Floriculture DisordersFloriculture Disorders

Eddie McKieEddie McKieGeorgiaGeorgia

February, 2007February, 2007

APHIDSAPHIDS

• Small (up to ¼”) soft-bodied 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 GNATSFUNGUS GNATS

• Adult fungus gnats are about 1/8 to 1/10 inch (2.5 mm) long, grayish to black, slender, mosquito-like, and delicate with long legs, antennae and one pair of wings.

LEAF MINERLEAF MINER

• Insect larvae that feed inside a leaf, between the upper and lower surfaces.

MEALY BUGMEALY BUG

• Mealybugs derive their name from the white, waxy, mealy secretions that cover their bodies.

SCALESCALE

• Either soft scales or armored scales

• Covered with waxy shell for most of their life which protects them from predators or insecticides

SLUGSLUG

• Slugs are gastropod mollusks without shells or with very small internal shells, in contrast to snails.

SPIDER MITESPIDER 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 MILDEWPOWDERY MILDEW

• Infected plants will display white powder-like 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

THRIPTHRIP

• 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.

WHITEFLYWHITEFLY

• 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.

BLACKLEGBLACKLEG• 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 SPOTBLACK SPOT• 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.

BOTRYTISBOTRYTIS

• 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 OFFDAMPING OFF

• A common fungal disease that attacks seedlings, weakening the stems right at the soil level. Infected seedlings usually die.

MOSAIC VIRUSMOSAIC VIRUS

• Characterized by the presence of intermingled patches of normal and light green or yellowish colored plant tissue.

ODEMAODEMA

• 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 wart like corky bumps on the lower leaf surface.

COLD WATER DAMAGECOLD WATER DAMAGE

• Often begins with “halo” spots of the leaves caused by overhead watering with cold or cool water.

IRON CHLOROSISIRON 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.

BERMUDAGRASSBERMUDAGRASS• 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.

CRABGRASSCRABGRASS• 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.

NUTGRASSNUTGRASS

• Nutgrass has yellow-green, 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

OXALISOXALIS• 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