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RESULTS

(11)

DISEASE: Aster yellows

HOST: Barley

Infection by this phytoplasm causes twisted awns and sterile florets.

DISEASE: Aster yellows

HOST: Barley

Small necrotic spots on lower leaves and red coalescing streaks on upper leaves.

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.

DISEASE: Bacterial kernel blight (Leaf blight)

HOST: Barley

Dark, brown discolored kernels at the embryo end and posterior surface.

DISEASE: Bacterial leaf blight

HOST: Barley

Diseased barley plants with typical bleaching of flag leaves. Initial symptoms are water-soaked lesions that later coalesce. Eventually, the entire leaf becomes necrotic and edges roll inward.

DISEASE: Bacterial leaf spot

HOST: Nephthytis

Leaf with concentric rings of dark tissues. There has been confusion of the causal agent with Dickeya sp., which also causes mushy leaf spots.

DISEASE: Bacterial leaf spot

HOST: Nephthytis

Water-soaked tissues and large, dark brown necrotic areas at leaf margins. Healthy (center leaf).

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.

DISEASE: Black chaff (Bacterial leaf streak)

HOST: Barley

Black chaff is characterized by water-soaked and darkened glumes on barley heads and streaks and stripes on leaves.