Herbicide Injury Symptoms

Cell Membrane Disrupters:
Bipyridylium Herbicides

Common Herbicides in the Group:

• paraquat (Gramoxone)

• diquat

How Applied:

Foliar applied.

Movement in the Plant:

Enter the plant through leaf and green stem tissue and move little once absorbed.

Mode of Action:

These herbicides intercept the energy of the photosynthetic process and produce distructive compounds which result in membrane disruption and plant desiccation.

Common Symptoms:

Water soaked appearance followed rapidly by necrosis and desiccation of leaves and stems, may cause chlorotic spots in dilute concentration.

Effects of Bipyridylium Herbicides

These almond leaves show effects of varying exposure to paraquat. The leaves on the left were exposed to a very light drift while those on the right had complete coverage. Leaves in between were exposed to intermediate levels of the herbicide.

These bean plants were exposed to paraquat seven days earlier. Plants on the left received more spray.