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UC Pest Management Guidelines

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Floriculture and Ornamental Nurseries

Thread-footed (Tarsonemid) Mites

Scientific names:
Cyclamen mite: Phytonemus pallidus
Broad mite: Polyphagotarsonemus latus
Bulb scale mite: Stenotarsonemus laticeps

(Reviewed 3/09, updated 3/09)

In this Guideline:

Description of the pests
Damage
Management

DESCRIPTION OF THE PESTS

Thread-footed mites are tiny and cannot be readily seen without magnification (20X to 40X). The life stages of these thread-footed mites are: egg, nymph, pseudopupa, and adult (one less stage than for spider mites). Eggs of the cyclamen mite are one-half the length of the adult and are oval shaped. Eggs of the closely related broad mite are distinguishable from cyclamen mite eggs by rows of white pegs on the egg's upper surface. Immature stages of these mites are white.

These mites get the name "thread-footed" from the appearance of the hind pair of legs in the adult female, which is threadlike; adult males, on the other hand, have stout legs for clasping the female. Adult males carry female pseudopupae on their back. As soon as the adult female emerges, they mate.

Cyclamen mite is generally found feeding on growing terminals, in buds, or on unfolding leaflets. Their development is optimal under moderately warm (60° to 80°F) temperatures and high humidity (80 to 90%). Broad mite is similar to cyclamen mite, but is generally found mostly on the undersides of plant leaves. Mites disperse between plants on air currents and by mechanical transport such as on worker's clothing. These mites can complete one generation in 7 to 21 days, depending on temperature. Female bulb scale mites lay up to 28 eggs. Adults are usually found between the scales of the bulb and the neck region. Bulb mites overwinter in bulbs between the scales, emerging as the leaves grow. They re-enter bulbs as the bulbs dry in the field. One generation can be completed in about 7 weeks under field conditions.

DAMAGE

Feeding by cyclamen and broad mites is easily recognized on all hosts because affected leaves become characteristically cupped, dwarfed and thickened, and the internodes are greatly shortened. Broad mite damage occurs more generally over the plant than cyclamen mite damage. Bulb scale mites feeding in developing shoots can cause longitudinal bronze streaks of discoloration, horizontal cracks, distortion, and death of leaves and flowers.

MANAGEMENT

Biological Control
Neoseiulus californicus and other species of predatory mites have been used for broad mite and cyclamen mite control. For more information, see BIOLOGICAL CONTROL.

Cultural Control
Because these mites feed on a large variety of plant species, keep production areas free of weeds that can serve as hosts for mite populations. Carefully inspect plants being brought in to start a new crop to ensure that they are free of pests, and disinfest the plants if needed. Disinfestation can be accomplished by immersing propagation stock in 110.3°F water for 30 minutes, or treatment at 100% relative humidity and 110.3°F for 1 hour. If hot spots of these mites are found in production areas, consider roguing affected plants and treating the surrounding plants.

Monitoring and Treatment Decisions
Visually inspect plants for typical damage symptoms as part of a weekly scouting program.

TREATMENT

Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals
Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact.

Class		Pesticide (commercial name)	Manufacturer	R.E.I.¹	Mode of action²	Comments

macrocyclic lactone	A.	abamectin (Avid 0.15EC)	Syngenta	12	6	Label permits low-volume application.
oil³	A.	clarified hydrophobic extract of neem oil# (Triact 70)	OHP	4	26	Do not spray plants under stress. Target pest must be completely covered with spray. Check label for list of plants that can be treated. May cause injury to flowers.
	B.	horticultural oil⁴ (Ultra-Fine Oil) (SafTSide) (JMS Stylet Oil)	Whitmire MicroGen Brandt JMS Farms	4 4 4	— — —	Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions.
organochlorine	A.	endosulfan* (Endosulfan 3EC)	Drexel	48	2A	Check local water/runoff restrictions. Some varieties of chrysanthemum exhibit phytotoxicity. Do not apply more than 3 lb a.i./ acre/season.
	B.	dicofol (Kelthane 50WSP)	Dow Agro Sciences	48	20	Also labeled for low-volume use.
pyridazinone	A.	pyridaben (Sanmite 75WP)	BASF	12	21	Use at least 2 different chemicals between applications of Sanmite. Do not use fertilizers containing boron or apply through any type of irrigation system. Do not exceed 10.67 oz/acre/application.
soap³	A.	potash soap# (M-Pede)	Dow Agro Sciences	12	—	Must contact insect, so thorough coverage is important. Repeat weekly as needed up to 3 times. Test for phytotoxicity. Do not spray new transplants or newly rooted cuttings. Do not add adjuvants.

¹	Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing.
²	Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.
³	Notethat single doses of soaps or oils can be used at anytime in a pesticide rotation scheme without negatively impacting resistance management programs.
⁴	Check with certifier to determine which products are organically acceptable.
*	Restricted use pesticide. Permit require for purchase or use.
#	Acceptable for use on organically grown ornamentals.

PUBLICATION

UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries
UC ANR Publication 3392
Insects and Mites
J. A. Bethke, Entomology, UC Riverside
Acknowledgment for contributions to Insects and Mites:
K. L. Robb, UC Cooperative Extension, San Diego County
H. S. Costa, Entomology, UC Riverside
R. S. Cowles, Connecticut Agricultural Experiment Station, Windsor, CT
M. P. Parrella, Entomology, UC Davis

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