Cottony camellia scales, Pulvinaria floccifera, are cream to tan, elongate oval, and relatively flat.They are also called cottony taxus scales as this scale is a fairly common pest of yew. These caterpillars are black with rows of white or pale yellow spots, reddish brown legs, head and neck area and are 2 1/2 inches when mature. Damage usually begins in early May on old leaves and later appears on new growth. Curled leaf tips in June indicate the completion of the first generation. Beneficial insects often control this pest. REC, Lower Eastern Shore Make any pruning cuts slightly angled and next to a junction with another branch or main stem. Damage usually begins in early May on old leaves and later appears on new growth. The adult moths, about ¼” long, resemble wasps, have mostly clear wings, and black bodies with 3 gold bands on the abdomen. Azalea bark scale (Fig. Rhododendrons and azaleas are some of the most popular spring-flowering shrubs in the landscape, and healthy plants can give years of pleasure. The adult female azalea bark scale is dark red with a long sucking mouthpart. The moths are 3/8 inch long and yellowish brown. Healthy plants that are not under water stress can better withstand and recover from scale feeding. Heavy infestations cause wilting and eventual branch dieback. Boring larvae may cause branches to crack. Eggs hatch into tiny white maggots less than 1/16 inch in length. Overwintering immature scales (nymphs) are less than ⅛-inch long, gray, and are usually found in twig forks. Continue changing the double-sided tape and observing crawler numbers. There is one generation a year and larvae overwinter in tunnels in branches. Beneficial predators and parasites will usually provide adequate control of light bark scale infestations. Gall midge larvae feed on the developing leaf tissue causing leaves to become distorted with puckered and curled margins. Susceptible cultivars include those of. Adult feeding damage appears in late April and early May as adults become active and notch leaf margins on azalea and rhododendron. Adults are present in June and July. Rhododendron Diseases by R. K. Jones and D. M. Benson Azalea & Rhododendron Diseases by Clemson University Cooperative Extension Common Problems of Rhododendron and Azalea by Dr. Sharon M. Douglas How To Identify Rhododendron and Azalea Problems by A.I. Photo: M. Raupp, University of Maryland. This weevil prefers azalea, rhododendron, privet, mountain laurel, forsythia, spirea, deutzia, lilac, and euonymus. Mines are initially formed near the midrib and caused by caterpillars feeding between the upper and lower leaf surface. Wrap several branches that are infested with scales tightly with narrow bands of double-sided sticky tape in late winter or early spring. Lace bug damage is indicated by stippling (very tiny spots) on leaves of plants growing on dry sites and those with low plant diversity. To check for the presence of whiteflies, shake the branches of symptomatic azaleas to flush out adult whiteflies which look like tiny white moths. Larvae also feed on roots and crowns of hosts. blooms drifting above dense branches of lush green foliage illuminate countless spring gardens with weeks of color. Numerous species of scale insects, typically classified as soft or armored, can attack a broad array of shrubs. Spray the young lacebug nymphs off the leaves as they hatch. Management: Rake and destroy fallen leaves in the fall to remove overwintering pupae. Plant azaleas in partial sun (morning sun and afternoon shade). There are two generations each year in Maryland. The females appear totally white when they produce their white, waxy egg sacs. Make sure shrubs receive an inch of water weekly through rainfall and supplemental irrigation, or water whenever soil about 3 inches below the soil surface near the shrub feels dry to the touch. If hand removal is not feasible, spray shrubs with. Branches or entire plants may be defoliated. Blend 5 tablespoons of an ultra-fine horticultural oil with a gallon of water, and use a garden sprayer to thoroughly spray the infested plants once you observe a decline in the number of scales trapped. The larvae live in the soil and feed on roots and may also girdle the plant at the root crown, causing the plant to wilt and die. There are as many of four generations of azalea lace bug during the growing season and into the fall. This will interrupt the life cycle and reduce subsequent populations. Broadleaf evergreen, 6 ft (1.8 m) in 10 years, upright, vigorous, grows to a large plant. The leaves are spirally arranged; leaf size can range from 1–2 cm (0.4–0.8 in) to over 50 cm (20 in), exceptionally 100 cm (40 in) in R. sinogrande. Damage caused by the stem borer, which includes wilting terminals and dieback, is similar to the Rhododendron borer. The most common pests of rhododendrons and azaleas in Maryland are lace bugs, azalea bark