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UC Pest Management Guidelines


Brown mite adults and eggs.

Plum

Brown Mite

Scientific name: Bryobia rubrioculus

(Reviewed 5/06, updated 4/09)

In this Guideline:


DESCRIPTION OF THE PEST

Brown mites can be recognized by their flattened bodies and long front legs. Adults are brownish green; nymphs are red at first. Brown mites overwinter as eggs on twigs and branches. Eggs hatch in spring and the young move out to leaves where they feed but do not produce webbing. Brown mites feed only during the cool parts of the day and migrate off the leaves during midday.

DAMAGE

Brown mites feed by sucking the contents out of leaf cells. Such leaf damage reduces tree vitality and can adversely affect fruit size. Leaf injury caused by brown mites begins as a mottling and browning of leaves. Trees can tolerate low to moderate populations of brown mite, but heavy populations can remove almost all the chlorophyll from leaves and entire trees will take on a pale yellow appearance.

MANAGEMENT

Predators will generally keep brown mite populations below damaging levels. Allowing low populations of brown mites in the orchard during spring enables mite predators to increase their population to levels that are more effective in controlling webspinning mites. Generally, hot weather and predators cause brown mite populations to decline in summer.

Biological Control
Several predaceous species feed on brown mite, including lacewings (Chrysoperla spp., Chrysopa spp., and Hemerobius sp.), damsel bugs (Nabis sp.), lady beetles (Hippodamia convergens and Stethorus picipes), and minute pirate bug (Orius tristicolor).

Organically Acceptable Methods
Oil sprays and naturally occurring predators serve as organically acceptable management tools.

Monitoring and Treatment Decisions
Monitor for brown mite eggs along with other pests when taking the dormant spur sample. See DORMANT SPUR SAMPLE for details and record results on a sampling form (139 KB, PDF). Use dormant sprays with oils at the high rate to help control the overwintering eggs if more than 20% of spurs have mite eggs. An insecticide can be added to control other pests. Miticides may be necessary in some orchards in spring or summer but only when mite populations begin damaging foliage (brown mites can be monitored using beating trays).

Common name Amount to Use** R.E.I.+ P.H.I.+
(trade name) (conc.) (dilute) (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, impact on natural enemies and honey bees, and impact of timing on beneficials. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
DORMANT or DELAYED DORMANT (Preferred timing)
A. DORMANT OIL such as:
  DORMANT FLOWABLE EMULSION 6–8 gal 1.5–2 gal 4 0
  NARROW RANGE OIL# 6 gal 1.5 gal 4 0
  MODE OF ACTION: Contact including smothering and barrier effect.
  COMMENTS: Oil applications at this time to kill overwintering eggs may cause some young shoots to burn or dieback, especially in years when trees are water-stressed, or have recently been subjected to freezing temperatures or to dry winds. Dormant flowable emulsion is less likely to cause burn. Some varieties, especially those that are weak growers or low in vigor because of soil or other location-related issues, can be especially sensitive to oil. Not all oil products are organically acceptable; be sure to check individual products.
 
SPRING and SUMMER
A. FENBUTATIN OXIDE*
  (Vendex) 50WP 2 lb 0.5 lb 48 14
  MODE OF ACTION GROUP NUMBER1: 12B
  COMMENTS: This material appears to be most effective if applied when temperatures are warm earlier in the season rather than later. Do not apply more than twice a season in not more than 400 gal water/acre. Do not apply more than 3 lb/acre/season.
 
B. NARROW RANGE OIL# 2% 4% 4 0
  MODE OF ACTION: Contact including smothering and barrier effect.
  COMMENTS: Oil used alone will only provide partial control; thorough coverage is essential. Always apply oils to well-watered trees and never when trees are stressed by hot (above 90°F), windy, dry (relative humidity lower than 20%) conditions or when such conditions are likely to occur within a few days after application. Additional applications may be needed at 2 week intervals, which may increase the potential for phytotoxicity. Do not apply oil within 2 weeks of captan or sulfur. Not all oil products are organically acceptable; be sure to check individual products.
 
** For dilute applications, rate is per 100 gal water to be applied in 300–500 gal water/acre, according to label; for concentrate applications, use 80–100 gal water/acre, or lower if the label allows.
* Permit required from county agricultural commissioner for purchase or use.
+ 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 use on organically grown produce.

IMPORTANT LINKS

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Plum
UC ANR Publication 3462
Insects and Mites
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
K. R. Day, UC Cooperative Extension, Tulare County
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier

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