Description of the Pest
At low numbers, cyclamen mites (Family: Tarsonemidae) are usually found along the midvein of young, unfolded leaves and under the calyx of newly emerged flower buds; when numbers increase, these mites can be found anywhere on nonexpanded plant tissues. They are not visible to the naked eye, and when mature, they only measure about 0.01 inch (0.25 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. Cyclamen mite numbers increase rapidly soon after a field becomes infested. They 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 from nondamaging tarsonemid mites in the genus Tarsonemus through microscopic examination, by examining the fourth femur of male mites. The cyclamen mite has a "flange" or distinct bulge present while the males of both Tarsonemus species do not.
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 of cyclamen mite requires carefully timed sprays of miticides that do not harm natural enemies. Prevent its introduction into strawberry fields by following good cultural practices. Propagating nursery stock free of cyclamen mites is essential to prevent their introduction 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.
Two naturally occurring predatory mites of cyclamen mite are Typhlodromus bellinus and T. reticulatus, but their numbers increase 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.
Pickers, bees, birds, and equipment, including strawberry freezer trays, can easily transfer cyclamen mites from one location to another. 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.) To prepare plants for this treatment:
- Thoroughly wash them to remove all dirt.
- Place them in a circulating water bath that is held at a constant temperature of 120°F.
- Submerge them in very cold water.
- 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
Use biological and cultural control methods 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.
- Spray the area of the field where infestation is expected when densities of one cyclamen mite in 10 leaves are found.
To control cyclamen mites, a high volume 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 numbers of this mite can increase rapidly. Roguing and spraying infested hot spots with a hand-sprayer can be useful in suppressing infestations without having to spray the entire field. In nurseries, early season control before plant canopy closes over is critical.
|Common name||Amount per acre||REI‡||PHI‡|
|(Example trade name)||(hours)||(days)|
|Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Always read the label of the product being used.|
|(Agri-Mek SC)||3.5 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 pesticide into the crown of the plant. Works poorly under cold weather conditions. Make two applications 7 to 10 days apart when mites reach detectable levels under warmer temperatures in late winter or spring. Repeat this sequence of applications if necessary to maintain cyclamen mite control. Do not repeat treatment within 21 days of second application. Not registered for strawberry nurseries. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.|
|(Kanemite 15 SC)||31 fl oz||12||7|
|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 per year. Allow a minimum of 21 days between treatments. Crops other than strawberries may not be rotated for at least 1 year following treatment.|
|(FujiMite 5EC)||2 pt||12||1|
|MODE-OF-ACTION GROUP NUMBER1: 21A|
|COMMENTS: FujiMite provides an alternative mode of action to manage development of resistance in mites. Although it is a contact insecticide, it is effective on all developmental stages of mites. It is active on all important mite species including: two-spotted spider mite, Lewis mite, and cyclamen mite. FujiMite is toxic to predatory mites but is non-toxic to most other natural enemies. Spray coverage is key in obtaining maximum results.|
|(Oberon 2SC)||12–16 fl oz||12||3|
|MODE-OF-ACTION GROUP NUMBER1: 23|
|‡||Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) 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 insecticides 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; insecticides with a 1B group number should be alternated with insecticides that have a group number other than 1B. Mode-of-action group numbers for insecticides and miticides (un=unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee).|