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 streak
HOST: Oat
Leaf with long, dark red streaks.
Bacterial leaf streak | Oat
DISEASE: Bacterial leaf streak
HOST: Oat (Avena sativa)
PATHOGEN: Xanthomonas translucens pv. cerealis
SOURCE: L. Claflin
DISEASE: Bacterial stripe (Blight)
HOST: Oat
Leaves with irregular necrotic spots and elongated stripes that are light tan in the center. Symptoms begin as water-soaked lesions.
Bacterial stripe (Blight) | Oat
DISEASE: Bacterial stripe (Blight)
HOST: Oat (Avena sativa)
PATHOGEN: Pseudomonas syringae pv. striafaciens
SOURCE: S. Thomson
DISEASE: Fire blight
HOST: Pear
Blossom blight is first seen as water-soaked spots that rapidly turn brown to black as the disease becomes systemic and progresses down the shoot.
Fire blight | Pear
DISEASE: Fire blight
HOST: Pear (Pyrus communis)
PATHOGEN: Erwinia amylovora
SOURCE: S. Thomson
DISEASE: Halo blight
HOST: Oat
Oat leaves with oval lesions that darken in time and have distinctive yellow halos.
Halo blight | Oat
DISEASE: Halo blight
HOST: Oat (Avena sativa)
PATHOGEN: Pseudomonas syringae pv. coronafaciens
SOURCE: N. Schaad
DISEASE: Halo blight
HOST: Oat
Close-up of young and old lesions surrounded by halos.
Halo blight | Oat
DISEASE: Halo blight
HOST: Oat (Avena sativa)
PATHOGEN: Pseudomonas syringae pv. coronafaciens
SOURCE: N. Schaad