How to Manage Pests

UC Pest Management Guidelines

Almond

European Red Mite

Scientific name: Panonychus ulmi

(Reviewed 3/09, updated 3/09)

In this Guideline:


DESCRIPTION OF THE PEST

These mites overwinter as eggs located at the base of buds and spurs on small branches, in wounds, or bark cracks. Eggs are red with a slender stalk arising from the center. Newly hatched mites are green, but with feeding, turn red. They have white spots at the base of the large hairs on the back. These mites have 5 to 10 generations per year.

DAMAGE

European red mites cause leaf stippling. Prolonged feeding causes leaves to pale and appear bronzed and burned at the tips and margins. Almond trees that are not stressed for water or by any other factor can tolerate high infestation levels (in excess of 50 mites per leaf) for extended periods without experiencing leaf drop. If the trees are stressed, however, these levels can cause defoliation. At low levels, this mite can be beneficial as it serves as an alternative food for mite predators. European red mites do not commonly reach damaging levels in almonds. Populations often decline when temperatures turn hot. Occasionally, red mite populations build up between late summer and fall on the west side of the Sacramento Valley.

MANAGEMENT

European red mite is often kept below damaging levels by natural enemies and is an important food source for building up natural enemies of spider mites early in the season. Monitor this mite as part of your regular monitoring program throughout the season. The best time for treatment in an IPM program is an oil spray during the dormant season as determined by a dormant spur sample.

Biological Control

The western predatory mite feeds on the immature and adult stages, but is unable to break through the egg shell so it is not as effective in controlling European red mites as it is other mite species. The brown lacewing, Hemerobius sp., is an effective predator, but is not always present.

Organically Acceptable Methods

Biological control and certain oil sprays are organically acceptable.

Monitoring and Treatment Decisions

Monitor the European red mite eggs as part of the dormant spur samples during the dormant season as described in the Dormant Spur Sampling Section. A delayed dormant oil spray is the preferred treatment and is intended to control mite eggs and is suggested when 20% of spurs have mite eggs. During the growing season, monitor orchards once a week along with other pests. No treatment thresholds have been established, but almond trees are able to tolerate greater numbers of European red mites than webspinning spider mites per leaf.

Common name Amount/Acre** 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 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 the label of the product being used.
 
DELAYED DORMANT
A. NARROW RANGE OIL#
  (Superior, Supreme) 6–8 gal 1.5–2 gal See label 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: Delayed dormant applications are more effective because eggs are closer to hatch. Cover all parts of the tree. Oil alone will control low to moderate infestations. Do not use oil sprays on water-stressed trees. Check with certifier to determine which products are organically acceptable.
 
SPRING
A. SPIRODICLOFEN
  (Envidor 2SC) 16–18 fl oz 4–4.5 fl oz 12 7
  MODE OF ACTION GROUP NUMBER1: 23
  COMMENTS: Most effective when applied with oil at 0.5 to 1% concentration.
 
B. ACEQUINOCYL
  (Kanemite 15SC) 31 fl oz 7.75 fl oz 12 7
  MODE OF ACTION GROUP NUMBER1: 20B
  COMMENTS: Do not apply more than twice a year.
 
C. NARROW RANGE OIL#
  (Omni Supreme and others) 4–6 gal 1–1.5 gal See label 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: Be sure that trees are well-watered to avoid phytotoxicity. Works by contact activity only, so good coverage is essential. Check with certifier to determine which products are organically acceptable.
 
D. BIFENAZATE
  (Acramite 50WS) 0.75–1 lb 0.1875–0.25 lb 12 7
  MODE OF ACTION GROUP NUMBER1: 25
  COMMENTS: Relatively safe for beneficial/predaceous mites. Apply with ground equipment; requires complete coverage of both leaf surfaces for effective control.
 
E. ABAMECTIN*
  (Agri-Mek 0.15 EC) 10–20 fl oz 2.5–5 fl oz 12 21
  MODE OF ACTION GROUP NUMBER1: 6
  COMMENTS: May be combined with oil. Do not make more than 2 applications/growing season and allow at least 21 days between treatments. Do not exceed 20 fl oz/acre/application.
 
F. HEXYTHIAZOX
  (Onager) 12–24 oz 3–6 oz 12 28
  MODE OF ACTION GROUP NUMBER1: 10B
  COMMENTS: Do not apply more than once a year.
 
G. ETOXAZOLE
  (Zeal) 2–3 oz 0.5–0.75 oz 12 28
  MODE OF ACTION GROUP NUMBER1: 10B
  COMMENTS: Acts as a contact toxin to eggs, inhibits molting of juveniles, and causes adult female mites (both pest and beneficial) to produce sterile eggs. Do not apply more than once/season. Use for bearing trees allowed under a Supplemental Label.
 
H. FENPYROXIMATE
  (Fujimite 5EC) 1–4 pt 0.25–1 pt 12 14
  MODE OF ACTION GROUP NUMBER1: 21
  COMMENTS: Effective, but long residual toxicity to predatory mites is a concern.
 
I. PROPARGITE
  (Omite 6EC) 1.5–2 qt 0.375–0.5 qt 21 days 28
  (Omite 30WP) 2–8 lb 0.5–2 lb 21 days 28
  MODE OF ACTION GROUP NUMBER1: 12C
  COMMENTS: Do not apply more than twice/season. Do not apply less than 40 days after or 30 days before an oil application. Use lower rates when western predatory mites are present.
 
** For dilute applications, rate is per 100 gal water to be applied in 300–500 gal water/acre, depending on the label; for concentrate applications, use 80–100 gal water/acre, or lower if the label allows.
+ 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 these two intervals is the minimum time that must elapse before harvest may occur.
* Permit required from county agricultural commissioner for purchase or use.
# Acceptable for use on organically grown produce.
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/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Almond
UC ANR Publication 3431

Insects and Mites

F. G. Zalom, Entomology, UC Davis
C. Pickel, UC IPM Program, UC Cooperative Extension, Sutter/Yuba counties
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
D. R. Haviland, UC IPM Program, UC Cooperative Extension, Kern County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier
L. C. Hendricks, UC Cooperative Extension, Merced County
R. L. Coviello, UC Cooperative Extension, Fresno County
M. W. Freeman, UC Cooperative Extension, Fresno County

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