Adults are present in June and July. Studies in Connecticut indicate as many as three to five generations annually depending on climatic conditions. The females appear totally white when they produce their white, waxy egg sacs. There are two generations each year in Maryland. Damage caused by the stem borer, which includes wilting terminals and dieback, is similar to the Rhododendron borer. Janet Flower Shop Network Plant Expert Reply: First we need to determine if you really have a fungus. Damage is indicated by the presence of blotch mines in leaves of azalea beginning in May. Heavy infestations of lace bug may cause leaves to turn yellow and then brown. These pests generally appear on plants as immobile bumps with no recognizable body parts. Scale insects feed on shrubs' sap using their long, piercing mouthparts, causing twig and branch dieback and sometimes killing the plants. Large populations cause leaves to brown and drop prematurely. Weevils can be hand-picked and dropped into a container of soapy water for disposal. Mature larvae are about 1/4 inch long, “C-shaped”, legless, and white with brown heads. Damage on new foliage will be evident in May and July. This borer, however, is a longhorned beetle. White flowers grow on top of the previous year's growth and tucked underneath the leaves from the current year. Management. Consider hand–removal by squishing the scales to prevent populations from increasing. There is one generation a year and all stages overwinter in the soil. 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. Black fecal spots will be present on the lower sides of stippled leaves. This beetle prefers rhododendron, but will also attack azaleas and mountain laurel. Beneficial insects often control this pest. Black fecal spots will be present on the lower sides of stippled leaves. A small brown insect with transparent wings sucks on the bottom of the leaf causing a mottled appearance on the top with yellowish, brownish or white spots. Hand saws and pruning shears are helpful for smaller, less established branches, or when you are cutting less of the rhododendron. Healthy plants that are not under water stress can better withstand and recover from scale feeding. Adult beetles feed for two to three weeks before laying eggs. Adult Japanese weevils feed during the day and will drop from the plants when disturbed. The moths are 3/8 inch long and yellowish brown. Look for discoloration of foliage and signs of sooty mold to indicate the presence of the scales. The moths are 3/8 inch long and yellowish brown. Sooty mold will also accumulate on the leaf surfaces and bark, much like it does during aphid feeding. The second generation mines begin in July. Fully developed larvae drop to the ground where they will pupate. Eggs hatch into tiny white maggots less than 1/16 inch in length. Damage occurs in late summer and fall. Photo: David Held, Auburn University, Bugwood.org. They may be injected into the active borer tunnels. If the infestation is light, little or no plant symptoms are evident, and if beneficial insects are present, spray the undersides of leaves with insecticidal soap or horticultural oil at the 2% summer rate. Lacebugs perfer sunny areas so plant in more shaded areas if possible. Azalea Bark Scale, Eriococcus azalea: This insect prefers azalea or rhododendron but can infest andromeda, maple, willow, poplar and other plants. 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. Azalea lace bug adult and fecal spots. Beneficial nematodes are not effective on these borers. Photo: Dow Gardens, Bugwood.org. Watching the white mounds during hatching season will reveal the small crawlers moving along the plant searching for a spot to suck the sap. Sometimes, these growths may get covered with white spots. She holds a Bachelor of Arts in urban and regional studies. Curled leaf tips in June indicate the completion of the first generation. The azalea bark scale, Eriococcus azaleas, is a prominent pest of rhododendron, azalea, and huckleberry (Vaccinium spp.). Black Vine Weevil (adult). Management: Look for caterpillars when chewing damage occurs. Adult beetles feed on the underside of leaves on the midvein, causing the leaves to curl. If soft scales are present on the shrub and producing a large quantity of honeydew that is attracting ants, plan to control the ants, because they protect the scales from their natural enemies. Azalea leafminer overwinters as pupae in the leaf mines. Azaleas are visited by pollinators. All stages occur on the undersides of leaves. giganteum, reported to 30 m (100 ft) tall. Continue changing the double-sided tape and observing crawler numbers. Check inner branch forks in May and June for the white egg sacs and for reddish crawlers in late June into July. Back then, they were known to classical writers only and were referred to as Chamaerhododendron which meant low-growing rose tree.Rhododendrons were first introduced in Britain in 1656. 