DISEASE: Blister spot
HOST: Apple
Fruit with water-soaked spots.

Blister spot | Apple
DISEASE: Blister spot
HOST: Apple (Malus domestica)
PATHOGEN: Pseudomonas syringae pv. papulans
SOURCE: T. Burr
DISEASE: Blister spot
HOST: Apple
Water-soaked blister spots on leaves of blighted twig.

Blister spot | Apple
DISEASE: Blister spot
HOST: Apple (Malus domestica)
PATHOGEN: Pseudomonas syringae pv. papulans
SOURCE: T. Burr
DISEASE: Blister spot
HOST: Apple
Apple with brownish blister spots.

Blister spot | Apple
DISEASE: Blister spot
HOST: Apple (Malus domestica 'Mutsu')
PATHOGEN: Pseudomonas syringae pv. papulans
SOURCE: S. Thomson
DISEASE: Blister spot
HOST: Apple
Late stage of blister spot. The purplish black lesions are associated with lenticels and stomata.

Blister spot | Apple
DISEASE: Blister spot
HOST: Apple (Malus domestica 'Crispin')
PATHOGEN: Pseudomonas syringae pv. papulans
SOURCE: T. Burr
DISEASE: Head rot (Jelly rot)
HOST: Lettuce
Sliced head of lettuce. Typical symptoms are a translucent appearance and browning or jelly rot of the stalk (crown).

Head rot (Jelly rot) | Lettuce
DISEASE: Head rot (Jelly rot)
HOST: Lettuce (Lactuca sativa)
PATHOGEN: Pectobacterium carotovorum
PATHOGEN SYNONYM: Erwinia carotovora subsp. carotovora
SOURCE: J. Cho, A. Alvarez
DISEASE: Head rot (Jelly rot)
HOST: Lettuce
Advanced stage of lettuce stalk rot (crown).

Head rot (Jelly rot) | Lettuce
DISEASE: Head rot (Jelly rot)
HOST: Lettuce (Lactuca sativa)
PATHOGEN: Pectobacterium carotovorum
PATHOGEN SYNONYM: Erwinia carotovora subsp. carotovora
SOURCE: J. Cho, A. Alvarez
DISEASE: Head rot (Jelly rot)
HOST: Lettuce
Head rot of lettuce first appears as rapid wilt of outer wrapper leaves. Wilt is caused by collapse of vascular tissues, which develop a pinkish to brown discoloration.

Head rot (Jelly rot) | Lettuce
DISEASE: Head rot (Jelly rot)
HOST: Lettuce (Lactuca sativa)
PATHOGEN: Pectobacterium carotovorum
PATHOGEN SYNONYM: Erwinia carotovora subsp. carotovora
SOURCE: L. Fucikovsky
DISEASE: Witches'-broom
HOST: Alfalfa
Alfalfa plant (center) exhibiting stunting and proliferation of stems. Other symptoms are small, rounded, chlorotic, often puckered leaves and a yellowish cast.

Witches'-broom | Alfalfa
DISEASE: Witches'-broom
HOST: Alfalfa (Medicago sativa)
PATHOGEN: 'Candidatus Phytoplasma trifolii'
PATHOGEN SYNONYM: Phytoplasma Clover proliferation group
SOURCE: S. Thomson
DISEASE: Witches'-broom
HOST: Alfalfa
Young plant (left) with small, numerous stems (witches'-broom). Healthy stems (right).

Witches'-broom | Alfalfa
DISEASE: Witches'-broom
HOST: Alfalfa (Medicago sativa)
PATHOGEN: 'Candidatus Phytoplasma trifolii'
PATHOGEN SYNONYM: Phytoplasma Clover proliferation group
SOURCE: S. Thomson