Garden Pests Series: W…

…is for Whiteflies.

The Garden Pests Series is reaching its conclusion! But luckily, the letter ‘W’ isn’t the last in the Latin alphabet so there’s still some more educational fun to have! In this edition, the featured garden pest is the whitefly, a common – there are over 1,400 species all over the world, 56 of which are found in Europe – and detrimental enemy of the valiant gardener. The information provided for you here by Oakleigh Manor has been aided by an online archive from the BBC website. Therefore, without further ado, read on to find out more about them and what you can do if they are currently residing in your garden and no doubt wreaking havoc!

Whiteflies feed on the sap from a number of different garden plants; a large number of vegetables, ornamental plants and trees are known to be affected. Therefore, a whitefly infestation is a cause for concern for sustainable gardeners and ornamental gardeners alike. Two of the most common species of whitefly found in the UK are the glasshouse whitefly (Trialeurodes vaporariorum) and the cabbage whitefly (Aleyrodes proletella). As both names suggest, the former typically affects plants grown indoors (within greenhouses and conservatories) and the latter affects only cabbages and other members of the Brassica genus.

Despite being small, these moth-like creatures are relatively easy to identify. You may see them fly away in tandem when you move or water your garden plants. Alternatively, you may have also noticed some other indications of their presence, yellowing leaves, honeydew deposits much like aphids and/or a sooty mould on leaves. Either way, when you know your garden has a whitefly infestation, it is important to deal with it immediately, as they multiple incredibly quickly; females can lay up to 200 eggs apiece on the underside of leaves. In addition, the knowledge that it takes only three to four weeks for a whitefly egg to develop into a larvae and then to an adult should only exacerbate the situation.

Without any measures of control implemented against a whitefly infestation, plants, as mentioned, will discolour to a yellowish colour along with suffering with stunted growth. Plants will also die due to the actions of whiteflies. Luckily, there are control methods available, including chemical means. If you choose to use chemicals, please rmember to always read the label and take the necessary precautions when handling potential irritants. However, organically, you can:

• Thoroughly inspect plants every day, with focus on any new growth;
• Remove and destroy any leaves with whitefly larval scales;
• Cover greenhouse vents with netting and/or fleeces;
• Utilise yellow sticky traps to capture whiteflies in the greenhouse; and,
• Buy the commercially-available wasp Encarcia formosa that will kill those in the greenhouse.

These have been proven effective, proof of which is widely available online and, I’m sure, from other gardeners in-the-know! However, it is important that once control is implemented a prevention strategy or two is also introduced. Try these on for size:

• Deal with whitefly infestation indications as soon as they appear;
• Hang yellow sticky traps among greenhouse and conservatory plants;
• Weeds often host whitefly, so be wary of any that are situated near susceptible plants;
• Encourage natural enemies, such as spiders and the ladybird;
• Avoid broad spectrum insecticides, as these will also kill natural predators to the whitefly;
• Destroy leaves with any infestation of larvae – do not just simply discard them; and finally,
• Ol’ Reliable! Encourage insectivorous birds to your garden with feeders and nesting boxes during the Winter and the Spring respectively.

Photo credit: <a href=”https://www.flickr.com/photos/gails_pictures/13541287375/”>gailhampshire</a> / <a href=”http://foter.com/explore/”>Foter</a> / <a href=”http://creativecommons.org/licenses/by/2.0/”>CC BY</a>