The Science Behind Alcohol as a Herbicide

Rubbing alcohol, typically isopropyl alcohol (IPA) with concentrations of 70% or 91%, works as a contact herbicide through a process of rapid desiccation and cellular disruption. Unlike systemic herbicides that are absorbed and translocated throughout the plant, alcohol's action is immediate and localized.

1. Mechanism of Action

When sprayed directly onto foliage, the high concentration of alcohol quickly dissolves the protective waxy cuticle on leaves and stems. This breach allows the alcohol to penetrate plant cells and dehydrate them by drawing out essential moisture. Furthermore, it denatures (breaks down) the proteins within the plant cells, causing immediate damage to the cellular structure. The effect is often visible within hours as the treated foliage wilts, turns brown, and desiccates.

2. Why It's Non-Selective

This mode of action does not discriminate between weed and desirable plant cells. Any green tissue contacted by the spray will suffer the same fate, making precise application paramount. It is ineffective on roots since it is not translocated, meaning perennial weeds may regrow from untouched root systems.

3. Advantages of This Approach

The primary advantages are speed and accessibility. It acts faster than many vinegar-based solutions and utilizes a product found in most medicine cabinets. It leaves no long-term residue in soil, as alcohol evaporates completely and quickly after application.