Rhododendrons can be affected by a condition called "physiological leaf spot." 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. The two primary reasons that rhododendron leaves turn brown are cold weather and rhododendron wilt. The two primary reasons that rhododendron leaves turn brown are cold weather and rhododendron wilt. Asked May 11, 2019, 11:23 AM EDT. Do not let the leaves fall to the ground to infect the soil. Benson, plant pathologists at North Carolina State University, infected leaves will have a "water-soaked" appearance; then they will become dried out and fall off of the shrub. Brown spots on rhododendron leaves may not be a sign of disease. Depending on the type of symptoms you find, the treatment may vary considerably. 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. Brown Spots On The Leaves. This is a very common issue afflicting ornamental and shade trees and most of the time no action needs to be taken and your tree will remain in overall good health. If you see brown spots on leaves it is likely caused by a fungal infection. Asked August 30, 2016, 3:27 PM EDT. A second type of Rhododendron issue is brown spots on the leaves. 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. Rhododendron With Yellowing Leaves. Bud Blast on Rhododendron Plants ... Then water lightly so the product doesn't pool up in one spot. They sometimes contain numerous small, black fruiting bodies of the causal fungus; Rust: 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. Fact Check: What Power Does the President Really Have Over State Governors? 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. None are blooming yet. These fungi attack the shrub's new growth, its leaves and stems. The latter is … Healthy, vibrant leaves are an important part of the spring performance of a rhododendron (Rhodenderon spp.). 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. December 1, 2014. 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). This includes balancing the soil condition at the proper pH range and adding fertilizers, mulch and adequate watering. Can you help me with my rhododendron? These flowering beauties belong to the Ericaceae, heath, family and are sometimes affected with brown spots on their leaves. Prune your rhododendrons in the fall or late winter/early spring before the flowers bloom to promote adequate air circulation through the shrubs to keep their leaves and flowers dry and aerated, according to Daniel H. Gillman, plant pathologist of the University of Massachusetts Extension landscape, nursery and urban forestry program. Aside from browning leaves, the roots of infected plants are often described as mushy and dark in color. Brown spots on rhododendron leaves may not be a sign of disease. The latter is … Manal received her Bachelor of Science in biology/pre-medical studies from Molloy College in 1994 and has been a freelance writer, teacher and homeschooling mom since 1993. Rhododendron brown leaves. Rather than using fungicides to combat such spotting, the best Knowing what causes brown spots and understanding how to prevent and treat them may save your rhododendrons from irreversible damage. Apply fungicides specifically formulated for brown spots on rhododendrons to help kill the fungus and prevent its spread. Infection usually occurs in the springtime, but may not be fully manifested until the winter or the next spring. If decreasing temperatures aren't the culprit, attention should be turned toward the plant soil. Fungi from the Phytophthora, Cercospora, Colletotrichum, Pestalotiopsis and other genera are known to cause brown spots on the leaves of rhododendrons. Is the Coronavirus Crisis Increasing America's Drug Overdoses? Fungal Disease Powdery Mildew . The shrub's colorful blossoms are meant to be viewed against a lustrous backdrop of green. Soil contaminated with phytophthora will continue to infect or kill rhododendron until steps are taken to eliminate the conditions that are causing the fungus to grow. Promoting healthy growth of your rhododendrons may prevent brown spot infections. ... On a couple of them the older leaves are turning yellow, then brown and some are falling off. You may baby your rhododendron, but the popular shrubs can’t cry if they are not happy.Instead, they signal distress with yellow rhododendron leaves. Phytophthora, the formal name for rhododendron rot, breeds in very wet soil and often occurs in locations that are naturally wet or in areas of poor drainage. When you ask, “Why does my rhododendron have yellow leaves”, the answer could be anything from improper irrigation to incorrect planting to inappropriate soil. What causes it? Combat the fungus growth by planting drain tiles, implementing a formal irrigation system or constructing a raised bed for better soil drainage.