Cookies on Plantwise Knowledge Bank

Like most websites we use cookies. This is to ensure that we give you the best experience possible.

Continuing to use www.plantwise.org/KnowledgeBank means you agree to our use of cookies. If you would like to, you can learn more about the cookies we use.

Plantwise Knowledge Bank
  • Knowledge Bank home
  • Change location
Plantwise Technical Factsheet

brown soft scale (Coccus hesperidum)

Host plants / species affected
Abelmoschus
Abutilon (Indian mallow)
Acacia (wattles)
Acalypha (Copperleaf)
Acer (maples)
Actinidia
Adiantum (maidenhair ferns)
Agave
Allamanda
Aloe (grey alder)
Alpinia
Althaea (hollyhocks)
Anacardium
Annona
Anthurium
Aralia
Ardisia
Areca
Arenga
Aristolochia (dutchman's pipe)
Artocarpus (breadfruit trees)
Asplenium (spleenworts)
Aster
Atalantia
Baccharis
Bauhinia (camel's foot)
Begonia
Berberis (barberries)
Bidens (Burmarigold)
Bignonia
Bougainvillea
Bromelia
Caesalpinia (divi-divi)
Cajanus
Caladium
Callistemon (Bottle brush)
Calophyllum (beauty-leaf)
Camellia
Camellia sinensis (tea)
Canavalia
Canna
Capsicum (peppers)
Carex (sedges)
Carica
Carissa
Carya (hickories)
Caryota
Cassia (sennas)
Casuarina (beefwood)
Cattleya
Cedrus (cedars)
Ceiba
Ceratonia
Cercis (redbud)
Cestrum (jessamine)
Chamaedorea
Chamaerops (fan palm)
Chlorophytum
Chrysalidocarpus
Chrysanthemum (daisy)
Chrysophyllum
Cinnamomum
Citrullus
Citrus
Clematis
Clerodendrum (Fragrant clerodendron)
Cleyera
Clivia
Cocculus (snailseed)
Coleus
Columnea
Coprosma
Cordyline
Cornus (Dogwood)
Cotoneaster
Crataegus (hawthorns)
Cucurbita (pumpkin)
Curcuma
Cycas
Cyclamen
Cydonia (quince)
Cyperus (flatsedge)
Dalbergia (rosewoods)
Datura (thorn-apple)
Davallia
Dendrobium
Dianthus (carnation)
Dieffenbachia (dumbcanes)
Dioscorea (yam)
Diospyros (malabar ebony)
Dizygotheca (false aralia)
Dodonaea
Dracaena
Duranta
Durio
Elaeagnus
Elettaria
Eriobotrya
Eryngium (sea-holly)
Eucalyptus
Eugenia
Euonymus (spindle trees)
Euphorbia (spurges)
Fatsia
Ficus
Fortunella (kumquats)
Fragaria (strawberry)
Fuchsia
Gardenia
Gazania (treasure-flower)
Genista (broom)
Geranium (cranesbill)
Gerbera (Barbeton daisy)
Gladiolus hybrids (sword lily)
Gliricidia
Glycine
Gossypium (cotton)
Grevillea
Grewia
Haemanthus (blood-lily)
Hedera (Ivy)
Heliconia
Hemerocallis (daylilies)
Hibiscus (rosemallows)
Hippeastrum
Hydrangea (hydrangeas)
Hymenosporum
Ilex (Holly)
Illicium
Impatiens (balsam)
Iresine (blood-leaf)
Iris (irises)
Ixora
Jacaranda
Jasminum (jasmine)
Jatropha
Kalanchoe
Korthalsella
Lantana
Laurus (laurel)
Lawsonia
Lespedeza
Ligustrum (privet)
Lilium (lily)
Lindera (spicebush)
Lonicera (honeysuckles)
Lycium (boxthorn)
Lysimachia (loosestrife)
Magnolia
Mahonia (holly grape)
Malus (ornamental species apple)
Malva (mallow)
Mangifera indica (mango)
Manilkara
Melastoma
Menispermum (moonseed)
Microcoelum
Microlepia
Milletia
Monstera
Morus (mulberrytree)
Murraya
Musa (banana)
Myoporum
Myrsine
Myrtus (myrtle)
Neoregelia
Nephelium (rambutan)
Nephrolepis (fishtail ferns)
Nerium (oleander)
Ocimum basilicum (basil)
Odontoglossum
Olea (olive)
Ornithogalum
Oxalis (wood sorrels)
Paphiopedilum (lady's slipper orchid)
Parkinsonia
Parthenocissus
Passiflora (passionflower)
Passiflora edulis (passionfruit)
Pelargonium (pelargoniums)
Pellaea
Pellionia
Peperomia
Pereskia
Persea
Persea americana (avocado)
Phalaenopsis
Phellodendron (cork tree)
Philodendron
Phoenix (date palm)
Phyllitis
Physalis (Groundcherry)
Pilea
Pimenta
Pinus (pines)
Pisonia
Pistacia
Pittosporum
Platanus (planes)
Platycerium (staghorn-fern)
Plumeria (frangipani)
Podocarpus
Polypodium (Plantae)
Poncirus
Populus (poplars)
Portulaca (Purslane)
Primula (Primrose)
Prunus (stone fruit)
Pseuderanthemum
Psidium (guava)
Pteris
Pueraria
Punica
Punica granatum (pomegranate)
Pyracantha (Firethorn)
Pyrostegia
Pyrus (pears)
Rhaphiolepis
Rhododendron (Azalea)
Rhoicissus (african grape)
Rhus (Sumach)
Ricinus
Robinia (locust)
Rosa (roses)
Rubus (blackberry, raspberry)
Ruellia
Sabal (palmetto-palm)
Saintpaulia (african violet)
Salix (willows)
Salvia (sage)
Sambucus (Elderberry)
Sanchezia
Santalum
Sapium
Schefflera (umbrella tree)
Schinus (pepper tree)
Scindapsus
Sedum (stonecrop)
Selaginella
Sempervivum (house-leek)
Senecio (Groundsel)
Solanum (nightshade)
Solidago (Goldenrod)
Sophora
Spartium
Spondias (purple mombin)
Stenocarpus (Firewheel tree)
Stephanotis
Strelitzia
Streptocarpus
Syngonium
Syzygium
Taxus (yew)
Tecoma
Terminalia
Tetrapanax
Theobroma
Tilia (limes)
Tillandsia
Toona
Typha (reedmace)
Umbellularia
Urena
Vaccinium (blueberries)
Vanda
Viburnum
Vinca (periwinkle)
Viola (violet)
Vitex
Vitis (grape)
Washingtonia (wshington-palm)
Wisteria
Yucca
Zamia
Zantedeschia (calla-lilies)
Zanthoxylum (prickly-ash)
Zephyranthes (Zephyrlily)
List of symptoms/signs
Leaves  -  honeydew or sooty mould
Stems  -  external feeding
Symptoms
The main damage is indirect, through the production of honeydew. This is often copious and quickly becomes infected by sooty moulds which can cover the leaves, flowers and fruit of the host. This has been shown to reduce photosynthesis and respiration, and to modify other physiological processes in the host plant (reviewed by Mibey, 1997); in addition, the presence of sooty mould can reduce the size of the fruit and cause them to be downgraded unless efficiently washed. The honeydew can attract a wide range of ant species, which feed on the honeydew, preventing a build up in sooty moulds but also protecting the scales from natural enemies (Das and Ganguli, 1961); the ants can also be a problem to the labour picking fruit.

