Water the mulch until the soil beneath it is evenly moist. Dieback is caused in rhododendrons by Botryosphaeria dothidea and in azaleas usually by members of the Phomopsis genus. For the best experience on our site, be sure to turn on Javascript in your browser. Form, growth habit, flower color and bloom time also depend on species, but all rhododendrons may defoliate and become crispy when exposed to disease or environmental damage. Each infected branch should be removed by cutting it below the infection site, and it should be disposed of in trash. My Rhododendrons Are Losing Leaves This Fall - Is This Normal? Some rhododendrons … While leaves die, they may remain brown and crispy on branches until they fall off in summer. Sarah Moore has been a writer, editor and blogger since 2006. The older, more interior red-purple leaves will drop from the plant and it is a very normal occurrence. The other difference is that true Rhododendrons have ten or more stamens, 2 per lobe and Azaleas have only five stamens – one per lobe and 5 lobes in a flower. © Copyright 2020 Hearst Communications, Inc. Rhododendrons and Azaleas, what is the difference anyway? Most Azaleas on the other hand (under the same Genus of Rhododendron) will lose their leaves at the end of the season. All Rhododendrons are evergreen which means that they will hold leaves all winter long. Both Rhododendrons and Azaleas are best pruned right after they bloom in spring only so hold off pruning this fall. Rhododendrons appreciate good fall moisture and love to have a nice 3” layer of mulch over their roots. Although rhododendron leaves tend to curl during cold weather, it may not always protect them from winter burn. Because the disease is difficult to control, avoid it by planting your rhododendron in a location with well-draining soil rather than one where water collects and stands. Leaf scorch also can occur when rainy, overcast weather is suddenly followed by windy, sunny days. Dieback is caused in rhododendrons by Botryosphaeria dothidea and in azaleas usually by members of the Phomopsis genus. Answered. Usually by the time that occurs, it is too late to save the plant. Even in a climate with mild winters, drying winter winds can sap moisture from leaves, especially when the rhododendron grows in an unprotected location. Protect the plant against winter burn by ensuring it has proper moisture provided by a 2 1/2-inch-thick layer of sphagnum peat mulch on the soil all around its root zone, but don't allow the mulch to contact the plant's stems. Their hardiness ranges vary by species. In colder climates and where your plants are exposed to winter winds you may want to consider some wind protection or maybe a spray on anti-transpirant later in the season to prevent the leaves from drying out. Leaves dry out, become crispy on the edges and, in severe cases, may fall off the plant. Leaf scorch occurs when a plant receives too little water to compensate for the moisture it loses through its leaves to hot summer air. Because dieback is hard to control, give your rhododendron the best chance at avoiding it by planting it in partial shade and by avoiding drought-stress and unnecessary plant wounds. Hybrids from the PJM group (Rhododendron PJM Group) are hardy in U.S. Department of Agriculture (USDA) plant hardiness zones 4 through 8, for example, while pinxterbloom azalea (Rhododendron periclymenoides) is hardy in USDA zones 4 through 9. Apply a 2 1/2-inch-thick layer of mulch, such as rotted leaves or bark, on the ground around a leaf scorch-afflicted rhododendron, but don't let the mulch touch the plant's stems. The Rhododendron genus is a hugely diverse group of plants that includes closely related azaleas. For the best experience on our site, be sure to turn on Javascript in your browser. Also, avoid planting the rhododendron deeper than the soil depth at which it grew in its nursery container. Most Azaleas on the other hand (under the same Genus of Rhododendron) will lose their leaves at the end of the season. Plant your rhododendron behind larger plants or a building, or use wind shields to protect the rhododendron during winter months.