Every once in a while I have a whole stem of a Rhododendron branch that dies in the middle of an otherwise healthy-looking plant. Use fungicides and follow the directions in the bottle. It has lost all but perhaps 10 leaves which are producing flowers. A fungus called phytophthera takes hold if the roots are in overly damp conditions. My Rhododendron Is Losing Leaves and Is Crispy. It is during July and August when rhododendron are finishing their yearly growth, forming flower buds for spring, and getting ready for winter. I also sometimes spray with diluted Miracle Grow ericaceous fertiliser. Cold temperatures resulted in the snow staying around and not melting. You may also find flower buds dried and brown in their center, but if you’re lucky, they will still be green. Rhododendron Care and Deadheading after Flowering. Rhododendron are often planted in afternoon shade so hot summer sun won’t burn the leaves. www.rhodogroup-rhs.org/ This society controls ‘The International Rhododendron Register and Checklist’ of the named 29,000 +varieties, cultivars and group names. The results of the disease are seen during the late spring when the plant is just beginning to grow and all of a sudden it drops dead. Rhododendron stem borers are not typically deadly, but an untreated infestation can be troublesome. Generally there are two leaf buds for each dead flower. After flowering and a wet spell in late spring I often give the Rhododendrons a top dressing of peat (Agh! Winter’s colder temperatures keep the leaves’ green chloroplasts from turning brown even after they are damaged. The adult borer is a moth, which lays eggs typically at the base of the shrub or at the bottom of the v-crotch of two branches. And, don’t forget about your rhododendrons when the weather turns hot and dry; if nature doesn’t provide any rain, a little bit of water each week will reduce their stress. If you search for and find bore holes, complete with saw dust-like material, it would be best to contact the Conn. It can be a long job on a large Rhododendron but I pinch out the seedheads to divert energy back to the shrub and give the leaf buds space to develop. Those buds are dead. P.O. In Praise of Rhododendrons | Gardeners Tips, Housekeeping for Small Rhododendrons | Gardeners Tips. The light green new buds will generate leaves and new branches that can develop in the space now vacated. The Rhododendron genus is a hugely diverse group of plants that includes closely related azaleas. If you look closely on the next picture you will see that at either side of the seed spikes there are leaf buds. Try some commonsense housekeeping but leave the pruning shears in the shed. It only takes a little practice, you soon pick up the knack without causing any damage. Fungicide application in late spring and summer help the shrub to recover. According to the Clemson University Cooperative Extension, this is caused by another kind of fungus that gets under the bark. Let’s assume you are seeing damage from stem borers. The other cause for dead branches on an otherwise healthy looking plant could be an infestation of Rhododendron stem borers. Let’s assume you are seeing damage from stem borers. Plump stems will also have growth buds that will easily snap off. Look out for plants with the Award of Garden Merit including the following Lepidote species Augustinii, Edgeworthii, Keiskei, Racemosum and Yunnanense. The staff at the Experiment Stations is extremely helpful and will explain how to find and treat the plants with insect damage. Rhododendrons are shallow rooted so they like a drink and an occasional feed of ericaceous fertiliser. Blooming rhododendrons look like colorful, puffy clouds floating through the landscape, so when they don’t deliver, not only is it a huge disappointment, but a cause for concern for many gardeners. It is not worth letting the seedheads fill up and develop as you are unlikely to be trying to breed your own from seed. These plants are therefore more susceptible to winter leaf burn because the sun reflecting off the snow reaches foliage that is not usually exposed to such intense light, resulting in a light to medium browning of their leaves, especially on the south facing side. Some of the most common dangers to your rhododendron include aphids, root rot and Japanese beetles. Old, browned leaves will drop off and be replaced with fresh green leaves. It can be a long job on a large Rhododendron but I pinch out the seedheads to divert energy back to the shrub and give the leaf buds space to develop. Because these shrubs have shallow roots, you won’t have to dig too far to get a look at them. Rhododendron are shallow rooted, with their roots mostly growing in the organic-rich layer on top of the soil to maybe two or three inches down into the soil, so they are highly susceptible to damage from extremes of heat, cold, rain, and drought. It would take a whole book to understand this wide world! The other cause for dead branches on an otherwise healthy looking plant could be an infestation of Rhododendron stem borers. Is my Rhododendron dead ...or not? (NOT the … The plants are able to survive and bloom for many years. So any energy put into the seedheads is energy lost from next years plant and flowers. If you look closely on the next picture you will see that at either side of the seed spikes there are leaf buds. On the above photo the petals have just fallen and the long,  tubular seedheads are just beginning to form. To see if this disease is the problem, you'll need to do a little digging. The damage was principally to the leaves and not stems of the plants, so when it is time for new growth to emerge, it will. Box 330966 Failing to deadhead is not to say leaving the shrub to its own devices will be a failure but as we are growing for ornamental purposes every bit to care helps. Dark brown dead roots= Phytophthora caused by poor drainage. To test this theory, you can check the stems to see if they look full and plump, or wrinkled and dry. And this past winter we had it all. The next thing I would do is check for any signs of pest or disease. Is my Rhododendron dead ...or not? This heat killed many small roots in the topmost layer of soil, preventing rhododendrons from adequately absorbing water and nutrients. Frigid temperatures, drying winds, heavy snow loads, and intense sun light can all impact a plant. Charlotta Wasteson / Flickr Creative Commons. Last but not least, we had many days with bright sunlight that reflected off the snow and burned the leaves of rhododendrons. Dry looking stems will have buds that will take some effort to break off the stems. Those plants with the highest degree of stress are the plants that are now dead. Why the sudden appearance of damaged leaves? Their hardiness ranges vary by species. Rhododendrons are lovely plants with enchanting blooms that range from dark red to lavender. Your email address will not be published. In the wild Rhododendrons manage quite nicely thank you without this TLC. But as temperatures increase in early spring, the damaged cells try to continue their assigned biological processes only to find they cannot, and subsequently, they die and turn brown. Agricultural Experiment Station, either in Windsor, or New Haven. In many cases, the plants can be saved, though they may be set back some. The excess of heat may not have prevented these shrubs from completing their biological preparedness for winter, but it did ensure that many plants started winter with unresolved stress-related problems. Any brown leaves will drop off as the new growth emerges. The two primary reasons that rhododendron leaves turn brown are cold weather and rhododendron wilt. Check to see if the stem tips of your rhododendron are still alive, look for physical damage and remove any broken branches, and keep an eye out for stem borers. Typically we combine several fungus diseases into a general category of "die-back." So, before you prune or hack your rhodies to the ground, try to assess the problem. More rhododendrons are killed by waterlogging and poor drainage than any other cause. Check the rhododendron for fungus disease. For now, be patient. Required fields are marked *. Scrape away some of the stem to see if there is any green healthy tissue before giving up on it completely. The eggs hatch and the immature caterpillars bore to the center of the stem and tunnel their way up the inside of the stem. Placing a layer of mulch or compost 2-3 inches thick under your rhododendron will help keep its roots cool and moist this summer. New flower buds for next year are formed on Rhododendrons during summer so I try keep them well supplied with water. The most significant are powdery mildew and bud blast. Pinching the often sticky seedsheads, I give a twist to break the stem just above the new leaf joint. Rhododendron Leaf Problems. The evergreen leafed species of Rhododendron are just that, they remain green throughout the winter months. Once you have the insect inside the stem, there is no chemical control, but you can snake a thin piece of wire into the entry hole and skewer the insect. Here you can see the seeds have been removed and added to the compost heap. This past year we saw all four extremes, with one after another increasing the stress on our plants. If the soil is boggy, heavy clay or compacted, rhododendrons will not grow for long and will likely die. Most rhododendrons will begin to grow in the next few weeks, showing you where they may need to be pruned, or that they don’t need to be pruned at all. The easiest style of pruning is trimming off any dead or dying parts of your rhododendron with pruning shears. Save my name, email, and website in this browser for the next time I comment. It is hard to know where to start with Rhododendrons and the 850+ species. Look at the bark on a stem or main branch of many rhododendrons and you will see tiny buds, little pink dots about the size of a pinhead that pepper the surface of older branches. With something organic instead of the RHS specialist section the Rhododendron genus, vary. Have had a tough year seed spikes there are more than 900 species in the.... 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