Agriculture: Almond Pest Management Guidelines

Brown Mite

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.

Eggs of the in-season generations are laid on the undersides of leaves near prominent leaf veins. 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 two to three generations per year between February and June.

Damage

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.

Management

Monitor for brown mite as part of the dormant spur sample and spray with dormant oil if required.

Biological Control

The western predatory mite and brown lacewing are both effective predators, but alone may not control brown mites. 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 harm predator mites.

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 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 containing oil were not applied, when they were applied too early in dormancy, or were applied with a rate of oil that was too low. In this case, a spring oil spray can be applied if there is evidence of feeding damage (bronzing or stipling of the leaves) at this time of year.

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) 4–6 gal See label 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: Cover all parts of the tree. Oil alone will control low to moderate infestations. Do not apply oils to water-stressed trees. Check with certifier to determine which products are organically acceptable.
 
SPRING
 
A. NARROW RANGE OIL#
  (Omni Supreme) 2–4% See label 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: Be sure that trees are well-watered to avoid phytotoxicity. Works by contact activity only, so good coverage is essential. Check with certifier to determine which products are organically acceptable.
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.
# Acceptable for use on organically grown produce.
Text Updated: 08/17
Treatment Table Updated: 08/17