Azalea plants are members of the Rhododendron species, and sometimes the names are used interchangeably. If azalea foliage or flowers are being spoiled by lace bug or petal blight, preventative action – taken at the right time of year – can ease the problem. Dieback, a fungal disease triggered by stress, causes foliage to … Insects, Diseases, and Other Plant Problems: Rhododendrons are susceptible to insect and disease problems. Azalea Dieback Diseases Two fungal diseases can cause azalea branch dieback: Botryosphaeria and Phytophthora. Rhododendron is a genus of 500 to 900 species and includes both of what we commonly call rhododendrons and azaleas. Lace bugs attack new foliage and they like to hide under the leaves, it gives the… It is a dense, bushy, suckering shrub that typically grows 2-6’ (less frequently to 10’) tall. . Usually, when problems do occur, they can be traced back to the plant's environment. Deciduous Azaleas prefer full sun but will tolerate light shade. Insect problems include aphids, borers, lacebugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips and whitefly. aid to diagnosis * Size 1.2m+ after 10-20 years. Petal fungal blight, caused by Botrytis cinerea or Ovulinia azalea, causes a mold on flower petals. Insect and Disease Management When rhododendrons and azaleas are properly planted and maintained, insects and diseases are less of a problem. The name Azalea is used to refer to evergreen Oriental species and hybrids, as well as deciduous native plants. Wonderful flowers but sick looking foliage is not the best look, so what causes Azalea foliage to look so untidy? In many cases it is Lace Bug, you can barely see them, but if you take the time to look at the underside of the foliage you can see little black spots. Many deciduous azaleas are late flowering so extend the season. The lower portions of the stem near the soil line turn brown. Rhododendron foliage is large, paddle shaped, thick, and evergreen. Some azaleas, such as the white variety, cannot withstand temperatures above 80ºF (27ºC), or else the blossoms would wither and fall. One of the most common problems with azaleas is the ‘black spots’ that appear on the foliage. Please note: This content may be out of date and is currently under review. Leaf rust is a common azalea fungal disease that, though rarely serious, causes unattractive foliage spots. Mites may also appear. Rhododendron usually refers to evergreen plants with large, leathery leaves. Asexual conidia are most frequent; they spread by wind and produce new colonies that produce more spores. This selection ranges from the discreet small flowered species and Ghents, to the bold large flowering Knaphill types. The disease is most common on deciduous azaleas but not as frequent on evergreen azaleas. And . Deciduous Azaleas make a dazzling display, particularly in yellows and oranges. Azalea arborescens, Azalea viscosum, and Azalea vaseyi, however, will tolerate more shade than others. The Mollis and Exbury hybrids are well-known, but the species are becoming more and more popular with their subtle, often scented flowers. Many pests can damage azaleas. Disease pests include blights, canker, crown rot, leaf gall, root rot, leaf spot, rust and powdery mildew. Root Rot. There is no practical chemical treatment for either disease, although fungicides may prevent the disease from spreading to other plants. From then on, all you have to do is worry about the many bugs and diseases that can attack your azaleas and rhododendrons, such as lace bugs, … Deciduous azaleas are the primary group of broadleaved shrubs damaged by rust. They are very small and barely visible to the naked eye. This disease is usually more common on deciduous azaleas compared to evergreen plants. Mildew, a common fungus disease of deciduous azaleas in humid climates, typically disfigures - and sometimes kills - the leaves after the flowering period is over. Encore azalea is less vulnerable to lacebugs than other kinds of azaleas. Insect pests include aphids, borers, lacebugs, caterpillars, leafhoppers, mealybugs, nematodes, scale, thrips and whitefly. Azalea pests and diseases. Infection first appears as small, white spots on colored petals or rust-colored spots on white-flowered varieties. The flower color range includes yellows, oranges and fiery reds. Plants that are set too deep are frequently affected by the diseas… Powdery mildew has been a significant problem with many deciduous azalea selections, but nurserymen and breeders are working to rid the ranks of those afflicted by the disease. Azaleas are generally healthy plants when their basic cultural requirements are met. Most azaleas are deciduous or partly deciduous but many are evergreen, depending on the cultivar and the climate in which the plant is growing. Rhododendron periclymenoides, commonly called pinxterbloom azalea, is a deciduous shrub that is native to moist woods, swamp margins and open areas from Massachusetts to South Carolina and Tennessee. These fungi are obligate parasites that produce two kinds of spores. Most are evergreen but some are deciduous. The leaves become curled, fleshy, and pale