19.4 Herbicides that Interfere with Photosystem II

It is important to understand how the Group 5, 6 and 7 Photosystem II Inhibitors interfere with photosynthesis.   In following video clip, Dr. Namuth-Covert demonstrates an animation that shows the effect of a herbicide binding to the D1 protein and how that negatively influences Photosystem II and creates widespread cellular damage.

When the D₁ protein is unable to function, the excited electron cannot be passed along the transport chain and the energy from the photon cannot be dissipated into chemical energy.  This will lead to formation of radicals like triplet chlorophyll and eventually lipids are broken down, which destroys membranes.  These short time-lapse video clips from Ohio State University’s Weed Science specialists show what these effects look like in susceptible plants.

Groups 5, 6, 7 – Photosystem II Inhibitors