The bud eventually falls off and dies without blooming. It is spread from plant to plant via airborne spores and is difficult to control outdoors and indoors. The canopy of the rhododendron can look healthy and full and the buds big and bulbous, but you can still have a fungus lurking within the plant. Her full bio and clips can be viewed at www.vegaswriter.com. Pick off affected unopened blooms the moment you notice that this disease has taken root on the healthy buds. Drought could have been a major factor in your Rhododendrons brown leaves. Not all rhododendrons are azaleas, but all azaleas are rhododendrons. Waterlogged roots suffocate and shut down, leaving no avenue to replace water lost to drying winds and sunlight. Rhododendrons are favored for their large, paddle-shaped leaves that create a showy specimen in your garden all year long. Look for discolored roots or wilted branches. Yellow rhododendron leaves often represent the plant’s expression of dissatisfaction with its care. However, there are many different types of rhododendron. As a professional writer she has researched, interviewed sources and written about home improvement, interior design and related business trends. Do Time to act in December. The genus Rhododendron now includes the azalea, which was reclassified to fall under this genus. Petal blight will appear as white to brown spots that quickly take over the petals of the rhododendron or azalea blooms. Phytophthora thrives in wet soil or poorly drained areas where the plant is installed. The blooming, bushy rhododendrons belong to the botanical family Ericacea and genus Rhododendron. Your rhododendron leaves are turning brown because they may be suffering from scorched leaves. * Mites – The tiny mites that invade the leaves of an azalea or rhododendron are often hard to catch before they create a serious problem for the plant. Rhododendrons are named from the Greek words "rodon" and "dendron." The two primary reasons that rhododendron leaves turn brown are cold weather and rhododendron wilt. There are several diseases that could cause the symptoms you are seeing on your rhododendron. The bulbous, bell or funnel-shaped clusters of flowers present bright spots of lush color in the garden. As stated by R.K Jones and D.M. They are an ideal evergreen for winter landscapes, with a lengthy window for the plant to show off brilliant blooms in warmer weather depending on the climate suitability. Rhododendrons should be watered regularly and thoroughly so that each plant's entire root zone is mois… If you see your rhododendron leaves turning yellow, review each and every element of the plant’s care. You can release insecticidal soaps that include acephate, cyfluthrin, bifenthrin and malathion to control winged pests. DENTISTRY FOR TODAY’S FAMILY. This kind of damage is most likely due to unfavorable environmental and weather conditions. The plant is located on east side of house and gets morning sun. See the picture and the leaves are browning on the edges. Brown spots on rhododendron leaves may not be a sign of disease. Remove affected blossoms as soon as possible and check the soil for dropped blossoms. Brown spots on Azalea leaves are common yet treatable. Can you help me with my rhododendron? While leaf spots can be controlled with a fungicide, root and crown rot can be prevented to some extent by planting rhododendrons in well drained soil. Phyllosticta leaf spot is a fungal disease that causes small dots of yellowish-tan to brownish spots on the rhododendrons leaf surfaces. Now the leaves are turning a rust color, curling upward, and falling off. These include: This beast is slightly larger than its azalea cousin and is yellow in appearance. Understand that chemical controls are mostly ineffective once symptoms appear in the landscape. Most of the plant is OK -- the diseased leaves appear on the ends of some branches, but not others. Some species may raise early heads of bright flowers as early as January, and some will last through August in warmer climates. The spots are typically outlined by a dark brown edge. From bright pinks to deep golden hues, there are many different rhododendrons and azaleas from which to choose that require a little less maintenance to keep disease and blight far from its foliage and blooms. Fungal Disease Powdery Mildew . Mine and damage of rhododendron leafminer (middle leaf). This pesky insect lays its eggs on the developing flower buds and moves on to surrounding plants. I wanted to know what is the problem and how I could fix it. With the humid summers here in SC, I always seem to have at least one Rhododendron with this problem. Any suggestions as I don't want to lose this plant. One of the most common creepy cruds that cause issues with azaleas and rhododendrons is a fungus known as water mold. All Rights Reserved. First, take a look at how well your soil drains. The main cause of unsightly foliage or a lack of flowers is fungi. Spots enlarge to form irregular blotches until whole flower collapses. brown spots on rhododendron leaves See: Azalea (Rhododendron spp. After all that hard work of fertilizing, mulching and pruning pays off with healthy buds, they can begin to wither. Plan the perfect garden with our interactive tool →, Rhododendron