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My plants are covered in white fluff PDF Print E-mail

Cryptolaemus Ladybird Mealybug are a group of small, sap sucking insect pests that attack a wide range of garden plants, especially house plants and plants grown in shade houses, igloos and glasshouses. Their soft bodies are 1-3mm long and can be grey, pink or yellow and are usually covered with white, waxy, water-repellent powder and encircled by a fringe of white, waxy hairs.

Mealybug breed in warm conditions, mostly during spring and summer. They are slow moving and large infestations can be mistaken for a white mould. Infestations spoil the appearance of plants and fruit, cause foliage to wilt and/ or become distorted, weakening their hosts. Mealybug excrete excess sugars harvested from sap and this sticky substance falls on and adheres to leaves below, encouraging sooty mould.

Infestations often begin hidden deep inside growing points and can be difficult to detect in dense bromeliads and prickly succulents. Common garden ant species will transfer mealybug to healthy plants to farm them, harvesting the sugar-rich honeydew.

Cultural controls:

There are 400 known species of Ladybirds in Australia. Many are voracious mealybug predators at all stages of their lives. Juvenile ladybirds of some species superficially resemble mealybug and woolly aphid, but are more active and less numerous. You can learn to identify them by observing them feeding. They take time to locate and control mealbug numbers.

Supporting strategies include:

  • feeding plants with a low nitrogen ‘flower and fruit’ fertiliser to prevent the production of soft, sappy growth;
  • regular removal of dead and dying foliage which can harbour mealybug;

Other controls:

Control is rarely completely effective and mealybug have become resistant to many pesticides.

  • If one plant in a collection is infested with mealybug it may be easier to dispose of that specimen in the compost heap than trying to eradicate mealybug and risk it spreading to other plants;
  • Control small infestations by hand using a cotton bud dipped in either soapy water or an emulsion made of equal parts of methylated spirits and water. Dab mealybug individually;
  • Control large infestations by spraying once with a horticultural oil. Ensure sprays saturate both sides of foliage, stems and any bark fissures. Control is most effective during the spring and summer breeding season.
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