Mite infestation in roses

Two-Spotted Mite

The two-spotted spider mite (Tetranychus urticae) originated from Europe and lives in temperate and subtropical climates. They are oval shaped and can be brown, orange-red, green, green-yellow or translucent in color. Female two-spotted mites turn orange or orange-red in color if they are overwintering in greenhouses. The body of the two-spotted spider mite has two large dark spots near the back end. These dark spots are transparent areas of the mite's body where body waste accumulates. Mites that have recently molted may lack the two spots directly after molting has occurred.

Pacific Spider Mite

The web-spinning Pacific spider mite ( Tetranychus pacificus) lives in the San Joaquin Valley and along the northern coast of California. They can be light amber to green in color and have red forelegs. When entering diapause (a period of rest where they do not grow) or when they are living together with a high concentration of other spider mites, the female adult Pacific spider mite turns orange to red in color. After feeding, two large spots appear at the front and two small spots appear near the end of the mite's body.

Strawberry Mite

The strawberry mite (Phytonemus pallidus), also called the cyclamen mite, lives on the mid-vein of young leaves and under the calyx of flower buds. Strawberry mites are very small, with the adult mite being an average length of 0.01 inch in size, which makes them not readily visible without a magnifying glass or microscope. Strawberry mites are a shiny pale pink-orange color. Female strawberry spider mites have whip-like hind legs. Male strawberry spider mites have grasping pincers.

Signs of Mites

Two-spotted spider mites live on the underside of leaves, where they leave webbing and molted skins. They feed on the leaves, which turns the leave tissue white in a bleached stippled pattern. Leaves that are eaten by mites soon turn gray or yellow and then black or dark brown as they die off. Roses infested by spider mites will have brown withering petals. Signs of Pacific spider mites are yellow spots on leaves, which turn into black dead areas. When there is a high population of the mites, leaves appear sunburned or scorched and will be covered with spun webbing. The microscopic strawberry mite damages leaves and causes them to crinkle and grow stunted. This causes a compact leaf mass to form at the center of the rose bush.

Mite Infestation Control

Mites overwinter in pokeweed, Jimson weed, wild blackberry bushes, Jerusalem oak and wild geraniums. Removal of these plants will reduce their numbers. Irrigate the soil frequently to reduce the presence of dust on the rose leaves. Misting the leaves with a spray water bottle will also help to reduce mite numbers, as they prefer to consume dry leaves. Insecticidal oils or soaps that kill mites aren't very toxic to people or other organisms and are safe to use. Another option is to encourage natural predators to feed on rose mites to eliminate them.

Natural Predators

According to the University of Florida Phytoseiulus persimilis is a predatory mite that consumes rose mites in all life stages, from eggs to adult. This predatory mite is more active than plant mites and can consume five adult mites or 20 eggs per day, which significantly reduces the mite population without the use of insecticides. Phytoseiulus persimilis mites are orange or red in color have longer front legs that face forward. Other natural predators of rose mites include lady bugs, minute pirate bugs (Orius insidiosus), lacewing fly larvae and the black predatory thrip (Leptothrips mali).

Source: Homeguides
Photo by Rafael romero on Unsplash

Source: Homeguides