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Broad and Cyclamen Mites by Paul Pilon

August 16, 2011

Most growers are all too familiar with spider mites, but several growers are not aware of very tiny mites in the Tarsonemidae family that also feed on a number of ornamental plant species.  The two most common mites in this family known to infest ornamentals are the broad mite (Polyphagotarsonemus latus) and cyclamen mite (Steneotarsonemus pallidus).  Broad and cyclamen mites have become a more frequent occurrence for growers in recent years since many of the pesticides on the market today targets a specific type of pest (or a relatively small number of pests) compared to past products which often controlled a broader spectrum of pests.

Feeding injury is often confused with thrips feeding injury, chemical phytotoxicity, or physiological disorders. Injury symptoms appear as bronzing of the leaves or stunted and severely distorted terminal shoots. Expanding leaves appear curled and distorted.  Broad and cyclamen mites and eggs are commonly found near buds, flowers, or the growing points of the plant.  For the most part, they have colorless bodies, although broad mites often have a light amber to dark green appearance and cyclamen mites may have a yellow to pale brown coloration.

Tarsonemid mites are very small, measuring less than 0.25 millimeters; they are about one quarter the size of two-spotted spider mites.  With their small size, they cannot be seen by the naked eye and are difficult to detect until significant crop injury has occurred. To verify their presence requires the use of high powered hand lens (20x) or a dissecting microscope. If the characteristic symptoms are present and you do not have high power magnification available, send samples to a diagnostic clinic for proper identification.

Broad and cyclamen mites are usually most problematic under cool, humid conditions.  The females do not require mating to lay viable eggs.  Each female lays one to three tiny, oval shaped eggs on the undersides of young leaves each day.  Female broad mites lay up to 25 eggs during her lifetime and female cyclamen mites lay up to 16 eggs during her lifespan.  Broad mites complete their life cycle from egg to adult in less than 1 week.  Cyclamen mites complete their life cycle in 1 to 3 weeks.

The predatory mites Amblyseius californicus and Neoseiulus californicus can be used to control broad mites. When using predatory mites, it is best to release them when the broad and cyclamen mite populations are low and to make multiple releases throughout the production cycle.  Applications of horticultural oils, insecticidal soaps, or products containing neem oil are also effective biological control agents.  When done properly, controlling broad and cyclamen mites biologically can be just as effective as using chemical strategies.

Early detection of mites is essential and allows growers to treat isolated areas before they spread throughout an entire crop and cause significant economic losses.  Miticides containing the active ingredients abamectin, chlorfenapyr, dicofol, fenpyroximate, and spiromesifen are effective at controlling various life stages of broad and cyclamen mites.  Refer to each products label to determine which mite and life stages they control.  Growers should note that the feeding injury symptoms will persist long after the mites have been controlled.

It is particularly important to rotate the chemical families of the miticides being applied to prevent resistance to these chemistries.  Several miticides have minimal impact on predators (check the label of each product) which allows growers to combine both biological and chemical control strategies.  To obtain effective control of mites using miticides, it is very important to ensure good coverage of the upper and lower leaf surfaces.  In most instances, it will be necessary to make multiple spray applications to obtain adequate control of mite populations.

Paul Pilon
P
erennial Solutions Consulting
paul@perennialsolutions.com

The mention of specific active ingredients does not constitute an endorsement or recommendation of, or discrimination against similar products not mentioned. ALWAYS READ PRODUCT LABELS AND USE THEM AS DIRECTED ON THE LABEL.

 

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