Biology Reference
In-Depth Information
etching, usually toward base of leaves. Plants are
stunted with smaller, mottled leaves. Transmis-
sion is by peach, lily, bean and other aphids.
after handling virus-infected plants and remain
a source of infection.
There are many strains of the virus, causing
cowpea mosaic,
tomato
aucuba mosaic,
tomato enation mosaic,
tomato streak, orchid
Tobacco Mild Green Mosaic
Tobamovirus
aucuba, etc.
Control Remove and burn any suspicious plants
in the seedbed along with neighboring plants.
Destroy weeds, especially ground cherry and
other solanaceous species. Never smoke while
working with plants, and always wash hands
thoroughly with soap after handling tobacco in
any form or touching diseased plants, before han-
dling young seedlings or healthy plants.
Transmitted on the surface of the affected seeds.
Infectious virus particles were found in water
used for irrigation in greenhouses.
Tobacco Mosaic Tobamovirus
Tomato Mosaic; Pepper Mosaic. General in gar-
dens, fields, greenhouses on tobacco, tomato,
pepper, eggplant, petunia, Moraine ash,
Achimenes, Aeschynanthus, Chirita,
Codononthe, Episcia , gloxiana, Kohleria,
Nematanthus, Streptocarpus, Smithantha,
Rhoeo , and nearly all solanaceous plants. Tomato
foliage has a light and dark green mottling,
accompanied by some curling and malformation
of leaflets, often with a fernleaf effect. A yellow
strain of the virus causes striking yellow mottling
of leaves, sometimes stems and fruits. Yield is
greatly reduced. In pepper, yellowish chlorotic
lesions are followed by systemic chlorosis.
Spinach has some mottling, stunting, necrosis.
Eggplant is often killed.
Transmission is by mechanical means -by
handling, on tools, through soil, by grafting, pos-
sibly but not probably by seed. The virus can be
transmitted by feeding of grasshoppers, but
apparently there is little spread by the usual
aphid vectors. This is the most resistant and
highly infectious of all viruses. It withstands
heat, even alcohol and various germicides, and
retains infectivity in a dried state for many years.
The most common source of inoculum is
smoking tobacco. Gardeners contaminate their
hands by smoking and then infect plants as they
transplant, tie, prune, etc., the virus entering
through scratches or broken hairs. The first symp-
toms appear in 8 to 10 days. In greenhouses, even
doorknobs, faucets, and flats can be contaminated
Tobacco Necrosis Necrovirus
On tobacco, tomato, aster, geranium and bean,
confined to roots, or systemic without symptoms,
or systemic with symptoms. In Holland, the virus
causes a severe crippling of tulips called Augusta
disease, often preventing flowering, resulting in
death.
Tobacco Rattle Tobravirus
On Romaine
lettuce
and
transmitted
by
Paratrichodorus christiei .
Tobacco Ring Spot Nepovirus
General on tobacco, petunia, potato, cucumber,
celery, Moraine ash and geranium, causing pim-
ple disease of watermelon, bud blight of soy bean,
in gladiolus, iris, Astilbe, and Easter lily without
symptoms. Causing large chlorotic areas on spin-
ach leaves; faint zigzag lines on beet; pin-point
necrotic spots with yellow haloes on cucurbits
and fruits first pitted, then with elevated pimples;
eggplant yellows, “bouquet disease” of potatoes,
with stems curved, shortened, sometimes with
black lesions on underside of veins. Petunia seed-
lings are stunted, first leaves are mottled, and
seed pods have few seeds. Mint is stunted.
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