Biology Reference
In-Depth Information
digging at 85 F with 90 % humidity; then store
at 55 F, except seed stocks, which should be kept
at 70 F so that lots with internal cork can be
selected and discarded.
Sweet Clover Sweet Latent
Nucleorhabdovirus
Virus often together with Bean Common Mosaic
Potyvirus caused leaf chlorosis.
Sweet Potato Mosaic
Sweet Potato Caulimovirus
Transmitted by fleshy-core and sprout grafts and
by sweet potato whitefly.
There are no conspicuous symptoms on Ipomoea
batata . There is no evidence of it spreading in the
United States.
Sweet Potato Russet Crack - Strain of
Sweet Potato Feathery Mottle
Potyvirus
Sweet Potato Feathery Mottle
Potyvirus
Dark lesions and fine cracks in skin of fleshy
roots.
First symptom is a yellowing along veins or small
diffuse yellow spots. Some leaves are abnormally
dark green with feathery yellow areas along
veins. Leaves may be slightly rugose and
dwarfed. Transmitted by aphids, whiteflies, and
sprouts. Caused feathering, clearing and chlorotic
spots on Ipomoea batata but symptoms usually
disappeared soon after infection.
Teasel Mosaic Potyvirus
On Fuller's teasel and scabiosa, with vein-clear-
ing, asymmetry, strong mosaic pattern, malfor-
mation, death of plant. Transmission by peach
and rose aphids.
Sweet Potato Internal Cork
Sweet
Potato Feathery Mottle Potyvirus
¼
Tigridia Mosaic
Pale to yellow-green irregular streaks and
blotches in leaves and flower bracts, occasionally
dark streaks in flowers. Transmission by lily and
melon aphids.
First recognized in South Carolina in 1944, now
in most sweet potato areas, most prevalent in
Georgia and the Carolinas. Dark brown to black-
ish corky spots in flesh of roots, which appear
normal outside. Some are present when sweet
potatoes are dug, but cork spots increase in num-
ber and size during storage, especially at temper-
atures higher than the recommended 55 to 60 F.
Foliage symptoms are vein feathering and mot-
tling followed by reddish to purple blotching
sometimes in ring form. Quality of Porto Rico
variety is severely affected, but not yield. Trans-
mission is by peach and potato aphids and by
grafting, with morning-glories used as index
plants. Control insects to reduce disease; there is
little spread to new plantings 100 yards or more
from diseased fields. Cure immediately after
Tobacco Broad Ring Spot
In tobacco, Wisconsin, experimentally to other
plants. Chlorotic or necrotic rings, sometimes
concentric; young leaves puckered at first.
Tobacco Etch Potyvirus
Mild and severe strains widespread on tobacco,
tomato, pepper, petunia, potato and other plants.
Symptoms are vein clearing with fine necrotic
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