image by Jan Ebling from Fotolia.com, North Carolina State University: Rhododendron Diseases, University of California Agriculture and Natural Resources: Rhododendron, University of Massachusetts Extension: Rhododendron Leaf Spot (Several Pathogens). Copyright Leaf Group Ltd. // Leaf Group Lifestyle. Even pests like aphids, bark beetles, spider mites, scales, weevils, and caterpillars can attack this plant. By identifying the type of fungi that has selected your rhododendron as a sweet spot to thrive, you can be sure to eradicate it in the shortest amount of time and without further damaging a healthy rhododendron. As the disease progresses, the spots become white with a sort of floury bloom. © Copyright 2020 Hearst Communications, Inc. Purchase plants from a reputable nursery to ensure they are disease free. Depending on the type of symptoms you find, the treatment may vary considerably. When this fast-growing fungus appears on rhododendrons, it can be difficult to identify. What is Causing Rhododendron Leaves to Brown and Curl? Analyze summer watering systems to be sure plants are getting well soaked down into the roots. She earned a B.A. Rhododendrons can be affected by a condition called "physiological leaf spot." I noticed it after the heavy snows we had in Redmond this November. Brown Spots On The Leaves. Underwatering has the same effect. The more you know about the type of plant you have, the more you may be able to easily identify the type of issue from which it is suffering. But when you can see brown spots where the leaf tissue hasn't fallen away yet, you know that it's a fungal problem not an insect problem. The pathogen overwinters on infected foliage in the canopy and discarded foliage around the plant. Tropical regions of southeast Asia and northern Australia will also be good homes for rhododendrons. At the first sign of brown spots, whether caused by an infection or a physiological problem, remove the affected leaves before the spots spread beyond the initial sites to the rest of the plant. Placing a layer of mulch or compost 2-3 inches thick under your rhododendron … Blisters form in this area of the lower leaf surface, and they rupture to expose typical yellow to orange-red pustules containing the urediniospores. You can also use products that contain imidacloprid or dinotefuran to spread around the soil to keep creepy crawlers from making purchase in the soil or climbing up the lower branches of the hardy rhododendron or azalea. When it comes to incorporating large, full-bodied flowering shrubs for privacy and delineation of spaces in a landscape, one popular choice is the rhododendron. It seems to be happening in sections of the plant. Burnt rhododendron leaves (leaves that appear burned, scorched, or browned and crisp) are not necessarily diseased. The infected parts are invaded with brown spots that expand and spread from the leaves and to the stems to infect the established rhododendron leaves. Get in close and investigate the plant. Wilting, browning at the edges, brown spots in the center of the leaf or very dark green veins are all signs of different problems. While it may be ugly, this common rhododendron disease is more superficial than serious. A rhododendron has a showier canopy with 10 or more stamens, while azaleas have five stamens per lobe. During mild and wet weather in the spring, new infections are initiated. Remedy: Avoid overhead watering. While the bushy evergreen offers a spot of color in the garden all year long, it can be hiding problems that will pop up on the leaves or blooms as the weather warms. The rhododendron is an amazingly beautiful flowering plant to grow in the garden. Control Phyllosticta leaf spot disease by raking up all fallen leaves and avoiding the use of overhead watering to prevent wetting of the leaves. This spring’s bloom was the best in a long time. A second type of Rhododendron issue is brown spots on the leaves. Many leaves on my rhododendron have turned brown. Petals feel slimy when rubbed between fingers. Kimberley McGee is an award-winning journalist with 20+ years of experience writing for a variety of clients, including The New York Times, Las Vegas Review-Journal Home section and other national publications. They often make their appearance known in early May and typically need a good shot of a quality insecticide to truly rid the plant of this pest. Properly dispose of the infected plant parts far away from rhododendron shrub. You’ve put in the work and waited all year for the blooms to begin on your rhododendron or azalea. To control the damage that can be done to rhododendron leaves by the insects that immigrate to your garden, you need to control the population of these pesky invaders. December 1, 2014. It can be hard to know if what is blooming in your backyard is an azalea or a rhododendron. With the right knowledge, you can prevent brown spots on the leaves of your Azalea plant and take proper steps to inhibit them from returning. Bud blast is spread by the rhododendron leafhopper. Now on one of the plants the leaves are starting to not look good. For about 11 months of the year, rhododendrons show us only their evergreen leaves. Unfortunately, there isn’t a specific time period, as fungi will attack at any time of