Many of these insects also cause damage to azalea and mountain laurel. Yes it looks like it has both sun burn and a lace bug infestation. … Azaleas and rhododendrons planted in full sun are very susceptible to damaging attacks by these insects. There are three main kinds of dormant spray ± oils, Lime Sulfur, and Copper based sprays. Chemical control with permethrin is directed at the adults. The good news is they are fairly easy to control without resorting to harmful insecticides. Korean rhododendrons (Rhododendron mucronulatum) are also a good cold-hardy choice, though they lose their leaves in the cold months. Rhododendron Borer Control: Nonchemical control is limited to pruning and destroying wilted branches. Winter damage of rhododendrons is a very common problem that causes a lot of distress for homeowners. Epsom Salts* According to the American Rhododendron Society, if the plant has older leaves that have turned … make sure to spray both the top and undersides of leaves. Start with a lower concentration and … We are not keen on this practice and will only spray … Bud blast: the fungus causing bud blast produces its spores on the black fungal 'bristles' that appear on infected buds.They are spread by water and potentially infect buds through wounds made by the rhododendron … Spraying leaves … The adults are 8-9mm long and have pale yellow heads with a bluish green … Thrips are tiny dark-coloured insects approximately one millimetre long which live on a variety of plants, including rhododendrons and other evergreen shrubs such as Viburnum davidii in particular. However, when using these products, you must hit the lace bugs on the underside of the leaves with the spray. Spray the rhododendron with Subdue or another fungicide labeled for the treatment of die-back in rhododendron. To control white flies encouraging natural predators to hang around will help (green lacewings, lady bugs, minute pirate bugs, big eyed bugs, and damsel bugs) or if you choose the insecticidal route use Malathion, Diazinon or Orthene. Identifying Lace Bug Damage. As noted above, lace bug damage on thick leaved rhododendrons can look like this and the leaf undersides, although not entirely clear in the photo, show some evidence lace bug nymph excrement. Printable PDF The rhododendron is a commonly used landscape plant that has a specific complex of pests. Other diseases of Rhododendron include petal blight, leaf gall, and leaf spots. Christchurch Rhododendron/Garden Expert. Old scales … This life stage is enclosed in a cocoon that is surrounded by frass and other debris. If you spot lace bugs around your rhododendron plant soon enough and notice no severe damage to the plant, simply wash it off using a garden hose with high water pressure. At this point they are most vulnerable to insecticide. At Crystal Springs Rhododendron Garden, Stewart says gardeners are using a mechanical device … WSU research also found that rhododendrons … Symptoms: Leaves silver and dry. Agitate the water with your hands to create suds. This will clear … This native pest was first described from specimens collected in Pennsylvania in 1909. Adult insects … It stands to reason that evergreens, like rhododendrons, can handle a tough winter without much help, but the fact is that even sturdy plants get the blues when its cold. Spraying with horticultural oil or insecticidal soap will control lace bugs. Insects Another pest on rhododendrons is the root weevil. Treatment should take place in May and … The azalea and rhododendron are both from the same plant genus, rhododendron, but have distinct characteristics. 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