RESULTS

(7)

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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.

Bacterial blight | Hazelnut

DISEASE: Bacterial blight

HOST: Hazelnut (Corylus americana)

PATHOGEN: Xanthomonas arboricola pv. corylina

SOURCE: J. Pscheidt

DISEASE: Elm yellows

HOST: Elm

Symptoms of elm yellows occasionally appear on one branch before others, but more often they involve the entire crown.

Elm yellows | Elm

DISEASE: Elm yellows

HOST: Elm (Ulmus americana)

PATHOGEN: 'Candidatus Phytoplasma ulmi'

PATHOGEN SYNONYM: Phytoplasma Elm yellows group

SOURCE: W. Sinclair

DISEASE: Elm yellows

HOST: Elm

Diseased twig (right) with epinasty, chlorosis, and yellowing of leaves. Sometimes both yellow and green leaves occur on same branch. Healthy branch (left).

Elm yellows | Elm

DISEASE: Elm yellows

HOST: Elm (Ulmus americana)

PATHOGEN: 'Candidatus Phytoplasma ulmi'

PATHOGEN SYNONYM: Phytoplasma Elm yellows group

SOURCE: W. Sinclair

DISEASE: Elm yellows

HOST: Elm

Branches with butterscotch discoloration (center) and necrotic flecks in phloem and vascular cambium (right). Healthy branch (left). Sudden wilt and browning is common with small trees.

Elm yellows | Elm

DISEASE: Elm yellows

HOST: Elm (Ulmus americana)

PATHOGEN: 'Candidatus Phytoplasma ulmi'

PATHOGEN SYNONYM: Phytoplasma Elm yellows group

SOURCE: W. Sinclair

DISEASE: Elm yellows

HOST: Elm

Elm yellows is characterized by witches'-brooms and stunting. Some cultivars have both yellow and reddish foliar discoloration.

Elm yellows | Elm

DISEASE: Elm yellows

HOST: Elm (Ulmus parvifolia)

PATHOGEN: 'Candidatus Phytoplasma ulmi'

PATHOGEN SYNONYM: Phytoplasma Elm yellows group

SOURCE: W. Sinclair

DISEASE: Elm yellows

HOST: Elm

Late stage of elm yellows disease.

Elm yellows | Elm

DISEASE: Elm yellows

HOST: Elm (Ulmus rubra)

PATHOGEN: 'Candidatus Phytoplasma ulmi'

PATHOGEN SYNONYM: Phytoplasma Elm yellows group

SOURCE: W. Sinclair

DISEASE: Rugose leaf curl

HOST: Clover

Two rugose, distorted white clover leaves and a healthy leaf. Rugose leaf curl is caused by an unidentified phloem-infecting bacterium.

Rugose leaf curl | Clover

DISEASE: Rugose leaf curl

HOST: Clover (Trifolium repens)

PATHOGEN: Phloem-infecting bacterium

SOURCE: D. Teakle