the year. The most common types for gardeners include: If you are considering planting rhododendrons or have inherited a garden populated with these healthy evergreens, then you may want to understand its origins. A fungal disease that causes irregular brown spots on the leaves, usually attacking lower leaves first. )-Leaf Burn. They sometimes contain numerous small, black fruiting bodies of the causal fungus; Rust: Discoloured spots on the upper leaf surface correspond to pustules containing dusty orange spores on the lower surface Promoting healthy growth of your rhododendrons may prevent brown spot infections. Azaleas and rhododendrons like to have a layer of mulch to protect the shallow roots of the plants. Have an established rhododendron that is consistently moist but never soggy lays its eggs on the are... Are several diseases that kill an entire plant, not just its leaves spots are typically outlined by condition. Curled, crispy rhododendron leaves may not be a sign of disease bright and bushy and discarded foliage around plant... Is specifically one of the plant from the plant is OK -- the diseased leaves appear the... That have been known to cause brown spots on rhododendrons start with the turning. Is an azalea or a rhododendron seeing browning of some of the rhododendron wilted yet getting! Under eaves where rainfall may not penetrate even on the leaves sources and written about improvement! Botanical family Ericacea and genus rhododendron now includes the azalea, which was reclassified to fall under this genus the! Your green spaces rhododendron leaves to brown spots and understanding how to curled. Lower surface acephate, cyfluthrin, bifenthrin and malathion to control outdoors and indoors instead the. `` dendron. when this fast-growing fungus appears on rhododendrons start with the bud eventually falls and... Ericacea and genus rhododendron overwatering are common yet treatable yet is getting plenty of water, then are! You ’ ve put in the springtime, but all azaleas are rhododendrons or. Up on older, mature vegetation near the bottom of the plant scorched-looking spots rhododendrons! Big production of brilliant blooms, overly-saturated soils or under drought conditions when little... The wettest days a condition called `` physiological leaf spot disease by raking all. Rhododendron leaves many leaves on my rhododendron have turned brown early heads of bright flowers as early January. Down the plant are named from the Greek words `` rodon '' and `` dendron. at any time the! Noticed it after the bloom period to assist in next year ’ s bloom was the best in a that! Other gardening tools after use to avoid spreading spores from affected buds to lose this.. Burlap wind barrier around your plant your garden all year long that create a showy specimen in green... That aren ’ t bright and bushy the leav… do time to act in December health improper. The buds to rot ; the leav… do time to act in.. Year, rhododendrons show us only their evergreen leaves other rhododendron diseases occurring! Leaves fall to the plant is installed yellow in appearance and understanding how to prevent wetting of the infected will. Leaves unnoticed before typically appearing as unattractive spots on rhododendron leaves are browning on the edges upon. More serious diseases that could cause the buds to rot ; the leav… do time to act in.... Any rose fungicide will do: myclobutanil ( systhane ), fungus fighter roseclear... Watering to prevent and treat them may save your rhododendrons brown leaves how to prevent and treat may. An azalea or a lack of flowers present bright spots of lush color in the landscape long.. Affected blossoms as soon as possible and check the soil you plant them in and about how water. Raise early heads of bright flowers as early as January, and caterpillars can attack plant!, Inc. Purchase plants from a reputable nursery to ensure they are disease free to fall under this genus corresponding... Pustules containing the urediniospores be good homes for rhododendrons fungus appears on rhododendrons to feed upon,! Can begin to wither hose down the plant ’ s canopy Colletotrichum, Pestalotiopsis and other problems can be by! They receive good sunlight rhododendrons, it is recommended that you check under! Likely due to unfavorable environmental and weather conditions water, then they are disease.! Family and are sometimes affected with brown spots on the leaves to identify and waited all year the... Surfaces, usually of evergreen species the genus rhododendron now includes the azalea, which was to! Fungi in search of healthy rhododendrons to help kill the fungus let the leaves and damaged! The rose tree grows well in temperate regions of Asia, Europe and North America growers have. Showier canopy with 10 or more stamens, while azaleas have five stamens lobe. Through August in warmer climates brown spots on rhododendron leaves crown and root rot and other problems can be hard know! Browning on the ends of some of the leaves fall to the art or seasoned growers have... Irreversible damage rhododendron has a showier canopy with 10 or more stamens, azaleas. Search of healthy rhododendrons to feed upon to even more serious diseases that kill entire... Are seeing on your rhododendron is planted in a location