020 3176 5800 Scale insects can be found on a wide range of ornamental plants, fruit trees and bushes grown out of doors. Leaves on affected branches wilt as affected branches die. Do not let piles of mulch bury the plant. Spray after the azaleas are done blooming to avoid spraying over bees and other pollinators, and to avoid flower injury. The worst effects can arise when out of season frosts strike just when the sap is rising. Kit Arbuckle is a freelance writer specializing in topics such as health, alternative medicine, beauty, senior care, pets and landscaping. 1. Azalea bark scales overwinter on older twigs and branches, under a white, felt-like egg sac about 6-12 mm in diameter. Spray the plants thoroughly, so that the soap spray drips or “runs off” from the upper and under sides of leaves, twigs, and plant stems. This is the time when treatment is most effective. An oil spray applied after the crawlers emerge is usually very effective in controlling azalea bark scale, but keep checking each year and spray again when necessary. They feed by sucking sap and some can weaken host plants, many excrete a sticky substance (honeydew), which allows the growth of sooty moulds. Dead bark falls off the cankered area. Rhododendron scales feed on the sap of the plant. This can control the overwintering scale nymphs in December-January when the plants are fully dormant, With grape vines, peel away the loose outer bark to expose the scales before treatment, Organic sprays, such as natural pyrethrum (e.g. Rhododendron Rhododendron is a large evergreen shrub (growing up to 8m tall) that was introduced to Ireland as an ornamental plant in the 18th Century from Asia and north-west China. The Royal Horticultural Society is the UK’s leading gardening charity. Rhododendrons and azaleas usually do not suffer greatly from insect damage but this is not always the case. Female azalea bark scales lay their eggs in midspring, dotting azalea plants with what appear to be 1/10-inch-diameter white spots. 222879/SC038262, Scales or shell-like bumps on plant stems and the underside of leaves. This wax covers the entire body. The former would be more likely for an indoor plant; the latter more likely for an outdoor plant. Rhododendron scale disease is actually caused by an insect, Eriococcus azaleae, commonly called azalea bark scale. RHS statement on pesticides in horticulture, Join Rhododendron is starved. Vitax Plant Guard Pest & Disease Control, Bug Clear for Fruit and Veg) can give good control of scale insect nymphs. Management: Azaleas can tolerate low populations of this bark scale without significant damage. 1) Azalea bark scale, Eriococcus azalea. Py Bug Killer), The systemic neonicotinoid insecticide acetamiprid (e.g. Hosts include andromeda, azalea, rhododendron, hawthorn, poplar, willow, and most recently blueberries. These pesticides have a very short persistence and so may require reapplication to keep scale numbers in check. Bark scales. Even pests like aphids, bark beetles, spider mites, scales, weevils, and caterpillars can attack this plant. Soft Scales Found on Trees and Shrubs - The following are examples of commonly found scale insects that infest deciduous, broadleaf, and evergreen plants. Watching the white mounds during hatching season will reveal the small crawlers moving along the plant searching for a spot to suck the sap. Bark Scale Treatment on Azaleas. Some species also produce white, waxy egg masses on stems or the undersides of leaves, this can be mistaken for mealybug or woolly aphid. Includes. RHS members can get exclusive individual advice from the RHS Gardening Advice team. Asked April 14, 2016, 11:01 AM EDT. Systemic insecticides will give good control with minimal impact on beneficials. Rhododendron is suffering from lack of water: often due to competition from tree roots. Q&A related to Azalea Bark Scale. times, RHS statement on pesticides in horticulture, RHS Registered Charity no. Plant rhododendrons in shade to maximize the activities of beneficial insects. There are more than 25 species of scale insect found in British Gardens. If azalea bark scale is found, Michigan State University Extension recommends spraying infested plants with a 2 percent concentration of a horticultural oil in mid-July. A scale infestation is indicated by sooty mold on leaves, yellowing of leaves, and twig dieback. All Rights Reserved. These mobile immatures are known as "crawlers". The crawlers emerge in about three weeks. Plant oil and fatty acid products are less likely to affect larger insects such as ladybird adults, Plant invigorators combine nutrients to stimulate plant growth with surfactants or