Biology Reference
In-Depth Information
Cotton Leaf Curl Bigeminivirus
Crimson Clover Latent Nepovirus
Caused chlorosis, thickening and malfor-
mation of veins, petioles and leaves on
Gossypium barbadense
and
Hibiscus esculentus
plants.
Symptomless on
Trifolium incarnatum
.
Cucumber Mosaic Cucumovirus
Cowpea Chlorotic Mottle Bromovirus
General with many strains in cucumber,
squash, melon, winged bean, periwinkle, wild
violets, desert-rose, and a wide range of other
plants, including spinach, where the disease is
called blight; tomato, causing shoestring disease
with filiform leaflets; pepper, petunia, grlic mus-
tard, fuschia, and tobacco. Wintering is on
ground cherry, milkweed, pokeweed, catnip,
Texas bluebell and
Peristroph
sp. and other
weed hosts. Transmission is by peach, cotton,
potato, and lily aphids and,
Reported in peanut, common bean, cowpea and
soybean plants.
Cowpea Mosaic Comovirus
Clearing of veins is followed by chlorotic mot-
tling, slight convex cupping of leaflets, shortened
internodes, abortion of flowers, twisting of
petioles, and delayed maturity. Yield is reduced.
Vectors are potato, pea, and cotton aphids.
Another cowpea mosaic, known in Trinidad and
probably the same as one in the United States,
is transmitted by bean leaf beetles. May
infect soybeans, hoary-tick clover (
Desmodium
canescens
).
in some cases,
through seed.
In cucurbits there is a yellow-green systemic
mottling, with leaves small, distorted, curled,
plants dwarfed with shortened internodes, few
fruits set and those mottled and misshaped,
a condition called “white pickle.” The lily mosaic
strain produces a masked infection or chlorotic
mottling and necrosis when mixed with Lily
Symptomless Virus. The lima-bean, southern cel-
ery mosaic, and cowpea strains cause chlorotic
mottling.
Geraniums are stunted and mottled; gladiolus
flowers are color-broken; dahlia foliage has
oakleaf patterns; periwinkle (myrtle) has
a streaky mottle, down-curved leaves, small
flowers with a white streak in the blue color.
Petunias have distorted leaf blades, few or no
blossoms. In delphinium, which is very suscepti-
ble, the disease is called ring spot, stunt, witches'
broom.
Control
Resistant varieties of spinach,
cucumber, and squash are available. Diseased
lilies and other flowers should be rogued imme-
diately. Control aphids by systemic ground treat-
ments or sprays; repel aphid vectors by an
aluminum foil mulch. Lilies may possibly be
freed of the virus by scale propagation.
Cranberry False Blossom
The most serious cranberry disease in Massachu-
setts, New Jersey, and Wisconsin; known also on
the Pacific Coast. American and European cran-
berries are the only natural hosts, but the virus
has been dodder-transmitted to other plants.
Cranberry flowers are erect, instead of pendent,
with calyx lobes enlarged, petals short, streaked
with red or green, stamens and pistils abnormal.
Flowers may be replaced by leaves or short
branches. Axillary buds produce numerous erect
shoots forming witches' broom; diseased fruits
are small and irregular. Transmission is by the
blunt-nosed leafhopper. Select strains resistant to
the vector or flood the bogs after leafhoppers have
hatched. Spray with pyrethrum.