scale, rhododendron borer, and weevils. Borne at the tips of the upright branches, the blossoms contrast beautifully with the evergreen foliage of rounde… They were first discovered by a Flemish botanist, Charles l’Ecluse. Decide what tool you need for your rhododendron size. The adult moths, about ¼” long, resemble wasps, have mostly clear wings, and black bodies with 3 gold bands on the abdomen. Adult beetles feed on the underside of leaves on the midvein, causing the leaves to curl. Frass (sawdust-like material) indicating the presence of rhododendron borer. Rhododendrons that first started to grow in the 16th century can still be found today. Azaleas can tolerate low populations of this bark scale without significant damage. Damage occurs in late summer and fall. Noted for its lavender-blue spring flowers, Rhododendron 'Blue Tit Magor' is a compact, mounding, dense, evergreen shrub producing incredibly eye-catching flower clusters. Blooming in mid spring, each cluster (or truss) can hold up to 3-5 attractive, trumpet-shaped violet-blue flowers, whose color intensifies with age. Females are approximately 1/8-inch long White felt-like sacs are secreted in May that enclose the body and eggs. Prune off branches touching the ground or nearby structures to force ants up the main stem where they are trapped. All types of fruit and ornamental trees, shrubs. They were introduced to the European Alps and thus the name, Alpine Rose (Rhododendron histru… Spinosad, a biorational insecticide (which has the least toxic classification), may also be used on young and older caterpillars. Rhododendrons and azaleas, in general, grow best in landscape conditions that mimic natural mountain habitats: acidic soil (pH between 4.5 - 5.5), good drainage, ample soil moisture and organic matter, understory areas with light shade, cool soil temperature, and protection from strong winds. When lace bug populations are high, sprays of horticultural oil (at a 2% summer rate) or insecticidal soap will control lace bugs if the lower surfaces of the leaves where lace bugs are active are thoroughly covered. Mature female scale are about 0.13 inch long and appear like white cottony sacs, often located on twigs and stems of azalea, especially in branch axils. Large populations cause leaves to brown and drop prematurely. The adult weevils are about 3/16 inch long, brown, broadly oval, thick bodied, and brown to gray with two darker bands across the wing covers. Hosts include andromeda, azalea, rhododendron, hawthorn, poplar, willow, and most recently, blueberry in the Pacific Northwest. A registered insecticide (e.g., Imidacloprid) may be applied by a certified pesticide applicator only (as per the Maryland Pollinator Protection Act.). Do not apply broad-spectrum, persistent pesticides to attempt to control scale insects or other pests, as these chemicals will injure the populations of beneficial scale predators and parasites. Weevils can be hand-picked and dropped into a container of soapy water for disposal. If there are no yellowing leaves, no treatment is necessary. Photo: John Davidson, University of Maryland. Apply a sticky, nondrying compound intended for trapping insects in a band around the main stem or stems of the shrub. The adult beetles are about 5/8 inch long, have long antennae, and are pale yellow with two black spots on the thorax and on the margins of the wing covers. Azalea Bark Scale. Eggs hatch into tiny white maggots less than 1/16 inch in length. Buds with several to many imbricate scales. Pull mulch back prior to application. This borer prefers rhododendron, but occasionally attacks deciduous azalea and mountain laurel. Follow instructions on label for timing and soil temperatures. Branches or entire plants may be defoliated. Management: Rake and destroy fallen leaves in the fall to remove overwintering pupae. Photo: Bruce Watt, University of Maine, Bugwood.org. Originally written by Mary K. Malinoski, University of Maryland Extension Specialist. Examine egg sacs for holes which indicates control by parasitoids, and look for predators such as ladybird beetles. Check inner branch forks in May and June for the white egg sacs and for reddish crawlers in late June into July. If so, you have a fungus called powdery mildew. These pests generally appear on plants as immobile bumps with no recognizable body parts. Boring larvae may cause branches to crack. Janet Flower Shop Network Plant Expert Reply: First we need to determine if you really have a fungus. How to Kill Borers on Weeping Cherry Trees, Sooty Mold Caused by Whiteflies on Rhododendron Stems, How to Kill Aphids on Aureo Variegated Boxwood, University of California Statewide Integrated Pest Management Program: Scales, Purdue University Cooperative Extension: Scale Insects on Shade Trees and Shrubs, Colorado State University/Denver County Master Gardeners: Scale Insect Pests, How to Kill Spider Mites