未有時間translate, 睇得明就睇住先啦Rhizoecus is a genus which belongs to the Pseudococcidae family. Soil mealy bug is a relative to the mealy bug. This shows the evolution of some representatives of the mealy bug which have adapted to the subterranean life conditions. There are near 130 species of Rhizoecus. The most spread species are Rhizoecus cacticans, R. falcifer Kunckel and R. Aloes. Last few years, were introduced in Europe the species of R. dianthi and R. Americanus.
These parasites prefer light, dry, aerated soils. They look like tiny white, cream or grey, oval, almost cylindrical insects, reminding small rice grains. These insects achieve 1-2 mm and sometimes cannot be seen without magnifying instruments. The most part of the insects can be observed in the soil, feeding with the fragile roots, sometimes they gather around the main stem, and go up several centimetres above the surface of the soil, the stem being covered with white fluff, the eliminations of the parasites. In this case the infestation is severe.
Symptoms
The first and most important symptom that you have soil mealy bag, are the white sediments on the plants’ roots, which looks like ash or mold. The lateral conglomerates of mildew from the soil of the pot represent the places where these parasites lay their eggs.
Infested plant has a slow growth.
Plant is rarely blooming.
Leaves are pale, yellowish or greyish, without gloss.
As the soil mealy bug feeds with tiny roots, the plant cannot insure the transportation of water and minerals to the leaves, because the roots are damaged and they do not function properly. Besides this, soil mealy bug, by biting the root introduces a substance which modifies the proper exchange of substances of the plant, and the plant weakens. By numerous injuries suffered by the root system, an untreated weakened plant will die of secondary bacterial and fungus infections.
Treatment
Isolate infested plants, especially those with common tanks from the rest of your collection.
Rhizoecus dies from insecticides like Aktara, Mospilan, Dantop, Regent. Prepare the solution and water the soil with it. Repeat this procedure 3 times each 10 days. The insecticides with contact action and on intestinal tract will be almost inefficient in fighting these parasites.
Optimara site recommends Acephate and Malathion (1 tea spoon to 4 liters of water). Repeat several times the treatment.
Another alternative to the chemical insecticides, is use of Diatomaceous Earth, this is an inert substance, which shows good results in fighting against some insects. Diatomaceous Earth is not an insecticide, but sediment which is made from skeleton remains of diatomee, a microscopically form of algae. Being transformed in Diatomaceous Earth, this skeleton remains form sharp particles as blades which damages the tiny bodies of the small insects. While destroying the insects, Dianaceous Earth is not harming African violets.
To treat African violets against these parasites, you will have to transplant in a new soil composition the plants, by adding to it Diatomaceous Earth. Use one spoon of Diatomaceous Earth to 1 liter of soil.
Prevention
Isolate all new plants which enter your collection and follow their evolution several months to ensure that they are not infested with any kind of parasites.
Pasteurize the soil before planting in it. In order to prevent infestation with Rhizoecus and other tiny insects which live in soil, add ¼ tea spoon of Diatomaceous Earth in each liter of soil. Wash, clean, disinfect the pots which you intend to reuse, instruments which you have worked with, shelves, windowsills on which the plants grow.
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