Biology Reference
In-Depth Information
Oat Blue Dwarf Marafivirus
Opuntia Sammons' Tobamovirus
Synonym for Flax Crinkle Virus transmitted by
aster leafhopper. Infected
Avena
sp. plants turned
deep blue.
Symptomless on
Opuntia
spp., virus is transmit-
ted only by mechanical inoculation.
Orchid (Cattleya) Blossom Brown
Necrotic Streak
Oat Golden Stripe Furovirus
Transmitted by fungus,
Polymyxa graminis
; sys-
temically infected
Avena
sp. plants.
Brown spots, streaks of whole flower; leaves may
have yellow streaks; transmission by knife. In
removing flower spikes use “hot knife,” with
attached propane torch.
Oat Mosaic Bymovirus
Orchid Fleck Rhabdovirus
Only
Avena
sp. are susceptible (developing
mottle). Virus transmitted by fungus,
Polymyxa
graminis
.
Caused chlorotic and necrotic fleck on many
orchid species. Virions are typical rhabdo or
bullet-shaped.
Odontoglossum Ringspot
Tobamovirus
Orchid (Cattleya) Mosaic Potexvirus
It is synonym for orchid strain of TobaccoMosaic
Tobamovirus.
Flower-Break. On
Cattleya
and other orchids.
There are apparently two diseases: mild color
break, with variegation in the flower but no
distortion, and severe color break, with flowers
distorted or twisted as well as variegated.
Leaves are mottled and sometimes twisted.
Thevirusmaybepresentin apparently healthy
plants but can be detected with antisera, and
infected plants removed. Transmission is by
the green peach aphid.
Onion Yellow Dwarf Potyvirus
Yellow streaks develop at base of leaves, with
yellowing crinkling, and flattening of new
leaves. Leaves may be prostrate, flower stalks
bent, twisted, and stunted; yield is reduced.
Some species are relatively tolerant; tree onions
are symptomless. Bean, apple-grain, corn leaf,
and other aphids are vectors. Control is by
indexing, growing sample lots of sets and
mother bulbs in greenhouse beds or production
of virus-free stocks in areas where disease is
absent, and roguing of infected volunteer
onions. Some varieties are resistant to the
onion strain of the virus but not to the strain
from shallot or garlic.
Orchid (Cymbidium) Mosaic
Potexvirus
Black Streak; Cattleya Leaf Necrosis. The most
common virus disease on many kinds of orchids.
On
Cymbidium
there is initially a mosaic mottle,
then necrotic spots, streaks, and rings on leaves
but no effect on flowers. In
Cattleya
there are
sunken brown to black leaf patterns, sometimes
