Damage from broad mites is common on New Guinea impatiens, garden impatiens and dahlias. Broad mites can also be a problem on African violet, ageratum, azalea, begonia, dahlia, gerbera, gloxinia, ivy, jasmine, impatiens, lantana, marigold, snapdragon, verbena, zinnia and vegetable plants. Broad mites inject a toxin from their saliva as they feed. Their toxic saliva causes twisted, hardened and distorted growth in the terminal of the plant and bronzed, rough lower surfaces. Young terminal buds can be killed and leaves turn downward. Broad mites are extremely small which makes them difficult to detect before severe feeding damage appears. Both broad mites and cyclamen mites are too small to be seen without the aid of a microscope. If characteristic symptoms are seen, send samples to a diagnostic laboratory that can inspect samples under a microscope.
Mites can be spread by workers hands or on clothing. Infested hanging plants can infest plants below. If detected early, rogue infected plants as soon as possible. The following pesticides are registered for broad mites: abamectin (Avid), bifenthrin (Talstar Flowable, Talstar Nursery Flowable), chlorfenapyr (Pylon), dicofol (Kelthane), pyridaben (Sanmite), fenpyroximate (Akari). Repeat applications are usually necessary. The effects of their feeding may persist long after the mites have been eradicated.
Close-up of broad mite injury on New Guinea impatiensNote twisted, hardened and distorted terminal growth and bronzing on the flower petioles. Young terminal buds can be killed and leaves turn downward. Injury can be confused with thrips damage, herbicide injury, physiological or nutritional disorders. Broad mites have a wide host range. Broad mites are too small to be seen without the aid of a microscope. If characteristic symptoms are seen, send samples to a diagnostic laboratory for identification.
Reprinted from the June, 2005 edition of the New England Greenhouse Update.
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