Whitefly are sap suckers of plants and can consume huge amounts . Much of this sap contains sugar and is excreted back onto plants as honeydew, which sooty moulds can grow on. Plant growth can be stunted or slowed down when whitefly is present in large numbers and leaves can wilt or drop. Produce such as Tomatoes can also be soiled with sticky deposits. Whitefly can also transmit plant viruses from plant to plant. The most common species to attack indoor grown plants is the glasshouse whitefly [ Trialeurodes vaporariorum ]. There is also another species of whitefly that can be found on outdoor produce such as Cabbage called Brassica whitefly [ Aleyrodes prolletella ].
How to control Whitefly
First monitor for whitefly with yellow sticky traps, if growing indoors.
Biological control of whitefly in greenhouses and indoor plantings is best acheived with a tiny parasitic wasp called ; Encarsia formosa. This requires warm temperatures to be fully active. Once temperatures are high enough; Encarsia formosa provides an efficient form of biological control. It should also be introduced on a regular basis to keep control of whitefly populations. Whitefly Killer Encarsia formosa can now be supplied as a choice of programmes, giving regular introductions or purchased as an individual one off delivery.
Encarsia formosa is not suitable for the control of brassica whitefly or glasshouse whitefly in cooler conditions, which may occur earlier in the year in un-heated glasshouses. For cooler conditions or for Brassica whitefly control outdoors; introduce the predatory mite; Amblyseius andersoni, which will feed on the whitefly eggs. This is now available as Whitefly Killer Andersoni. If conditions are not suitable for the use of predators or parasites; spot treat with a non-toxic product like SB Plant Invigorator.