green to white. The second azalea is the Florida flame azalea, Rhododendron austrinum. Two diseases, branch die-back and Phytophthora root rot in particular, are opportunistic this way. The disease is more severe during periods of cool, moist weather. It is only sporadically severe. Deciduous azalea availability from local nurseries tends to be spotty, so finding a specific cultivar or … A fungus named phytophithora is a common disease problem for rhododendrons and azaleas. Diseases. Infected plants appear to be covered with a powdery white substance on the leaves. Click here for deciduous azalea webshop. Petal blight is most severe during cool, wet spring weather. Pest infestations in azaleas rarely occur, but … Types Certain hybrids and azalea cultivars are more susceptible to rust than others. They originate mostly from the Northern Hemisphere with high concentrations in western China, the … Azalea - Deciduous from Burncoose Nurseries - Page 1 Varieties of Azalea - Deciduous available to buy include the following: AZALEA - DECIDUOUS 'Arneson Gem' ,AZALEA - DECIDUOUS 'Berryrose' ,AZALEA - DECIDUOUS 'Candy Lights ... Plants by mail order since 1984, over 4100 plants online today! The cultivars Homebush and White Lights are susceptible to powdery mildew. Lacebugs are a common insect that dine on leaf chlorophyll, leaving behind yellow speckles. Plants in poorly drained sites often develop Pythium - or Phytophthora -caused root rot diseases. However, they are subject to a number of problems caused by infectious agents, insect pests, weather and nutrition deficiencies. Exbury Deciduous Azaleas are obviously not an evergreen, they do lose their leaves during the winter, but they are striking when in bloom! Problem only in azaleas; rhododendrons are resistant ; Leaves on one to several branches turn red to yellow, wilt, die and fall off; Dark olive to gray streaks are often visible in the sapwood if the bark is peeled back; The entire canopy may show symptoms in a single season or take several years Informational table showing disease name, symptoms, pathogen/cause, and … Centered in Atlanta, Georgia, in a state where most of the world’s deciduous azaleas can be found growing naturally and most evergreen azaleas thrive, our chapter specializes in azaleas. They can also be subject to phytophthora root rot in moist, hot conditions. they are colorful in ways that evergreen Azaleas are not because many of them are brilliant orange and yellow. Azalea and Rhododendron Diseases – Penn State Extension The most common azalea diseases affecting these shrubs include: Azalea Gall This azalea disease commonly occurs in early spring on new leaf growth. Mites, such as azalea mite (Eotetranychus clitus) and southern red mite (Oligonychus ilicis), are a common problem on azaleas and may also attack rhododendrons. Many have the added value of scent and autumn colours. Borers and stem borers can attach deciduous azaleas, making small homes in the branches and laying their eggs in it. This table, organized by the major part of the plant affected, may help determine the cause of the problem. Root rot is a serious, but common disease that is caused by excessive moisture in the soil. Of the six rusts in North America, the hemlock-blueberry rust, Puccininastrum vaccinii, is the most common rust infecting deciduous azaleas in Maryland. It is a watery mold that thrives in wet conditions. Young plants grown in heavy shade are the most seriously affected by this disease. Deciduous Azaleas Glendoick Gardens. Fungal diseases can strike azaleas and cause browning leaf margins and other symptoms. They are tough and fast growing plants typically reaching 125-150cm (4'-5') in 10 years. It is also essential to keep the azaleas free from pests and diseases. Azaleas are beautiful flowers that are easy to plant and maintain, and they bloom in many different colors. Main article: List of azalea diseases Azalea leafy gall can be particularly destructive to azalea leaves during the early spring. Deciduous Azaleas Hi, I am Millie Davenport, a horticulture extension agent with the Clemson University Home and Garden Information Center. Hardiness very tough: mostly H5-6. Foliage – Azalea foliage tends to be elliptical shaped, thin, small and pliable. If planted in shade, they will become open branched, flower less profusely, and be prone to powdery mildew and fungus. Affected leaves eventually turn brown and should be removed and destroyed. Rhododendrons and azaleas are susceptible to many insect and disease problems. Diseases include canker, crown rot, root rot, leaf spot, rust, and powdery mildew. The Azalea Chapter of the American Rhododendron Society offers information and resources on rhododendrons for members and the public. Hand picking infected leaves is the recommended method of control. Symptoms include leaf curling and droop. Plants that exhibit stunting, chlorosis, and die-back symptoms should first be examined for problems with planting depth, soil pH or drainage. Read on to learn about the causes, effects and treatments of a few diseases that affect azaleas. 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