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 on top. Newly hatched mites are green, but with feeding, turn red. They have white spots at the base of the large hairs on the back. European red mite has 5 to 10 generations per year and is more common in the Sacramento and northern San Joaquin valleys than in other almond growing areas.
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 numbers, 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. Mite numbers often decline when temperatures turn hot. Occasionally, red mite numbers increase 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 other mite pests. Several generalist predators also feed on European red mite.
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 to control mite eggs and is suggested when 20% of spurs have 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.
| 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. | ||||
| DELAYED DORMANCY | ||||
| A. | NARROW RANGE OIL# | |||
| (Superior, Supreme) | 6–8 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) | 16–34 fl oz | 12 | 7 | |
| MODE-OF-ACTION GROUP NUMBER1: 23 | ||||
| COMMENTS: Most effective when applied with oil at 0.5 to 1% concentration. | ||||
| B. | NARROW RANGE OIL# | |||
| (Omni Supreme) | 4–6 gal | See label | 0 | |
| MODE OF ACTION: Contact including smothering and barrier effects. | ||||
| COMMENTS: Be sure that trees are watered well to avoid phytotoxicity. Works by contact activity only, so good coverage is essential. Check with certifier to determine which products are organically acceptable. | ||||
| C | CYFLUMETOFEN | |||
| (Nealta) | 13.7 fl oz. | 12 | 7 | |
| MODE-OF-ACTION GROUP NUMBER1: 25A | ||||
| COMMENTS: Works primarily on contact. Do not apply more one Nealta application before using an effective miticide with a different mode of action. | ||||
| D. | HEXYTHIAZOX | |||
| (Onager) | 12–24 oz | 12 | 7 | |
| MODE-OF-ACTION GROUP NUMBER1: 10A | ||||
| COMMENTS: Do not apply more than once a year. | ||||
| E. | BIFENAZATE | |||
| (Acramite 50WS) | 0.75–1 lb | 12 | 7 | |
| (Vigilant 4SC) | 16–24 floz | 12 | 7 | |
| MODE-OF-ACTION GROUP NUMBER1: un | ||||
| COMMENTS: Relatively safe for beneficial predaceous mites. Apply with ground equipment; requires complete coverage of both leaf surfaces for effective control. | ||||
| F. | ACEQUINOCYL | |||
| (Kanemite 15SC) | 21–31 fl oz | 12 | 7 | |
| MODE-OF-ACTION GROUP NUMBER1: 20B | ||||
| COMMENTS: Do not apply more than twice a year. | ||||
| G. | ABAMECTIN* | |||
| (Agri-Mek SC, others) | Label rates | See label | See label | |
| MODE-OF-ACTION GROUP NUMBER1: 6 | ||||
| COMMENTS: May be combined with oil. Do not make more than two applications per growing season and allow at least 21 days between treatments. Do not exceed 20 fl oz/acre per application. Certain formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations. Regulations affect use for the San Joaquin Valley from May 1 to October 31, 2018 and 2019. Review the Department of Pesticide Regulation's updated fact sheet . | ||||
| H. | ETOXAZOLE | |||
| (Zeal) | 2–3 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. | ||||
| I. | FENPYROXIMATE | |||
| (Fujimite 5EC) | 2–4 pt | 12 | 14 | |
| MODE-OF-ACTION GROUP NUMBER1: 21A | ||||
| COMMENTS: Effective, but long residual toxicity to predatory mites is a concern. | ||||
| ‡ | 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 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 pesticides 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; pesticides with a 1B group number should be alternated with pesticides that have a group number other than 1B. Mode-of-action group numbers (un = unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee). |