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How to Manage Pests

UC Pest Management Guidelines

Citrus flat mites.


Citrus Flat Mite

Scientific name: Brevipalpus lewisi

(Reviewed 2/07, updated 2/09)

In this Guideline:


This mite is smaller than tetranychid (spider) mites. It is slow-moving, flat, and oblong in shape, being wider at the anterior end. Coloring ranges from red brown to more reddish.

Citrus flat mite is a warm season pest with populations increasing in June and peaking in late July and August, then gradually declining.


Mite feeding damages the stems (rachis) of clusters as well as nuts. Feeding on the stems causes a browning that gradually develops into a severely roughened, black area that resembles a scab. This feeding damage is usually on the inside or back portion of nut clusters. Under heavy population pressure, stems and nuts begin to shrivel. Damaged nuts remain on the tree and can provide an overwintering source for navel orangeworm. Close examination will reveal citrus flat mite. They are most easily observed around shriveled and damaged areas.


No precise guidelines are available to determine the need for treatment. Pistachio orchards located near citrus or pomegranates are most likely to be attacked by citrus flat mite. Populations can be spotty, and in following years become more widespread in the orchard. Initiate treatments when flat mite populations in nut clusters can be easily detected but before nut shriveling.

Biological Control
A predaceous phytoseiid mite, Metaseiulus mcgregori, which is common in several crops throughout California, feeds on citrus flat mite. Its numbers begin increasing in August and reach their highest level at the same time as citrus flat mite, but experience has been that their numbers are insufficient to reduce flat mite populations below economic injurious levels.

Organically Acceptable Methods
Sulfur sprays are acceptable for use in an organically managed orchard.

Common name Amount/Acre** R.E.I.+ P.H.I.+
(trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
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. SULFUR DUST 98%# 50 lb 24 0
  MODE OF ACTION: Unknown. An inorganic miticide.
  COMMENTS: Best results are obtained by ground treatments; however, aerial treatments are effective. Use higher rates by air. Check label to confirm product is labeled for pistachio.
B. WETTABLE SULFUR# 15–20 lb 24 0
  MODE OF ACTION: Unknown. An inorganic miticide.
  COMMENTS: May be applied by ground or air. Check label to confirm product is labeled for pistachio.
** Unless otherwise noted, apply with enough water to ensure adequate coverage.
+ 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.
# Acceptable for organically grown produce.



[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Pistachio
UC ANR Publication 3461
Insects and Mites
W. J. Bentley, Kearney Agricultural Center, Parlier
R. H. Beede, UC Cooperative Extension, Kings County
K. M. Daane, Biological Control, UC Berkeley/Kearney Agricultural Center, Parlier
D. R. Haviland, UC Cooperative Extension, Kern County
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier

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