and Whiteflies on Shrubs. This tiny fly attacks the new growth of rhododendrons. White Rhododendron, with a bumblebee. Fully developed larvae drop to the ground where they will pupate. Soapy … Watching the white mounds during hatching season will reveal the small crawlers moving along the plant searching for a spot to suck the sap. 5) appears as small white cottony masses on the bark. The caterpillars feed in groups when young and disperse as they mature. White Rhododendron Rhododendron albiflorum. The underside will show a brownish residue. Photo: M. Raupp, University of Maryland. Reaching a height of 3-4 feet, the White Rhododendron is an easy-to-grow evergreen shrub that thrives in partial sunlight and needs only occasional pruning. Mature larvae are about 1/4 inch long, “C-shaped”, legless, and white with brown heads. Heavy infestations over several seasons may kill plants. Black Vine Weevil (adult). As larvae mature they curl the tips of the leaves with silk and feed inside the curl. Photo: Jim Baker, North Carolina State University, Bugwood.org. Adult Japanese weevils feed during the day and will drop from the plants when disturbed. Older and more established rhododendrons may need a chainsaw to cut through the large woody branches, especially toward the middle of the plant. Description. The azalea bark scale also feeds on ornamental cherry, poplar, willow and hawthorn trees. This deformation will last as long as leaves remain on the plant. Is the white substance powdery and can you wipe it off. Lacebugs perfer sunny areas so plant in more shaded areas if possible. Whiteflies would be found underneath the leaves. More on Mildew by Fred Minch Pests Of Rhododendrons by Arthur L. Antonelli There are multiple generations of lace bug per year. Mulch with chopped oak leaves, leaf mold, or pine needles and water deeply during drought periods. To check for adults, place a tray under damaged shrubs and shake the plants. Plan to spray the shrub once the number of crawlers trapped begins to decline. Members of the genus Rhododendron support the following specialized bee: Andrena (Andrena) cornelli. Scale insects also secrete a sticky liquid called honeydew, which promotes the fungal disease black sooty mold. Studies in Connecticut indicate as many as three to five generations annually depending on climatic conditions. Photo: Jim Baker, North Carolina State University, Bugwood.org. (This was diagnosed from a photo I sent to your service a couple of years ago.) Damage is indicated by the presence of blotch mines in leaves of azalea beginning in May. Various scales attack azaleas and rhododendrons, but one of the most common is azalea bark scale (Eriococcus azaleae). Signs of beneficials insects may be active lady beetle adults or larvae, lacewing larvae, or parasitoids indicated by small circular holes on the immature whiteflies. Photo: John Davidson, University of Maryland. Native to China, Myanmar and Laos, Rhododendron decorum (Great White Rhododendron) is a very fragrant, large, evergreen shrub or small tree with attractive spring flowers, decorative bark and handsome dark green leaves. Dormant oil spray can be applied to kill overwintering nymphs prior to new plant growth. Armored scales measure less than 1/8 inch across and have a flattened cover over their bodies. Antonelli, et al. Bark scales are a type of soft scale and an infestation is indicated by clear sticky honeydew with attendant sooty mold (black fungus) on leaves or stems, yellowing of leaves, and twig dieback. … This scale primarily attacks azalea and rhododendron, but also has been found on andromeda, maple, arborvitae, willow, poplar, and hackberry. We embody the University's land-grant mission with a commitment to eliminate hunger, preserve our natural resources, improve quality of life, and empower the next generation through world-class education. Azaleas are visited by pollinators. Damage occurs in late summer and fall. The largely immobile nature of scales and their protective covering makes chemical control challenging. Flowers are a deep rose-pink, funnel-shaped, to 10 cm wide, 10-12 per cluster. Rhododendron 'Charles Dickens'. Photo: P.M. Shrewsbury, University of Maryland. Scale Download a PDF of this article Plants Affected. If hand removal is not feasible, spray shrubs with Bacillus thuringiensis (Bt), a microbial insecticide, that is specific for young caterpillars and is sold under various trade names. Female scales are dark red, but remain hidden under the white mass. Damage on new foliage will be evident in May and July. The larvae bore down the center of twigs causing individual branches to wilt, and eventually die back to the ground. The moths are 3/8 inch long and yellowish brown. Interior leaves usually show most damage. Video shows close ups of Azalea Bark scale and provides some plant inspection tips. 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