How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Avocado

Sixspotted Mite

Scientific name: Eotetranychus sexmaculatus

(Reviewed 1/07, updated 1/07)

In this Guideline:

General information
Description of the pest
Damage

Management
Publication
Glossary

MITE PESTS OF AVOCADO — GENERAL INFORMATION

Spider mites (family Tetranychidae) and predatory mites (Phytoseiidae) are tiny 8-legged arthropods. Persea mite is a key pest of California-grown avocados. Avocado brown mite and sixspotted mite are sporadic pests. Several beneficial mites are important predators of pest mites and certain insects. Natural enemies and certain management strategies vary among pest mites. Identify the pest and natural enemy species in your grove and learn their biology so you can manage these pests appropriately as needed. For details about sampling techniques, see MONITORING PERSEA AND SIXSPOTTED MITES.

DESCRIPTION OF THE PEST (View photos)

The oval adults are about 0.01 inch (0.3 mm) long. Their body is lemon yellow, often with about six dark blotches on the abdomen, although some individuals have no distinct spots. Females lay tiny, globular, pale greenish yellow to translucent or pearly white eggs, which have a slender projecting stalk. About 25 to 40 eggs are laid over 10 to 20 days. Eggs hatch in 5 days to 3 weeks, depending on temperature. In summer, mites reach maturity in 8 to 12 days. Populations are heaviest in spring and early summer.

DAMAGE

Sixspotted mite is an occasional pest, mostly near the coast in foggy areas of San Luis Obispo and Santa Barbara counties. It generally is under good control in the interior growing areas (Riverside and San Diego counties) because of predators and warm weather. Sixspotted mite can become a problem anywhere if trees are drought-stressed or pesticides used to control other pests disrupt mite biological control.

Sixspotted mite feeds only on the lower avocado leaf surface. It causes irregular brown to purplish discoloring, mostly along the midrib and larger veins. Sixspotted mite produces webbing, but not the dense roundish silk patches formed by persea mite.

MANAGEMENT
Enhance biological control by conserving natural enemies. Minimize dust. Avoid applying non-selective pesticides that are toxic to predaceous insects and beneficial mites that control plant-feeding mites and other pest insects. Limit any needed applications to spots where pests are most abundant.

Biological Control (View photos)
Sixspotted mite is controlled primarily by predatory mites (family Phytoseiidae). These phytoseiids include Amblyseius (=Typhlodromalus) limonicus and Galendromus helveolus. Euseius hibisci, a shiny pear-shaped predator, is important in part because it can maintain and increase its populations on avocado pollen when pest mites are scarce. Typhlodromus rickeri also preys on sixspotted mite around Santa Barbara County. The spider mite destroyer lady beetle (Stethorus picipes) and sixspotted thrips (Scolothrips sexmaculatus) are other important natural enemies.

Cultural Control
Encourage predators by oiling or paving main orchard roads to control road dust. Drive slowly when it is necessary to use dirt roads. Consider using a water truck or trailer to wet dirt roads, especially before travel during summer months when heat convection currents carry dust well up into the tree canopies. Individual backyard trees can be hosed down in early to mid-summer to remove dust and enhance biological controls.

Organically Acceptable Methods
Biological and cultural controls and sulfur and certain oil sprays are acceptable for use on an organically certified crop.

Monitoring and Treatment Decisions
Look for sixspotted mite when monitoring persea mite (see MONITORING PERSEA AND SIXSPOTTED MITES). Be sure to distinguish the mite species present. When specifically monitoring for sixspotted mite, select trees in dusty and more humid locations of groves. Use a hand lens to examine along the midrib and lateral veins on the underside of interior canopy leaves. Look for brown to purplish discoloring, mite webbing, and mites.

Sixspotted spider mite can severely stress trees at relatively low densities by causing premature leaf drop. However, populations rarely exceed an average of 2 to 3 mites per leaf. At this low abundance sixspotted mite is not damaging, does not warrant treatment, and is easily overlooked.

Common name

Amount to use

R.E.I.+

P.H.I.+

(trade name)

(hours)

(days)

When choosing a pesticide, consider information relating to the impact on natural enemies and honey bees and environmental impact.

NARROW RANGE OIL#

Label rates

MODE OF ACTION: Contact including smothering and barrier effects.

COMMENTS: Requires good coverage to be effective. Check with certifier to determine which products are organically acceptable.

WETTABLE SULFUR#

Label rates

1 day

MODE OF ACTION: Unknown. An inorganic miticide.

COMMENTS: Do not treat with sulfur when temperatures exceed 90°F to avoid leaf damage. Sulfur sprays are often not effective in coastal areas where temperatures do not promote fuming action.

+	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 until harvest. In some cases the REI exceeds the PHI. The longer of these two intervals is the minimum time that must elapse before harvest.
#	Certain products are acceptable for organically grown produce.

PUBLICATION

UC IPM Pest Management Guidelines: Avocado
UC ANR Publication 3436
Invertebrates
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura County
B. A. Faber, UC Cooperative Extension, Santa Barbara/Ventura counties
J. G. Morse, Entomology, UC Riverside
M. S. Hoddle, Entomology, UC Riverside
Acknowledgment for contributions to the invertebrate section:
M. Blua, Entomology, UC Riverside
P. Oevering, UC Cooperative Extension, Ventura County
D. Machlitt, Consulting Entomology Services, Moorpark, CA
T. Roberts, Integrated Consulting Entomology, Ventura, CA
B. B. Westerdahl, Nematology, UC Davis

Top of page

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See How to manage pests, or in the U.S., contact your local Cooperative Extension office for assistance. /PMG/r8400311.html revised: April 6, 2007. Contact webmaster.