How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

The European red mite is bright red and has a round body with white spots at the base of hairs on its back. The European red mite overwinters 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. During summer there are numerous overlapping generations, with eggs being laid on upper and lower surfaces of leaves during summer and on twigs or larger limbs in fall.

DAMAGE

European red 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 European red mite begins as a mottling and browning of leaves. Unless populations are very heavy, European red mite does not cause defoliation.

MANAGEMENT

Predators will generally keep European red mite populations at low levels. Allowing low populations in the orchard during spring enables predators populations to increase to levels that are more effective in controlling webspinning mites. Generally, hot weather and predators cause European red mite poulations to decline in summer.

Biological Control
Several predaceous species feed on European red 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). Western predatory mites, Metaseiulus (=Galendromus) occidentalis, also feed on European red mite but are not as effective predators as they are on webspinning mites because of their inability to break through the egg shell of the European red mite.

Cultural Control
Minimize the potential for mite problems by reducing dusty conditions in the orchard and by keeping the trees well irrigated.

Organically Acceptable Methods
Biological and cultural controls as well as oil sprays are organically acceptable management tools.

Monitoring and Treatment Decisions
Monitor for European red 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 (126KB, PDF). Use dormant sprays with oils at the high rate to help control the overwintering eggs if 20% or more 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.

Common name		Amount to Use**		P.H.I.+
(trade name)		(conc.)	(dilute)	(days)
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 the timing on beneficials. When choosing a pesticide, also consider information relating to environmental impact.
DORMANT or DELAYED DORMANT (Preferred timing)
A.	DORMANT OIL such as:
	DORMANT FLOWABLE EMULSION	6 gal	1–1.5 gal
	NARROW RANGE OIL#	4 gal	1.5 gal
	MODE OF ACTION: Contact including smothering and barrier effects.
	COMMENTS: Oil applications at this time 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	14
	MODE OF ACTION: Unknown. An organotin miticide.
	COMMENTS: This material appears to be most effective when applied earlier in the season rather than later. Do not apply more than twice a season in not more than 400 gal water/acre.
B.	NARROW RANGE OIL#	2%	4%
	MODE OF ACTION: Contact including smothering and barrier effects.
	COMMENTS: Oil used alone will only provide partial control. Always apply oil 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. 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. + Preharvest interval. Do not apply within this many days of harvest. * Permit required from county agricultural commissioner for purchase or use. # Acceptable for use on organically grown produce.

PUBLICATION

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 the insects and mites section:
R. E. Rice, Kearney Agricultural Center, Parlier

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