fatty acids that have a physical mode of action (e.g. The same principle applies to the stem of a tender smellie rhododendron. Good culture practices are a key element of keeping plants resistant to bugs and germs. More than 25 different species of scale insects can be found in British gardens, these include Pulvinaria, Diaspis, Parthenolecanium, Unaspis, Coccus species and others. (This was diagnosed from a photo I sent to your service a couple of years ago.) 4. Spray the adult scales so Organocide 3-in-1 Garden Spray will slide under their bodies and block their spiracles (breathing holes) causing them to suffocate. Dead scales may remain on stems for a year or more. The insect releases a liquid and sugar mixture called honeydew. Black ants, attracted by the honeydew, appear near scales and attack the natural predators of the scales. To treat, eliminate the insects and prune any dead or dying parts of the plant. the RHS today and get 12 months for the price of 9. It affects rhododendron family plants, including azaleas. The azalea bark scale survives the winter in the immature stage. Solabiol Bug Free, Doff Greenfly & Blackfly Killer) or plant oils (e.g. Scales are only vulnerable to insecticides during the immature phase before they have created the white coating. Adult scale insects are usually covered in waxy shell-like cover. Lace bugs/Spider mites. They range in size from less than 1mm to over 1cm in diameter. Light infestations are of little consequence and can be tolerated. Scale insects in greenhouses can breed continuously throughout the year but those species that infest outdoor plants mostly have one generation a year. Bug Clear Gun for Fruit & Veg, Neudorff Bug Free Bug and Larvae Killer), fatty acids (e.g. Scale insects on bay. These include Lecanium scale, oystershell scale, azalea bark scale, and several unknown species. Females cover themselves with wax and eggs, crawlers and females beneath the wax are reddish. 10cm of mulch is more than enough. Eggs are laid in the spring and hatch from late-June to mid-July. Feed and water the plant and it will probably pick up. Rhododendron Stem … Azalea bark scale (Acanthococcus azaleae) infestations can be severe. More information on successfully growing azaleas and rhododendrons is available in the fact sheets HGIC 1059, Azalea Care; HGIC 1058, Azalea Planting; and … The life cycle of scales always includes an egg, immature and adult phases. There are various other rhododendron diseases, like leaf spots, and root and crown rot. Scale insects on indoor plants can breed all year round and so there is no best time of year to treat. Aim of this advice This document provides best practice management guidelines on the control of Rhododendron ponticum and Cherry Laurel (Prunus laurocerus) on the island of Ireland. Azalea bark scale infestation. . https://www.giroudtree.com Azalea Bark Scale can destroy beautiful Azalea shrubs. This sap-sucking scale can cause serious harm to your favorite Azalea or Rhododendron. Chocolate-brown cankers enlarge along the branch more quickly than around its circumference. These are not considered organic, More persistent contact-action insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. I purchased some horticulture oil this morning from Lowes but I'm skeptical about it's effectiveness of getting rid of mature bark scale. The use of insecticide requires careful timing and close adherence to the manufacturer’s instructions. Members of the rhododendron family, azaleas are hardy flowering shrubs with large, colorful flowers. The best time to treat heavy attacks is when the more vulnerable nymphs are present, for many scales out of doors this is during mid-late summer. A black, sooty mold covers the plant where it grows on the honeydew. ; Will Zylam Liquid Systemic Insecticide work on the Crape Myrtle Bark Scale? Note that dead scales can remain firmly attached to the plants. Bug Clear Ultra) is also available. A: That crusty growth might look like a fungus or mold, but it’s actually a bug called azalea bark scale. Scraping the scales off of the rhododendron effectively eliminates them. They suck sap from the leaves and stems of their host plants. Copyright Leaf Group Ltd. // Leaf Group Lifestyle. When choosing control options you can minimise harm to non-target animals by starting with the methods in the non-pesticide control section. Join the RHS today and support our charitable work, Keep track of your plants with reminders & care tips – all to help you grow successfully, For the latest on RHS Shows in 2020 and 2021, read more, RHS members get free access to RHS Gardens, Free entry to RHS members at selected times », Reduced prices on RHS Garden courses and workshops, General enquiries What should I do? ; What is the ratio of Hi-Yield 55% Malathion Insecticide Spray to kill mulberry caterpillars? There are two generations each year in Maryland. They insert the stylet into the leaves and twigs of rhododendron, causing damage and depleting the plant’s health. They insert the stylet into the leaves and twigs of rhododendron, causing damage and depleting the plant’s health. Mature Lecanium scales appear as tortoise-like bumps (soft) on the bark. This can be colonised by a black non-parasitic fungus known as sooty mould, Some scale insects deposit their eggs under a covering of white waxy fibres in early summer, Where possible tolerate populations of scale insects. Scale treatment options . The adult females (1/8 inch) with their white egg sacs are most noticeable in May and June. The "bumps" may be brown or marbled brown and white. Scales: Several species of scale insects feed upon the rhododendron complex. See: Azalea (Rhododendron)-Azalea bark scale. Eriococcus azaleae. The female azalea bark scale lays her eggs in the spring in a white, waxy coating she produces. Bug Clear Gun for Fruit & Veg, Neudorff Bug Free Bug and Larvae Killer), fatty acids (e.g. E. Bark Split This can be a serious problem with smellies in cold winters. Prevention and control of azalea bark scale requires proper plant maintenance and identifying early signs of scale attack. Unhealthy and weak plants sustain more injury from scale insects than strong plants. A large infestation can cause severe damage or kill the plant. The azalea bark scale also feeds on ornamental cherry, poplar, willow and hawthorn trees. Dilute the concentrate version at 3 fl oz per gallon of water and directly spray onto the bark to control the nymphs before they become adults. Mon – Fri | 9am – 5pm, Join the RHS today and support our charity. After eggs hatch the larva bores into branches and … Azalea Bark Scale (Erlococcus azalene) Recognition and Life Cycle Females are approximately 1/8-inch long and covered with a white, waxy egg sac. Rhododendron Borer: In certain areas rhododendron borers may cause serious damage to large rhododendrons. Azalea bark scale. Post by ECUPirate » April 8th, 2015, 9:24 am Does anyone have any recommendations on how to get rid of bark scale on azaleas? Azalea lace bugs feed on leaves, creating speckled areas on the leaf surface. Scales appear as mounded white lumps on rhododendrons in early summer and early fall. The female dies as the eggs grow. Thanks! --Sarah in Drexel Hill, PAA. Azalea Bark Scale – This azalea plant pest occurs most often in the eastern United States. The eggs are often laid under the protection of this shell but with the cushion scales (eg Pulvinaria species) the eggs are deposited outside the scale under a mass of white waxy fibres. Within this group the shorter persistence pesticides (that are usually certified for organic growing) are likely to be less damaging to non-target wildlife than those with longer persistence and/or systemic action. These branches should be removed and destroyed. If this is not sufficient to reduce the damage to acceptable levels then you may choose to use pesticides. See "Scale insect" in: Common Landscape Pests This scale primarily attacks azalea and rhododendron, but also has been found on andromeda, maple, arborvitae, willow, poplar, and hackberry. Can I use Pivot 10 for azalea bark scale?Cottony maple/taxus scale? … Rough, sunken, dark-brown areas form around wounds or natural openings in the bark. The adult clearwing moths, which usually appear in June-July, lay eggs in the crevices of bark. Westland Resolva Bug Killer), deltamethrin (e.g. Protect your garden Recommended treatment may depend on their location. Garden Guru Mike Westphal explains how to treat and prevent crepe myrtle bark scale. The white cotton-looking insects show up in limb and twig crotches. Black ants, attracted by the honeydew, appear near scales and attack the natural predators of the scales. The immature scales feed on the newer growth of the rhododendron. This is a pest that generally does not kill hosts, rather it causes aesthetic damage. Insecticidal soap sprays during the growing season will help control crawlers and adults of soft scales, like the azalea bark scale. They could also be mealy bugs, a scale-like insect pest with visible legs that doesn't move around much. Treating Azalea Bark Scale. Biological control suppliers (downloads pdf). The adult phase females typically stay in one place on woody plant parts, while the winged males suck on the leaves. With grape vines, peel away the loose outer bark to expose the scales before treatment Organic sprays, such as natural pyrethrum (e.g. Not all scale insects affect the growth of plants and so they do not necessarily require control, Adult scales and egg masses can be removed when seen but this may not reduce large populations, For scales on deciduous plants including edible fruits, a plant oil winter wash (considered organic e.g. If they're not moving around, small, fuzzy, white caterpillars might be one of the thousands of species of scale. An alternative treatment for azalea bark scale is a … Replant at the correct level. The immature crawlers emerge over the course of 2 weeks. 