Download Floriculture Disorders Eddie McKie

Floriculture Disorders
Eddie McKie
Georgia
February, 2007
APHIDS
• Small (up to ¼”) softbodied insects.
• The characteristic
feature that
distinguishes aphids
from other insects are
the “tail pipes” (called
cornicles) which
extend from the rear
of their abdomen.
FUNGUS GNATS
• Adult fungus gnats
are about 1/8 to 1/10
inch (2.5 mm) long,
grayish to black,
slender, mosquitolike, and delicate with
long legs, antennae
and one pair of wings.
LEAF MINER
• Insect larvae that feed
inside a leaf, between
the upper and lower
surfaces.
MEALY BUG
• Mealybugs derive
their name from the
white, waxy, mealy
secretions that cover
their bodies.
SCALE
• Either soft scales or
armored scales
• Covered with waxy
shell for most of their
life which protects
them from predators
or insecticides
SLUG
• Slugs are gastropod
mollusks without
shells or with very
small internal shells,
in contrast to snails.
SPIDER MITE
• To the naked eye,
spider mites look like
tiny moving dots
• Adults have eight legs
and an oval body,
with two red eyespots
near the head end of
the body.
POWDERY MILDEW
• Infected plants will
display white powderlike spots on the
leaves and stems.
• The fungus is favored
by periods of high
relative humidity or
site conditions that
promote a more
humid environment
THRIP
• Thrips are small
(~1/8” long) and
narrow-bodied insects
commonly found
feeding on leaves and
stems.
• The presence of
thrips gives a splotchy
appearance to leaves.
WHITEFLY
• Adults are less than
1/8” long and, like
their name suggests,
have white wings with
pale yellow bodies.
• Adult whiteflies
congregate above
and under leaf
surfaces, and
disperse in clouds
when disturbed.
BLACKLEG
• Plants with blackleg are
stunted and have a stiff, erect
growth habit.
• Foliage becomes chlorotic and
the leaflets tend to roll upward
at the margins.
• Stems of infected plants exhibit
an inky black decay. The base
of the stem is often completely
rotted.
• In relatively dry soil, only the
pith may show blackening.
BLACK SPOT
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•
Round to irregular black splotches
with fringed margins are quite
obvious, mostly on upper leaf
surfaces.
Round to irregular black splotches
with fringed margins are quite
obvious, mostly on upper leaf
surfaces. Leaf yellowing develops
around these black spots, with
defoliation of these infected leaves
common. Round to irregular black
splotches with fringed margins are
quite obvious, mostly on upper
leaf surfaces. Leaf yellowing
develops around these black
spots, with defoliation of these
infected leaves common. Leaf
yellowing develops around these
black spots, with defoliation of
these infected leaves common.
BOTRYTIS
• Botrytis is by far the
most common fungal
disease encountered
under cool, humid
conditions,
particularly were
crops are grown at a
high density with
limited air movement.
DAMPING OFF
• A common fungal
disease that attacks
seedlings, weakening
the stems right at the
soil level. Infected
seedlings usually die.
MOSAIC VIRUS
• Characterized by the
presence of
intermingled patches
of normal and light
green or yellowish
colored plant tissue.
ODEMA
• appears as small,
sometimes corky
blisters which form on
the lower surface of
leaves or needles.
• These blisters may
eventually harden to
form white, tan, or
brown wartlike corky
bumps on the lower
leaf surface.
COLD WATER DAMAGE
• Often begins with
“halo” spots of the
leaves caused by
overhead watering
with cold or cool
water.
IRON CHLOROSIS
• Iron chlorosis is a
yellowing of plant leaves
caused by iron deficiency
that affects many
desirable landscape.
• The primary symptom of
iron deficiency is
interveinal chlorosis, the
development of a yellow
leaf with a network of
dark green veins.
BERMUDAGRASS
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Bermudagrass is creeping
perennial warm-season grass.
Bermudagrass spreads by both
rhizomes and stolons.
The leaves of bermudagrass are
folded in the bud, and the sheath
is strongly compressed.
The leaf is short, approximately
1/8 inch wide with rough edges.
The roots of bermudagrass are
deep and fibrous allowing it to be
highly drought tolerant.
The stolons root at the nodes
forming a thick dense mat.
The seedhead of Bermudagrass
consists of 3 - 7 finger-like spikes.
Common bermudagrass can
spread by seed.
CRABGRASS
• Crabgras is a low-growing
summer annual that spreads
by seed and from rootings of
nodes that lie on the soil.
• It may grow upright to a height
of 2 feet. It will not tolerate
close mowing as well as
smooth crabgrass.
• True leaves are generally 3
inches long and hairy on the
upper surface of the leaf and
leaf sheath.
• The branches are l about 2 to
5 inches at the end of the stalk.
NUTGRASS
• Nutgrass has yellowgreen, wide-bladed
leaves that are
smooth and shiny or
waxy on the upper
side.
• Nutgrass grows 1-3
feet tall if not mowed.
• Yellow and purple
varieties
OXALIS
• The leaves are divided
into three to ten or more
round, heart-shaped or
lanceolate leaflets,
arranged in a whorl with
all the leaflets of roughly
equal size.
• The majority of species
have three leaflets; in
these species, the leaves
are superficially similar to
those of some clovers