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 (Head rot)
HOST: Lettuce
Leaf with black, greasy spots that tend to be vein delimited. Lesions begin as small, angular, water-soaked lesions that coalesce, resulting in large necrotic areas.
Bacterial leaf spot (Head rot) | Lettuce
DISEASE: Bacterial leaf spot (Head rot)
HOST: Lettuce (Lactuca sativa)
PATHOGEN: Xanthomonas axonopodis pv. vitians
PATHOGEN SYNONYM: Xanthomonas campestris pv. vitians
SOURCE: A. Alvarez
DISEASE: Bacterial leaf streak
HOST: Millet
Leaf with small, linear, water-soaked, reddish brown stripes.
Bacterial leaf streak | Millet
DISEASE: Bacterial leaf streak
HOST: Millet (Pennisetum glaucum)
PATHOGEN: Xanthomonas campestris pv. pennamericanum
SOURCE: L. Claflin
DISEASE: Bacterial leaf streak
HOST: Millet
Advanced stage of disease.
Bacterial leaf streak | Millet
DISEASE: Bacterial leaf streak
HOST: Millet (Pennisetum glaucum)
PATHOGEN: Xanthomonas campestris pv. pennamericanum
SOURCE: L. Claflin
DISEASE: Bacterial leaf stripe
HOST: Millet
Leaf with long reddish stripes, usually vein delimited.
Bacterial leaf stripe | Millet
DISEASE: Bacterial leaf stripe
HOST: Millet (Pennisetum glaucum)
PATHOGEN: Acidovorax avenae
PATHOGEN SYNONYM: Acidovorax avenae subsp. avenae
SOURCE: L. Claflin
DISEASE: Bacterial leaf stripe
HOST: Millet
Leaf with reddish stripes delimited by veins.
Bacterial leaf stripe | Millet
DISEASE: Bacterial leaf stripe
HOST: Millet (Pennisetum glaucum)
PATHOGEN: Acidovorax avenae
PATHOGEN SYNONYM: Acidovorax avenae subsp. avenae
SOURCE: L. Claflin
DISEASE: Bacterial wilt
HOST: Squash
Field with severe symptoms of wilt. Foliage often is chlorotic and leaf margins may be chlorotic and necrotic before plant death. Bacterial ooze may be seen streaming from the xylem when infected stems are cut.
Bacterial wilt | Squash
DISEASE: Bacterial wilt
HOST: Squash (Cucurbita maxima)
PATHOGEN: Erwinia tracheiphila
SOURCE: B. Jacobsen, M. Shurtleff
DISEASE: Corky root
HOST: Lettuce
Corky root causes a reduction in size of lettuce heads and root systems; susceptible cultivar (right) and resistant cultivar (left).
Corky root | Lettuce
DISEASE: Corky root
HOST: Lettuce (Lactuca sativa)
PATHOGEN: Sphingomonas suberifaciens
PATHOGEN SYNONYM: Rhizomonas suberifaciens
SOURCE: E. J. Ryder
DISEASE: Corky root
HOST: Lettuce
Close-up of root with malformed, corky appearance and longitudinal ridges of brown tissues.
Corky root | Lettuce
DISEASE: Corky root
HOST: Lettuce (Lactuca sativa)
PATHOGEN: Sphingomonas suberifaciens
PATHOGEN SYNONYM: Rhizomonas suberifaciens
SOURCE: A. van Bruggen