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RESULTS

(62)

DISEASE: Apple proliferation

HOST: Apple

Spring form of the adult black-veined psyllid, Cacopsylla melanoneura, a vector of apple proliferation. In winter, adults are more greenish in color.

DISEASE: Apple proliferation

HOST: Apple

Typical apple proliferation symptom of witches'-broom resulting from suppression of apical dominance and growth of dormant axillary buds. Branches are not usually bent down as shown here.

DISEASE: Aster yellows

HOST: Onion

Infected plants with yellowish, malformed leaves.

DISEASE: Aster yellows

HOST: Onion

Onion flower with unusual symptoms (left) compared with healthy inflorescence (right). Flowers are distorted and often have abnormally long pedicels. Young leaves may have yellow streaks or a general yellowing of basal portions.

DISEASE: Aster yellows

HOST: Potato

Chlorotic and stunted foliage with necrotic leaf margins. Other symptoms may be phyllody, virescence, purple or yellow pigmentation, and rolling of leaflets.

DISEASE: Aster yellows

HOST: Potato

Stunted, chlorotic plants (left) with stiff, rolled leaves.

DISEASE: Aster yellows

HOST: Potato

Diseased plant with malformed tubers.

DISEASE: Bacterial flower stalk and leaf necrosis

HOST: Onion

Dark, rotted areas of stalk and leaves caused by systemic invasion of the pathogen.

DISEASE: Bacterial flower stalk and leaf necrosis

HOST: Onion

Gray-brown rot of onion after inoculation. Disease starts as small, water-soaked lesions that later develop into slimy, gray-brown rot. The disease progresses downward from the stalk and may rot the entire bulb.