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. In spring, adults emerge from the soil and fly to the tips of branches where they lay eggs in new developing leaf tissue. Flowers are a deep rose-pink, funnel-shaped, to 10 cm wide, 10-12 per cluster. Symptoms/Damage. Rhododendrons and azaleas are some of the most popular spring-flowering shrubs in the landscape, and healthy plants can give years of pleasure. Azalea Leafminer (early instar) inside of a leaf. Prune off branches touching the ground or nearby structures to force ants up the main stem where they are trapped. Their feeding causes leaf margins to curl and the maggots complete their development within the curled leaf tissue. Commonly seen in azaleas, leaf gall is a springtime disease, that may affect other rhododendron species. This will interrupt the life cycle and reduce subsequent populations. Members of the genus Rhododendron support the following specialized bee: Andrena (Andrena) cornelli. Mature larvae are 1/2 inch long and yellowish brown. This whitefly is usually limited to azalea varieties that have hairy leaves. Originally written by Mary K. Malinoski, University of Maryland Extension Specialist. Inspect plants for signs of early damage and remove curled leaves promptly. Preferred host plants are azaleas, but they may also attack witch hazel, sumac, apple, red oak, and andromeda. Azalea Lace Bug (Stephanitis pyriodes) andRhododendron Lace Bug (Stephanitis takeyai) Lace bug damage is indicated by stippling (very tiny spots) on leaves of plants growing on dry sites and those with low plant diversity. There are no conventional insecticides that will kill stem borer larvae once they are inside the branches. Follow instructions on label for timing and soil temperatures. A common shrub, also known as Cascade Azalea, found in the park on open slopes and meadow edges above 3,500 feet (1,066 meters). Black vine weevil feeding damage (leaf notching) to rhododendron. Angela Ryczkowski is a professional writer who has served as a greenhouse manager and certified wildland firefighter. Larvae also feed on roots and crowns of hosts. White Rhododendron, with a bumblebee. Susceptible cultivars include those of. Ask the Expert: what would get the white fungus off azaleas , leaf the azalea has white on them , on the leafs is it a fungus , what can spray on them will mild soapy water work. Prune off portions of the shrub that are heavily infested with scales if the scales are largely concentrated on a limited number of branches. 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. Water the infested shrubs deeply and infrequently during extended dry spells. Females produce white, waxy egg masses in late June to early July. Borne at the tips of the upright branches, the blossoms contrast beautifully with the evergreen foliage of rounde… Check these sticky tape bands regularly and replace them with fresh tape once per week. There are multiple generations of lace bug per year. Is the white substance powdery and can you wipe it off. Inspect the tape closely using a hand lens, if possible; look for the crawlers, which get trapped on the tape and look like yellow or orange specks. Thoroughly cover the infested plant, making sure you completely reach leaf undersides, twigs and other parts of the plant infested with scales. As soon as you notice the black fungus on rhododendron shrubs, check the leaves carefully to determine which insect is responsible and treat it appropriately. 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. White prunicola scale is most partial to members of the Prunus species, peach chinaberry, flowering peach, French mulberry, and persimmon. Examine egg sacs for holes which indicates control by parasitoids, and look for predators such as ladybird beetles. Studies in Connecticut indicate as many as three to five generations annually depending on climatic conditions. Noted for its lavender-blue spring flowers, Rhododendron 'Blue Tit Magor' is a compact, mounding, dense, evergreen shrub producing incredibly eye-catching flower clusters. (This was diagnosed from a photo I sent to your service a couple of years ago.) Stressed plants are more susceptible to lace bug feeding. Azalea lace bug damage. Adult feeding damage begins on lower leaves in mid-June. The borer causes wilting of leaves and twig dieback. If there are no yellowing leaves, no treatment is necessary. Scales are so unusual looking that most people don’t recognize them as insects. This scale primarily attacks azalea and rhododendron, but also has been found on andromeda, maple, arborvitae, willow, poplar, and hackberry. The caterpillars feed in groups when young and disperse as they mature. If hand removal is not feasible, spray shrubs with. The females appear totally white when they produce their white, waxy egg sacs. Inspect for adult weevils at night using a flashlight. Photo: John Davidson, University of Maryland. This borer prefers rhododendron, but occasionally attacks deciduous azalea and mountain laurel. The largely immobile nature of scales and their protective covering makes chemical control challenging. Leaves olive green, 20 x 8 cm. If necessary a 2% summer rate of horticultural oil may be applied in July after all of the eggs have hatched. Eggs overwinter in leaves and may begin to hatch as early as late April. To check for the presence of whiteflies, shake the branches of symptomatic azaleas to flush out adult whiteflies which look like tiny white moths. Mulch