Many of you will recognise the clusters of 2mm long blackfly, setting up colonies that rapidly develop on fresh young shoots and leaves of vegetable and other plants during spring and summer in years gone by, but this year seems to be particularly bad for these sap sucking insects. Blackfly are similar to greenfly and there are several different species. Each species has a different host plant species, and are carried by the wind. Not all will behave as pests, so infestation can be a bit sporadic most of the time, but this year they seem to be everywhere.
Due to the apparent population boom this year, we are noticing heavier than usual infestations are quickly weakening host plants, stunting growth, and in some cases the plants wither and die. This is because blackfly feed on the sap of plants, and by doing so they take essential nutrients and water away from the plant, leaving it struggling to thrive.
You may notice some of your less well-established plants struggling, so also keep an eye out for the tell-tell signs of curled leaves and damaged flower formations as the blackfly could be hidden under leaves and flowerheads.
Usually, infestations occur in small numbers, and they do little harm, which is why we would always advise to tolerate populations wherever possible. However, this year you may need to take matters into your own hands and we encourage all gardeners and planet lovers to try to do so with as little impact to the environment as possible and use non-pesticide controls.
Reducing the environmental impact
Encouraging aphid predators into your garden such as ladybirds, ground beetles, hoverflies, parasitoid wasps, and earwigs, is always a good idea, but be aware that sometimes blackfly populations can build quickly before these natural enemies are around in sufficient numbers to act as a control.
Use a finger and thumb to squash aphid colonies where practical or, using a mixture of diluted washing up liquid with a generous pinch of chilli powder in a spray bottle, can also be an eco-friendly pest control measure. You can use it on edible plants too so you can harvest your crops for the table with little delay once the infestation has been dealt with. You can also find a range of organic pest control treatments at most garden centres.
Where clusters of blackfly have been particularly dense, you may also need to wash them away after successful treatment to avoid further damage through rotting. This is particularly important where stems grow closely together.
So, with a few simple, planet-safe tips under your belt and an eagle eye for spotting signs of damage, we hope you are able to enjoy your beans and flowers blackfly-free this year.