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RESULTS

(25)

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: Cassava

Leaf with angular, water-soaked, vein-delimited lesions.

DISEASE: Bacterial blight

HOST: Cassava

Cassava with angular leaf spots and yellow ooze. Symptoms include leaf spots, wilt, and dieback. The bacterium frequently invades systemically.

DISEASE: Bacterial leaf spot (Bacterial necrosis)

HOST: Cassava

Cassava with yellowish leaves and water-soaked, angular spots. The disease is primarily on foliage, although the pathogen may invade stem buds and young branches.

DISEASE: Bacterial leaf spot (Bacterial necrosis)

HOST: Cassava

Cassava with brownish lesions and blackish edges. Leaves turn yellow with multiple infection sites.

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: Citrus canker

HOST: Citrus (Orange)

Leaf with leaf miner tunnels and numerous cankerlike lesions.

DISEASE: Citrus canker

HOST: Citrus (Orange)

Upper side of leaves with corky, raised lesions surrounded by yellow halos, a late stage of disease. Such infections usually are visible on lower sides of leaves first and soon after on upper sides.

DISEASE: Citrus canker

HOST: Citrus (Orange)

Yellowish halos are seen around lesions on the upper leaf surface, whereas lesions on the lower surface are more corky in appearance and have sunken centers without halos.