Whitefly

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If you give your plant a quick shake and lots of tiny white flies burst into flight then without a doubt you have an infestation of whitefly.

Whiteflies are tiny pests that feed by piercing and sucking sap from a plant, causing the leaves to go yellow and mottled. The adults look like small moths approximately 2-3mm long and are covered with a fine white powdery wax – hence their name. They are usually found on the underside of the leaf clustered together with a mess of eggs and wingless juveniles called nymphs. Both adults and nymphs secrete lots of waste called honeydew which attracts ants and causes sooty mould to grow.

A female whitefly lays around 200 eggs. When they hatch nymphs move about for a few days but then settle into one position where they remain until eventually turning into winged adults. Sometimes these nymphs are mistaken for scale.

There are several different types including greenhouse, silverleaf, ash and spiralling whitefly. They vary slightly in size and colour (some are pale green or yellowish) but all have similar habits of clustering on the underside of leaves and sucking sap.

Adult whitefly with pale yellow eggs

Adult whitefly with pale yellow eggs

Whitefly outbreaks cause plants to lose vigour, drop leaves and even fruit loss if the infestation is heavy.  Sooty mould develops which again reduces vigour by blocking sunlight to the foliage.  Whitefly can also transmit many viruses which harm plants further.

Plants Attacked

Whitefly attack a fairly broad range of plants including fruits and vegetables (eg tomatoes, beans, citrus, eggplants and others), soft leaf ornamentals, ferns, azaleas and roses. They are particularly troublesome in the veggie patch where numbers can explode and greatly impact on plant growth and yields.

Organic Control Method for Whitefly

  • Release Gracey  (green lacewing)  and the juveniles will feed on whitefly nymphs along with other pests like aphids. Works best before whitefly populations get out of hand.
  • Apply eco-oil when whitefly first appear. Apply two sprays 3 days apart and repeat applications if whiteflies reappear. Spray both upper and underside of leaves to run-off. It is very important to do the two sprays close together to break their life cycle.
  • Apply eco-neem when they first appear and reapply every 7 days if required. Again aim for good coverage on both sides of the leaves.

Some people have good success using companion planting to deter whitefly eg basil next to tomato plants. Another useful thing is to attract predatory insects by planting a range of flowering plants eg daisies, alyssum and herbs.