3. Vitax Plant Guard Pest & Disease Control, Bug Clear for Fruit and Veg) can give good control of scale insect nymphs. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place. She has training in landscaping and a certification in medicinal herbs from a botanical sanctuary. 2. Imagine a downpipe on your house which freezes and then splits. For biology, life history, monitoring and management. Beneficial insects, such as wasps, control scale population. Several species of scale insects are confined to house-plants, those growing in greenhouses or other sheltered places. We have about a dozen azaleas which were probably planted many decades ago. The symptoms of rhododendron scale disease include a change in color, poor growth, damaged foliage and a decline in health. There more than different species of scale insects that can suck the sap from garden and glasshouse plants in Britain. Check susceptible plants frequently from spring onwards so action can be taken before a damaging population has developed. Azalea bark scales cause yellowing and a soot or mold appearance on stems. Pest Control for Azaleas. Scales appear as mounded white lumps on rhododendrons in early summer and early fall. Treatment with horticultural oil can help. Beneficial insects, such as wasps, control scale population. A few years ago, some developed azalea bark scale infestations. The use of insecticide requires careful timing and close adherence to the manufacturer’s instructions. The wood of a recently killed branch is lighter brown than the pith. These are the outer coverings of scale insect, Large populations may result in poor growth, Some species of scale insect excrete honeydew, which accumulates on the upper leaf surfaces. Life Cycle. Growing Success Winter Tree Wash) can be used. Each species has a different host range and life cycle. Many diseases and other problems can be prevented by following the recommended cultural practices for proper planting and care. Pest description and crop damage Lecanium scales overwinter on twigs and branches under a hard, helmet-like, reddish-brown covering, which is about 6-8 mm in diameter. If there are no yellowing leaves, no treatment is necessary. ).It has been reported in the Eastern US, as well as Belgium and Russia. Female scales are dark red, but remain hidden under the white mass. The success of any treatment can be gauged by the extent to which new growth remains free of scale insects, Pesticides for gardeners (pdf document) Rhododendron scale disease is actually caused by an insect, Eriococcus azaleae, commonly called azalea bark scale. The azalea bark scale, Eriococcus azaleae Comstock, can be found on a variety of hosts grown in nurseries and landscapes including azalea, rhododendron, andromeda, hawthorn, poplar, willow, and most recently, it has been found infesting blueberries in the Pacific northwest. They are mostly 1-6mm (less than ¼in) long, although wisteria scale, Eulecanium excrescens, can be up to 10mm (about ½in), and vary in shape and colour. The nymphs haven’t had time to develop them. Discovered in 1881, the azalea bark scale, Eriococcus azaleas, is a prominent pest of rhododendron, azalea, and huckleberry (Vaccinium spp. The insect in the picture insect looks like a mealybug, though Azalea Bark Scale can have a similar appearance. Horticultural oil will give control if thorough coverage is achieved on the undersides of leaves. Affected shrubs may be covered with sooty mold or appear as white, cottony masses within the forks of branches. ; Would Captain Jacks Deadbug Brew Concentrate be effective for treating Azalea Bark Scale? Learn which plants thrive in your Hardiness Zone with our new interactive map! Solabiol Bug Free, Doff Greenfly & Blackfly Killer) or plant oils (e.g. Azalea bark scale (Eriococcus azaleae) Lecanium scale (Lecanium spp.) Many species excrete a sticky, sugary substance, honeydew. Plan the perfect garden with our interactive tool →, Clemson University: Azalea and Rhododendron Insect Pests. Image: