Home > Great Big Greenhouse Blog > July 2017 > IN THE GARDEN with DOUG - AZALEA PEST ALERT

IN THE GARDEN with DOUG - AZALEA PEST ALERT

Azaleas and rhododendrons, two very popular plants in the Richmond area landscape, are now under the threat of the azalea lace bug.  We have customers stopping into the garden center daily with small samplings from their azaleas and wondering what is wrong with them.  The azalea lace bug infestation is somewhat common this time of year.  And, now is the time to be pro-active and stop the damage.
                If you have azaleas and rhododendrons then take some time to go out into your landscape and do some inspection of these plants.  Look for spotting on the upper surface of the leaves and dark brown or black, shiny fecal pellets on the underside of the leaves.  Shrubs planted in full sun or exposed sites are often the first and most severely damaged by lace bug.
                Lace bugs are small (1/8 inch) insects of the family Stephanitis pyroides. The adults have delicate, transparent wings with a lacy pattern, hence their name. They can attack most all azaleas, rhododendrons, pieris, and cotoneaster.
                Lace bugs damage plants by sucking the sap and cell contents from the undersides of leaves.  This damage looks similar to spider mite damage, first appearing as tiny yellow spots on the upper leaf surfaces.  When feeding damage becomes severe, the leaves take on a gray, blotched appearance and appear almost white.
                The female lace bug will lay eggs in the leaf tissue, typically along the midrib of the leaf.  Lace bugs overwinter as eggs.  Egg hatching time in the spring can vary in Richmond.  This year, the evidence of lace bug damage is beginning to show its presence now.  As I stated earlier, we recommend careful monitoring of your plants.  It is important to catch an infestation quickly, as lace bugs reproduce rapidly.
                Once you have identified the presence of lace bugs, treat with an insecticide.  Years ago when I first started in the garden center business our recommendation of insecticides were Orthene, Isotox, Malathion, and Diazinon (ugh!).  Thank goodness our green industry has developed better, more environment friendly products for control.  What we now recommend is insecticidal soap, all seasons horticultural oil, neem oil, and Natria.  Some of these better, more environmentally-friendly products contain pyrethrins.
                You may be asking yourself “what is pyrethrins”?  Pyrethrins are a natural insecticide produced by certain species of the chrysanthemum plant.  It is a class of organic compounds that have potent insecticidal activities by targeting the nervous system of insects.  In general, pyrethrins are low in toxicity.  As always, apply any insecticide properly and timely.  ALWAYS READ THE LABEL THOROUGHLY!  We need to avoid harm to our bees and to other beneficial insects.  Therefore, only use pyrethrin in situations where it will not affect our beneficial insects.  For azalea lace bug control, be sure to only spray affected azalea or shrub.  Do not do a general broadcast spray.  In other words, concentrate your spray to the top and underside of the leaves on the affected shrub(s) only.
Posted: 7/12/2017 by Doug Hensel | with 0 comment(s)
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