How to Manage Pests
UC Pest Management Guidelines
Citrus Flat Mite
Scientific name: Brevipalpus lewisi
(Reviewed 10/13, updated 10/13)
In this Guideline:
Description of the pest
Citrus flat mites are common pests of pomegranate fruit. Citrus flat mites are very small and difficult to see, even with a hand lens. They are sluggish, translucent, flat and oblong. Adults have internal spots of red and brown. These mites overwinter under flakes of bark on large branches. They move to the leaves and fruit in summer, with numbers increasing in June, peaking in July and August, and then gradually declining.
Citrus flat mite feeding results in a brown scabbing or leathering ("alligator skin") of the fruit that looks similar to sunburn. Occasionally, the damage can be quite serious. Mite damage starts at the stem end and the brown discoloration extends further than the cracking. Mites and their cast skins may be found in the cracks. Sunburn and other unknown causes of leathering can be mistaken for flat mite damage. If the fruit surface next to the stem is not damaged, flat mites are not the cause.
Predaceous mites may keep flat mites below economic levels, but most growers use preventive applications of sulfur in early summer. It has not been documented in pomegranate, but in other crops sulfur can disrupt the natural enemies of other pests (e.g., mealybug and soft scale). However, it is the best control method to prevent flat mite damage.
A predaceous mite has been observed associated with flat mite in pomegranates and likely keeps this pest in check in some orchards.
Organically Acceptable Methods
Some formulations of sulfur are organically acceptable.
Monitoring and Treatment Decisions
Monitor for damage starting in mid to late May by examining the stem end of fruit for scabbing and the presence of flat mites with a high-power hand lens (15–20x) or microscope. If flat mites are present treat immediately with sulfur.
To protect fruit from mites, apply sulfur one to three times at monthly intervals beginning in late May or early June. Sulfur works better in warm weather. Wettable sulfur is less disruptive to predators.
UC IPM Pest Management Guidelines:
Insects and mites
D. R. Haviland, UC Cooperative Extension, Kern County
Acknowledgments for contributions to Insects and Mites:E. E. Grafton-Cardwell, Entomology, UC Riverside and Kearney Agricultural Center, Parlier