MITES IN YOUR ORCHARD AND GARDEN
COMMON NAME: Mites, Red mites, Spider Mites
SCIENTIFIC NAME: Arachnida (Order: Acarina)
DESCRIPTION: ADULTS - Teeny, tiny (1/150 to 1/50 of an inch long) with eight legs like their cousins the spiders. Ranging from reddish-brown to tan in color, they have only one body segment and no antennae or wings. EGGS - Laid on twigs, foliage, fruit, or buds and are usually covered by webbing. LARVAE - The newly hatched young have only six legs, NYMPHS - After the first molt (shedding of skin) the fourth pair of legs appear and the young mites are called nymphs.
LIFE CYCLE: Mites LOVE hot, dry weather. The females spin a silken web and lay their eggs. The larvae quickly hatch and develop into nymphs and then into adults. The adults and young alike use sharp piercing-sucking mouthparts to feed on plant buds and foliage. Some (beneficial) mites are parasitic or predaceous on other (harmful) mites, insect pests and their eggs, or on roundworms in the soil. In our area many generations of mites are produced and adults have been known to move into dwellings with the coming of the cold weather. Outside mites usually overwinter in the egg stage, but adults may pass a very mild winter in debris or underneath bark.
HOST PLANTS: Just about all garden veggies and fruit trees.
TIME OF YEAR: Spring through early winter. Worse during mid-summer.
WHAT TO LOOK FOR: Infested leaves become silvery, curl up and may turn yellow. A sure sign is a fine silky web. Blisters may form on foliage or pale yellow or white dots may appear. Fruit may be dry and rough or russeted and deformed. Fruit may drop early. Since mites are so tiny, they are extremely difficult to see on the plant. The best way to get a look at them is probably to hold a piece of white paper under the foliage and shake or tap it to make any resident pests drop onto the paper.
PROBLEMS AND DAMAGE: Damage to foliage weakens the plant and may leave openings for other pests and diseases. Damaged leaf and fruit buds may result from early sring infestations and later feeding may lead to early fruit drop or produce that is so damaged as to be inedible or unsalable.
CULTURAL CONTROLS: Misting plants discourages drought-loving mites. A winter spraying of horticultural oil will smother overwintering pests. Make sure you have good air circulation around your plants and consider planting early in the spring or later in fall to avoid the worst outbreaks. Some strains of tomatoes are advertised as being mite resistant.
COMPANION PLANTING AND REPELLENTS: None.
TRAP PLANTS: Same as host plants, pulled up and destroyed (along with the pests) before your regular crop are put in.
MECHANICAL CONTROLS: Periodic spraying with plain water goes a long way toward eliminating minor infestations. Adding a little pure soap to the water will greatly increase the pest mortality rate if your plant can handle the soap. A slurry of flour, water, and buttermilk has also been reported as effective. Diatomaceous earth can be used to dust the plant, especially the undersides.
NATURAL CONTROLS: Ladybugs (ladybird beetles), lacewings, and predatory species of mites are excellent predators and are even commercially available.
BIOLOGICAL INSECTICIDES: Insecticidal soap (such as Safers') work well and may be combined with a light horticultural oil on appropriate plants. Make sure you get the underside of the leaves. Pyrethrum or Sabadilla can be used for extensive infestations.
CHEMICAL CONTROLS: Please consult the Agricultural Extension Agent or a Master Gardener Volunteer for current recommendations (Tel. 520-458-1104 in Sierra Vista or 520-384-3594: in Willcox). Whatever you use, FOLLOW LABEL DIRECTIONS EXACTLY and take the necessary precautions to protect yourself, other humans, non-target animals, and the environment.