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RESULTS

(6)

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 blight

HOST: Poppy

The disease begins with water-soaked lesions that turn brown to black. They may be surrounded by a translucent ring. Buds, leaves, flowers, and pods are affected.

DISEASE: Bacterial leaf spot

HOST: Larkspur

Infected leaflets with many purplish spots with necrotic centers.

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: Crown gall

HOST: Poppy

Crown gall of California poppy, a native wild flower.

DISEASE: Larkspur virescence

HOST: Larkspur

Two diseased plants with stunted and small leaves, lack of flower coloration, and bunched flower buds. Healthy plant (left).