DISEASE: Bacterial blight
HOST: Hazelnut
Diseased young tree with discoloration of the cambium. Dieback of young twigs and branches is characteristic. Other typical symptoms are bud and twig necrosis and small, angular or round, water-soaked leaf spots.
Bacterial blight | Hazelnut
DISEASE: Bacterial blight
HOST: Hazelnut (Corylus americana)
PATHOGEN: Xanthomonas arboricola pv. corylina
SOURCE: J. Pscheidt
DISEASE: Pear decline
HOST: Pear
Healthy pear shoot (left) and diseased shoots (center and right). Leaves are reddish and growth is stunted.
Pear decline | Pear
DISEASE: Pear decline
HOST: Pear (Pyrus communis)
PATHOGEN: 'Candidatus Phytoplasma pyri'
PATHOGEN SYNONYM: Phytoplasma Apple proliferation group
SOURCE: S. Thomson
DISEASE: Pear decline
HOST: Pear
Close-up of infected pear branch showing premature reddish coloration of leaves and cupped, stunted leaves.
Pear decline | Pear
DISEASE: Pear decline
HOST: Pear (Pyrus communis)
PATHOGEN: 'Candidatus Phytoplasma pyri'
PATHOGEN SYNONYM: Phytoplasma Apple proliferation group
SOURCE: S. Thomson
DISEASE: Pear decline
HOST: Pear
Reduced growth of infected trees in center of image.
Pear decline | Pear
DISEASE: Pear decline
HOST: Pear (Pyrus communis)
PATHOGEN: 'Candidatus Phytoplasma pyri'
PATHOGEN SYNONYM: Phytoplasma Apple proliferation group
SOURCE: W. Sinclair
DISEASE: Pear decline
HOST: Pear
Psylla pyricola, the psyllid vector of pear decline phytoplasma.
Pear decline | Pear
DISEASE: Pear decline
HOST: Pear (Pyrus communis)
PATHOGEN: 'Candidatus Phytoplasma pyri'
PATHOGEN SYNONYM: Phytoplasma Apple proliferation group
SOURCE: J. Clark, A. Purcell, M. Davis
DISEASE: Pear decline
HOST: Pear
'Bartlett' pears were grafted onto tolerant rootstock. All trees are infected. Note yellowish, diseased branches.
Pear decline | Pear
DISEASE: Pear decline
HOST: Pear (Pyrus communis 'Bartlett')
PATHOGEN: 'Candidatus Phytoplasma pyri'
PATHOGEN SYNONYM: Phytoplasma Apple proliferation group
SOURCE: C. Smart
DISEASE: Slippery skin
HOST: Onion
Rot progresses from the top of infected scales and eventually internal tissues rot. In early stages, the only external symptoms may be softening of the neck.
Slippery skin | Onion
DISEASE: Slippery skin
HOST: Onion (Allium cepa)
PATHOGEN: Burkholderia gladioli pv. alliicola
PATHOGEN SYNONYM: Pseudomonas gladioli pv. alliicola
SOURCE: H. Schwartz