Whiteflies can often be seen around the vegie patch on brassicas including kale, broccoli and cauliflower or eggplants and tomatoes. They also like herbs, fruit and ornamental plants. They are often described as looking like flying dandruff around a leaf. White or pale in colour, they are not flies but sap-sucking insects related to aphids, scale insects and mealybugs. They are about 1.5 mm long (adult) and have four delicate wings.
There are more than 100 species, most of them being introduced to Australia. Adults and their nymphs (young) feed on the sap of plants. You will usually find them congregating on the undersides of leaves which results in yellow spots on the upper leaves. They produce large amounts of sweet, sticky honeydew, which has the added problem of producing sooty mould and attracting ants run up and down the stems. Sooty mould can affect the photosynthesis of a plant causing it to lose leaves and retarding growth.
Prevention is the best way to curb whitefly from taking over the garden. Whiteflies are one of the hardest pests to detect because they are not usually noticed until the development of sooty mould and the infestation has caused serious damage. Control starts by removing weeds as they are the perfect location for whiteflies to breed. Also remove and destroy older plant leaves that are infested with whiteflies. Natural enemies include lacewings and ladybirds.
There are a couple of natural insecticides which may help to control whitefly infestation including EarthCare White Oil insect spray and Earthcare Enviro Pest Oil insect spray. When spraying the foliage follow the directions on the back of the pack and spray both sides of the foliage. Repeat applications maybe needed for further control. Remember not to spray when beneficial insects and bees are around.
A healthy garden can also help prevent pest infestation. If your plants are strong and healthy, they may be able to handle and reduce the stress of pests and diseases. Applying Seasol regularly every two weeks during the year can help them to cope with environmental stress. Keeping plants fed with fertilisers such as PowerFeed All Purpose including Natives, better watering and appropriate light exposure can also help build tougher plants.