If you see clusters of tiny black aphids on the tops of your broad bean plants at this time of year, you’re probably looking at a blackfly infestation.
What does blackfly look like?
Clusters of black dot-like aphids, measuring no more than 2mm.
Where do they hide?
Blackfly usually choose the softer part at the top of a broad bean plant. They are usually quite easy to spot.
How can I prevent an infestation?
Once your broad bean plants reach a couple of foot tall and begin flowering, you can pinch out the growing tips (the very tip of the plant) to help prevent infestations forming. We’d also recommend planting some companions to try and entice ladybirds and other natural predators of aphids to your plot.
How do I deal with a blackfly infestation?
Ue secateurs to cut off the infestation which will most likely be at the top of the plant, and remove the infested foliage. You can bury the infested shoot in your compost pile/bin and the blackfly will not be able to survive there. The plant should then bounce back it as long as it is kept well watered and healthy. A liquid feed is a good idea to give the plant a nutritional boost.