Although it’s unsightly, leaf spot is only a significant problem on poorly growing or unhealthy plants, which might end up dropping a substantial number of 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. A shortage of this vital element results in the withering of new growth, curled tips, and yellow or brown leaf spots. The most common include: Each unsightly fungus has its own set of issues with which a gardener needs to contend. Rhododendrons are favored for their large, paddle-shaped leaves that create a showy specimen in your garden all year long. Tropical regions of southeast Asia and northern Australia will also be good homes for rhododendrons. The former is a naturally occurring phenomenon that takes place as the result of changing weather patterns and doesn't necessarily indicate a dead plant. Phytophthora thrives in wet soil or poorly drained areas where the plant is installed. Check the underside of the plant’s leaves on a regular basis. Properly dispose of the infected plant parts far away from rhododendron shrub. Brown leaf edges or entire leaves that have turned crispy are winter damage, usually from a combination of the ground being frozen (the plant can’t absorb water that is being lost through the leaves), sunburn from direct sun or sunlight being reflected off snow, or wind burn. Infected leaves … Now the leaves are turning a rust color, curling upward, and falling off. Landscape designers and home gardeners plant rhododendrons in hedge arrangements or as stand-alone specimens for the splashes of color that their spring flowers and dark green foliage add to their landscapes. Brown edges to leaves, called "marginal leaf necrosis" (this simply means that the edge of the leaf has died), may be fairly narrow with a lot of green leaf remaining in the middle. A second type of Rhododendron issue is brown spots on the leaves. 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. Most gardeners, whether new to the art or seasoned growers, have come across powdery mildew on plants. As the disease progresses, the spots become white with a sort of floury bloom. The blooming, bushy rhododendrons belong to the botanical family Ericacea and genus Rhododendron. Rhododendron borer – Heavily infested branches weak, breaking easily; leaves wilt and turn brown; holes in infested branches with fine sawdust; white caterpillars in tunnels. Water stress can occur under both extremes of flooded, overly-saturated soils or under drought conditions when too little water is present. Previous. Prolonged saturation leads to diseases that kill an entire plant, not just its leaves. More information on successfully growing azaleas and rhododendrons is available in the fact sheets HGIC 1059, Azalea Care; HGIC 1058, Azalea Planting; and … If the plant looks wilted yet is getting plenty of water, then it may be suffering from water mold. The plant is located on east side of house and gets morning sun. Unfortunately, there isn’t a specific time period, as fungi will attack at any time of the year. Waterlogged roots suffocate and shut down, leaving no avenue to replace water lost to drying winds and sunlight. Rhododendrons and azaleas are some of the most popular spring-flowering shrubs in the landscape, and healthy plants can give years of pleasure. The symptoms of bud blast on rhododendrons start with the bud turning a silvery grey color before growing black bristles. This can leave the healthy plant open to even more serious diseases that can take it down to the roots. "Rodon" means "rose," and "dendron" means "tree." Understand that chemical controls are mostly ineffective once symptoms appear in the landscape. This kind of damage is most likely due to unfavorable environmental and weather conditions. These show up on older, mature vegetation near the bottom of the plant. But I started seeing browning of some of the leaves. After all that hard work of fertilizing, mulching and pruning pays off with healthy buds, they can begin to wither. Dark-brown, pimple-like fungal fruiting structures form within the spots. While it may be ugly, this common rhododendron disease is more superficial than serious. 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. Yellow rhododendron leaves often represent the plant’s expression of dissatisfaction with its care. It will spread under the leaves unnoticed before typically appearing as unattractive spots on the top of the leaves. Anything that dehydrates roots and plant tissues can lead to red leaves. 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. There are more than 800 species within the genus Rhododendron. What causes it? First, take a look at how well your soil drains. This is specifically one of the most common ailments that affect azaleas and rhododendrons. Properly dispose of the infected plant parts far away from rhododendron shrub. All Rights Reserved. She earned a B.A. Diseased flowers dry up and cling to the plant (leaves and stems are not affected). There are many types of fungi in search of healthy rhododendrons to feed upon. How to Prune Lower Branches of a Rhododendron, Organic Treatment for Apple Tree Diseases, Gardening Know How: Azalea Insect Problems – Lace Bug Damage To Azaleas, Gardenia: Hardiest Azaleas and Rhododendrons, Clemson Cooperative Extension: Azalea & Rhododendron Diseases, Rhododendron Horticulture Society: Rhododendron Diseases, The American Rhododendron Society: Plant Culture and Care, My Gardenia's Leaves Are Turning Yellow & the Buds Are Falling Off, How to Get Rid of Fungus on a Rhododendron's Leaves. The ground to infect the soil heads of bright flowers as early as January, and yellow or brown more! Main cause of unsightly foliage or a recent rain quickly take over the petals the... Soil only to return a fungus known as water mold Australia will also be good homes rhododendrons... The roots will show up on older, mature vegetation near the bottom of fungus. Die off, then it may be suffering from scorched leaves the underside of leaves. 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