Whiteflies can cause major damage to ornamentals

Published: Thursday, August 29, 2013 at 09:13 AM.

Whiteflies are common pest on many ornamental plants.  Some of the most economically important species in Florida are the silver leaf whitefly, fig or ficus whitefly, citrus whitefly, and the rugose spiraling whitefly.  The most frequently attacked plants include allamanda, chinaberry, citrus, fig, fringe tree, gardenia, ligustrum, various palms, persimmon, viburnum and many annuals.

Adult whiteflies look like tiny white moths, but are most closely related to scale insects.  Most are about 1/16 inch long and have four wings.  The wings and body are covered with a fine white powder wax.  Reliable identification is based on the adults.  The immature whiteflies (nymphs) typically occur on the underside of leaves, and flat, oval in outline, and slightly smaller than a pin head.  Some species are light green to whitish and somewhat transparent.  Others are black in the center and have a white waxy fringe around the edge.

Like soft scales, mealy bugs, and aphids, whiteflies excrete large amount of honeydew, a sweet substance that provides an excellent medium for the growth of sooty mold.  Besides being unattractive, this black fungus may retard a plant’s growth by interfering with photosynthesis.

Fortunately, once the insects are controlled, sooty mold usually weathers away.  You can get rid of it faster by applying a cooper spray. In fact, by mixing copper with an insecticide, you can solve both problems at the same time.

Of course, you must apply the recommend products correctly, according to directions, and with the right equipment.  You can use a pump-up or hose attachment sprayer.  If you use a hose attachment until, be sure it’s designed for ornamentals not laws. Spray plants to the point of run off, covering the undersides of leaves thoroughly, and spray again about two weeks.  This should solve your problem until the next major broad emerges.

Of course, you shouldn’t spray at all until you’re sure whiteflies are the real villains.  May other problems can cause plants to decline.  So, carefully examine the undersides of leaves for the presence of the whitefly nymphs we’ve already described.  If you confirm that whiteflies are infesting you plants, don’t try to control the adults.  After large numbers of adults are seen, wait about two weeks before spraying.  This two week delay will allow the eggs to hatch. The small nymphs, which are the most damaging to plants, are the easiest stage to control.  You should concentrate your efforts on them rather than the mature whiteflies.

Chemical controlthe first type of product to try is an insecticidal soap or horticultural oil spray.   Some other chemical that are labeled for homeowners are:  Bifenthrin, Imidacio Prid, Malathion, Neem Oil, Permethrin, Potassium Salts and Pyrethrins.  Remember these are active ingredient that may be sold under different trade names.



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