Key Plants and Key Pests in North Florida

Landscapes Podocarpus, Gardenia,

Camellia, and Pyracantha

Rebecca McNair

University of Florida Extension

IPMIntegrated Pest

Management•Natural processes of control are emphasized

–Host plant resistance–Pest exclusion–Prevention and through cultural practices–Physical Control–Biological control through natural enemies–Chemical control as a last resort

•Tolerance •Monitoring

Podocarpus

Nageia nagi

Podocarpus- Key Pests

Diseases

•Mushroom root rot

Other

• Nematodes

• Magnesium deficiency

Mushroom Root Rot •Slow decline,

thinning of canopy

•Gray-green color

•White mycelia under bark at soil line

Armillaria tabescens

•Remove diseased plants and roots

•Fumigate soil before replanting

Root Rot Management

Armillaria tabescens fruiting body appears in fall.

Root nodules •Beneficial nitrogen-fixing blue green algae

•Often mistaken for root knot nematodes

•Active nodules have a pink milky fluid in their centers

Hemoglobin within the nodule fixes atmospheric nitrogen. When exposed to

oxygen, the fluid inside changes from blue to pink!

•Endoparasitic nematode

•Feeds on root tissues

•Dieback, decline, chlorosis

•Identify under microscope

Roots infected with Meloidogyne are

swollen.

Root Knot Nematodes

Nematode Management

Meloidogyne sp.•Fumigate•Solarize soil•Buy plants grafted with resistant varieties•Provide adequate water and fertilizer•Remove and replace plants and soil

egg mass

•Yellow inverted “V”

•Occurs on mature leaves

•Low soil pH

•Lack of soil Mg

Management

•Increase pH with dolomite

•Apply Epsom salts or Mg fertilizers

Magnesium Deficiency

Gardenia augusta

• Acid loving plant

• Fragrant flowers

Gardenia- Key Pests

Other

•Nematodes

•Manganese deficiency

•Environmental stress

Diseases

•Stem Canker

Stem Canker

•Sudden wilting

•Chlorosis

•Leaf spots

•Yellow halo around lesions

•Stem cankers

•Galls, usually at the soil line

•Girdling may occur

Stem Canker

•Fungus pathogen enters injured tissue

•Spores spread by splashing water

Management

•Minimize plant injury

•Avoid overhead irrigation Phomopsis

gardeniaeNotice the yellow halo around the leaf spots on this gardenia.

Nematodes

•Roundworms

•Root Knot nematodes live inside plant roots

•All live in liquids, i.e. water in soil

•Feed on plant sap

•Damage roots

•Inhibit growth

Root-Knot Nematodes•Decline and thinning of canopy

•Roots brown, stunted and galled

Decline due to root knot nematodes compared to a

healthy gardenia.

Nematode Management

•Fumigate•Solarize soil•Buy plants grafted with resistant varieties•Provide adequate water and fertilizer•Remove and replace plants and soil

Meloidogyne sp

Manganese Deficiency•Interveinal chlorosis on new growth

•Reduced leaf size

•Necrotic distortion of new growth

•Common in alkaline soils high in phosphorousManagement

Use a complete fertilizer with micronutrients

Environmental Stress

Bud drop

Chlorosis

•Excessive water or fertilizer•Cold or temperature fluctuation

•Nutrient Deficiency•Drought

•High pH

•Mechanical damage

Management•Correct cultural problems•Provide cold protection•Prune and re-grow

Camellia japonica

•Acid loving

•Prefers partial shade

•Fragrant flowers from late winter to early spring

Camellia- Key Pests

Diseases

•Crown Gall

•Petal blight

•Leaf spot

•Twig dieback

Other

•Environmental stress

Gall

Agrobacterium tumefaciens is a common soil bacterium that causes crown gall

disease by transferring some of its DNA to the plant host. This has enabled

scientists to genetically manipulate plants, a technique called transformation.

•Galls can appear on any plant part and may be due to bacteria, fungi, nematodes, or insects.

Petal Blight

Cibornia camelliae (formerly Sclerotinia)

•Irregular, brown spots

•Dark veins

•Blighted flowers drop

•Prefer warm, moist conditions

•Ascospores are spread by water

•Fungus overwinters as sclerotia, a hard black structure that remains viable for 5 years Sclerotia

Petal Blight Control

•Suppress sclerotia development

•Remove all infected flowers, leaves, and litter

•Promptly burn or bury diseased materials (at least 1 ft deep)

•Limit overhead irrigation Cibornia

camelliae fruiting body.

Cerscospora caloloma

•Circular or irregular lesions

•Margins raised

•Brown - gray

•Fungus favors high humidity and partial shade

Management

•Limit overhead irrigation

•Avoid crowding

•Copper fungicides

Fungal Leaf Spot

Algal Leaf Spot

Cephaleuros virescens

•Wide host range

•Smooth leathery leaves are more prone to infection

•One of the few green algae parasitic on higher plants

Management

•Limit overhead irrigation

Twig Dieback

Twig dieback and a healthy camellia.

•Fungus

•Summer-winter:

• cankers

•Spring:

•Young shoots wilt and die

•Brown leaves remain on the dead shoots

Glomerella cingulara

Twig Dieback

Management

•Prune infected areas, including cankers

•Fungicides

•Leaf scars are most common point of entry

•Often confused with root rots

•Plants can be infected by both

•Root rot increases the severity of twig dieback

Environmental Stress

Bud Drop

•High heat and light

•Temperature fluctuation

•Drought

•Mechanical damage

Management

•Maintain adequate water

Pyracantha coccinea

•Firethorn

•Prefers full sun

•Will grow in partial to fairly heavy shade

•Fast growing

Pyracantha- Key Pests

Diseases

•Fireblight

Fireblight

•Bacterium

•New shoots wilt suddenly and die

•Dead leaves remain on the shoots

•Spread by bees and splashing water

Erwinia amylovora

Fireblight•Bacteria enter through flowers and infection spreads into the stem

Management

•Limit overhead irrigation

•Remove infected branches

•Use resistant varieties

Authors: Rebecca McNairReviewers: Dr. Russ Mizell, Dr. Norman Leppla, Dr. Doug Caldwell, Celeste White, and Christine Kelly- BegazoFunding: Florida Yards and NeighborhoodsPhotos: Thanks to the Florida Dept. of Agriculture and Consumer Services, Division of Plant Industry, and University of Florida Extension faculty for providing photographs, including:

Dr. James Castner Dr. Catherine MannionDr. Lance Osborne Dr. Avas HamonDr. Norman Leppla Dr. George AgriosBill Graves Dr. Doug CaldwellHolly Glenn Dr. Tim SchubertDr. Eileen Buss

Acknowledgements