Whitefly are a common pest, but those that affect outdoor crops such as cabbages, rhododendrons and even viburnum are not the same species as those annoying clouds of ghostly flies that waft around the greenhouse.
In the garden
The most commonly affected plants outdoors are leafy members of the cabbage family such as cabbage, kale, sprouts and broccoli. Heavy infestations can be controlled with an insecticide which is approved for use on edible plants such as Resolva Bug Killer.
Give your plants a helping hand and keep them in good health. Avoid overfeeding them with high nitrogen fertilisers that will encourage soft and sappy growth, which is far more susceptible to pest attack. Young cabbage plants can also be covered with horticultural fleece to keep flying insects at bay. This will provide a protected environment as the plants develop.
Glasshouse whitefly poses a different problem. Over the years this pest has evolved to develop resistance to some chemical controls.
Tomatoes and cucumbers are a favourite delicacy of the greenhouse whitefly (Trialeurodes vaporariorum) but they also attack many other greenhouse plants including Gerbera, Fuchsias, Pelargoniums and Begonias. The whitefly lay their eggs in batches on the underside of plant leaves and these hatch into larvae a week later. These then develop into immobile scale-like nymphs that suck plant sap, until they become adult whitefly.
Control greenhouse whitefly with an integrated approach. First identify whitefly as the pest that is present. Hang yellow sticky traps and the growing tips of your plants to catch passing bugs, these will give a clear indication of what flying pests are present. Act as soon as they are seen. Use Resolva Bug Killer to treat all signs of whitefly before the population gets a hold. This product can be used on edibles, roses and flowers in gardens and greenhouses.
Greenhouse whitefly can also be deterred using Tagetes (marigold) plants. Grow these in close proximity to your tomatoes and cucumbers to reduce pest infestations.
Always read the label. Use pesticides safely.