And our smaller rhododendron has a small amount of the black … 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. 5. Easy to get and hard to eradicate, blight can quickly ruin one plant or a whole garden full. At the time the trunk looked fine, but yesterday I noticed that the trunk and branches are turning black! While a few scattered branches may have been injured on a Disinfect pruning tools between cuts with a 10% bleach or 70% rubbing alcohol solution, and apply a fungicide that contains copper.. The latter is … Think about thinning the shade or moving the plant if it is suffering. In most cases much of the damage appears to have occurred at random. The two primary reasons that rhododendron leaves turn brown are cold weather and rhododendron wilt. Apply fertiliser April-May to Late June. Watching plants slowly wilt and die after their stems turn black leads to frustration and anger. Rhododendron Leaf Problems. 3. Feed and water the plant and it will probably pick up. Over the last couple of weeks, there have been many reports of damaged rhododendrons. A couple weeks ago we trimmed our largest rhododendron, cutting off a good amount of branches around it’s base. Dieback is a difficult Rhododendron disease to control. This condition is caused by a fungus called Botryosphaeria dothidea. The GARDENA gardening expert Your rhododendrons were obviously attacked last year by the rhododendron cicada, as a result of which the young buds were infected with a fungi which caused them to die off. If your azalea branches are covered with a gray, white or black powder, then your culprit is powdery mildew. Rhododendron is a genus of plants with more than 850 species, from ground covers to shrubs and trees. It has been observed that the inner parts of the bark of the dying branches develop a reddish brown discoloration. Blackened, twisted branches can indicate azalea blight caused by phomopsis and botryosphaeria fungi. Is there an effective medium against the occurrence of buds which turn brown and then black? Infected branches should be pruned well below the discolored wood, then disposed of. Blight is the all-purpose name for a number of fungi in the soil that affects plants in this way. Most people have noticed that some of the branches on their plants have curled leaves that don’t open on warm days, indicating they have been injured in some way. Leaf gall is a common springtime Rhododendron disease, but it is not particularly serious. 4. Rhododendron is starved. This may also cause the plants to lose leaves or flowers. Rhododendron is suffering from lack of water: often due to competition from tree roots. The most common rhododendron disease is stem dieback, which is characterized by death of the branches, in an otherwise healthy plant.