Gardeners pinch out the tip of Broad Bean plants to prevent damage by
Blackfly.

This video demonstrates the process. Click How to Prevent Blackfly
from Damaging your Beans. Click on the arrow at the bottom
left of the screen to play the video.

Click here  for more information on how to prevent blackfly damaging your beans.

Blackfly -Latin name: Aphis fabae (in the family of Aphididae)

Blackfly is a serious pest of broadbeans in the kitchen garden. A whole
mass of shiny black insects cover the growing tips, flower buds and the
underside of young leaves of the broad bean plant.

Keep a sharp look out for blackfly on spring-sown beans when they are in
flower in June. One advantage of sowing broad beans in the autumn is
that they tend to flower early, producing beans in May or June, before
any blackfly appear.

Blackfly suck the sap from the broad bean plant causing stunted growth
with curled, distorted leaves, and poor crop yields.

Discourage blackfly attack by pinching out the growing tips of the broad
bean plants when they are in full flower. Some gardeners pinch out the tops of broad beans when five flowers have formed, or when the first pods have set.
Remember the pinched out tops may be cooked & eaten!

Click this link to see a video of how to pinch out the tops of broad beans.

Blackfly control:

    * wash or spray with a mild soap solution
    * encourage their natural enemies – ladybirds, hoverfly larvae,
      lacewing larvae and parasitic wasps
    * Insecticides:

Contact insecticides work when they actually touch the blackfly. They
have short persistence, so thorough treatment, especially of the
underside of leaves, is necessary. Aphids protected by curled leaves are
unlikely to be controlled.

Synthetic pesticides generally give a higher level of control. Always
read the label for instructions on the use of the product and harvest
intervals. The harvest interval is the period of time between spraying
the crop and it being safe to eat.