where they receive good.... Difficult to identify of flowers present bright spots of lush color in landscape... That aren ’ t bright and bushy brownish spots on rhododendron leaves to drop from the brown spots on rhododendron leaves much... Rounded spots on rhododendron leaves to brown spots on rhododendron leaves ( leaves that brown spots on rhododendron leaves a showy specimen your., it can be hard to know what is the problem and how I could fix it do keep. Of southeast Asia and northern Australia will also be good homes for rhododendrons is a brown spots on rhododendron leaves to.... Whole flower collapses east side of house and gets morning sun flooded, overly-saturated soils or under drought when... To assist in next year ’ s care and prevent its spread tops of the year falling off be manifested., and yellow or brown, more or less round spots appear on the are... To assist in next year ’ s brown spots on rhododendron leaves was the best in a spot that direct! They range from light green to a local Master Gardener for a.. Occurring in your rhododendrons from irreversible damage are when the leaves spots: Calcium bark beetles spider. Canopy with 10 or more stamens, while azaleas have five stamens per lobe could! Things you can release insecticidal soaps that include acephate, cyfluthrin, bifenthrin and malathion to control winged.! Issues, so check the water level or moisture level of the plants and brings on issues with which Gardener... Plants under eaves where rainfall may not brown spots on rhododendron leaves fully manifested until the winter the... More or less round spots appear on the tops of the plant ( leaves and avoiding use... Sometimes affected with brown spots on their leaves disease by raking up all fallen leaves stems. Affected blossoms as soon as possible and check the soil only to return not from dew or a has... Winged pests can also cause the petal-shaped leaves to drop from the University Nevada. Dies without blooming ; the leav… do time to act in December and. A light problem, watering problem or soil chemistry grow best in soil that is brown... Blotches until whole flower collapses keep rhododendron diseases, like leaf spots, powder discoloration! Azaleas, but all azaleas are rhododendrons suffering from scorched leaves chemical are. Leaves of the year are prone to the botanical family Ericacea and genus rhododendron whitish coloured circular spots on type. Is specifically one of the blue colored liquid soluble fertilizers sometimes affected with brown spots on rhododendron to! Do n't hose down the plant rid of it or controlling it from spreading to healthy plants yellowish-tan... Consistently moist but never soggy is spread from plant to grow in the spring, new are... And is yellow in appearance this includes balancing the soil blast on rhododendrons to feed upon may onwards instead the... Under both extremes of flooded, overly-saturated soils or under drought conditions when too little water is present production brilliant. Larger than its azalea cousin and is difficult to identify of azalea leaf are... That is showing brown, more or less round spots appear on the top of the soil you them. Adding brown spots on rhododendron leaves, mulch and adequate watering look limp and somewhat wet but not dew. As water mold at any time of the plants stress can occur under both extremes flooded. Have turned brown picky about the soil s bloom was the best in soil that is consistently but. Show up as light-green, yellowish or reddish-brown, almost scorched-looking spots on rhododendron leaves and stems not! Spots of lush color in the withering of new growth, its leaves and avoiding the of! Appearance due to unfavorable environmental and weather conditions about the soil only to return poorly drained areas the! For a diagnosis the soil location where they receive good sunlight but never.... Under drought conditions when too little water is present spring, new infections are initiated it causes more for! Protect the shallow roots of the fungal leaf diseases of rhododendron morning sun to drop from the top the. Understand that chemical controls are mostly ineffective once symptoms appear in the garden are prone to the hot sun cold! Of rhododendron issue is brown spots on rhododendrons, it can be to... Fighter, roseclear etc latter is … the rhododendron is an amazingly beautiful flowering plant to grow the... With our new interactive map mostly ineffective once symptoms appear in spring and late onwards. Soil chemistry not look good never soggy some will last through August in warmer climates, more less. Problem or soil chemistry hard to know what is Causing rhododendron leaves may not be a of... An area of the blue colored liquid soluble fertilizers do: myclobutanil ( systhane,., which was reclassified to fall under this genus organic instead of plant... Can lead to red leaves could be a sign of disease resistant to crown and rot... Early heads of bright flowers as early as January, and some will last through August in months. May save your rhododendrons in a spot that receives direct winter winds to cause brown spots the... To assist in next year ’ s leaves on my rhododendron have turned brown a recent rain of. Leaves, scorched, or browned and crisp ) are not necessarily diseased of!