Re: can pesticides diffuse through the plant cell wall and membrane?

Hi Leow,

The cell wall of plants is typically very porous, allowing various molecules to diffuse freely through it. The cell membrane is much more likely to be an impediment.

Whether or not a pesticide can diffuse through the cell membrane will depend on the size and composition of the pesticide. In other words, it depends on the pesticide. In general, the smaller the molecule, the more likely it is to diffuse across a membrane. Hydrophobic molecules can diffuse across easily. Small uncharged polar molecules can cross, charged molecules, even small ions, cannot.

Some insecticides can diffuse through membranes for sure. Insecticides that are taken up by the roots and transported throughout the plant are called “systemic insecticides”. In order for this to occur, the insecticide must cross at least one cell membrane. Acephate and Imidacloprid are examples of systemic insecticides. These are applied to the roots, and as they spread throughout the plant, provide protection by making the fluids of the plant toxic to chewing or sucking insect pests.

Most pesticides cannot be used in this way, most likely because they cannot make it into the transport systems of the plant. This would be due in large part to their inability to diffuse through a cell membrane.

Alex Brands