Disease on the Stems of Azaleas
Azaleas (Rhododendron spp.) are deciduous or evergreen shrubs that make colorful, trumpet-shaped flowers. Based around the range, these ornamental plants develop in U.S. Division of Agriculture plant hardiness zones four by means of ten. Cultivars thrive in complete sun to partial shade and well-drained soil having a pH in between four.five and six.0. Azaleas variety in size from three to 20 feet higher and wide, and their flowers measure from 1/2 inch to four inches wide. Poorly drained soil, improper planting and plant injuries boost the danger of stem illnesses in azaleas.
Phytophthora Crown RotPhytophthora crown rot is really a frequent illness in azaleas, notes Clemson University Cooperative Extension. The fungus Phytophthora thrives in wet or poorly drained soil and typically infects azaleas which are set as well deeply within the soil. The primary symptom is brownish stem discoloration close to the soil. To stop crown rot, don't acquire azaleas which have discolored roots or wilted or discolored leaves, and plant your azaleas in well-drained soil. Resistant cultivars are obtainable, including pink- and white-flowered Indian azalea (Rhododendron simsii), which grows in U.S. Division of Agriculture plant hardiness zones eight by means of ten.
Phomopsis DiebackThe fungus Phomopsis causes stem dieback, which usually happens in 1 branch or stem on an azalea. The wood beneath the bark turns chocolate brown, the stem and its leaves die, as well as the leaves might stay around the stem till summer time. Wounded or stressed azaleas are most susceptible to this illness, so you need to offer water for the duration of drought and keep away from injuring your azaleas. Prune diseased branches nicely under infected regions and dispose of them. To prevent spreading the illness, clean pruning tools within a dilution of 1 component bleach in 9 components water.
Other Stem IssuesOther ailments and circumstances result in symptoms in azalea stems. The bacteria Exobasidium mostly causes leaf gall, nevertheless it sometimes causes stem galls on azaleas. The galls are unsightly but generally not dangerous, and also you can prune the galls to handle the illness. Cold injury could make stems seem diseased, because it causes cracking and peeling close to the soil surface. Prune away impacted stems beneath the injured location.
FungicidesIf cultural practices usually do not manage azalea stem ailments, you'll be able to use fungicides. By way of example, mancozeb controls Phomopsis dieback in azaleas. Dilute 1 tablespoon of 75 % mancozeb item in 1 gallon of water, and spray the azalea plant, concentrating around the flowers along with the region close to the soil. Mefenoxam assists stop and suppress Phytophthora root rot but doesn't remedy the illness. Dilute four drops of 24 % mefenoxam fungicide per gallon of water, and drench the soil with 1 1/2 to two pints per square foot for soil depth higher than four inches. Stick to label precautions, and put on protective clothes and eyewear. Maintain pets and youngsters away from fungicides.
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