with chopped oak leaves, leaf mold, or pine needles and water deeply during drought periods. The second generation mines begin in July. Prune the suspected branches and split them open longitudinally to see if larvae are present. Azalea caterpillar. Adult feeding damage is very similar to that of black vine weevil but notches on leaf margins tend to be smaller. Scale … The larvae overwinter in branches the first year and in roots the second year. The caterpillars feed in groups when young and disperse as they mature. Azalea bark scale (Fig. Cushion scale is a sap-sucking insect that feeds on the foliage of mainly evergreen trees and shrubs, especially camellia, rhododendron, Trachelospermum, Euonymus japonicus and holly. Photo: Jim Baker, North Carolina State University, Bugwood.org. Be sure to observe all cautionary statements on labels to protect pollinators. As with black vine weevil, soil drenches of entomopathogenic nematodes may reduce populations of grubs in the soil. This scale primarily attacks azalea and rhododendron, but also has been found on andromeda, maple, arborvitae, willow, poplar, and hackberry. Examine the lower surfaces of leaves for the presence of nymphs, which are flat, yellowish green, and resemble scale insects. Lace bug damage is indicated by stippling (very tiny spots) on leaves of plants growing on dry sites and those with low plant diversity. Photo: University of Maryland Extension, Rhododendron Borer (adult). 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. Heavy infestations cause the margins of terminal leaves to cup. Spray the young lacebug nymphs off the leaves as they hatch. Armored scales measure less than 1/8 inch across and have a flattened cover over their bodies. Description. Young females have a dark stripe down the middle and mottling at the sides. Azalea, rhododendron, and andromeda each have their unique species of lace bug. This borer prefers rhododendron, but occasionally attacks deciduous azalea and mountain laurel. Masses of azalea (Rhododendron spp.) blooms drifting above dense branches of lush green foliage illuminate countless spring gardens with weeks of color. Gall Midge damage. This deformation will last as long as leaves remain on the plant. Rhododendron varieties with resistance to weevils are available and include species such as, A registered insecticide (e.g., Imidacloprid) may be applied by a certified pesticide applicator only (as per the, Rhododendron gall midge immatures spend the winter and early spring in the soil where they complete development and pupate. Beneficial predators and parasites will usually provide adequate control of light bark scale infestations. The following azalea cultivars have shown resistance to azalea lace bug damage: ‘Autumn Amethyst’, ‘Autumn Twist’, ‘Autumn Royalty’, ‘Autumn Sangria’, ‘Autumn Cheer’, ‘Indica alba’, ‘Flame Creeper,’ and ‘Delaware Valley White’, among others. Azalea leafminer overwinters as pupae in the leaf mines. Apply either spray when caterpillars are numerous and young (less than 3/4 of an inch long). Azalea whitefly damage. Insecticidal soap may also be used. Photo: John Davidson, University of Maryland, Rhododendron borer is the larvae (caterpillar) of a clear wing moth. Adult lace bugs are flat, about 1/8 inch long, with transparent lace-like wings. Follow instructions on label for timing and soil temperatures. Insect problems include aphids, borers, lacebugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips and whitefly. Rhododendron gall midge immatures spend the winter and early spring in the soil where they complete development and pupate. 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. All types of fruit and ornamental trees, shrubs. Azalea Bark Scale. Healthy shrubs can usually withstand some amount of scale feeding, but a heavy infestation can force leaves to wilt, turn yellow and drop prematurely. Adult feeding damage appears in late April and early May as adults become active and notch leaf margins on azalea and rhododendron. Photo: Bruce Watt, University of Maine, Bugwood.org. See the package for specific instructions. Heavy infestations over several seasons may kill plants. Antonelli, et al. The most common pests of rhododendrons and azaleas in Maryland are lace bugs, azalea bark scale, rhododendron borer, and weevils. This weevil prefers azalea, rhododendron, privet, mountain laurel, forsythia, spirea, deutzia, lilac, and euonymus. The borer causes wilting of leaves and twig dieback. Most adult scales do not move, they look like brown or white “tortoise shells” on branches or foliage. Make any pruning cuts slightly angled and next to a junction with another branch or main stem. Adult moths are present in late June and August. 'Patty Bee': Has scaly foliage, like an azalea, that turns maroon in winter. Damage on new foliage will be evident in May and July. Photo: P.M. Shrewsbury, 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. Plant azaleas in partial sun (morning sun and afternoon shade). Adult moths are present in late June and August. Scale Download a PDF of this article Plants Affected. 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. 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