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Root and onion mites can be detected only by removing the plant from the ground and looking through a microscope.
These include several different types of mites, which have in common that they damage the underground parts of plants. Root mites of the genus Rhizoglyphus and bulbous mites of the genus Steneotarsonemus are more common among the root mites.
These mites harm not only bulbous plants (amaryllis, hyacinths, tulips), but also other flowers, for example, orchids, cacti. Root mites are usually very small in size from about 0.5 to 1.5 mm, with a wide oval body of light yellow, gray or brown color. Outwardly, they are in the form of a translucent ball, with tiny, hair-like legs. The eggs of the mites are broadly oval, large, whitish or gray. Usually eggs are laid in the ground, but some types of root mites make clutches near the surface of the ground - in the axils of the lower leaves, near the bulbs in orchids, in the neck of the bulbs.
Root mites gnaw out the tissues of the bulbs, laying eggs there in huge quantities - about 300 eggs from one female bulbous or root mite. At the same time, at the initial stage of the lesion, the eaten places and ticks are visible, however, gradually the ticks eat up the entire bulb. A damaged onion falls apart in the hands, all internal tissues are eaten away in it, only white dust remains, and clusters of mites can be seen with the naked eye.
Signs of onion and root mite damage are the appearance of red or brown spots on the bulbs, the formation of white dust, similar to semolina. Externally, the plants stop growing, then yellowing of the leaves begins, deformation of peduncles and leaves, sometimes corky and dry areas appear. The plant will eventually die.
Root mites actively reproduce and develop in a wide temperature range, optimally from 10 to 26 ° C and even higher, when conditions change, they do not die, but enter a state of diapause. The development of root mites is facilitated by a high humidity of 60-65%. Therefore, one of the measures to prevent the appearance of bulbous and root mites is proper storage. Tubers, bulbs, root crops are stored in a cool dry room, with a humidity not higher than 30%.
Root mite control measures
Inspect the bulbs carefully before planting. Affected bulbs and plant roots are kept in a solution of acaricide - you can use neoron, actellic, karbofos, apollo, with full immersion in the solution for 20-30 minutes. The drug Borneo (the active substance is etoxazole), a hormonal acaricide from eggs and larvae, has shown very high efficiency, but it does not work on adults, i.e. it must be combined with other acaricides.
Preparations with the active substance spiromesifen (Oberon) also help well - a very wide range of pest damage - many types of ticks, destroys all forms of the pest - eggs, larvae, adult ticks.
When buying bulbs, pay attention to the integrity - infected bulbs with spots, dry, brown areas of scales, and only with a strong infection are pressed in places under the fingers. Ticks hide under one or two top sheets of onion scales, you can make out them with a magnifying glass. Before planting, the bulbs can be soaked in a solution of acaricide for a few minutes, and then dried before planting.
Complete instructions for acaricide preparations.