Direct damage is rare or not obvious. The large amounts of sap removed almost certainly reduces the growth rate of the plant, but this has not been measured. Occasionally there is a slight creasing of the leaf surface. C. hesperidum rarely kills the host plant.

The effect of coccoids on plants is reviewed by Vranjic (1997) while the interaction of soft scales with ants is reviewed by Gullan (1997).
Prevention and control

Whilst there is a large amount of literature describing various chemical methods for controlling soft scales, particularly C. hesperidum, it is generally agreed that, under most conditions, natural enemies are very effective and the modern approach is to aim for Integrated Pest Management (IPM). A wide range of pesticides have been recommended in the past but all tend to have side effects, mainly killing the natural enemies of both the scales and other pest species present. Resistance by C. hesperidum to some pesticides (e.g. methidothion) has also been recorded (Panis, 1977). One suggested approach is to control the sooty moulds by spraying with a fungicide (Panis, 1980) as the scale itself does relatively little direct damage. IPM programmes, mainly combining the judicious use of selected pesticides and the introduction of a range of parasitoids, are being introduced in most major citrus growing areas of the world.

When natural enemies are present, the chemical control of ants can also be important. Ant control may be either indirect, by the exclusion of ants from the trees (by applying a barrier around the stems or trunks of the host plants) or direct, by destroying the ants' nest. If the ants are controlled in the absence of natural enemies, sooty mould can become very severe. Ant-coccid interactions have been reviewed by Gullan (1997) and discussed by Rosen (1967). Another group of arthropods that can reduce the effectiveness of natural enemies are spiders which snare the predators and/or parasites in their webs (Campbell, 1972) .

Under conditions of protected cultivation, the use of natural enemies is relatively easily controlled (see Stauffer and Rose, 1997). In addition, entomopathogenic fungi, especially Verticillium lecanii, have been used, particularly under glass. The entomopathogenic fungi which attack soft scales are reviewed by Evans and Hywel-Jones (1997), who also outline the history of the use of these fungi. However, the commercial production of strains of V. lecanii has now, apparently, ceased. Nonetheless, entomopathogenic fungi can still offer good control in the field under suitable conditions of relatively high humidity.

Another fairly modern approach is to use insect development and reproduction disruptors. The use of these chemicals against Coccoidea was reviewed by Darvas (1997). Darvas and Virag (1983) tested the juvenile hormones kineprene and hydroprene against a range of coccoids and found that the latter compound gave excellent control of C. hesperidum after three sprays in two weeks. However, the use of some insect growth regulators has been found to effect the natural enemies, particularly coccinellids, causing a breakdown in biocontrol similar to that with conventional pesticides.

For inundative release and for research purposes, it is often necessary to mass rear C. hesperidum. This has been reviewed by Rose and Stauffer (1997).
 

Impact

C. hesperidum is generally not an important pest where there is a range of natural enemies but, even then, it can become a major problem if biocontrol is disrupted by use of broad spectrum, non-selective pesticides (Bartlett, 1978). It is generally accepted as being most important on Citrus (see Talhouk, 1975) and on ornamental or greenhouse plants.

The scale is generally kept under reasonable control by a range of natural enemies; it often reaches economic importance when non-selective insecticides have disrupted control by natural enemies or in their absence (as in glasshouses). Indeed, an additional side effect of low dosages of synthetic insecticides could be an increased reproductive rate of C. hesperidum (Hart et al., 1966).

Related treatment support
 
External factsheets
IVIA factsheets, Instituto valenciano de investigaciones agrarias, Spain, 2015, Spanish language
University of California IPM Pest Management Guidelines, University of California, 2007, English language
University of California IPM Pest Management Guidelines, University of California, 2007, English language
PlantVillage disease guide, PlantVillage, English language
Department of Agriculture and Food Western Australia Farmnotes, Government of Western Australia, 2007, English language
Zoomed image