How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

At low population densities, cyclamen mites (Family Tarsonemidae) are usually found along the midvein of young, unfolded leaves and under the calyx of newly emerged flower buds; when populations increase, these mites can be found anywhere on nonexpanded plant tissue. They are not visible to the naked eye, and when mature, they measure only about 0.01 inch (2.5 mm) long. Mature mites are pinkish orange and shiny. The hind legs are thread- or whiplike in the female and grasping or pincerlike in the male. Eggs are translucent and comparatively large.

Adult females lay about 90 eggs, 80% of which develop into females. During summer, newly hatched mites develop into mature adults within 2 weeks. Populations build rapidly soon after a field becomes infested. Cyclamen mites overwinter as adult females in the strawberry crown and can be present on transplants if the nursery field was infested.

Cyclamen mite can be distinguished under magnification from nondamaging tarsonimid mites in the genus Tarsonemus by examining the 4th femur of male mites. The cyclamen mite has a "flange" or distinct bulge present while the males of both Tarsonemus species do not.

DAMAGE

Cyclamen mites are primarily pests in fall-planted and second-year plantings, but they can be transplanted into first-year fields and the damage symptoms become apparent on leaves as the season progresses. Leaves heavily infested with cyclamen mites become severely stunted and crinkled, resulting in a compact leaf mass in the center of the plant. Feeding on flowers can cause them to wither and die. Fruit on infested plants is dwarfed, and the seeds stand out on the flesh of the berry. When uncontrolled, this mite can prevent plants from producing fruit.

MANAGEMENT

Management of cyclamen mite requires carefully timed sprays of miticides that do not harm natural enemy populations. Prevent its introduction into strawberry fields by following good cultural practices. Propagating nursery stock free of cyclamen mites is essential to prevent introducing populations to fruit-producing fields. This mite may survive in furrows of fields that have been bed fumigated. Because other nondamaging tarsonemid mite species, including Tarsonemus setifer and Tarsonemus confusus, occur in strawberry fields and it is very difficult to distinguish one species from another, focus control efforts in those fields where damage symptoms occur.

Biological Control
Two naturally occurring predatory mites of cyclamen mite are Typhlodromus bellinus and T. reticulatus, but their populations build up too slowly to provide economic control. Early season releases of the commercially available predatory mite, Amblyseius californicus, may be able to control this pest mite. Amblyseius cucumeris releases have not proven to be effective.

When pest populations become large, the sixspotted thrips, minute pirate bugs, and western predatory mite (Galendromus occidentalis) all feed on cyclamen mites.

Cultural Control
Cyclamen mites can easily be transferred from one location to another by pickers, bees, birds, and equipment, including strawberry freezer trays. It may be worthwhile to dip trays of long-term cold storage (28°F) transplants into a hot water bath for 7 minutes right before planting to prevent infestation. (Infested nursery plants are the major source of this pest in annual plantings; be sure to use uninfested nursery stock.) Prepare plants for this treatment by thoroughly washing them to remove all dirt; then place them in a circulating water bath that is held at a constant temperature of 120°F. Afterwards, submerge them in very cold water and then plant them as soon as possible. (This treatment is not recommended for fresh-dug transplants that have only been stored at 33°F.) Avoid second-year plantings in problem areas. To slow the spread of infestations, rogue infested plants as soon as symptoms appear.

Organically Acceptable Methods
Biological and cultural control methods are acceptable for use on organically certified strawberries.

Monitoring and Treatment Decisions
If any damage symptoms are observed, be sure to monitor the rest of the field carefully to determine the extent of the infestation. Monitor newly unfolding leaves and treat the area of the field believed to be infested when densities of one cyclamen mite in 10 leaves are found. To control cyclamen mites, a high rate of water per acre (300–500 gal) is necessary to soak the folded leaves and immature flower buds located in the crowns. Effective control requires a high rate of kill because populations of this mite can increase rapidly. Roguing and treating infested hot spots with a hand-sprayer can be useful in suppressing infestations without having to treat the entire field. In nurseries, early season control before plant canopy closes over is critical.

Common name		Amount/Acre	R.E.I.+	P.H.I.+
(trade name)			(hours)	(days)
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy and impact on natural enemies and honey bees. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
A.	ABAMECTIN*
	(Agri-Mek) 0.15 EC	16 fl oz	12	3
	MODE OF ACTION GROUP NUMBER1: 6
	COMMENTS: Toxic to predatory mites and relatively toxic to parasites, but fairly safe for general predators. Apply in up to 600 gal water/acre to soak the material into the crown of the plant. Works poorly under cold weather conditions. Make 2 applications 7–10 days apart when mites reach detectable levels under warmer temperatures in late winter/spring. Repeat this sequence of applications if necessary to maintain cyclamen mite control. Do not exceed 16 fluid oz/acre/application or 64 fl oz (4 applications)/acre in a growing season. Do not repeat treatment within 21 days of 2nd application. Not registered for strawberry nurseries.
B.	DICOFOL 4E	2 pt	12	2
	MODE OF ACTION: un
	COMMENTS: Apply with a wetting agent. Toxic to predaceous mites and relatively toxic to general predators and parasites. Do not apply after fruit formation or when temperatures exceed 90°F. Do not make more than 2 applications/season,
C.	ENDOSULFAN*
	(Thionex) 3EC	2.66 pt in 400–600 gal water	48	4
	MODE OF ACTION GROUP NUMBER1: 2A
	COMMENTS: Do not reapply within 35 days. Use of this product may not be allowed in some counties; cannot be applied in any situation where run-off may occur. Consult county agricultural commissioner for local restrictions. Do not make more than 2 applications/year or exceed 2 lb a.i./acre/year.
D.	FENPROPATHRIN*
	(Danitol) 2.4EC	10.66 fl oz	24	2
	MODE OF ACTION GROUP NUMBER1: 3
	COMMENTS: Use of this material is limited to 2 applications/year (totaling 2.66 pt/acre), but to reduce the pressure for resistance development, make no more than 2 applications of all pyrethroids to the crop each year.
E.	ACEQUINOCYL
	(Kanemite) 15 SC	21–31 fl oz	12	1
	MODE OF ACTION GROUP NUMBER1: 20B
	COMMENTS: Control does not become evident until 48 to 72 hours after application. Do not use less than 100 gal water/acre and do not apply more than twice/year. Allow a minimum of 21 days between treatments. Crops other than strawberries may not be rotated for at least 1 year following treatment.
+	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. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
*	Permit required from county agricultural commissioner for purchase or use.
1	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 the 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/.

PUBLICATION

UC IPM Pest Management Guidelines: Strawberry
UC ANR Publication 3468
Insects and Mites
F. G. Zalom, Entomology, UC Davis
M. P. Bolda, UC Cooperative Extension Santa Cruz County
P. A. Phillips, UC IPM Program/UC Cooperative Extension Ventura County
Acknowledgment for contributions to the Insects and Mites:
N. C. Toscano, Entomology, UC Riverside

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