RESULTS

(4)

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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 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: Bacterial canker

HOST: Hazelnut

Primary symptoms are failure of buds to break and withering and death of new foliage in spring. Dead leaves remain attached to limbs after normal leaf fall.

Bacterial canker | Hazelnut

DISEASE: Bacterial canker

HOST: Hazelnut (Corylus americana)

PATHOGEN: Pseudomonas syringae pv. avellanae

PATHOGEN SYNONYM: Pseudomonas avellanae

SOURCE: P. Psalidas

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