greenhouse pest
Fighting whiteflies: How to protect your plants from infestation
Whiteflies are pests that prefer to attack greenhouse vegetables
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They prefer warm and sheltered places such as greenhouses or closed balconies: once whiteflies spread, vegetable or ornamental plants are particularly at risk. To protect your crops, you must act quickly.
Due to their white wings, the pests are at least visually reminiscent of flies (hence the name), but they belong to the whitefly. There are almost 1,500 different species, of which two in particular target vegetable plants and balcony flowers in this country: the greenhouse whitefly and the cotton whitefly. Annual tomatoes and cucumbers, peppers and courgettes are on their menu – as well as ornamental plants such as primroses, geraniums and rhododendrons. To stop the rapid multiplication, you should fight whiteflies. Read on to find out which methods are particularly effective and which indications speak for an infestation.
Characteristics: This is how you recognize whiteflies
Whiteflies are only a few millimeters in size and have milky-white wings covered with wax dust. This is to protect the insects from moisture. The pests use their little legs to jump, for example when they touch an infested plant and the animals flee to another plant. A female is able to lay up to 400 eggs in just four weeks (insects don’t live that long). Only a few days after being laid, the long, oval eggs change colour: from white-yellow to brown-black. About a week later, the first larvae begin to hatch and suck out and weaken the host plant. If the rapid reproduction of whiteflies is not stopped immediately, the leaves can die off or the growth of vegetables and ornamental plants can be disrupted.
What are the indications of a plant infestation?
To find out if one or more plants from white flies are infested, you have to inspect the underside of the leaves more closely: If you find millimeter-small, long and oval eggs (usually white, yellowish or green in colour) – which have been laid in a circle – or larvae, the pest has already multiplied. Another indication is the fine, white wax dust that the pests carry on their wings and thus spread on the parts of the plant or the potting soil. The excretions of the white fly, also called honeydew, speak at least as clearly for an infestation: a kind of sticky film. Since both the insects and their offspring harm the plant, yellow spots spread over the leaves over time. In the worst case, the pests transmit viruses that promote fungal infestation (sooty mildew).
And another tip:
If you shake the plant, you can watch the whiteflies jumping around. In that case, the evidence is clear – even if you haven’t found any eggs or larvae on the undersides of the leaves.
Fight whiteflies: the best (home) remedies
The pests prefer warm places, as they cannot withstand sub-zero temperatures for long. For this reason, hardy balcony plants are less endangered. However, since most vegetables are sown in spring and only harvested in summer or autumn, whiteflies have an easy time of it. To keep the insects out of your greenhouse or to combat an initial infestation, you can use the following (home) remedies:
yellow boards
So-called glue traps have a magical attraction for many pests such as fungus gnats, thrips – or even whiteflies. The yellow color attracts adult insects, but not their larvae. It is important that you yellow sticker Only use in closed greenhouses, otherwise other animals such as bees or ladybugs will stick to it and die.
parasitic wasps
Another way to fight whiteflies is the targeted use of parasitic wasps. The millimeter-small insects place their larvae in the eggs of the plant pests, so that new parasitic wasps hatch and no whiteflies. If there are no more eggs for the biological pest controller to parasitize, the parasitic wasps automatically disappear.
spray
There is insecticides against whiteflies, which must be sprayed on the infested areas in the early morning or late evening hours. If you would prefer to use a natural spray, you can also make it yourself: for example with tea tree oil, more precisely ten drops in one liter of water plus one drop of washing-up liquid. Alternatively, you can also use rapeseed oil (1:3 ratio) and a drop of washing-up liquid.
And one last tip:
Whiteflies also have natural enemies such as parasitic wasps, which you can attract with certain plants such as cornflowers, marigolds or wild herbs. In addition, certain herbs have a repellent effect on the pests, for example basil or thyme – a natural spray can also be made from them (as a brew).
Sources: my beautiful garden, garden journal,Utopia
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