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RESULTS

(18)

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.

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.

DISEASE: Bacterial leaf spot (Head rot)

HOST: Lettuce

Leaf with black, greasy spots that tend to be vein delimited. Lesions begin as small, angular, water-soaked lesions that coalesce, resulting in large necrotic areas.

DISEASE: Corky root

HOST: Lettuce

Corky root causes a reduction in size of lettuce heads and root systems; susceptible cultivar (right) and resistant cultivar (left).

DISEASE: Corky root

HOST: Lettuce

Close-up of root with malformed, corky appearance and longitudinal ridges of brown tissues.

DISEASE: Corky root

HOST: Lettuce

Initial symptoms of disease are yellow lesions on taproot and main laterals. Greenish brown bands occur around roots. Root pith may become brown and hollow.

DISEASE: Corky root

HOST: Lettuce

Differences in corky root symptoms between susceptible cultivar (right) and resistant cultivar (left).

DISEASE: Drippy nut disease

HOST: Oak

Ooze from young twig inoculated with Brenneria quercina.

DISEASE: Drippy nut disease

HOST: Oak

Ooze from infected acorn. Copious ooze drips from infected acorns, leaving sticky spots on objects under tree canopy. Infections are associated with insect oviposit wounds.