How to Manage Pests
UC Pest Management Guidelines
Scientific name: Bryobia rubrioculus
(Reviewed 3/09, updated 3/09)
In this Guideline:
DESCRIPTION OF THE PEST
The brown mite is the largest in size of all almond pest mites and emerges first in the spring. Brown mite eggs are red, without a stalk, and overwinter in masses on twigs, especially at the junction of wood growth from the two previous seasons. Eggs hatch at the same time leaf and flower buds open. Newly hatched mites are red with six legs; after the first molt they are brown with eight legs, resembling the adult. Adults are flattened with long front legs. The mites feed only during the cool parts of the day, and migrate off the leaves during midday. They are not active during hotter periods of the summer. There are 2 to 3 generations per year between February and June.
Generally these mites are not considered major pests and low to moderate numbers can be beneficial in spring by providing mite predators with a food supply. Feeding by these mites can cause chlorosis, but leaves rarely drop. Infestations are generally confined to a few trees.
Monitor for brown mite as part of the dormant spur sample and treat with dormant oil if required.
The western predatory mite and brown lacewing are both effective predators, but alone may not control brown mite populations. It is important to avoid using insecticides that kill these natural enemies; residues of certain pesticides, such as pyrethroids used during the dormant season, can negatively impact predator mite populations.
Organically Acceptable Methods
Biological control and certain oil sprays are acceptable for use on organically grown crops.
Monitoring and Treatment Decisions
Brown mites are best controlled by the delayed-dormant spray. Sample for these mites as part of the dormant spur sample. If more than 20% of spurs are infested, an application of oil is suggested. Occasionally there is an infestation during a cool spring when dormant treatments were inadequate—either they were applied too early in dormancy, the rate of oil used was not adequate, or it was not applied.
UC IPM Pest Management Guidelines:
Insects and Mites
F. G. Zalom, Entomology, UC Davis