With spring well underway, I’m sure you’ve come across them. Swarms of soft bodied insects swarming around and eventually ruining your young buds.
They are present in my garden too. Used to attack my roses but much less now, having implemented some preventative measures discussed below. However, they still attack my hellebores!
Here’s some insights into what aphids are and what you should consider when dealing with them.
What are aphids?
Aphids are generally small round bodied insects which are sometimes referred to as plant lice, blackfly or greenfly. They are usually 1 – 2 mm long, although some can grow larger. Different species have different colours but I’ve only seen the green species in my garden attacking both my roses and my hellebores.
Why are aphids a problem for your garden
Aphids have piercing or sucking mouthparts with which they withdraw sap from plants. They prefer soft plant material in the form of new shoots and buds. Some species feed on older leaves and they are usually found underneath them.
Given that essential water and nutrients are being sucked away by the aphids, leaves and shoots fed on by aphids may wilt and become twisted and curled. Buds fed by aphids may not open at all or may produce distorted flowers. For fruit producing plants, a loss of healthy buds means a loss of delicious fruit and we don’t want that!
Some aphids are even more sinister, they carry viruses which spread diseases from plant to plant and extend their attack to other above ground parts of the plant and root systems. The Black peach aphid (Brachycaudus persicae) is such a pest.
Although aphids generally lay eggs, some species are also capable of giving birth to living young. Therefore, large populations build up relatively quickly. When the colony increases in numbers and the shoot or bud becomes crowded, some winged forms develop and these aphids can fly to other plants or other parts of the same plant. So an infestation that starts on one plant may spread quickly throughout the garden!
Aphids also produce honeydew, a sticky substance which falls from the end of the aphid’s digestive tract on to anything beneath. This usually makes leaves and fruit sticky and provides a food supply for fungi called sooty mould which develops into a black coating over leaves, stems and fruit. Aside from being unsightly the sooty mould can block sunlight to leaves and reduce plant vigour in severe cases.
Ants and other insects are also attracted by the honeydew. Ants collect, or “milk”, honeydew directly from the aphids, which benefit from their presence due to their driving away predators such as ladybugs or parasitic wasps (refer further below).
How to identify if you have an aphid problem
Check your plants often as a matter of routine – My sincere advice to all my clients is to venture out into your garden at least once every 2 weeks to not only immerse yourselves in its beauty but to also check on whether your plants are going ok. If you can do that more often, your garden’s health will be better off as things change in your garden, quickly.
Seasonal impacts – Pay close attention during the warmer months as pests such as aphids rely on heat to multiply. The first signs of aphids usually appear in early spring when the weather starts warming up and as there’s plenty of soft food material around.
How to – Inspect the top of young buds, shoots and young leaves for signs of aphids. As an added precaution, do also inspect other parts of the same plant too to see if they are also present. You’ll be able to see them immediately as there will be many of them swarming on just that one bit of plant material. Visually inspect any neighbouring plants and see if they are showing any signs of stress. Perform the same inspection on them to see if they are infected. Even if they are not, a preventative measure would be to treat them with seasol to de-stress the plants so that the aphids don’t opportunistically attack it given that it’s in a weakened state.
Step-by-step instructions for getting rid of aphids
Go organic – You can either go the organic way and plant scented herbs such as fennel, coriander and dill or flowering plants like geraniums, marigolds, sweet alyssum and yarrows (achillea) which lure beneficial insects like ladybugs to wander in and stay in your garden but this is a long term measure. These beneficial insects and others such as parasitic wasps, beetles, hoverflies and lacewings naturally prey on aphids.
It is quite an effective method though if you’re not keen
on introducing chemicals into your garden. I’ve trialled it on my own roses and have not had an aphid infestation for many years. However, I do have a limited infestation on my hellebores which are located in another part of my garden and are quite naturally susceptible to aphid attacks in early summer anyway.
The other thing to be mindful off when applying the above method is that you may also have to bolster it with (i) hosing the plant down with water to “wash” off the aphids as best you can, (ii) plant decoy plants such as the nasturtium which aphids love to devour and (iii) having effective ant control – that is if you’ve got the presence of ants accompanying the aphids infestation. The activities of ants running up and down the plant may discourage any predatory behaviour and therefore reduce the effectiveness of the natural control outlined above.
Chemical based – The other way is to spray the affected plants with a proprietary systematic insecticide as soon as the infestation in noticed and repeat as directed by the manufacturer. A gentler approach through (and less harmful to beneficial insects) is to use a home-made spray made up of normal dish washing soap and water. You may have to repeat daily though to effectively control the infestation this way.
The systematic insecticide will harm beneficial insects such as the ladybug but the dish soap shouldn’t.
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