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 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: Black rot

HOST: Rutabaga

Rutabaga with discoloration of vascular system.

Black rot | Rutabaga

DISEASE: Black rot

HOST: Rutabaga (Brassica napus var. napobrassica)

PATHOGEN: Xanthomonas campestris pv. campestris

SOURCE: M. Shurtleff

DISEASE: Phytoplasma disease

HOST: Armeria

Phytoplasma-infected armeria (left and right) compared with healthy plant (center).

Phytoplasma disease | Armeria

DISEASE: Phytoplasma disease

HOST: Armeria (Armeria maritima)

PATHOGEN: 'Candidatus Phytoplasma' sp.

PATHOGEN SYNONYM: Phytoplasma (undefined)

SOURCE: R. Raabe