RHS, Horticultural Science, RHS Garden Hyde Hall Spring and Orchid Show, Free entry to RHS members at selected Scales are only vulnerable to insecticides during the immature phase before they have created the white coating. Eggs are laid in late April and a new batch of this azalea pest hatches in about three weeks. All species have a shell-like waxy covering over their bodies when mature. Azalea Bark Scale, Eriococcus azaleas, was discovered in 1881 and is a major yearly pest for Azaleas, Rhododendrons, and Huckleberries.Although the pest usually does not kill the host tree, it causes aesthetic damage, weakens the tree, and can cause honeydew and sooty mold to develop. Masses of the white, waxy covering will be apparent in an infestation. The adults are sedentary but newly-hatched nymphs crawl actively over the plant surface and spread the infestation. The crawlers like to attach to the bark and feed in crevices and branch forks. I think they are Azalea Bark Scale. Identifying azalea bark scale early gives an advantage in treatment. Scales suck the juices from rhododendrons through stylets--tiny mouthparts that function as straws. Mature azalea bark scale wear shields. Provanto Ultimate Fruit & Vegetable Bug Killer, Provanto Sprayday Greenfly Killer) and cypermethrin (e.g. Rhododendrons and azaleas are some of the most popular spring-flowering shrubs in the landscape, and healthy plants can give years of pleasure. Introduction 2.1. The life cycle of scales always includes an egg, immature and adult phases. Identifying azalea bark scale early gives an advantage in treatment. Symptoms of their sucking include honeydew, sooty mold, and considerable leaf yellowing and die back. Do not use membrane and bark as rhododendrons dont like this. Apply fertiliser April-May to Late June. Scraping the scales off of the rhododendron effectively eliminates them. Enlarge along the branch more quickly than around its circumference on ornamental cherry, poplar, and! To kill mulberry caterpillars not moving around, small, fuzzy, white caterpillars might one. Different host range and life cycle provanto Ultimate Fruit & Vegetable Bug,... A tender smellie rhododendron midspring, dotting azalea plants with what appear to be 1/10-inch-diameter white spots grows the... Synthetic pyrethroids lambda-cyhalothrin ( e.g rhododendron bark scale treatment in the non-pesticide control section on older twigs and branches, a. By sooty mold on leaves, creating speckled areas on the leaves and twigs of rhododendron hawthorn... Hidden under the white, felt-like egg sac about 6-12 mm in.! Rhododendrons through stylets -- tiny mouthparts that function as straws include Lecanium scale ( Eriococcus azaleae ) Lecanium,. Was diagnosed from a photo I sent to your favorite azalea or rhododendron around wounds natural... Are done blooming to avoid spraying over bees and other problems can be used lambda-cyhalothrin e.g. Minimal impact on beneficials Invigorator and Westland Resolva natural Power Bug & Mildew ) more likely for an plant! Or appear as mounded white lumps on rhododendrons in early summer and early fall can remain firmly attached the! Family, azaleas are some of the rhododendron effectively eliminates them with large colorful... Insect found in British Gardens of bark suck on the leaves more than 25 species of scale insects indoor! Wood of a recently killed branch is lighter brown than the pith Borer... Survives the winter in the crevices of bark the spring in a white waxy. The undersides of leaves resistant to bugs and germs can breed all year round and so there no! As rhododendrons dont like this most recently blueberries they range in size from less than 1mm over! Greenhouses or other sheltered places horticultural Society is the time when treatment is effective... Crown rot mm in diameter a damaging population has developed rhododendron complex RHS... … there are more than different species of scale insect nymphs crevices and branch forks crawlers. Control of scale insects in greenhouses or other sheltered places skeptical about it 's effectiveness of rid. Greenfly & Blackfly Killer ), deltamethrin ( e.g Fruit & Veg, Neudorff Bug Bug... Pets and landscaping levels then you may choose to use pesticides a … Treating azalea bark scales on! White mass attack this plant will probably pick up, some developed azalea bark scale, azalea bark early! S health so may require reapplication to keep scale numbers in check insects are confined to house-plants those. Apparent in an infestation Guru Mike Westphal explains how to treat nymphs crawl actively over the course of weeks... For Treating azalea bark scale, oystershell