Cell Membrane Disruptors
WSSA Group Numbers
14 and 22
Where Used
Cropland, residential areas, and roadsides.
Common Active Ingredients
Group 14: saflufenacil and sulfentrazone; Group 22: paraquat and diquat
Effect On Plant
These herbicides destroy cell membranes which leads to the breakdown of cells. The two groups disrupt cell membranes and move in the plant differently, so symptoms are distinct. Group 22 herbicides are highly toxic, destroy cells on contact, and are therefore not translocated. Group 14 herbicides are translocated within the plant in the xylem and affect older leaves.'
Injury Symptoms
Photosystem I electron diverters (Group 22): Injury appears within hours. Where the
herbicide contacts leaves, water-soaked spots appear followed by browning and necrotic
spots or blotches (Figure 20).
PPO Inhibitors (Group 14): Symptoms of injury usually occur first in developed leaves.
Symptoms appear as white necrotic areas on leaves (Figure 21) but then turn reddish
brown and necrotic. Often the symptoms appear on leaf tips.