chinensis)
PATHOGEN: Pseudomonas syringae pv. actinidiae
SOURCE: J. Young
DISEASE: Bacterial canker (Leaf and fruit spot)
HOST: Kiwi
Leaf spot stage of the disease with small, brown lesions with yellow halos.

Bacterial canker (Leaf and fruit spot) | Kiwi
DISEASE: Bacterial canker (Leaf and fruit spot)
HOST: Kiwi (Actinidia chinensis)
PATHOGEN: Pseudomonas syringae pv. actinidiae
SOURCE: M. Goto
DISEASE: Bacterial canker (Leaf and fruit spot)
HOST: Kiwi
Leaf spots on young leaves. Note dark brown to black lesions on lower surface (left) and similar lesions on upper surface but with yellow halos (right).

Bacterial canker (Leaf and fruit spot) | Kiwi
DISEASE: Bacterial canker (Leaf and fruit spot)
HOST: Kiwi (Actinidia chinensis)
PATHOGEN: Pseudomonas syringae pv. actinidiae
SOURCE: J. Young
DISEASE: Bacterial canker (Leaf and fruit spot)
HOST: Kiwi
Rusty-colored exudate oozing from cankers on infected trunk.

Bacterial canker (Leaf and fruit spot) | Kiwi
DISEASE: Bacterial canker (Leaf and fruit spot)
HOST: Kiwi (Actinidia chinensis)
PATHOGEN: Pseudomonas syringae pv. actinidiae
SOURCE: M. Goto
DISEASE: Carrot yellows
HOST: Carrot
Flowers with shoot proliferation (witches’-broom) (left). Healthy flower (right). Virescence and phyllody of flower parts are common.

Carrot yellows | Carrot
DISEASE: Carrot yellows
HOST: Carrot (Daucus carota)
PATHOGEN: 'Candidatus Phytoplasma asteris'
PATHOGEN SYNONYM: Phytoplasma Aster yellows group
SOURCE: M. Schroth
DISEASE: Carrot yellows
HOST: Carrot
Carrot with proliferation of roots. Initial symptoms include yellowing and narrowing of veins of young leaves. The entire leaf later becomes necrotic.

Carrot yellows | Carrot
DISEASE: Carrot yellows
HOST: Carrot (Daucus carota)
PATHOGEN: 'Candidatus Phytoplasma asteris'
PATHOGEN SYNONYM: Phytoplasma Aster yellows group
SOURCE: G. S. Abawi