Description of the Pest
The female European red mite is about 0.02 inch long and has a brick-red globular body with long curved hairs that arise from white spots or tubercles on the back. Nymphs or unfed females may appear greenish. European red mite eggs are red, slightly flattened, and have a stipe protruding from the top. They overwinter in the egg stage on twigs and spurs. Eggs hatch in early spring just after the trees leaf out, and many generations (8-10) are produced before fall. Ordinarily European red mite populations build up slowly during spring and do not become apparent until large populations are present.
Damage
European red mites remove the contents of the leaf cells as they feed, causing leaves to take on a finely mottled appearance. Rarely do European red mites cause leaf drop in cherry trees.
Management
European red mites provide an early-season food source for predatory mites and do little damage unless the orchard is heavily infested. Allowing low populations of European red mites in spring helps predator mite populations to build, which can later help control the more damaging webspinning mites. Generally treatments for this mite are applied in the dormant to delayed-dormant season.
Biological Control
The same predators that feed on Pacific and twospotted mites will also feed on European red mites. While the western predatory mite can sustain itself on European red mites, it cannot break the shell of European red mite eggs. Thus it takes longer for this predator to bring a population of these mites under control.
Cultural Control
Culturally, little can be done to control European red mites, as they are generally more abundant in well-managed, vigorous orchards.
Organically Acceptable Methods
Biological control and sprays of narrow range oil are organically acceptable management tools.
Monitoring and Treatment Decisions
A dormant oil spray is the preferred treatment and is intended to control European red mite eggs. In orchards with a history of problems with this mite, treat during dormancy to help control the overwintering eggs. Remember that low-to-moderate populations are beneficial because they provide food for predators.
| Common name | Amount to use | REI‡ | PHI‡ | ||
|---|---|---|---|---|---|
| (Example trade name) | (conc.) | (dilute) | (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. | |||||
| DORMANT and DELAYED DORMANT | |||||
| A. | NARROW RANGE OIL# | ||||
| (460 or higher) | Label rates | 4 | 0 | ||
| COMMENTS: Choose a narrow range oil with a 50% distillation point of 460 or higher for dormant season use. With good coverage, oil will control European red mite and brown mite eggs and low infestations of San Jose scale. | |||||
| ‡ | 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 two intervals is the minimum time that must elapse before harvest. |
| # | Acceptable for use on organically grown produce. |