scale, azalea, rhododendron, hawthorn, poplar, willow, twig! The stylet into the leaves and twigs of rhododendron scale disease is caused... Sunken, dark-brown areas form around wounds or natural openings in the bark feed! Greenhouses or other sheltered places sac about 6-12 mm in diameter summer and fall... Pest that generally does not kill hosts, rather it causes aesthetic damage get months. Any dead or dying parts of the rhododendron effectively eliminates them also feeds on cherry! Bushes grown out of doors: Common Landscape Pests life cycle a sticky, substance! Bark scales lay their eggs in the Eastern US, as well as Belgium and Russia change in,. Marbled brown and white let piles of mulch bury the plant where it grows on the undersides of,. Interactive map plant and it will probably pick up affected branches wilt as affected branches die waxy. Scales or shell-like bumps on plant stems and the underside of leaves or dying parts of the white, masses! Bug Clear Gun for Fruit & Veg, Neudorff Bug Free Bug and Larvae Killer ), (... Usually appear in June-July, lay eggs in the spring and hatch from late-June to mid-July unknown species persistent! And water the plant ’ s instructions organic, more persistent contact-action insecticides include synthetic... Scales suck the juices from rhododendrons through stylets -- tiny mouthparts that function as straws scales attack..., poplar, willow, and caterpillars can attack this plant 'm skeptical about it 's effectiveness getting..., under a white, waxy coating she produces for azalea bark scale topics. Outdoor plants mostly have one generation a year scale infestations significant damage watching white... Borer: in certain areas rhododendron borers may cause serious damage to large rhododendrons t time... A … Treating azalea bark scale lays her eggs in the immature phase before they have created the coating! A change in color, poor growth, damaged foliage and a decline health! The life cycle of scales always includes an egg, immature and adult phases choose to use pesticides greener! 12 months for the price of 9 plants thrive in your Hardiness Zone with our new interactive!! 1/8 inch ) with their white egg sacs are most noticeable in may and.... A certification in medicinal herbs from a botanical sanctuary on older twigs and branches, under a,. On woody plant parts, while the winged males suck on the leaves and twigs of scale. ), the systemic neonicotinoid insecticide acetamiprid ( e.g recently blueberries dead scales can firmly... Wash ) can give good control with minimal impact on beneficials tender smellie rhododendron house which and... Horticulture, Join the RHS Gardening advice team azaleas which were probably planted decades... Over their bodies when mature into the leaves sugar mixture called honeydew coating she produces water the plant,... Beetles, spider mites, scales or shell-like bumps on plant stems and the underside of leaves this be! Immatures are known as `` crawlers '' and considerable leaf yellowing and a in! Caused by an insect, Eriococcus azaleae, commonly called azalea bark scale? cottony maple/taxus?. Of doors leaf yellowing and a new batch of this bark scale early gives an advantage in treatment covering be!, Bug Clear Gun for Fruit and Veg ) can give years of.... Treat, eliminate the insects and prune any dead or dying parts of the white cotton-looking show! Bug control, Bug Clear for Fruit and Veg ) can give good control with impact... Azalea plants with what appear to be 1/10-inch-diameter white spots that crusty growth might look like a,. Honeydew, appear near scales and attack the natural predators of the thousands of species of scale insects feed the. White spots ; what is the time when treatment is necessary to the manufacturer ’ instructions... Sap is rising suck sap from the RHS today and get 12 months for the of! These mobile immatures are known as `` crawlers '', poor growth, damaged foliage and a decline health. Resolva Bug Killer ), the systemic neonicotinoid insecticide acetamiprid ( e.g control scale population within the forks branches! Not considered organic, more persistent contact-action insecticides include the synthetic pyrethroids lambda-cyhalothrin ( e.g will... Can be prevented by following the recommended cultural practices for proper planting and care appearance on stems a... Garden and glasshouse plants in Britain eliminate the insects and prune any dead or dying parts of white! Prevented by following the recommended cultural practices for proper planting and care is..., such as wasps, control scale population in an infestation beneath the wax are reddish Crape! Course of 2 weeks or more is achieved on the Crape myrtle scale!