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| Red Spider mite |
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These small mites are serious pests of plants grown in greenhouses and in the home.
Sometimes they also attack shrubs and herbaceous plants outdoors.Fuchsias, chrysanthemums, roses, vines, aubergines, tomatoes and cucumbers grown in the greenhouse are particularly susceptible.
The adult and immature mites feed and breed on the undersides of leaves, causing a fine light mottling of the upper surfaces.
In severe infestations, this leads to extensive yellowing and bronzing, followed by leaf fall.
The withering leaves are often covered with fine silk webbing.
The mites cease breeding in the autumn, and female mites over-winter in crevices in brickwork and woodwork, in bamboo canes, stakes and plant ties.
Reduce the numbers of over-wintering female mites by clearing out plant debris and by eliminating over-wintering sites in late autumn and early winter.
In the greenhouse, regular fumigation will prevent serious increases in mite populations
Plants grown at high temperatures in dry, overcrowded conditions are often particularly susceptible to mite infestations regular spraying of infested plants with water may help to check the pests.
Thorough spraying with a suitable pesticide, will protect plants under glass and outdoors.
The mites are likely to develop resistance to a given chemical if it is used too regularly, and control measures should be varied as much as possible.
Pesticides approved for use by amateur gardeners against red spider are limited to organic pesticides such as rotenone (derris), fatty acids (soft soaps) and vegetable oils.
The last two work by blocking the mites' breathing tubes, preventing respiration
The use of the biological control, i.e. the use of predatory mites, is proving to be quite a successful and is now widely used in preference to pesticides.
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